古川 亮(フルカワ リョウ)

工学部 情報学科教授

Last Updated :2024/07/20

■教員コメント

コメント

コンピュータビジョンとは、コンピュータでものを「見る」方法を研究する分野です。画像からモノの形を計測する基礎技術研究や、その技術の医療分野応用を進めています。

■研究者基本情報

学位

  • 博士(工学)(奈良先端科学技術大学院大学)
  • 修士(工学)(奈良先端科学技術大学院大学)

ORCID ID

0000-0002-2063-1008

研究キーワード

  • 仮想現実感   コンピュータグラフィックス   画像認識   画像処理   

現在の研究分野(キーワード)

コンピュータビジョンとは、コンピュータでものを「見る」方法を研究する分野です。画像からモノの形を計測する基礎技術研究や、その技術の医療分野応用を進めています。

研究分野

  • 情報通信 / データベース

■経歴

経歴

  • 2022年04月 - 現在  近畿大学工学部 情報学科教授
  • 2013年04月 - 2022年03月  広島市立大学情報科学部 知能工学科准教授
  • 2007年04月 - 2013年03月  広島市立大学大学院 情報科学研究科 知能工学専攻 講師
  • 1997年04月 - 2007年03月  広島市立大学 情報科学部 情報メディア工学科 助手

学歴

  •         - 1997年   奈良先端科学技術大学院大学   情報科学研究科   情報システム学専攻
  •         - 1993年   京都大学   工学部   電気工学第二科

委員歴

  • 2017年04月 - 2021年03月   情報処理学会 コンピュータビジョンとイメージメディア研究会   運営委員
  • 2009年04月 - 2013年03月   情報処理学会 コンピュータビジョンとイメージメディア研究会   運営委員
  • 2005年04月 - 2006年03月   情報処理推進機構 未踏ソフトウエア創造事業 16年度上半期「3Dファクスの開発」に共同開発者として参加. 情報処理推進機構 未踏ソフトウエア創造事業16年度上半期「3Dファクスの開発」 共同開発者   情報処理推進機構 未踏ソフトウエア創造事業 16年度上半期「3Dファクスの開発」に共同開発者として参加. 情報処理推進機構 未踏ソフトウエア創造事業16年度上半期「3Dファクスの開発」 共同開発者
  • 電子情報通信学会   正員
  • 情報処理学会   正会員

■研究活動情報

受賞

  • 2017年09月 KUKA Best Paper Award MICCAI 2017 3rd Place
  • 2017年08月 MIRUフロンティア賞
  • 2017年03月 IEEE Winter Conference on Applications of Computer Vision, Best Paper Honorable Mention
     international_society
  • 2016年04月 生体医工学 平成27年度日本生体医工学会論文賞・阪本賞
     グリッドアクティブステレオを用いた三次元消化器内視鏡におけるキャリブレーション手法 official_journal 
    受賞者: 青木広宙;古川 亮;西谷 維心;青山 正人;日浦 慎作;小南 陽子;松尾 泰治;吉田 成人;田中 信治;佐川 立昌;川崎 洋
  • 2015年10月 Miccai International Workshop on Computer-Assisted and Robotic Endoscopy (CARE) Best paper award - runner up.
     international_society 
    受賞者: Marco Visentini-Scarzanella;Tatsuya Hanayama;Ryunosuke Masutani;Shigeto Yoshida;Yoko Kominami;Yoji Sanomura;Shinji Tanaka;Ryo Furukawa;Hiroshi Kawasaki
  • 2014年10月 IEVC2014, Gold prize Best Paper Award)
     international_society 
    受賞者: Tatsuya Hanayama;Shota Kiyota;Ryo Furukawa;Hiroshi Kawasaki
  • 2014年07月 MIRU優秀論文賞
     japan_society 
    受賞者: Hitoshi Masuyama;Hiroshi Kawasaki;Furukawa Ryo
  • 2014年 情報処理学会 山下記念研究賞
     "プロジェクタ・カメラシステムによるワンショット計測に最適なモノクロパターンに関する検討" japan_society 
    受賞者: 森永寛紀;川崎洋;益山仁;小野智司;古川亮
  • 2012年 IPSJ IPSJ Transactions on CVA Outstanding Paper Award
     
    受賞者: Ryo Furukawa;Ryusuke Sagawa;Hiroshi Kawasaki;Kazuhiro Sakashita;Yasushi Yagi;Naoki Asada
  • 2011年07月 画像の認識・理解シンポジウム(Meeting on Image Recognition and Understanding, MIRU 2011) MIRU長尾賞
     平行線投影を用いた連続領域の検出による高密度なワンショット形状復元
  • 2010年11月 The 4th Pacific-Rim Symposium on Image and Video Technology (PSIVT 2010) The Best Paper Award
  • 2009年12月 電気学会優秀論文発表賞A
     デブルーイン系列とBelief-Propagationを用いた高密度ラインパターン検出による高速動体の 3次元計測手法 japan_society 
    受賞者: 佐川 立昌;大田雄也;古川 亮;川崎 洋;八木康史
  • 2007年11月 8th Asian Conference on Computer Vision (ACCV2007) Three Best Papers:Songde Ma Outstanding Paper Award
  • 2007年08月 第10回 画像の認識・理解シンポジウム(MIRU2007) インタラクティブセッション優秀賞
  • 2005年07月 MIRU2005 画像の認識・理解シンポジウム,インタラクティブセッション優秀賞

論文

  • Ryo Furukawa; Elvis Chen; Ryusuke Sagawa; Shiro Oka; Hiroshi Kawasaki
    Healthcare Technology Letters 2024年04月
  • Takeshi Masuda; Ryusuke Sagawa; Ryo Furukawa; Hiroshi Kawasaki
    Healthcare Technology Letters 2023年12月 [査読有り]
     
    Abstract Reconstructing 3D shapes from images are becoming popular, but such methods usually estimate relative depth maps with ambiguous scales. A method for reconstructing a scale‐preserving 3D shape from monocular endoscope image sequences through training an absolute depth prediction network is proposed. First, a dataset of synchronized sequences of RGB images and depth maps is created using an endoscope simulator. Then, a supervised depth prediction network is trained that estimates a depth map from a RGB image minimizing the loss compared to the ground‐truth depth map. The predicted depth map sequence is aligned to reconstruct a 3D shape. Finally, the proposed method is applied to a real endoscope image sequence.
  • Hiroto Harada; Michihiro Mikamo; Ryo Furukawa 0001; Ryusuke Sagawa; Hiroshi Kawasaki
    MVA 1 - 5 2023年
  • Ryo Furukawa 0001; Ryusuke Sagawa; Shiro Oka; Shinji Tanaka; Hiroshi Kawasaki
    EMBC 1 - 5 2023年
  • Ryo Furukawa; Michihiro Mikamo; Ryusuke Sagawa; Yuki Okamoto; Shiro Oka; Shinji Tanaka; Hiroshi Kawasaki
    Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization 1 - 9 2022年12月 [査読有り]
  • Ryusuke Sagawa; Yusuke Higuchi; Ryo Furukawa; Hiroshi Kawasaki
    Journal of Robotics and Mechatronics 34 5 1024 - 1032 2022年10月 [査読有り]
     
    The acquisition of micro-vibrations is important for analyzing machinery. In the present study, we propose a method for measuring and visualizing the three-dimensional (3D) displacements of such micro-vibrations, especially in the case of sound waves propagating through space. The proposed method uses the speckle patterns of coherent light to measure the minute displacements. Speckle patterns are useful for detecting extremely small displacements owing to their sensitivity to the pose of the object. However, it is impossible to measure the displacement at each position because the pattern changes nonlinearly with respect to large depth changes. Therefore, a method of nonlinear low-dimensional embedding of the speckle pattern is proposed to analyze the displacements and extended to measure micro-displacements in a 3D space. We divided the 3D space into multiple slices and synchronously captured each speckle pattern. The displacements in the entire 3D space were simultaneously recovered by optimizing the embedded vectors, which were consistent in a 3D lattice. The propagation of sound waves in the 3D space was visualized using the volume-rendering technique. The experiments confirmed that the proposed method correctly measured the displacements by comparing them with the ground truth captured by microphones. We also visualized the wavefront of the sound wave propagating through space.
  • Michihiro Mikamo; Ryo Furukawa; Shiro Oka; Takahiro Kotachi; Yuki Okamoto; Shinji Tanaka; Ryusuke Sagawa; Hiroshi Kawasaki
    2022 44th Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) 2022年07月 [査読有り]
  • Yi Tang; Takafumi Iwaguchi; Hiroshi Kawasaki; Ryusuke Sagawa; Ryo Furukawa 0001
    Computer Vision - ACCV 2022 - 16th Asian Conference on Computer Vision 120 - 137 2022年
  • Ryo Furukawa; Michihiro Mikamo; Ryusuke Sagawa; Hiroshi Kawasaki
    2022 IEEE/CVF Winter Conference on Applications of Computer Vision (WACV) 2022年01月 [査読有り]
  • Ryo Furukawa
    Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization 1 - 9 2022年 [査読有り]
  • Michihiro Mikamo; Ryo Furukawa; Shiro Oka; Takahiro Kotachi; Yuki Okamoto; Shinji Tanaka; Ryusuke Sagawa; Hiroshi Kawasaki
    2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) 2021年11月 [査読有り]
  • Michihiro Mikamo; Ryo Furukawa; Hiroshi Kawasaki
    2021 IEEE International Conference on Image Processing (ICIP) 2021年09月 [査読有り]
  • Michihiro Mikamo; Hiroshi Kawasaki; Ryusuke Sagawa; Ryo Furukawa
    IW-FCV 2021: Frontiers of Computer Vision 253 - 266 2021年 [査読有り]
  • Ryusuke Sagawa; Yusuke Higuchi; Hiroshi Kawasaki; Ryo Furukawa; Takahiro Ito
    Asian Conference on Computer Vision 700 - 715 2021年 [査読有り]
  • Ryo Furukawa; Shiro Oka; Takahiro Kotachi; Yuki Okamoto; Shinji Tanaka; Ryusuke Sagawa; Hiroshi Kawasaki
    2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) 2020年07月 [査読有り]
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    63 - 87 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    289 - 303 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    157 - 181 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    183 - 209 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    213 - 239 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    241 - 262 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    263 - 287 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    31 - 62 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    89 - 103 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    107 - 123 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    125 - 155 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    3 - 29 2020年
  • Katsushi Ikeuchi; Yasuyuki Matsushita; Ryusuke Sagawa; Hiroshi Kawasaki; Yasuhiro Mukaigawa; Ryo Furukawa; Daisuke Miyazaki
    2020年
  • Ryo Furukawa
    Healthcare Technology Letters 6 6 249 - 254 2019年12月 [査読有り]
  • Ryo Furukawa
    PROCEEDINGS OF FOURTH INTERNATIONAL CONFERENCE ON 3D VISION (3DV) 2019年09月 [査読有り]
  • Yuki Shiba; Satoshi Ono; Ryo Furukawa; Shinsaku Hiura; Hiroshi Kawasaki
    IPSJ Transactions on Computer Vision and Applications 11 6 2019年07月 [査読有り]
  • CNN based dense underwater 3D scene reconstruction by transfer learning using bubble database
    Kazuto Ichimaru; Ryo Furukawa; Hiroshi Kawasaki
    1543 - 1552 2019年01月 [査読有り]
  • Ryo Furukawa
    PROCEEDINGS OF MVA INTERNATIONAL CONFERENCE ON MACHINE VISION APPLICATIONS (MVA) 1 - 6 2019年 [査読有り]
  • Ryo Furukawa; Masaki Mizomori; Shinsaku Hiura; Shiro Oka; Shinji Tanaka; Hiroshi Kawasaki
    Computer Assisted Robotic Endoscopy: MICCAI 2018 workshop 139 - 150 2018年09月 [査読有り]
  • Ryo Furukawa
    PROCEEDINGS OF FOURTH INTERNATIONAL CONFERENCE ON 3D VISION (3DV) 2018年09月 [査読有り]
  • Marco Visentini-Scarzanella; Hiroshi Kawasaki; Ryo Furukawa; Marco Bonino; Simone Arolfo; Giacomo Lo Secco; Alberto Arezzo; Arianna Menciassi; Paolo Dario; Gastone Ciuti
    Endoscopy International Open 06 05 E602 - E609 2018年05月 
    Abstract Background and study aims Polyp size measurement is an important diagnostic step during gastrointestinal endoscopy, and is mainly performed by visual inspection. However, lack of depth perception and objective reference points are acknowledged factors contributing to measurement errors in polyp size. In this paper, we describe the proof-of-concept of a polyp measurement device based on structured light technology for future endoscopes. Patients and methods Measurement accuracy, time, user confidence, and satisfaction were evaluated for polyp size assessment by (a) visual inspection, (b) open biopsy forceps of known size, (c) ruled snare, and (d) structured light probe, for a total of 392 independent polyp measurements in ex vivo porcine stomachs. Results Visual assessment resulted in a median estimation error of 2.2 mm, IQR = 2.6 mm. The proposed probe can reduce the error to 1.5 mm, IQR = 1.67 mm (P = 0.002, 95 %CI) and its performance was found to be statistically similar to using forceps for reference (P = 0.81, 95 %CI) or ruled snare (P = 0.99, 95 %CI), while not occluding the tool channel. Timing performance with the probe was measured to be on average 54.75 seconds per polyp. This was significantly slower than visual assessment (20.7 seconds per polyp, P = 0.005, 95 %CI) but not significantly different from using a snare (68.5 seconds per polyp, P = 0.73, 95 %CI). However, the probe’s timing performance was partly due to lens cleaning problems in our preliminary design. Reported average satisfaction on a 0 – 10 range was highest for the proposed probe (7.92), visual assessment (7.01), and reference forceps (7.82), while significantly lower for snare users with a score of 4.42 (P = 0.035, 95 %CI). Conclusions The common practice of visual assessment of polyp size was found to be significantly less accurate than tool-based assessment, but easy to carry out. The proposed technology offers an accuracy on par with using a reference tool or ruled snare with the same satisfaction levels of visual assessment and without occluding the tool channel. Further study will improve the design to reduce the operating time by integrating the probe within the scope tip.
  • アクティブステレオ法による3次元内視鏡のためのHDR画像生成と投光器位置の自己校正
    古川 亮; 内藤 雅仁; 溝森 将輝; 宮崎 大輔; 馬場 雅志; 日浦 慎作; 佐野村 洋次; 田中 信治; 川崎 洋
    電子情報通信学会誌 和文D J101-D 8 1150 - 1164 2018年04月 [査読有り]
  • Ryo Furukawa
    Lecture Notes in Computer Science 222 - 236 2018年 [査読有り]
  • Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki
    2017 IEEE International Conference on Computer Vision (ICCV) 2017年10月 [査読有り]
  • Yuki Shiba; Satoshi Ono; Ryo Furukawa; Shinsaku Hiura; Hiroshi Kawasaki
    2017 IEEE International Conference on Computer Vision (ICCV) 2017年10月 [査読有り]
  • Reproducibility Analysis of Case-Based Reasoning and Evolutionary Computation Method for Surface Reflectance Parameters Estimation
    Albane Robert; Yuki Matsugano; Michihiro Mikamo; Satoshi Ono; Hiroshi Kawasaki; Hisato Fukuda; Ryo Furukawa
    The 20th Meeting on Image Recognition and Understanding 1 - 4 2017年08月 [査読有り]
  • Ryusuke Sagawa; Ryo Furukawa; Akiko Matsumoto; Hiroshi Kawasaki
    2017 IEEE International Conference on Robotics and Automation (ICRA) 2017年05月 [査読有り]
  • Daisuke Miyazaki; Takuya Shigetomi; Masashi Baba; Ryo Furukawa; Shinsaku Hiura; Naoki Asada
    OPTICAL ENGINEERING 56 4 041303 - 041303 2017年04月 [査読有り]
     
    Polarization is a phenomenon that cannot be observed by the human eye, but it provides rich information regarding scenes. The proposed method estimates the surface normal of black specular objects through polarization analysis of reflected light. A unique surface normal cannot be determined from a polarization image observed from a single viewpoint; thus, we observe the object from multiple viewpoints. To analyze the polarization state of the reflected light at the corresponding points when observed from multiple viewpoints, the abstract shape is predetermined using a space carving technique. Unlike a conventional photometric stereo or multiview stereo, which cannot estimate the shape of a black specular object, the proposed method estimates the surface normal and three-dimensional coordinates of black specular objects via polarization analysis and space carving. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
  • HDR Image Synthesis Technique for Active Stereo 3D Endoscope System
    Ryo Furukawa; Masahito Naito; Daisuke Miyazaki; Masashi Baba; Shinsaku Hiura; Hiroshi Kawasaki
    Engineering in Medicine and Biology Society (EMBC) 2017年 [査読有り]
  • Hiroshi Kawasaki; Hideaki Nakai; Hirohisa Baba; Ryusuke Sagawa; Ryo Furukawa
    2017 IEEE WINTER CONFERENCE ON APPLICATIONS OF COMPUTER VISION (WACV 2017) 302 - 310 2017年 [査読有り]
     
    Underwater 3D shape scanning technique becomes popular because of several rising research topics, such as map making of submarine topography for autonomous underwater vehicle (UAV), shape measurement of live fish, motion capture of swimming human, etc. Structured light systems (SLS) based active 3D scanning systems are widely used in the air and also promising to apply underwater environment. When SLS is used in the air, the stereo correspondences can be efficiently retrieved by epipolar constraint. However, in the underwater environment, the camera and projector are usually set in special housings and refraction occurs at the interfaces between water/glass and glass/air, resulting in invalid conditions for epipolar constraint which severely deteriorates the correspondence search process. In this paper, we propose an efficient technique to calibrate the underwater SLS systems as well as robust 3D shape acquisition technique. In order to avoid the calculation complexity, we approximate the system with central projection model. Although such an approximation produces an inevitable errors in the system, such errors are diminished by a combination of grid based SLS technique and a bundle adjustment algorithm. We tested our method with a real underwater SLS, consisting of custom-made laser pattern projector and underwater housings, showing the validity of our method.
  • Ryo Furukawa
    Lecture Notes in Computer Science 16 - 28 2017年 [査読有り]
  • Takuto Hirukawa; Marco Visentini-Scarzanella; Hiroshi Kawasaki; Ryo Furukawa; Shinsaku Hiura
    Computer Vision – ACCV 2016 10114 440 - 455 2016年11月 [査読有り]
     
    We propose a new system to visualize depth-dependent patterns and images on solid objects with complex geometry using multiple projectors. The system, despite consisting of conventional passive LCD projectors, is able to project different images and patterns depending on the spatial location of the object. The technique is based on the simple principle that multiple patterns projected from multiple projectors interfere constructively with each other when their patterns are projected on the same object. Previous techniques based on the same principle can only achieve (1) low resolution volume colorization or (2) high resolution images but only on a limited number of flat planes. In this paper, we discretize a 3D object into a number of 3D points so that high resolution images can be projected onto the complex shapes. We also propose a dynamic ranges expansion technique as well as an efficient optimization procedure based on epipolar constraints. Such technique can be used to the extend projection mapping to have spatial dependency, which is desirable for practical applications. We also demonstrate the system potential as a visual instructor for object placement and assembling. Experiments prove the effectiveness of our method.
  • Ryo Furukawa
    Journal of Imaging Science and Technology 60 6 60502 - 1 2016年11月 [査読有り]
  • Ryo Furukawa; Yoji Sanomura; Shinji Tanaka; Shigeto Yoshida; Ryusuke Sagawa; Marco Visentini-Scarzanella; Hiroshi Kawasaki
    2016 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) 2016年08月 [査読有り]
  • プロジェクタ用符号化開口と階層的復元を用いたDepth from Defocus
    堀田 祐樹; 芝 優希; 小野 智司; 古川 亮; 日浦 慎作; 川崎洋
    電子情報通信学会論文誌D J99-D 5 559 - 570 2016年05月 [査読有り]
  • 河本悠; 日浦慎作; 宮崎大輔; 古川亮; 馬場 雅志
    情報処理学会論文誌 57 2 783 - 793 情報処理学会 2016年02月 [査読有り]
     
    非合焦画像からぼけを取り除くために符号化開口が有効であることが知られている.しかし,その開口形状の設計に関する研究は十分に行われていない.そこで本論文では実用的な設計法とその詳細な実装を示すことを目的とし,特に最適化に用いる遺伝的アルゴリズムの性能を大きく左右する交叉法の比較と評価を行う.また,ぼけ除去画像を認識に用いる場合,その画像の良し悪しは画質(視覚的品質)ではなくその後の認識率により評価されるべきである.そこで本論文では,PSNRを基準とした画質評価と,その画像を認識した際の認識率との関係を示す.Although coded aperture is known as an efficient technique to remove the optical blur from the defocused image, studies on designing the shape of the aperture have not been well explored yet. Therefore in this paper, we will show a practical method with detailed implementation of the optimization of the coded apertures. Especially, crossover process which strongly affects to the performance of genetic algorithm is intensively evaluated and compared with the other methods. In the context of object recognition, the performance of the deblurring should be evaluated by not the visual quality but the resultant recognition rates. Therefore we will show the relationships between PSNR-based image quality criterion and actual recognition rates through experiment.
  • Hiroshi Kawasaki; Takuto Hirukawa; Ryo Furukawa
    2016 23RD INTERNATIONAL CONFERENCE ON PATTERN RECOGNITION (ICPR) 1743 - 1749 2016年 [査読有り]
     
    One-shot active stereo using structured light is a practical solution for dynamic scene acquisition. Basically, those methods are based on encoding positional information of the pixel into the single projected pattern. A disadvantage of such methods is decreases of the spatial resolution caused by requiring a certain area of the pattern to encode the positional information. Among those methods, grid-based patterns are promising at the point of accuracy and robustness, since triangulation for 3D reconstruction is conducted with light-sectioning method and a line detection is usually a stable image processing. However, no shapes are recovered between the grid lines, and thus, the whole reconstructed shape tends to be sparse. To deal with the problem, integrating multiple shapes that are sequentially captured using registration algorithm such as ICP is one solution. In previous work, we show that naive ICP works poorly for grid-like structured point clouds, and proposed a specialized ICP algorithm for aligning a set of grid-like structured 3D shapes. In this paper, we extend this approach and propose a process for entire shape modeling by capturing objects from all the directions using turn table, and integrating into a single shape using our improved ICP. To achieve this, setting good initial 3D shapes is important. For solution, we interpolation grid shapes to create smooth surface so that common ICP works. Comprehensive experiments are conducted to show the strength of our method compared to common ICP.
  • Ryusuke Sagawa; Yuki Shiba; Takuto Hirukawa; Satoshi Ono; Hiroshi Kawasaki; Ryo Furukawa
    2016 23RD INTERNATIONAL CONFERENCE ON PATTERN RECOGNITION (ICPR) 234 - 239 2016年 [査読有り]
     
    Active one-shot scanning techniques have been widely used for various applications. Stereo-based active oneshot scanning embeds a positional information regarding the image plane of a projector onto a projected pattern to retrieve correspondences entirely from a captured image. Many combinations of patterns and decoding algorithms for active one-shot scanning have been proposed. If the capturing environment lacks the assumed conditions, such as the absence of strong external lights, then reconstruction using those methods is degraded, because the pattern decoding fails. In this paper, we propose a general reconstruction algorithm that can be used for any kind of patterns without strict assumptions. The technique is based on an efficient feature extraction function that can drastically reduce redundant information from the raw pixel values of patches of captured images. Shapes are reconstructed by efficiently finding correspondences between a captured image and the pattern using low-dimensional feature vectors. Such a function is created automatically by a convolutional neural network using a large database of pattern images that are efficiently synthesized by using GPU with wide variation of depth and surface orientation. Experimental results show that our technique can be used for several existing patterns without any ad hoc algorithm or information regarding the scene or the sensor.
  • Marco Visentini-Scarzanella; Takuto Hirukawa; Hiroshi Kawasaki; Ryo Furukawa; Shinsaku Hiura
    IMAGE AND VIDEO TECHNOLOGY - PSIVT 2015 WORKSHOPS 9555 113 - 126 2016年 [査読有り]
     
    We propose a new projection system to visualise different independent images simultaneously on planes placed at different depths within a volume using multiple projectors. This is currently not possible with traditional systems, and we achieve it by projecting interference patterns rather than simple images. The main research issue is therefore to determine how to compute a distributed interference pattern that would recombine into multiple target images when projected by the different projectors. In this paper, we show that while the problem is not solvable exactly, good approximations can be obtained through optimization techniques. We also propose a practical calibration framework and validate our method by showing the technique in action with a prototype system. The system opens up significant new possibilities to extend projection mapping techniques to dynamic environments for artistic purposes, as well as visual assessment of distances.
  • Michihiro Mikamo; Yoshinori Oki; Marco Visentini-Scarzanella; Hiroshi Kawasaki; Ryo Furukawa; Ryusuke Sagawa
    IMAGE AND VIDEO TECHNOLOGY, PSIVT 2015 9431 582 - 593 2016年 [査読有り]
     
    In this paper, we propose a novel approach to reconstruct triangle meshes from point sets by taking the silhouette of the target object into consideration. Recently, many approaches have been proposed for complete 3D reconstruction of moving objects. For example, motion capture techniques are used to acquire 3D data of human motion. However, it needs to attach markers onto the joints, which results in limiting the capturing environments and the number of data that can be acquired. In contrast, to obtain dense data of 3D object, multi-view stereo scanning system is one of the powerful methods. It utilize images taken by several directions and enables to reconstruct 3D dense point sets by using Epipolar geometry. However, it is still challenging problem to reconstruct 3D triangle mesh from the 3D point sets due to the abundant points originated by mismatched points between images. We propose a novel approach to obtain more accurate triangle mesh reconstruction method than the previous one. We take advantage of silhouette images acquired in the process of reconstructing 3D point sets that result in removing noises and compensating holes. Finally, we demonstrate that the proposed method can generate the details of the surface, where the previous method loses from a small number of points.
  • Hiroki Morinaga; Hirohisa Baba; Marco Visentini-Scarzanella; Hiroshi Kawasaki; Ryo Furukawa; Ryusuke Sagawa
    Image and Video Technology 9431 404 - 418 2016年 [査読有り]
     
    Structured Light Systems (SLS) are widely used for various purposes. Recently, a strong demand to apply SLS to underwater applications has emerged. When SLS is used in an air medium, the stereo correspondence problem can be solved efficiently by epipolar geometry due to the co-planarity of the 3D point and its corresponding 2D points on camera/projector planes. However, in underwater environments, the camera and projector are usually set in special housings and refraction occurs at the interfaces between water/glass and glass/air, resulting in invalid conditions for epipolar geometry which strongly affect the correspondence search process. In this paper, we tackle the problem of underwater 3D shape acquisition with SLS. In this paper, we propose a method to perform 3D reconstruction by calibrating the system as if they are in the air at multiple depth. Since refraction cannot be completely described by a polynomial approximation of distortion model, grid based SLS method solve the problem. Finally, we propose a bundle adjustment method to refine the final result. We tested our method with an underwater SLS prototype, consisting of custom-made diffractive optical element (DOE) laser and underwater housings, showing the validity of the proposed approach.
  • Marco Visentini-Scarzanella; Tatsuya Hanayama; Ryunosuke Masutani; Shigeto Yoshida; Yoko Kominami; Yoji Sanomura; Shinji Tanaka; Ryo Furukawa; Hiroshi Kawasaki
    Computer-Assisted and Robotic Endoscopy 9515 46 - 58 2016年 [査読有り]
     
    In situ 3D reconstruction from endoscopic images is important to determine the correct course of action for, e.g., treatment of abnormal growths. Currently, the endoscopist has to rely solely on visual cues in order to infer the growth’s shape and size and determine an appropriate treatment. However, tissue uniformity and scale ambiguity from traditional monocular endoscopes make this visual assessment prone to errors and time consuming. We propose a practical system to densely reconstruct both shape and size of tissues with minimal modifications to a standard endoscope. We present a custom single-fiber structured light probe projecting a wave pattern on the tissue surface that allows semidense reconstruction with few ambiguities. Based on the coarse reconstruction, we retrieve the surface reflectance parameters according to a hybrid diffuse/specular model which are used to initialise a close-range Photometric Stereo reconstruction. By taking into account the tissue characteristics and the light fall-off, our Photometric Stereo formulation provides dense metric 3D shape information without the need for surface normal integration. A preliminary study was carried out both on phantoms and ex vivo samples of human tissue.
  • Ryo Furukawa
    Lecture Notes in Computer Science 399 - 415 2016年 [査読有り]
  • Simulation of Real Tilted Lenses Using Distributed Ray Tracing
    Masashi Baba; Tomoe Nakane; Shinsaku Hiura; Ryo Furukawa; Daisuke Miyazaki; Masahito Aoyama
    IIEEJ Transactions on Image Electronics and Visual Computing 3 2 143 - 148 The Institute of Image Electronics Engineers of Japan 2015年12月 [査読有り]
  • Hiroshi Kawasaki; Shota Kiyota; Tatsuya Hanayama; Michihiro Mikamo; Ryo Furukawa
    画像電子学会英文誌 3 2 92 - 100 The Institute of Image Electronics Engineers of Japan 2015年12月 [査読有り]
  • 宮崎大輔; 實重貴文; 馬場雅志; 古川亮; 青山正人; 日浦慎作
    画像電子学会論文誌 44 4 649 - 654 画像電子学会 2015年09月 [査読有り]
     
    メタメリズムとはある光源下では2つの物体が異なる色として知覚されるが別の光源下では同じ色として知覚される現象である.本研究では,メタメリズムを利用したトリックアートの作成手法を提案する.与えられた光源下でメタメリズムが生起する条件を満たす油絵の具を提案手法によって計算する.本研究では,トリックアート作成のために与えられた光源下でメタリズムが生起する条件を満たす油絵の具の混合比率の計算法を提案する.実験では,2光源・4物体色の間で生起されるメタメリズムについて計算を行った.これにより擬似的な陰影を表現することができ,二次元の絵画が三次元の物体として知覚されるトリックアートを実現することができた.
  • Ryo Furukawa; Ryunosuke Masutani; Daisuke Miyazaki; Masashi Baba; Shinsaku Hiura; Marco Visentini-Scarzanella; Hiroki Morinaga; Hiroshi Kawasaki; Ryusuke Sagawa
    2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) 2015年08月 [査読有り]
  • Daisuke Miyazaki; Takafumi Saneshige; Masashi Baba; Ryo Furukawa; Masahito Aoyama; Shinsaku Hiura
    2015 14th IAPR International Conference on Machine Vision Applications (MVA) 2015年05月 [査読有り]
  • Yoshinori Oki; Marco Visentini-Scarzanella; Tomohito Wada; Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki
    2015 14th IAPR International Conference on Machine Vision Applications (MVA) 2015年05月 [査読有り]
  • Mixing oil paints for perception of shading illusions
    Daisuke Miyazaki; Takafumi Saneshige; Masashi Baba; Ryo Furukawa; Masahito Aoyama; Shinsaku Hiura
    Journal of the Institute of Image Electronics Engineers of Japan 44 4 649 - 654 2015年 
    Metamerism is a phenomenon where two objects recognized as having different colors under one light are also recognized as having the same color under another light. This short paper proposes a method that automatically calculates the blending ratios of oil paints satisfying the condition to occur metamerism under the specific light sources for actualizing artistic illusion. It entails metamerism occurring between four types of object colors under two types of light sources. This enables us to create false shading where the observer recognizes the 2D oil painting as if it is a 3D object with plausible shading.
  • Shota Eguchi; Yuki Matsugano; Hirokazu Sakaguchi; Satoshi Ono; Hisato Fukuda; Ryo Furukawa; Hiroshi Kawasaki
    International Conference on Learning and Intelligent Optimization; Lecture Notes in Computer Science 131 - 136 2015年 [査読有り]
  • Hiroshi Kawasaki; Satoshi Ono; Yuki Horita; Yuki Shiba; Ryo Furukawa; Shinsaku Hiura
    2015 IEEE INTERNATIONAL CONFERENCE ON COMPUTER VISION (ICCV) 3568 - 3576 2015年 [査読有り]
     
    The central projection model commonly used to model cameras as well as projectors, results in similar advantages and disadvantages in both types of system. Considering the case of active stereo systems using a projector and camera setup, a central projection model creates several problems; among them, narrow depth range and necessity of wide baseline are crucial. In the paper, we solve the problems by introducing a light field projector, which can project a depth-dependent pattern. The light field projector is realized by attaching a coded aperture with a high frequency mask in front of the lens of the video projector, which also projects a high frequency pattern. Because the light field projector cannot be approximated by a thin lens model and a precise calibration method is not established yet, an image-based approach is proposed to apply a stereo technique to the system. Although image-based techniques usually require a large database and often imply heavy computational costs, we propose a hierarchical approach and a feature-based search for solution. In the experiments, it is confirmed that our method can accurately recover the dense shape of curved and textured objects for a wide range of depths from a single captured image.
  • Ryusuke Sagawa; Ryo Furukawa; Hiroshi Kawasaki
    IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 36 9 1733 - 1747 2014年09月 [査読有り]
     
    Dense 3D reconstruction of fast moving objects could contribute to various applications such as body structure analysis, accident avoidance, and so on. In this paper, we propose a technique based on a one-shot scanning method, which reconstructs 3D shapes for each frame of a high frame-rate video capturing the scenes projected by a static pattern. To avoid instability of image processing, we restrict the number of colors used in the pattern to less than two. The proposed technique comprises (1) an efficient algorithm to eliminate ambiguity of projected parallel-line patterns by using intersection points, (2) a batch reconstruction algorithm of multiple frames by using spatio-temporal constraints, and (3) an efficient detection method of color-encoded grid pattern based on de Bruijn sequence. In the experiments, the line detection algorithm worked effectively and the dense reconstruction algorithm produces accurate and robust results. We also show the improved results by using temporal constraints. Finally, the dense reconstructions of fast moving objects in a high frame-rate video are presented.
  • Ryo Furukawa; Masahito Aoyama; Shinsaku Hiura; Hirooki Aoki; Yoko Kominami; Yoji Sanomura; Shigeto Yoshida; Shinji Tanaka; Ryusuke Sagawa; Hiroshi Kawasaki
    2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society 2014年08月 [査読有り]
  • 青木広宙; 古川亮; 西谷維心; 青山正人; 日浦慎作; 小南陽子; 松尾泰治; 吉田成人; 田中信治; 佐川立昌; 川崎洋
    生体医工学 52 2 97 - 107 2014年04月 [査読有り]
  • 青木 広宙; 古川 亮; 佐川 立昌; 川崎 洋; 鈴木 敦; 志賀 剛
    精密工学会誌 80 12 1109 - 1114 公益社団法人 精密工学会 2014年 [査読有り]
     
    We propose a method to observe cardiac beat from 3-D shape reconstruction by using the grid-based active stereo. In this study, we report preliminary experiments to evaluate validities of the proposed method. As the result of comparing experiments by our method and electrocardiogram (ECG), we confirm sufficient correspondences between the two peak intervals. Our method realizes the separate extraction of cardiac beat and respiratory movement. We try the visualization of cardiac beat by using the color mapping of the depth displacement plotted on the 3-D surface rendering of chest. And, the depth change and the spatial phase difference caused by cardiac pulsation is found on the chest region.
  • Ryusuke Sagawa; Yoshio Matsumoto; Hiroshi Kawasaki; Ryo Furukawa
    2014 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND BIOMIMETICS IEEE-ROBIO 2014 1976 - 1982 2014年 [査読有り]
     
    In this paper, we propose a method of parallel processing of one-shot structured-light system to realize online 3D reconstruction of moving objects. The proposed method is based on a projector-camera system that reconstructs a shape from a single image where a static pattern is cast by a projector; such a method is ideal for acquisition of moving objects at a high frame rate. The structured-light pattern is a grid pattern that consists of sinusoidal wave lines of vertical and horizontal directions. Since the intersection points of wave lines are used as feature points and the lines give the connectivity of the intersections, the correspondence between camera image and projected pattern can be found by the energy minimization of the graph. The energy minimization is accomplished by belief propagation. We propose a method to improve the computational time for online 3D reconstruction by GPU-based parallel processing for the steps of the structured-light system. In the experiment, we show the proposed method realizes online 3D reconstruction.
  • Marcos Slomp; Hiroshi Kawasaki; Ryo Furukawa; Ryusuke Sagawa
    2014 2ND INTERNATIONAL CONFERENCE ON 3D VISION, VOL. 2 49 - 56 2014年 [査読有り]
     
    Range-based scanners built upon multiple cameras and projectors offer affordable, entire-shape and high-speed setups for 3D scanning. The point cloud streams produced by these devices require large amounts of storage space. Compressing these datasets is challenging since the capturing process may result in noise and surface irregularities, and consecutive frames can differ substantially in the overall point distribution. Exploiting spatial and temporal coherency is difficult on such conditions, but nonetheless crucial for achieving decent compression rates. This paper introduces a novel data structure, the temporal sparse voxel octree, capable of grouping spatio-temporal coherency of multiple point cloud streams into a single voxel hierarchy. In the data structure, a bitmask is attached to each node; existing nodes can then be reused at different frames by manipulating their bitmasks, providing substantial memory savings. Although the technique yields some losses, the amount of loss can be controlled.
  • Ryusuke Sagawa; Nozomu Kasuya; Yoshio Matsumoto; Yoshinori Oki; Hiroshi Kawasaki; Ryo Furukawa
    2014 2ND INTERNATIONAL CONFERENCE ON 3D VISION, VOL. 2 14 - 21 2014年 [査読有り]
     
    In this paper, we propose a method with multiple cameras and projectors for 4D capture of moving objects. The issues of previous 4D capture systems are that the number of cameras are limited, and the number of images is very large to capture the sequence at high frame rate. We propose a multiple projector-camera system to tackle this problem. One of the issues of multi-view stereo is to determine visibility of cameras for each point of the surface. While estimating the scene geometry and its visibility is a chicken-and-egg problem for passive multi-view stereo, it was solved by, for example, iterative approach conducting the estimation of visibility and the reconstruction of the scene geometry repeatedly. With our method, since visibility problem is independently solved by using the projected pattern, shapes are recovered efficiently without considering visibility problem. Further, the visibility information is not only used for multi-view stereo reconstruction, but also for merging 3D shapes to eliminate inconsistency between devices. The efficiency of the proposed method is tested in the experiments, proving the merged mesh is suitable for 4D reconstruction.
  • 宮崎大輔; 高橋可菜実; 馬場雅志; 青木広宙; 古川亮; 青山正人; 日浦慎作
    電子情報通信学会論文誌D J97-D 8 1250 - 1262 電子情報通信学会 2014年 [査読有り]
  • Ryo Furukawa
    Lecture Notes in Computer Science 242 - 253 2014年 [査読有り]
  • Hitoshi Masuyama; Hiroshi Kawasaki; Ryo Furukawa
    IPSJ Transactions on Computer Vision and Applications 6 88 - 92 2014年 [査読有り]
  • Hiroshi Kawasaki; Hitoshi Masuyama; Ryusuke Sagawa; Ryo Furukawa
    IET COMPUTER VISION 7 5 293 - 301 2013年10月 [査読有り]
     
    In this study, the authors propose a new technique to achieve one-shot scan using single colour and static pattern projector; such a method is ideal for acquisition of moving objects. Since projector-camera systems generally have uncertainties on retrieving correspondences between the captured image and the projected pattern, many solutions have been proposed. Especially for one-shot scan, which means that only a single image is required for shape reconstruction, positional information of a pixel of the projected pattern should be encoded by spatial and/or colour information. Although colour information is frequently used for encoding, it is severely affected by texture and material of the object and leads unstable reconstruction. In this study, the authors propose a technique to solve the problem by using geometrically unique pattern only with black and white colour that further considers the shape distortion by surface orientation of the shape. The authors technique successfully acquires high-precision one-shot scan with an actual system.
  • Hirooki Aoki; Ryo Furukawa; Masahito Aoyama; Shinsaku Hiura; Naoki Asada; Ryusuke Sagawa; Hiroshi Kawasaki; Shinji Tanaka; Shigeto Yoshida; Yoji Sanomura
    2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) 2013年07月 [査読有り]
  • Optimization of 3D Shape Sharpening Filter Based onGeometric Statistical Values
    Masanari Yokomizo; Daisuke Miyazaki; Masashi Baba; Ryo Furukawa; Masahito Aoyama; Shinsaku Hiura; Naoki Asada
    International Conference on Machine Vision Applications 260 - 263 2013年05月 [査読有り]
  • High density shapes using photometric stereo and laser range sensor under unknown light-source direction
    Tomoyuki Kamikawa; Daisuke Miyazaki; Masashi Baba; Ryo Furukawa; Masahito Aoyama; Shinsaku Hiura; Naoki Asada
    Proceedings of the 13th IAPR International Conference on Machine Vision Applications, MVA 2013 125 - 128 2013年 
    Much research is in progress on the acquisition of high-density three-dimensional shapes by acquiring and combining shape data and normal data. The method proposed in this paper estimates normals to object surfaces by employing the photometric stereo method and combines the estimation with the three-dimensional shape acquired by a laser range sensor. Although the photometric stereo method presumes that light-source directions for each image are known, the proposed method uses its light-source direction estimates. By linearizing the images as preprocessing, specular reflection and shadow effects within the image are removed and the precision for the light-source direction estimations is increased. Since the proposed method does not require the light-source directions to be known, it offers the advantage of broad applicability for measurement work.
  • Calibration of the projector with fixed pattern and large distortion lens in a structured light system
    Xingdou Fu; Zuofu Wang; Hiroshi Kawasaki; Ryusuke Sagawa; Ryo Furukawa
    Proceedings of the 13th IAPR International Conference on Machine Vision Applications, MVA 2013 222 - 225 2013年 
    The most critical factor affects accuracy of a Structured Light System (SLS) is calibration. Camera calibration is easy to complete because of its extensive study. To simplify projector calibration, previous wor models the projector as an inverse camera and tries to build similar 3D-2D mapping data for projector calibration. Achieved mapping data is directly fed to some classic two-step camera calibration methods. When projector comes with a large distortion lens, this kind of methods will fail because their first steps use closed-form solution to calculate initial guess for optimization in next steps. We proposed a new method to calibrate the projector by removing its distortion first. Because projector cannot “see” anything, not like camera case, constraints such as “straight lines remain straight” working just on 2D image is invalid for distortion estimation. With 3D-2D mapping data, the estimation will involve several extra unknowns into a non-linear optimization. We use partial mapping data whose 2D points in a “small central area” of projector pattern image to acquire an initial guess for those unknowns, and then use all mapping data to refine them and estimate distortion parameters. Experiments show our method can still calibrate the projector when classic methods fail.
  • Exemplar based texture recovery technique for active one shot scan
    Thibault Yohan; Kawasaki Hiroshi; Furukawa Ryo; Sagawa Ryusuke
    Proceedings of the 13th IAPR International Conference on Machine Vision Applications, MVA 2013 331 - 334 2013年 
    Range scanners based on camera-projector configurations have been attracting the attention of many researchers and computer vision practitioners due to its ability of performing 3D scanning with high accuracy and frame rates. This class of scanners is more effective under dark capturing environments by projecting bright colored patterns on objects. As a consequence, the projected pattern is prone to interfere with the reflectance and texture characteristics of the surfaces of the objects. This paper introduces a novel technique for recovering texture information from objects obfuscated by projected patterns. To that end, prior to 3D scanning our method acquires a small amount of pairs of images of the object with and without the projected pattern. These pairs of images are then used to build a dictionary that establishes a relationship between the actual textures and the projected patterns. Following that, 3D scanning is performed normally using a camera-projector setup, and the video frames captured by the camera are matched against the dictionary to filter candidates that resemble the original textures. Regularization is applied on the potential set of candidates to cull out poorly detected one, resulting in smooth texture-aware images.
  • Nozomu Kasuya; Ryusuke Sagawa; Ryo Furukawa; Hiroshi Kawasaki
    Proceedings of the IEEE International Conference on Computer Vision 299 - 306 2013年 [査読有り]
     
    This paper proposes a method to reconstruct the entire shape of moving objects by using multiple cameras and projectors. The projectors simultaneously cast static grid patterns of wave lines. Each of the projected patterns is a single-colored pattern of either red, green, or blue. Those patterns can be decomposed stably, compared to multi-colored patterns. For the 3D reconstruction algorithm, one shot reconstruction with wave grid pattern is extended for entire-shape acquisition, so that the correspondences between the adjacent devices can be used as additional constraints to reduce shape errors. Finally, multiple shapes obtained from the different views are merged into a single polygon mesh model using estimated normal information for each vertex. © 2013 IEEE.
  • Daisuke Miyazaki; Daisuke Akiyama; Masashi Baba; Ryo Furukawa; Shinsaku Hiura; Naoki Asada
    Proceedings of the IEEE International Conference on Computer Vision 852 - 859 2013年 [査読有り]
     
    We propose a polarization-based method to enhance the visibility of an image by canceling the haze effect. Haze is a natural phenomenon that degrades the visibility of a scene. Aerosols in air reflect sunlight and cause polarization. Therefore, we analyze the polarization state of the observed light to remove the haze effect from a captured image. Our approach is to use two reference objects that are known a priori in estimating the parameters of the haze effect. Once the parameters are known, we can improve the image so that the scene is clearly visible. We also present an experimental result using a commercial polarization camera, which can obtain the polarization state of the scene. © 2013 IEEE.
  • Yasuhiro Akagi; Ryo Furukawa; Ryusuke Sagawa; Koichi Ogawara; Hiroshi Kawasaki
    Special Interest Group on Computer Graphics and Interactive Techniques Conference 79 - 79 2013年 [査読有り]
  • Daisuke Miyazaki; Kanami Takahashi; Masashi Baba; Hirooki Aoki; Ryo Furukawa; Masahito Aoyama; Shinsaku Hiura
    2013 IEEE INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW) 874 - 882 2013年 [査読有り]
     
    Metamerism is a phenomenon where two objects recognized as having different colors under one light are also recognized as having the same color under another light. This research proposes technology for actualizing artistic illusion that exploits metamerism. Specifically, the purpose of the research relates to automatic calculation of blending ratios of oil paints that cause metamerism to occur under specific light sources. We entails metamerism occurring between three types of object colors under two types of light sources. Also, we utilize plausible reflection model for the mixture of oil paints.
  • Yasuhiro Akagi; Ryo Furukawa; Ryusuke Sagawa; Koichi Ogawara; Hiroshi Kawasaki
    WSCG 2013, COMMUNICATION PAPERS PROCEEDINGS 21 E73 137 - 144 2013年 [査読有り]
     
    Facial animation is one of the most important contents in 3D CG animations. By the development of scanning and tracking methods of a facial motion, a face model which consists of more than 100,000 points can be used for the animations. To edit the facial animations, key point based approaches such as "face rigging" are still useful ways. Even if a facial tracking method gives us all point-to-point correspondences, a detection method of a suitable set of key points is needed for content creators. Then, we propose a method to detect the key points which efficiently represent motions of a face. We optimize the key points for a Radial Basis Function (RBF) based 3D deformation technique. The RBF based deformation is a common technique to represent a movement of 3D objects in CG animations. Since the key point based approaches usually deform objects by interpolating movements of the key points, these approaches cause errors between the deformed shapes and the original ones. To minimize the errors, we propose a method which automatically inserts additional key points by detecting the area where the error is larger than the surrounding area. Finally, by utilizing the suitable set of key points, the proposed method creates a motion of a face which are transferred form another motion of a face.
  • Nozomu Kasuya; Ryusuke Sagawa; Ryo Furukawa; Hiroshi Kawasaki
    2013 INTERNATIONAL CONFERENCE ON 3D VISION (3DV 2013) 247 - 254 2013年 [査読有り]
     
    In this paper, we propose an active 3D reconstruction method with two cameras and one projector (2C1P) system for capturing moving objects. The system reconstructs the shapes from a single frame of each camera by finding the correspondence between the cameras and the projector based on projecting wave grid pattern. The projected pattern gives the constraint of correspondence between the two cameras in addition to between a projector and a camera. The proposed method finds correspondence by energy minimization on graphs constructed by detecting a grid pattern in camera images. Since the graphs of two cameras are connected as a single graph by using the constraint between cameras, the proposed method simultaneously finds the correspondences for two cameras, which contributes to the robustness of correspondence search. By merging range images created by the correspondence of each camera, we reduce the occluded area compared to the case of one camera. Finally, the proposed method optimizes the shape as three-view stereo to improve the accuracy of shape measurements. In the experiment, we show the effectiveness of using two cameras by making comparison with the case of one camera.
  • Ismael Daribo; Hideo Saito; Ryo Furukawa; Shinsaku Hiura; Naoki Asada
    3D-TV System with Depth-Image-Based Rendering 277 - 298 2013年 [招待有り]
  • Ismael Daribo; Hideo Saito; Ismael Daribo; Ryo Furukawa; Shinsaku Hiura; Naoki Asada
    3D-TV System with Depth-Image-Based Rendering 169 - 189 2013年 [招待有り]
  • Yasuhiro Akagi; Ryo Furukawa; Ryusuke Sagawa; Koichi Ogawara; Hiroshi Kawasaki
    Journal of WSCG 21 2 137 - 144 2013年 [査読有り]
  • Hirooki Aoki; Ryo Furukawa; Masahito Aoyama; Shinsaku Hiura; Naoki Asada; Ryusuke Sagawa; Hiroshi Kawasaki; Tsuyoshi Shiga; Atsushi Suzuki
    2013 35TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC) 1756 - 1759 2013年 [査読有り]
     
    We propose a method to observe cardiac beat from 3D shape information of body surface by using the active stereo with waved-grid pattern projection, and report preliminary experiments to evaluate validities of the proposed method. By comparing results of our method with those of electrocardiogram (ECG), we confirmed sufficient correspondences between peak intervals of depth changes between contiguous frames measured by the active stereo and R-R intervals measured by ECG. We proposed the visualization of the spatial distribution of depth change plotted on the 3D shape of chest surface. We confirm that the spatial phase difference, which is caused by heart pump ability, appears in the 3-D shape change of chest surface.
  • 赤木 康宏; 古川 亮; 佐川 立昌; 小川 原光一; 川崎 洋
    精密工学会論文誌 79 11 1152 - 1158 2013年 [査読有り]
  • Hirooki Aoki; Ryo Furukawa; Shinsaku Hiura; Ryusuke Sagawa; Hiroshi Kawasaki
    Lecture Notes in Computer Science 7854, Advances in Depth Image Analysis and Applications, International Workshop, WDIA 2012 146 - 157 2012年11月 [査読有り]
  • Ismael Daribo; Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki
    3DTV-Conference 2012年 [査読有り]
     
    Recently, structured-light-based scanning systems have gain in popularity and are capable of modeling entire dense shapes that evolve over time with a single scan (a.k.a. one-shot scan). By projecting a static grid pattern onto the object surface, one-shot shape reconstruction methods can scan moving objects while still maintaining dense reconstruction. However, the amount of 3D data produced by these systems grows rapidly with point cloud of millions of points. As a consequence, effective point cloud compression scheme is required to face the transmission need. In this paper we propose a new approach to compress point cloud by taking advantage of the fact that arithmetic coding can be split into two parts: an encoder that actually produces the compressed bitstream, and a modeler that feeds information into the encoder. In particular, for each position point and normal, we propose to calculate the distribution of probabilities based on their spatial prediction as modeler, while classical point cloud coder mainly focus on the reduction of the prediction residual. Experimental results demonstrate the effectiveness of the proposed method. © 2012 IEEE.
  • Daisuke Miyazaki; Kazuki Nakamura; Masashi Baba; Ryo Furukawa; Masahito Aoyama; Shinsaku Hiura; Naoki Asada
    SIGGRAPH Asia 2012 Posters, SA 2012 2012年 [査読有り]
     
    The human brain recognizes pictures that are first obtained by the photosensitive cells in the retina. Color is a visual perception composed by the stimulus of three kinds of photoreceptors called L, M, and S cones. The human eye often recognizes different spectral distribution as same color since each cone has wide spectral response. This phenomenon is known as metamerism. Our research project aims to innovate a novel form of artistic illusion by fully making use of metamerism. This paper proposes a method which estimates the mixture ratio of paints that can cause metamerism. Copyright is held by the author / owner(s).
  • Daisuke Miyazaki; Takuya Shigetomi; Masashi Baba; Ryo Furukawa; Shinsaku Hiura; Naoki Asada
    SECOND JOINT 3DIM/3DPVT CONFERENCE: 3D IMAGING, MODELING, PROCESSING, VISUALIZATION & TRANSMISSION (3DIMPVT 2012) 104 - 111 2012年 [査読有り]
     
    Polarization is physical phenomena of the light which gives rich information of the scene even though it is undetectable by human eyes. In this paper, we analyze the polarization state of the light reflected on black specular objects in order to estimate the surface normal of the objects. Since polarization image of single view is not enough to uniquely determine the surface normal, we observe the object from multiple views. A rough estimate of the object geometry is obtained a priori by space carving so that the polarization state of the reflected light can be analyzed at the same surface point under multiple views. Unlike the photometric stereo or the multiview stereo which cannot estimate the surface normal and the geometry of black specular objects, the proposed method which is based on the polarization analysis and the space carving can estimate the surface normal and the geometry of black specular objects.
  • Hirooki Aoki; Masaki Miyazaki; Hidetoshi Nakamura; Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki
    2012 PROCEEDINGS OF SICE ANNUAL CONFERENCE (SICE) 614 - 618 2012年 [査読有り]
     
    We have examined a non-contact respiration measurement using Kinect, that is 3D sensor based on structured light, in order to decrease the burden of the pulmonary function test. In our proposed method, the respiratory waveform is produced from the volume change of thoracoabdominal part of examinee measured by the three-dimensional measurement function of Kinect. In this paper, we examine the validity of our proposed method by simultaneous measurement with the expiration gas analyzer and the flow meter. The experimental results implies that quantitative respiration measurement without contact-type sensor is realized by Kinect.
  • Hiroshi Kawasaki; Hitoshi Masuyama; Ryusuke Sagawa; Ryo Furukawa
    COMPUTER VISION - ECCV 2012, PT III 7585 486 - 495 2012年 [査読有り]
     
    In this paper, we propose a new technique to achieve one-shot scan using single color and static pattern projector; such a method is ideal for acquisition of a moving object. Since a projector-camera systems generally have uncertainties on retrieving correspondences between the captured image and the projected pattern, many solutions have been proposed. Especially for one-shot scan, which means that only a single image is used for reconstruction, positional information of a pixel on the projected pattern should be encoded by spatial and/ or color information. Although color information is frequently used for encoding, it is severely affected by texture and material of the object. In this paper, we propose a technique to solve the problem by using topological information instead of colors. Our technique successfully realizes one-shot scan with monochrome pattern.
  • Hirooki Aoki; Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki; Shinsaku Hiura
    2012 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC) 2012 2036 - 2039 2012年 [査読有り]
     
    We propose a new non-contact measurement of cardiac beat from 3D shape information of body surface by using grid-based active stereo, and basically examine the validity of the proposed method. By simultaneous measurement with our proposed method and ECG, there are sufficient correspondences between peak intervals of inter-frame depth changes measured by our method and R-R intervals measured by ECG.
  • Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki; Kazuhiro Sakashita; Yasushi Yagi; Naoki Asada
    IPSJ Transactions on Computer Vision and Applications 4 40 - 52 2012年 [査読有り]
     
    In the present paper, we propose a one-shot scanning system consisting of multiple projectors and cameras for dense entire shape acquisition of a moving object. One potential application of the proposed system is to capture a moving object at a high frame rate. Since the patterns used for one-shot scanning are usually complicated, and the patterns interfere with each other if they are projected onto the same object, it is difficult to use multiple sets of patterns for entire shape acquisition. In addition, the overlapped areas of each object have gaps and errors are accumulated. As such, merged shapes are usually noisy and inconsistent. In order to address this problem, we propose a one-shot shape reconstruction method using a projector to project a static pattern of parallel lines of one or two colors. Since each projector projects only parallel lines with a small number of colors, these patterns are easily decomposed and detected even if the patterns are projected multiple times onto the same object. We also propose a multi-view reconstruction algorithm for the projector-camera system. In the experiment, we built a system consisting of six projectors and six cameras, and dense shapes of entire objects were successfully reconstructed. © 2012 Information Processing Society of Japan.
  • Sakashita Kazuhiro; Sagawa Ryusuke; Furukawa Ryo; Kawasaki Hiroshi; Yagi Yasushi
    Information and Media Technologies 7 4 1556 - 1564 Information and Media Technologies Editorial Board 2012年 [査読有り]
     
    One of promising approach to reconstruct a 3D shape is a projector-camera system that projects structured light pattern. One of the problem of this approach is that it has difficulty to obtain texture simultaneously because the texture is interfered by the illumination by the projector. The system proposed in this paper overcomes this issue by separating the light wavelength for texture and shape. The pattern is projected by using infrared light and the texture is captured by using visible light. If the cameras for infrared and visible lights are placed at different position, it causes the misalignment between texture and shape, which degrades the quality of textured 3D model. Therefore, we developed a multi-band camera that acquires both visible and infrared lights from a single viewpoint. Moreover, to reconstruct a 3D shape using multiple wavelengths of light, namely multiple colors, an infrared pattern projector is developed to generate a multi-band grid pattern. Additionally, a simple method to calibrate the system is proposed by using the fixed grid pattern. Finally, we show the textured 3D shapes captured by the experimental system.
  • Ryusuke Sagawa; Kazuhiro Sakashita; Nozomu Kasuya; Hiroshi Kawasaki; Ryo Furukawa; Yasushi Yagi
    SECOND JOINT 3DIM/3DPVT CONFERENCE: 3D IMAGING, MODELING, PROCESSING, VISUALIZATION & TRANSMISSION (3DIMPVT 2012) 363 - 370 2012年 [査読有り]
     
    In this paper, we propose a method to reconstruct the shapes of moving objects. The proposed method is a projector-camera system that reconstructs a shape from a single image where a static pattern is cast by a projector; such a method is ideal for acquisition of moving objects at a high frame rate. The issues tackled in this paper are as follows: 1) realize one-shot 3D reconstruction with a single-colored pattern, and 2) obtain accurate shapes by finding correspondences in sub-pixel accuracy. To achieve these goals, we propose the following methods: 1) implicit encoding of projector information by a grid of wave lines, 2) grid-based stereo between projector pattern and camera images to determine unique correspondences, 3) (quasi) pixel-wise interpolations and optimizations to reconstruct dense shapes, and 4) a single-colored pattern which contributes to simplify pattern projecting devices compared to color-coded methods. In the experiment, we show the proposed method is efficient to solve the issues above.
  • 青木広宙; 古川亮; 青山正人; 日浦慎作; 佐川立昌; 川崎洋
    ビジョン技術の実利用ワークショップViEW2012 2012 IS1-D6, 4 pages  2012年
  • I. Daribo; R. Furukawa; R. Sagawa; H. Kawasaki; S. Hiura; N. Asada
    2011 Visual Communications and Image Processing (VCIP) 2011年11月 [査読有り]
  • Ryo Furukawa; Ryusuke Sagawa; Amael Delaunoy; Hiroshi Kawasaki
    2011 IEEE International Conference on Computer Vision Workshops (ICCV Workshops) 2011年11月 [査読有り]
  • Ryusuke Sagawa; Hiroshi Kawasaki; Shota Kiyota; Ryo Furukawa
    2011 International Conference on Computer Vision 2011年11月
  • Kazuhiro Sakashita; Yasushi Yagi; Ryusuke Sagawa; Ryo Furukawa; Hiroshi Kawasaki
    2011 International Conference on 3D Imaging, Modeling, Processing, Visualization and Transmission 49 - 56 2011年05月 [査読有り]
  • 古川亮; 川崎洋; 佐川立昌; 阪下和弘; 大田雄也; 頭師陵太; 八木康史; 浅田尚紀
    情報処理学会論文誌 52 6 1923 - 1938 情報処理学会 2011年05月 [査読有り]
     
    本論文では,プロジェクタ--カメラシステムを用いて,動きのある対象の形状を高密度かつ高フレームレートに計測するシステムを提案する.非常に速い動きがあるシーンを高密度に計測するためには,時系列にパターンを切り替える手法は向かず,ワンショットでの計測が望ましい.その解決手法として,縦横の線からなるグリッドパターンの交点を用いたワンショット形状計測法を提案されてきた.しかしこれまで提案された手法では,交点情報のみによる解には曖昧性があり,一意に解を決めるには線間隔の粗密といった追加情報が必要であった.そこで本論文では,追加情報なしに交点のみから一意解を得る手法を提案する.提案手法は,1つのカメラと2つのプロジェクタからなり,それぞれのプロジェクタは平行線パターンを投影することで交点を生じさせ,その交点から形状を復元する.このようなシステムでは交点のみから,線形解法によって一意に解を決定することができるため,線間隔に粗密をつける必要がなくパターン密度を上げることが可能となる.さらに,複数のプロジェクタを用いることによって,パターンが遮蔽されて形状計測できない部分を大きく減らすことが可能である.実験では,実際にシステムを構築し,動物体の高密度な形状をビデオレートで計測することに成功した.Development of active 3D scanning system that can capture fast-moving dynamic objects is an important research topic for many applications. To capture fast-moving objects, a oneshot scanning method that uses a single static image is preferable than those that uses multiple patterns. Recently, oneshot scanning methods that use intersection points of grid patterns have been proposed. In those methods, solutions only from intersection points have ambiguity, and thus, additional information, such as variation of grid intervals, were used to solve this. However, the variation of grid intervals makes it difficult to increase the density of the pattern. In this work, we propose a system that consists of a camera and multiple projectors and each of the projectors projects a parallel line patterns instead of grid patterns. Shape is reconstructed from the intersection points between those two sets of parallel lines. It is shown that a unique linear solution is possible for such a system, thus, dense grid patterns with uniform intervals can be used to increase density of the pattern. Furthermore, by using two projectors, blind areas caused by occlusion and self-occlusion are drastically reduced. In the experiment, we built a system which consists of two projectors and a single camera, i.e., a minimum configuration of the method, and successfully captured a dense shape of fast moving object with video rate.
  • Thibault Yohan; Kawasaki Hiroshi; Sagawa Ryusuke; Furukawa Ryo
    Proceedings - International Workshop on Database and Expert Systems Applications, DEXA 387 - 392 2011年 [査読有り]
     
    This paper proposes a method of retrieving texture from images containing pattern used for one shot 3D scanning system based on a grid pattern. Range scanners using projector-camera systems can be used for real-time 3D scanning with accurate results and at a low cost. However, these techniques cannot retrieve color information from the captured object since to obtain the best results, they require dark environments and the projection on the object to reconstruct dense and bright lines pattern masks most of the object textures. Therefore, we propose a technique of slightly modifying the input of a given 3D scanning system in order to have bright images with texture information and then retrieve the textures of the object using an inpainting method. The presented method adapts simple algorithms such as Canny filter and patches based inpainting in order to obtain a fully automatic method that does not require any user intervention. © 2011 IEEE.
  • Takuma Yamaguchi; Hisato Fukuda; Ryo Furukawa; Hiroshi Kawasaki; Peter Sturm
    COMPUTER VISION - ACCV 2010, PT IV 6495 127 - + 2011年 [査読有り]
     
    Video camera is now commonly used and demand of capturing a single frame from video sequence is increasing. Since resolution of video camera is usually lower than digital camera and video data usually contains a many motion blur in the sequence, simple frame capture can produce only low quality image; image restoration technique is inevitably required. In this paper, we propose a method to restore a sharp and high-resolution image from a video sequence by motion deblur for each frame followed by super-resolution technique. Since the frame-rate of the video camera is high and variance of feature appearance in successive frames and motion of feature points are usually small, we can still estimate scene geometries from video data with blur. Therefore, by using such geometric information, we first apply motion deblur for each frame, and then, super-resolve the images from the deblurred image set. For better result, we also propose an adaptive super-resolution technique considering different defocus blur effects dependent; on depth. Experimental results are shown to prove the strength of our method.
  • Ryo Furukawa
    Lecture Notes in Computer Science 323 - 334 2011年 [査読有り]
  • 大田雄也; 佐川立昌; 古川亮; 川崎洋; 八木康史; 浅田尚紀
    電子情報通信学会論文誌D J93-D 8 1544 - 1554 一般社団法人電子情報通信学会 2010年08月 [査読有り]
     
    非常に高速に動く3次元物体の形状を高密度,高フレームレートで取得できれば,多くの物体解析や事故防止等に大きく貢献できる.本論文ではラインベースによるグリッドパターンからのワンショットスキャンを拡張して密な形状を取得できるシステムを提案する.ワンショットスキャンは1枚の画像から物体の形状を計測できるが,密なパターンを使用できないため,計測結果が疎になるなど幾つかの解決すべき課題があった.そこで,パターンの交点を用いた形状計測の拡張,デブルーイン系列とbelief-propagationによる線検出の効率化,という手法を組み合わせてこれらの課題を解決した.この提案手法とハイスピードカメラを用いて実験を行ったところ,高フレームレートで高速移動物体の密な形状の取得に成功した.
  • Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki; Kazuhiro Sakashita; Yasushi Yagi; Naoki Asada
    Proceedings - 4th Pacific-Rim Symposium on Image and Video Technology, PSIVT 2010 107 - 114 2010年 [査読有り]
     
    In this paper, we propose an active scanning system using multiple projectors and cameras to acquire a dense entire shape of the object with a single scan (a.k.a. one-shot scan). One of the potential application of the system is to capture a moving object with high frame-rate. Since the pattern used for oneshot scan is usually complicated and those patterns interfere each other if they are projected on the same object, it is difficult to use multiple sets of them for entire shape acquisition. In addition, at the end of the closed loop, errors on each scan are accumulated, resulting in large gaps between shapes. To solve the problem, we propose a oneshot shape reconstruction method using a projector projecting a static pattern of parallel lines with one or two colors. Since each projector projects just parallel lines with a small number of colors, those patterns are easily decomposed and detected even if those patterns are projected multiple times on the same object. We also propose a kind of multi-view reconstruction algorithm for the proposed projector-camera system. In the experiment, we actually built a system which consists of six projectors and six cameras and dense shapes of entire objects were successfully reconstructed. © 2010 IEEE.
  • Hiroshi Kawasaki; Ryusuke Sagawa; Yasushi Yagi; Ryo Furukawa; Naoki Asada; Peter Sturm
    2010 IEEE Computer Society Conference on Computer Vision and Pattern Recognition - Workshops, CVPRW 2010 104 - 111 2010年 [査読有り]
     
    In this paper, we describe a new one-shot scanning technique using a camera and a projector. Generally, a 3D measurement system based on a camera and a projector requires pre-calibration, such as the measurement of the relative position of these devices. If we can eliminate the calibration process, it would greatly improve the convenience of the system. For example, a single capture by a handheld camera of an object illuminated by a hand-held projector would then allow to reconstruct the object shape. To achieve this, we propose a self-calibration technique using a projected grid pattern, computing the relative pose of projector and camera. This is similar to the relative pose or motion problem for two cameras, but in our case correspondences are not explicitly given. The actual algorithm is based on a simple exhaustive search of a finite set of hypotheses, with a cost function based on the epipolar constraint. In the experiments, successful reconstructions with our proposed method using synthetic and read data are presented. © 2010 IEEE.
  • Takuma Yamaguchi; Hiroshi Kawasaki; Ryo Furukawa; Toshihiro Nakayama
    COMPUTER VISION - ACCV 2009, PT III 5996 516 - + 2010年 [査読有り]
     
    In this paper, we propose a super-resolution technique for multiple independently moving 3D objects from a single camera, the camera is also allowed to move freely. Previous techniques were mostly focused on planar objects, and it was difficult to realize super-resolution for the scene containing 3D objects, due to significant appearance changes caused by objects' motion and viewpoint changes. In this paper, we propose a new technique which can solve the above mentioned problems by applying pixel-based registration instead of planar based registration, which are commonly used in the previous 3D super-resolution techniques. Since the technique is pixel-wise and is not required to divide the scene into planar patches, it can be applied to images containing objects with complex shapes or non-rigid objects, to which applying planar approximation is difficult.
  • Masahiro Ishikawa; Hiroshi Kawasaki; Ryo Furukawa; Yukiko Kawai
    Proceedings of the 11th ACM SIGMM International Conference on Multimedia Information Retrieval, MIR 2010, Philadelphia, Pennsylvania, USA, March 29-31, 2010 393 - 396 ACM 2010年 [査読有り]
  • Ryo Furukawa; Hiroshi Kawasaki
    COMPUTER VISION AND IMAGE UNDERSTANDING 113 11 1118 - 1129 2009年11月 [査読有り]
     
    In this paper, we propose a novel method to achieve both dense 3D reconstruction of the scene and estimation of the camera intrinsic parameters by using coplanarities and other constraints (e.g., orthogonalities or parallelisms) derived from relations between planes in the scene and reflected curves of line lasers captured by a single camera. In our study, we categorize coplanarities in the scene into two types: implicit coplanarities, which can be observed as reflected curves of line lasers. and explicit coplanarities, which are. for example, observed as walls of a building. By using both types of coplanarities, we can construct simultaneous equations and can solve them up to four degrees of freedom. To upgrade the solution to the Euclidean space and estimate the camera intrinsic parameters, we can use metric constraints such as orthogonalities of the planes. Such metric constraints are given by, for example, observing the corners of rectangular boxes in the scene, or using special laser projecting device composed of two line lasers whose laser planes are configured to be perpendicular. (C) 2009 Elsevier Inc. All rights reserved.
  • Hiroshi Kawasaki; Ryo Furukawa
    International Journal of Computer Vision 83 2 135 - 148 2009年06月 [査読有り]
  • Ryusuke Sagawa; Yuichi Ota; Yasushi Yagi; Ryo Furukawa; Naoki Asada; Hiroshi Kawasaki
    2009 IEEE 12TH INTERNATIONAL CONFERENCE ON COMPUTER VISION (ICCV) 1779 - 1786 2009年 [査読有り]
     
    Dense 3D reconstruction of extremely fast moving objects could contribute to various applications such as body structure analysis and accident avoidance and so on. The actual cases for scanning we assume are, for example, acquiring sequential shape at the moment when an object explodes, or observing fast rotating turbine's blades. In this paper, we propose such a technique based on a one-shot scanning method that reconstructs 3D shape from a single image where dense and simple pattern are projected onto an object. To realize dense 3D reconstruction from a single image, there are several issues to be solved; e. g. instability derived from using multiple colors, and difficulty on detecting dense pattern because of influence of object color and texture compression. This paper describes the solutions of the issues by combining two methods, that is (1) an efficient line detection technique based on de Bruijn sequence and belief propagation, and (2) an extension of shape from intersections of lines method. As a result, a scanning system that can capture an object in fast motion has been actually developed by using a high-speed camera. In the experiments, the proposed method successfully captured the sequence of dense shapes of an exploding balloon, and a breaking ceramic dish at 300-1000 fps.
  • Ryo Furukawa; Hiroshi Kawasaki; Ryusuke Sagawa; Yasushi Yagi
    IPSJ Transactions on Computer Vision and Applications 1 139 - 157 2009年 [査読有り]
     
    Shape acquisition of moving deformable objects with little texture is important for applications such as motion capture of human facial expression. Several techniques using structured light have been proposed. These techniques can be largely categorized into two main types. The first type temporally encodes positional information of a projector's pixels using multiple projected patterns, and the second spatially encodes positional information into areas or color spaces. Although the former technique allows dense reconstruction with a sufficient number of patterns, it has difficulty in scanning objects in rapid motion. The latter technique uses only a single pattern, so it is more suitable for capturing dynamic scenes however, it often uses complex patterns with various colors, which are susceptible to noise, pattern discontinuity caused by edges, or textures. Thus, achieving dense and stable 3D acquisition for fast-moving and deformable objects remains an open problem. We propose a technique to achieve dense shape reconstruction that requires only a single-frame image of a grid pattern based on coplanarity constraints. With our technique, positional information is not encoded in local regions of a projected pattern, but is distributed over the entire grid pattern, which results in robust image processing and 3D reconstruction. The technique also has the advantage of low computational cost due to its efficient formulation. © 2009 Information Processing Society of Japan.
  • 榎本和史; 猪瀬健二; 川崎洋; 古川亮
    情報処理学会論文誌コンピュータビジョンとイメージメディア(CVIM) 1 3 12 - 27 2008年11月 [査読有り]
     
    本論文では,ビデオカメラとプロジェクタを用いた3次元計測システムにおいて複数形状を計測し,それらの位置合わせ後に残る形状間のずれを最小化することで,計測精度を向上させる手法を提案する.プロジェクタ·カメラによる3次元計測では最初に校正を行い,その後,その校正パラメータを用いて計測を行う.校正の際,ノイズやレンズの歪みや量子化誤差などの影響により,校正パラメータに誤差が発生すると,復元される形状が歪むことになる.一般に,完全に誤差なく校正を行うことは困難であり,同じ物体を複数方向から計測し精密に位置合わせしても,各形状間には位置合わせ誤差が残る.そこで本論文では,この位置合わせ誤差を最小化するように,プロジェクタ·カメラの内部パラメータ(焦点距離),プロジェクタ·カメラ間の相対位置姿勢である外部パラメータ,複数のプロジェクタ·カメラセット間の剛体変換パラメータおよび点群の3次元座標を推定する.これはカメラのみにおけるバンドル調整法をプロジェクタ·カメラシステムに応用したものと考えることができる.提案手法により,3次元計測の精度向上および,それによる正確な形状統合が実現できることを示す.In this paper, we propose a new method to improve precisions of multiple 3D shapes acquired by a projector-camera active stereo system. The improvement of precision of the shapes is achieved by minimizing “gaps” between overlapping shapes that remains after registration algorithms are performed. To use projector-camera system for 3D acquisition, we must calibrate the system in advance. Then, we can measure 3D shapes using the calibrated parameters. Noise, lens distortions, or quantization errors can cause calibration errors, which often causes distortions of the reconstructed shapes. In general, error-free calibration is very difficult. So, even if we capture multiple shape data from an object and register all the shapes, there still remains errors between the shapes. In this paper, we re-estimate the extrinsic parameters between the camera and the projector and the focal length of the camera by minimizing the registration errors at the overlapping area of multiple shapes and the errors of epipolar constraints. The process improves the accuracies of the 3D measurement and corrects the rigid transformation parameters of the registrations of the shapes.
  • 古川 亮; 川崎 洋
    情報処理学会論文誌 コンピュータビジョンとイメージメディア(CVIM) 1 2 111 - 123 情報処理学会 2008年07月 [査読有り]
     
    シーンの形状復元に影を使う手法が,これまでに提案されて来た.影は,光のあるシーンにおいてつねに存在するため,特殊な装置を用いることなく,屋外など,あらゆるシーンで観測できるという利点がある.特に,直線状のエッジを含む物体から対象シーンの表面に影が投影されると,エッジによって作られる影の境界線(以下影曲線)上の点は,エッジと光源を含む単一の平面上にある(共面である)ため,これを利用した手法が多く提案されている.しかし,これらの手法では,カメラの内部パラメータや光源位置,参照平面のキャリブレーションなどが必要であるため,適用可能なシーンが限られており,これまで実際に利用されることはあまりなかった.もし,これらの値が未知であっても形状復元が可能であれば,利用範囲が広がりその利便性も増す.そこで,本論文では,影曲線を含む平面と,シーン中の平面の集合について,平面間に成り立つ関係式を導き,連立方程式として解くことで,内部パラメータが未知,あるいは既知の平面(参照平面)がない場合でも形状復元を実現する手法を提案する.シミュレーションおよび実画像を用いた実験により,提案手法により正しく形状が復元されることを示す.To date, various techniques for scene shape reconstruction using shadows have been proposed. Shadows have the advantage that they can be used in outdoor and various other scenes without using special devices, since they exist wherever light is present. When an object with a straight edge casts a shadow on a scene, the points on the shadow boundary (shadow curve) are on a single plane that includes the light source and the edge (i.e. the points are coplaner). Previous shape reconstruction techniques that use such shadow boundaries require calibration of camera parameters, knowledge of light source position, and a reference plane. Since their application ranges are limited, such techniques have not been widely used. Hence, a technique capable of realizing reconstruction even when some of the values are unknown would be applicable to various scenes. This paper realizes such a technique. This technique reconstructs a 3D shape by solving the simultaneous equations of planer regions in the scene and the planes that include shadow curves. We conducted an experiment using simulated and real images to verify the correct shape reconstruction by the proposed technique.
  • 複数計測による全周3次元モデル生成のための複数テクスチャのシームレスな合成手法
    猪瀬 健二; 榎本 和史; 川崎 洋; 古川 亮
    情報処理学会論文誌 コンピュータビジョンとイメージメディア(CVIM) 1 2 136 - 151 2008年07月 [査読有り]
  • Hiroshi Kawasaki; Ryo Furukawa; Ryusuke Sagawa; Yasushi Yagi
    2008 IEEE Conference on Computer Vision and Pattern Recognition 2008年06月 [査読有り]
  • Ryo Furukawa; Hiroshi Kawasaki; Ryusuke Sagawa; Yasushi Yagi
    BMVC 2008 - Proceedings of the British Machine Vision Conference 2008 2008年 [査読有り]
     
    An active 3D scanning method that can capture a fast motion is strongly required in wide areas. Since most commercial products using a laser projector basically reconstruct the shape with a point or a line for each scan, a fast motion cannot be captured in principle. In addition, an extended method using a structured light can drastically reduce the number of projecting patterns, however, they still require several patterns and a fast motion cannot be captured. One solution for the purpose is to use a single pattern (one shot scan). Although, one shot scanning methods have been intensively studied, they often have stability problems and their result tend to have low resolution. In this paper, we develop a new system which achieves dense and robust 3D measurement from a single grid pattern. A 3D reconstruction can be achieved by identifying grid patterns using coplanarity constraints. We also propose a coarse-to-fine method to increase the density of the shape with a single pattern.
  • Hiroshi Kawasaki; Inose Kenji; Ryo Furukawa; Ryusuke Sagawa; Yasushi Yagi
    PROCAMS 2008 - ACM/IEEE 5th International Workshop on Projector Camera Systems 2008年 [査読有り]
     
    An active 3D scanning device which can capture a sequential motion in realtime is strongly demanded for 3D display and other VR systems. Since most previous and commercial products basically recover the shape with a point or a line for each scan, fast motion can not be captured in principle. One solution for the purpose is to use a single pattern (one shot scan). However, they often have stability problems and their result tend to have low resolution. In our recent study, we have developed a system which achieved dense and accurate 3D reconstruction from only a single image. The proposed system also had the advantage of being robust in terms of image processing. In this presentation, we introduce outline of our system, several applications and results. ©2008 ACM.
  • 古川 亮; 猪瀬 健二; 川崎 洋
    The Journal of The Institute of Image Information and Television Engineers 62 12 1964 - 1968 2008年 [招待有り]
  • Ryo Furukawa; Huynh Quang Huy Viet; Hiroshi Kawasaki; Ryusuke Sagawa; Yasushi Yagi
    2008 15th IEEE International Conference on Image Processing 1524 - 1527 2008年 [査読有り]
     
    Methods for scanning dynamic scenes are important in many applications and many systems using structured light have been proposed. Many of these systems use either multiple patterns projected rapidly or a single pattern. Although the former allows dense reconstruction with a sufficient number of patterns, it has difficulty in capturing objects in rapid motion. The latter technique uses only a single pattern and have no such difficulties, however, they often have stability problems and their result tend to have low resolution. In this paper, we develop a system to achieve dense and accurate 3D measurement from only a single image. The proposed system also has the advantage of being robust in terms of image processing.
  • Yukiko Kawai; Shogo Tazawa; Ryo Furukawa; Hiroshi Kawasaki
    19th International Conference on Pattern Recognition (ICPR 2008), December 8-11, 2008, Tampa, Florida, USA 1 - 4 IEEE Computer Society 2008年 [査読有り]
  • 川崎 洋; 古川 亮
    電子情報通信学会論文誌 D J90-D 8 1848 - 1857 一般社団法人電子情報通信学会 2007年08月 [査読有り]
     
    コンピュータビジョンにおいて自己校正は重要な研究課題であり,ステレオカメラを中心に盛んに研究が行われてきた.ところが,光切断法などのようなアクティブビジョンシステムにおける自己校正に関する研究はこれまであまり行われてきていない.本論文では,光切断法におけるレーザ平面位置の自己校正手法について検討する.これは,固定カメラで撮影した画像系列で観測される複数のレーザ反射の曲線位置のみを用いて,各レーザ平面を推定する問題と定義される.この問題における拘束式は,観測された曲線間の交点から得ることができる.本論文では,相対的な位置関係が既知の2本のラインレーザを用いる場合には,この問題を解くことが可能であることを示す.最適化を用いてこの問題を解くには,目的関数の極小値の多さが問題となる.我々は近似された問題をGrobner基底を用いて解くことで,最適化のための初期解を得る方法を提案する.この初期解を用いれば,非線形最適化により最終的に高い精度で三次元復元が可能となる.
  • Ryo Furukawa; Hiroshi Kawasaki
    BMVC 2007 - Proceedings of the British Machine Vision Conference 2007 2007年 [査読有り]
     
    Coplanarity is a relationship of a set of points that exist on a single plane. Coplanarities can be easily observed in a scene with planer surfaces, and these types of coplanarities have been widely used for 3D reconstructions based on geometrical constraints. Other types of coplanarities that can be observed from images are those observed as cross sections of planes and scenes for example, points lit by a line laser, or boundary points of a shadow of a straight edge. Although these types of coplanarities have been implicitly used in variations of light sectioning methods, they have not been used in an unified manner with the former types. In this paper, we describe a new 3D reconstruction method based on coplanarities and other geometrical constraints. In particular, we make use of the above two types of coplanarities in an unified manner. This enables us to reconstruct 3D scenes scanned using line lasers or shadows of straight edges observed by a partially-calibrated single camera utilizing geometrical relationships between the planes in the scenes and the planes of line lasers or the planes of shadow boundaries.
  • Ryo Furukawa
    THIRD INTERNATIONAL SYMPOSIUM ON 3D DATA PROCESSING, VISUALIZATION, AND TRANSMISSION, PROCEEDINGS 2007年 [査読有り]
  • Hiroshi Kawasaki; Ryo Furukawa
    COMPUTER VISION - ACCV 2007, PT II, PROCEEDINGS 4844 847 - + 2007年 [査読有り]
     
    To date, various techniques of shape reconstruction using cast shadows have been proposed. The techniques have the advantage that they can be applied to various scenes including outdoor scenes without using special devices. Previously proposed techniques usually require calibration of camera parameters and light source positions, and such calibration processes make the application ranges limited. If a shape can be reconstructed even when these values are unknown, the technique can be used to wider range of applications. In this paper, we propose a method to realize such a technique by constructing simultaneous equations from coplanarities and metric constraints, which are observed by cast shadows of straight edges and visible planes in the scenes, and solving them. We conducted experiments using simulated and real images to verify the technique.
  • Ryo Furukawa; Tomoya Itano; Akihiko Morisaka; Hiroshi Kawasaki
    COMPUTER VISION - ACCV 2007, PT II, PROCEEDINGS 4844 206 - + 2007年 [査読有り]
     
    To merge multiple range data obtained by range scanners, filling holes caused by unmeasured regions, the space carving method is a simple and effective method. However, this method often fails if the number of the input range images is small, because unseen voxels that are not carved out remains in the volume area. In this paper, we propose an improved algorithm of the space carving method that produces stable results. In the proposed method, a discriminant function defined on volume space is used to estimate whether each voxel is inside or outside the objects. Also, in particular case that the range images are obtained by active stereo method, the information of the positions of the light sources can be used to improve the accuracy of the results.
  • Hiroshi Kawasaki; Ryo Furukawa
    3DIM 2007: SIXTH INTERNATIONAL CONFERENCE ON 3-D DIGITAL IMAGING AND MODELING, PROCEEDINGS 149 - + 2007年 [査読有り]
     
    In this paper we propose a novel method to achieve both dense 3D reconstruction of the scene and estimation of the camera intrinsic parameters by using coplanarities and other constraints (e.g. orthogonalities or parallelisms) derived from relations between planes in the scene and reflected curves of line lasers captured by a single camera. In our study, we categorize coplanarities in the scene into two types: implicit coplanarities, which can be observed as reflected curves of line lasers, and explicit coplanarities, which are, for example, observed as walls of a building. By using both types of coplanarities, we can construct simultaneous equations and can solve them up to four degrees of freedom. To upgrade the solution to the Euclidean space and estimate the camera intrinsic parameters, we can use metric constraints such as orthogonalities of the planes. Such metric constraints are given by, for example, observing the corners of rectangular boxes in the scene, or using special laser projecting device composed of two line lasers whose laser planes are configured to be perpendicular.
  • Ryo Furukawa; Tomoya Itano; Akihiko Morisaka; Hiroshi Kawasaki
    3DIM 2007: SIXTH INTERNATIONAL CONFERENCE ON 3-D DIGITAL IMAGING AND MODELING, PROCEEDINGS 289 - + 2007年 [査読有り]
     
    The merging of multiple range images obtained by 3D measurement systems for generating a single polygon mesh, and processing for filling holes caused by unmeasured data or insufficient range images are essential processes for CAD, digital archiving of shapes, and CG rendering. Many of the existing processes that have been proposed for merging and interpolating multiple shapes do not function well when the number of range images is small. In this paper, the space carving method is improved, and an interpolation algorithm is proposed which is capable of producing stable results even when the number of range images is small. In the proposed method, not only the observed voxels in a signed distance field, but also unseen voxels are determined as either inside or outside of an object using Bayes estimation. Characteristics of the proposed method include that closed surfaces are always obtained, and a GPU-based, efficient implementation is possible. In addition, in the case that the range image is obtained using an active stereo method, high precision estimation results can be achieved by using information regarding the light sources.
  • H. Kawasaki; R. Furukawa; Y. Nakamura
    18th International Conference on Pattern Recognition (ICPR'06) 1071 - + 2006年08月 [査読有り]
     
    In this paper, we propose a new 3D scanner which is easy to operate. Till date several 3D scanners, including commercial products, are available; however most Of these are usually large, heavy, and expensive. Although inexpensive 3D scanners manufactured using vision-based techniques, such as stereo vision, are available, they cannot be used in actual measurements because the techniques are still being researched. Our proposed scanner consists of only a laser projector and a single camera and is based on the self-calibarating technique; thus it does not require both precalibration and expensive mechanical devices. This implies that the system to be low-cost and the occlusions can be effectively reduced by moving the projector while scanning. Experiments of our method were performed using both synthesized and real data and the 3D information of the scene was successfully reconstructed.
  • 空間コード化法を用いた未校正ステレオシステムによる密な3次元形状復元
    川崎 洋; 大沢 裕; 古川 亮; 中村 泰明
    情報処理学会論文誌:コンピュータビジョンとイメージメディア 47 SIG 10(CVIM 15) 1 - 13 2006年07月 [査読有り]
  • 古川 亮; 川崎 洋; 中村 泰明; 大澤 裕
    映像情報メディア学会誌 60 4 545 - 552 2006年04月 [査読有り]
     
    In this paper, we developed a method for sampling and modeling reflectance of 3-D objects and performing real-time rendering of modeled objects. Our method can be used to render modeled objects from an arbitrary viewing direction with illuminations from point lights at any given place or with any illumination map. To achieve this goal, we developed a platform that can sample appearances of target objects with 4DOFs parameters of light and viewing directions. Light-dependent variations of sampled data were approximated using spherical harmonics functions as bases. To render a modeled object, we generated its appearance by synthesizing the effects of illuminations using spherical harmonics functions and by interpolating between sampled viewing directions. The appearance was then texture-mapped to the shape model. Using our method, we could represent reflectance properties of surfaces of 3-D objects that were parametrized by 4DOFs light and viewing directions. We also successfully rendered the modeled objects using programmable vertex/pixel shaders with real-time performance.
  • Hiroshi Kawasaki; Yutaka Ohsawa; Ryo Furukawa; Yasuaki Nakamura
    Computer Vision – ACCV 2006 882 - 891 2006年 [査読有り]
  • R Kadobayashi; R Furukawa
    VIDEOMETRICS VIII 5665 134 - 143 2005年 [査読有り]
     
    In this paper we propose "browsing by 3D scene" and "rendering by photographs" based on viewpoint-based approach. The idea is that by linking the 3D models and photographs via the spatial information, "viewpoint" in particular, we can use them as a reference for each other when browsing photographs or walking through the 3D scene. We use the camera parameters to express the viewpoint. Each photograph has the extrinsic camera parameters as metadata, which is defined according to the same coordinates as the 3D model, and hence we can compare the viewpoints of them and judge their similarity. Unlike content-base image retrieval, the viewpoint-based search is robust to the difference of features such as color and shape among images. The browsing by 3D scene method allows users to retrieve images that contain the same object but show it with different appearances and to browse the images taken from a similar viewpoint in groups. On the other hand, when a user want to see a particular 3D scene. the user specifies a sample image by selecting a photograph from the archive. The system then renders the 3D scene with the viewpoint similar to that of the selected photograph.
  • Synthesis of Textures with Intricate Geometries using BTF and Large Number of Textured Micropolygons
    Ryo Furukawa; Masaharu Harada; Yasuaki Nakamura; Hiroshi Kawasaki
    In Proc. of the 4th International Workshop on Texture Analysis and Synthesis 77 82 2005年 [査読有り]
  • Ryo Furukawa; Hiroshi Kawasaki
    Proceedings of International Conference on 3-D Digital Imaging and Modeling, 3DIM 302 - 309 2005年 [査読有り]
     
    In this paper, we propose an uncalibrated, multi-image 3D reconstruction, using coded structured light. Normally, a conventional coded structured light system consists of a camera and a projector and needs precalibration before scanning. Since the camera and the projector have to be fixed after calibration, reconstruction of a wide area of the scene or reducing occlusions by multiple scanning are difficult and sometimes impossible. In the proposed method, multiple scanning while moving the camera or the projector is possible by applying the uncalibrated stereo method, thereby achieving a multi-image 3D reconstruction. As compared to the conventional coded structured light method, our system does not require calibration of extrinsic camera parameters, occlusions are reduced, and a wide area of the scene can be acquired. As compared to image-based multi-image reconstruction, the proposed system can obtain dense shape data with higher precision. As a result of these advantages, users can freely move either the cameras or projectors to scan a wide range of objects, but not if both the camera and the projector are moved at the same time. © 2005 IEEE.
  • Hiroshi Kawasaki; Kyoung-Dae Seo; Yutaka Ohsawa; Ryo Furukawa
    Proceedings - International Conference on Image Processing, ICIP 1 393 - 396 2005年 [査読有り]
     
    In this paper, we propose a novel synthesis technique for BTFs. A BTF (bidirectional texture function) is a 6D function which can represent appearances of a texture under arbitrary view and lighting conditions. Until now, several approaches of BTF synthesis have been researched. For ordinary textures, patch based methods are promising techniques for texture synthesis. However, it has not been effectively tried to BTFs yet. This is mainly because data size of BTFs is so large and it is not easy to apply the techniques to BTFs. Further, efficient rendering of BTFs is still under research. In this paper, we extend a patch based synthesis technique for BTFs by utilizing compact representation of BTFs. In addition, we propose a novel technique to render the synthesized BTFs efficiently. With our proposed method, we can successfully and effectively render objects with complicated surfaces under arbitrary sizes. © 2005 IEEE.
  • Hiroshi Kawasaki; Ryo Furukawa
    Proceedings - International Conference on Image Processing, ICIP 3 369 - 372 2005年 [査読有り]
     
    In this paper, we propose an uncalibrated, multi-image 3D reconstruction technique, using coded structured light. Normally, a conventional coded structured light system consists of a camera and a projector and needs precalibration before scanning. Since the camera and the projector have to be fixed after calibration, reconstruction of a wide area of the scene or reducing occlusions are difficult and sometimes impossible. In the proposed method, precalibration can be successfully omitted by applying the uncalibrated stereo technique, thereby multiple scanning while moving the camera or the projector is possible. As the result, users can freely move either the cameras or projectors to scan a wide range of objects. © 2005 IEEE.
  • H. Kawasaki; R. Furukawa
    Proceedings. 2nd International Symposium on 3D Data Processing, Visualization and Transmission, 2004. 3DPVT 2004. 478 - 485 2004年09月 [査読有り]
     
    In this paper, a real-time, handheld 3D model acquisition system consisting of a laser projector, a video camera and a turntable is described. The user projects a stripe of light at the 3D object by hand while rotating the object on a turntable. The projected light and LED markers attached to the laser projector and turntable are captured by the video camera. By estimating the 3D orientation of the laser projector and the turntable angle from the 2D locations of the markers, the 3D location of the surface lit by the laser can be calculated. In addition, post-processing algorithms for refining the estimated 3D data have been proposed. The algorithm not only improves the accuracy of the 3D measurement, but also achieves to decrease the number of LEDs for 3D data estimation therefore, it significantly improves the user's convenience in scanning the object. With this system, users can measure an entire 3D object in real-time. © 2004 IEEE.
  • Comparison and evaluation of laser scanning and photogrammetry and their combined use for digital recording of cultural heritage
    Rieko Kadobayashi; N Kochi; H Otani; Ryo Furukawa
    The International Archives of Photogrammetry and Remote Sensing, ISTANBUL, XXth Congress, 2004 401 406 2004年 [査読有り]
  • R. Furukawa; H. Kawasaki
    Fourth International Conference on 3-D Digital Imaging and Modeling, 2003. 3DIM 2003. Proceedings. 2003年10月 [査読有り]
  • Integrated Presentation System for 3D Models and Image Database for Byzantine Ruins
    Rieko Kadobayashi; Ryo Furukawa; Yukiko Kawai; Daisuke Kanjo; Jun N. Yoshimoto
    Proceedings of the ISPRS Workshop on Vision Techniques for Digital Architectural and Archaeological Archives (ISPRS XXXIV-5/W12) 187 - 192 2003年07月 [査読有り]
  • Removal of shadows and shadings from texture images for archiving historical ruins
    Ryo Furukawa; Yutaka Kiuchi; Rieko Kadobayashi
    International archives of photogrammetry remote sensing and spatial information sciences, 34(5/W12), 157 - 162 2003年01月 [査読有り]
  • Real-Time Search System for Streaming Live Video on the Internet
    Yukiko Kawai; Ryo Furukawa; Rieko Kadobayashi
    Proceedings of the 7th IASTED International Conference on Internet and Multimedia Systems and Applications (IMSA 2003) 223 - 228 2003年 [査読有り]
  • Appearance based object modeling using texture database: Acquisition, compression and rendering
    Furukawa; R; Kawasaki, H; Ikeuchi, K; Sakauchi, M
    Eurographics Workshop on Rendering 257 - 266 2002年02月 [査読有り]
  • R. Furukawa; H. Kawasaki; K. Ikeuchi
    In Proceedings of the Fifth Asian Conference on Computer Vision (pp. 622-627). 2002年02月 [査読有り]
  • Ryo Furukawa; Masakazu Imai; Takeshi Uno
    Systems and Computers in Japan 30 13 84 - 95 1999年11月 [招待有り]
  • 加藤 浩巳; 古川 亮; 今井 正和; 烏野 武
    電子情報通信学会論文誌 D-II vol.J81-D-II 9 1975 - 1982 一般社団法人電子情報通信学会 1998年09月 [査読有り]
     
    コンピュータビジョンの分野においては, 画像から物体の輪郭を抽出し, その時間的な変化からシーン中の物体の動きの解析を行うことは重要でかつ難しい問題であり, これまでにもさまざまな方法が提案されている.その中で, Snakesに代表されるエネルギー最小化の原理に基づいた方法がある.我々は時空間においてSnakesに類似したエネルギー最小化の原理に基づいた物体抽出手法としてActive Tubesを提案している.しかしActive Tubesをはじめとしたエネルギー最小化の原理に基づいた方法では, エネルギー項の係数決定を経験的に行わなければならないという問題点がある.本研究ではその問題点を解決するため, エネルギー関数の極小値を求める計算にニューラルネットワークを用いることを提案する.望ましい収束結果を教師データとして用いることのよって, エネルギー項の係数をニューラルネットワークに学習させることを試みた.エネルギー最小化の原理に基づいた手法としてActive Tubesを例とし, 実画像を用いた実験を行いニューラルネットワークによる収束の有効性を確認した.
  • 古川 亮; 今井 正和; 烏野 武
    電子情報通信学会論文誌 D-II J81-D-II 4 611 - 622 一般社団法人電子情報通信学会 1998年04月 [査読有り]
     
    本論文では, 動的輪郭モデルに基づいた新しい輪郭追跡モデルを提案する.そのために, 多重スケール画像(ピラミッド画像)と時空間画像とを組み合わせた新しい画像空間を導入する.この画像空間に管状の動的輪郭モデルを適用することで, 輪郭追跡を実現している.本モデルの長所として, 画像系列を先頭から順に処理することができ, カメラ画像などを撮影と同時に処理するような処理モデルに適用可能なこと, フレーム間での目標物体の移動量が比較的大きい場合にも追跡が可能であること, 追跡対象輪郭上の点の位置や速度の連続性の条件を利用することで, 安定した輪郭追跡が可能であること, 処理効率が高いことが挙げられる.
  • Ryo Furukawa; Masakazu Imai; Takeshi Uno
    Systems and Computers in Japan 28 9 67 - 76 1997年08月 [招待有り]
  • R. Furukawa; M. Imai; T. Uno
    Proceedings of 13th International Conference on Pattern Recognition 1996年08月 [査読有り]
  • 古川 亮; 今井 正和; 烏野 武
    電子情報通信学会論文誌 D-II J79-D-II 6 1054 - 1063 一般社団法人電子情報通信学会 1996年06月 [査読有り]
     
    連続画像から物体の運動を解析することは, 重要でかつ困難な問題であり, これに対して多くの研究がなされてきた. 本論文で提案するActive Tubesは, 非剛体物体の運動を解析するためのモデルの一つである. このモデルは, Kassらの提案したSnakesを時間軸に沿って重ねたものとみなすことができ, Snakesと同様のエネルギー最小化の手法を用いて時空間画像中の物体を抽出する. 当初, Active Tubesの収束アルゴリズムとして, Greedy Algorithmを用いていた. しかし, Greedy Algorithmはノイズなどの影響を受けやすいため, 新しいアルゴリズムとしてRandomized Greedy Algorithmを提案する. 提案されたアルゴリズムはGreedy Algorithmと同程度に高速である上に, ノイズに対してより頑健である.
  • 中村 裕一; 古川 亮
    情報処理学会論文誌 36 1 196 - 205 一般社団法人情報処理学会 1995年01月 [査読有り]
     
    図と文章の相補的な利用はコミュニケーションの手段として非常に有効であり、計算機でこれらのメディアを統合的に解析、生成する必要性が高まっている。本稿では、そのようなメディアの統合を実現するための一つの手法として、教科書、専門用語辞典などに用いられる概念図を解析する手法について述ぺる。そのために、概念図のパターン憎報と説明文として付加されている自然言語テキストと両方の解析を行い、それらを統合する。統合の方法としては、概念図中の図形要素と説明文中の単語とのリンク付け、概念図の図形要素の意味を解釈することを行う。これにより、概念図とその説明文の有機的な結合、概念図の持つパターン情報の意味推定が可能になる。本研究では、情報科学辞典を対象に実際に解析を行い、その有効性を確かめた。
  • R. Furukawa; M. Imai; T. Uno
    Proceedings of 1994 IEEE Workshop on Motion of Non-rigid and Articulated Objects 1994年11月 [査読有り]
  • Y. Nakamura; R. Furukawa; M. Nagao
    Proceedings of 2nd International Conference on Document Analysis and Recognition (ICDAR '93) 1993年08月 [査読有り]

MISC

書籍等出版物

講演・口頭発表等

  • アクティブステレオ法における複数フレーム計測結果の全体最適化法  [通常講演]
    古川亮; 三鴨道弘; 佐川立昌; 川崎洋
    画像の認識理解シンポジウム MIRU2022 2022年07月 口頭発表(一般)
  • データ拡張による投影パターン検出の安定化とMRF最適化による対応付の改善によるワンショット三次元形状計測の高精度化  [通常講演]
    原田寛大; 三鴨道弘; 古川亮; 佐川立昌; 川崎洋
    画像の認識理解シンポジウム MIRU2022 2022年07月 ポスター発表
  • Oneshot dense 3D active stereo based on pixel-wise correspondence estimation using U-Nets and GCN  [通常講演]
    Michihiro Mikamo; Ryusuke Sagawa; Hiroshi Kawasaki; Ryo Furukawa
    画像の認識理解シンポジウム MIRU2021 2021年07月 ポスター発表
  • 微小振動によるスペックルパターン変化の時空間最適化による音波の三次元空間における観測と可視化  [通常講演]
    樋口雄介; 中村太郎; 古川亮; 佐川立昌; 川崎洋
    画像の認識理解シンポジウム MIRU2021 2021年07月 口頭発表(一般)
  • Auto-calibrated 3D endoscope with GCN-based correspondence search  [通常講演]
    Ryo Furukawa; Shiro Oka; Takahiro Kotachi; Yuki Okamoto; Shinji Tanaka; Hiroshi Kawasaki
    画像の認識理解シンポジウム MIRU2020 2020年08月 ポスター発表
  • 古川 亮, 内藤 雅仁, 宮崎 大輔, 馬場 雅志, 日浦 慎作(広島市大), 岡 志郎, 田中 信治(広島大病院), 川崎 洋(九大)  [通常講演]
    岩口 尭史; 栗田 拓弥; 時枝 康大; 古川 亮; 川崎 洋
    画像の認識理解シンポジウム MIRU2019 2019年08月
  • 3次元内視鏡におけるambient光源にロバストな投影パターン特徴抽出  [通常講演]
    古川 亮; 内藤 雅仁; 宮崎 大輔; 馬場 雅志; 日浦 慎作; 岡 志郎; 田中 信治; 川崎 洋
    画像の認識理解シンポジウム MIRU2019 2019年07月
  • MICCAI2018参加報告  [招待講演]
    小田昌宏; 大竹義人; 伊東隼人; 杉野貴明; 斉藤篤; 古川亮; 大西峻; 井宮淳; 森健策
    電子情報通信学会,医用画像研究会,MI2018-88 2019年01月 口頭発表(一般)
  • 能動ステレオ法のためのパターン検出におけるCNNによる複数特徴の同時抽出  [通常講演]
    溝森 将輝; 内藤 雅仁; 古川 亮; 馬場 雅志; 宮崎 大輔; 日浦 慎作; 川崎 洋
    第 21 回 画像の認識・理解シンポジウム 2018年08月 シンポジウム・ワークショップパネル(公募)
  • Grid-pattern feature detection technique using U-Nets for 3D endoscope  [通常講演]
    Masahito Naito; Ryo Furukawa; Masashi Okitomo; Daisuke Miyazaki; Masashi Baba; Shinsaku Hiura; Yoji Sanomura; Shinji Tanaka; Hiroshi Kawasaki
    第 21 回 画像の認識・理解シンポジウム 2018年08月 シンポジウム・ワークショップパネル(公募)
  • Underwater accurate shape reconstruction using CNNs  [通常講演]
    Kazuto Ichimaru; Ryo Furukawa; Hiroshi Kawasaki
    第 21 回 画像の認識・理解シンポジウム 2018年08月 シンポジウム・ワークショップパネル(公募)
  • Reproducibility Analysis of Case-Based Reasoning and Evolutionary Computation Method for Surface Reflectance Parameters Estimation  [通常講演]
    Albane Robert; Yuki Matsugano; Michihiro Mikamo; Satoshi Ono; Hiroshi Kawasaki; Kagoshima Uni; Hisato Fukuda(Saitama Univ; Ryo Furukawa; Hiroshima City
    画像の認識理解シンポジウム 2017年08月
  • Intra-frame motion encoding using high-fps structured light for temporal shape super-resolution  [通常講演]
    Yuki Shiba; Satoshi Ono(Kagoshima Univ; Ryo Furukawa; Shinsaku Hiura(Hiroshima City Uni; Hiroshi Kawasaki(Kagoshima U
    画像の認識理解シンポジウム 2017年08月
  • Depth and motion estimation from projected pattern's flow on object's surface  [通常講演]
    Ryo Furukawa; Hiroshima City Uni; Hiroshi Kawasaki(Kyushu Univ; Ryusuke Sagawa(AIST
    画像の認識理解シンポジウム 2017年08月
  • 見かけの大きさとぼけ量の関係に基づく物体認識の高速化  [通常講演]
    河本 悠; 宮崎 大輔; 古川 亮; 馬場 雅志; 日浦 慎作
    画像の認識理解シンポジウム 2017年08月
  • 3次元内視鏡のための点滅パターン光源によるHDR画像生成  [通常講演]
    内藤 雅仁; 古川 亮; 宮崎 大輔; 馬場 雅志; 日浦 慎作; 川崎 洋
    画像の認識理解シンポジウム 2017年08月
  • 焦点調節可能な複数レイヤディスプレイにおける光線空間近似精度の検討  [通常講演]
    中野 裕太; 多田野 司; 古川 亮; 馬場 雅志; 宮崎 大輔; 日浦 慎作; 川崎 洋
    画像の認識理解シンポジウム 2017年08月
  • 人体の動きを表現した3次元立体作品製作手法  [通常講演]
    古川 亮; 中野 裕太; 向井 貴昭; 馬場 雅志; 宮崎 大輔; 日浦 慎作
    情報処理学会研究会(CVIM第204回) 2016年11月 口頭発表(一般)
  • グリッド方式水中アクティブ・ワンショット計測システムのARマーカーを用いた校正および形状復元手法  [通常講演]
    馬場 博久; 華山 達也; 森永 寛紀; 中井 英晶; 古川 亮; 佐川 立昌; 川崎 洋
    画像の認識理解シンポジウム 2016年08月 ポスター発表
  • マルチバンドカメラを用いたワンショット照度差ステレオ法  [通常講演]
    津田 香林; 宮崎 大輔; 古川 亮; 日浦 慎作
    画像の認識理解シンポジウム 2016年08月 ポスター発表
  • GPUによるフィルタバンク演算の並列化の検討  [通常講演]
    向井 貴昭; 古川 亮; 宮崎 大輔; 馬場 雅志; 日浦 慎作
    画像の認識理解シンポジウム 2016年08月 ポスター発表
  • 3次元計測のための学習に基づく投影パターンの検出  [通常講演]
    沖友 真志; 古川 亮; 宮崎 大輔; 馬場 雅志; 日浦 慎作; 川崎 洋
    画像の認識理解シンポジウム 2016年08月 ポスター発表
  • 符号化開口付プロジェクタ・カメラシステムを用いたパターン特徴量の次元削減による高速・広範囲3次元計測  [通常講演]
    芝 優希; 堀田 祐樹; 小野 智司; 古川 亮; 日浦 慎作; 川崎 洋
    画像の認識理解シンポジウム 2016年08月 ポスター発表
  • 複数の任意形状に異なるパターンを同時投影するマルチプロジェクタ・システム  [通常講演]
    蛭川 琢斗; Marco Visentini-Scarzanella; 川崎 洋; 古川 亮; 日浦 慎作
    画像の認識理解シンポジウム 2016年08月
  • 超小型DOEパターン投光器を用いたアクティブステレオ方式3次元内視鏡  [通常講演]
    古川 亮; 川崎 洋; 佐川 立昌
    画像の認識理解シンポジウム 2016年08月
  • Compression and Interpolation of BTF Database using Non-negative Matrix Factorization  [通常講演]
    Kenshi Mizumoto; Shinsaku Hiura; Daisuke Miyazaki; Ryo Furukawa; Masashi Baba
    The 18th meeting on image recognition and understanding 2015年07月 ポスター発表
  • Simultaneous Independent Projections at Multiple Depths Using a Multi-Projector System  [通常講演]
    Marco Visentini-Scarzanella; Takuto Hirukawa; Hiroshi Kawasaki; Ryo Furukawa; Shinsaku Hiura
    The 18th meeting on image recognition and understanding 2015年07月 ポスター発表
  • Underwater 3D Shape Measurement with Static Wave Pattern for One-Shot Scan  [通常講演]
    Tatsuya Hanayama; Hirohisa Baba; Marco Visentini-Scarzanella; Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki
    The 18th meeting on image recognition and understanding 2015年07月 ポスター発表
  • メタメリズム生起のためのLED照明の最適化  [通常講演]
    宮崎 大輔; 中村 美亜; 馬場 雅志; 古川 亮; 日浦 慎作
    画像の認識理解シンポジウム 2015年07月 ポスター発表
  • 既知形状物体の陰影を利用したカメラ応答関数の推定  [通常講演]
    宮崎 大輔; 松原 充駿; 馬場 雅志; 古川 亮; 日浦 慎作
    画像の認識理解シンポジウム 2015年07月
  • スリット状符号化開口を備えたプロジェクタによる奥行き範囲の広いアクティブ3次元計測手法  [通常講演]
    芝 優希; 堀田 祐樹; 小野 智司; 古川 亮; 日浦 慎作; 川崎 洋
    画像の認識理解シンポジウム 2015年07月
  • 符号化開口の設計における交叉法の検討  [通常講演]
    河本 悠; 日浦 慎作; 宮崎 大輔; 古川 亮; 馬場 雅志
    画像の認識理解シンポジウム 2015年07月
  • アクティブステレオに基づく三次元内視鏡システムの2自由度自己校正  [通常講演]
    増谷 龍之輔; 古川 亮; 馬場 雅志; 宮崎 大輔; 青山 正人; 日浦 慎作; 川崎 洋; Marco Visentini-Scarzanella; 佐川 立昌
    画像の認識理解シンポジウム 2015年07月
  • Temporal Octrees for Compressing Dynamic Point Cloud Streams  [通常講演]
    Marcos Slomp; Hiroshi Kawasaki; Ryo Furukawa; Ryusuke Sagawa
    Dynamic Shape Measurement and Analysis 2014 (3DV 2014 Workshop) 2014年12月 口頭発表(一般)
  • 4D Capture using Visibility Information of Multiple Projector Camera System  [通常講演]
    Ryusuke Sagawa; Nozomu Kasuya; Yoshinori Oki; Hiroshi Kawasaki; Yoshio Matsumoto; Ryo Furukawa
    Dynamic Shape Measurement and Analysis 2014 (3DV 2014 Workshop) 2014年12月 口頭発表(一般)
  • 能動ステレオ法に基づく三次元内視鏡による生体組織の形状計測  [通常講演]
    古川 亮; 西谷維心; 青山正人; 日浦慎作; 青木広宙; 小南陽子; 松尾泰治; 吉田成人; 田中信治; 佐川立昌; 川崎 洋
    電子情報通信学会 PRMU研究会 2014年03月 口頭発表(一般)
  • Exemplar based texture recovery technique for active one shot scan  [通常講演]
    Yohan Thibault; Hiroshi Kawasaki; Ryusuke Sagawa; Ryo Furukawa
    The 13th IAPR Conference on Machine Vision Applications (MVA 2013) 2013年05月 ポスター発表
  • Calibration of the Projector with Fixed Pattern and Large Distortion Lens in a Structured Light System  [通常講演]
    Xingdou Fu; Zuofu Wang; Hiroshi Kawasaki; Ryusuke Sagawa; Ryo Furukawa
    The 13th IAPR Conference on Machine Vision Applications (MVA 2013) 2013年05月 ポスター発表
  • Hardware-Accelerated Geometry Instancing for Surfel and Voxel Rendering of Scanned 4D Media  [通常講演]
    Marcos Slomp; Ismael Daribo; Ryo Furukawa; Ryusuke Sagawa; Shinsaku Hiura; Naoki Asada; Hiroshi Kawasaki
    11th International Conference on Quality Control by Artificial Vision (QCAV) 2013年05月 ポスター発表
  • Inferring Texture for Active 3D Scan System  [通常講演]
    Yohan Thibault; Hiroshi Kawasaki; Yasuhiro Akagi; Ryusuke Sagawa; Ryo Furukawa
    ASIAGRAPH 2013 in Hawai'i 2013年04月 ポスター発表
  • A facial tracking and transfer method with a key point refinement  [通常講演]
    Yasuhiro Akagi; Ryo Furukawa; Ryusuke Sagawa; Koichi Ogawara; Hiroshi Kawasaki
    ACM SIGGRAPH 2013 2013年 ポスター発表
  • Extraction and Visualization of Cardiac Beat by Grid based Active Stereo  [通常講演]
    Hirooki Aoki; Ryo Furukawa; Masahito Aoyama; Shinsaku Hiura; Ryusuke Sagawa; Hiroshi Kawasaki
    ICPR-WS (International Workshop on Depth Image Analysis:WDIA 2012) 2012年11月 ポスター発表
  • Single Color One-shot Scan using Topology Information  [通常講演]
    Hiroshi Kawasaki; Hitoshi Masuyama; Ryusuke Sagawa; Ryo Furukawa
    Computer Vision – ECCV 2012. Workshops and Demonstrations 2012年10月 口頭発表(一般) 
    In this paper, we propose a new technique to achieve one-shot scan using single color and static pattern projector; such a method is ideal for acquisition of a moving object. Since a projector-camera systems generally have uncertainties on retrieving correspondences between the captured image and the projected pattern, many solutions have been proposed. Especially for one-shot scan, which means that only a single image is used for reconstruction, positional information of a pixel on the projected pattern should be encoded by spatial and/or color information. Although color information is frequently used for encoding, it is severely affected by texture and material of the object. In this paper, we propose a technique to solve the problem by using topological information instead of colors. Our technique successfully realizes one-shot scan with monochrome pattern.
  • Adaptive arithmetic coding for point cloud compression  [通常講演]
    Ismael Daribo; Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki
    Proc. 3DTV Conference 2012 2012年10月 ポスター発表
  • 全周囲形状計測システムにおける機器配置の評価  [通常講演]
    平田 信吾; 古川 亮; 日浦 慎作; 青山 正人; 青木 広宙; 佐川 立昌; 川崎 洋
    第17回知能メカトロニクスワークショップ 2012年08月 ポスター発表
  • Basic Study on Non-contact Measurement of Cardiac Beat by Using Grid-based Active Stereo  [通常講演]
    Hirooki Aoki; Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki; Shinsaku Hiura
    Proceedings of 34th Annual International Conference of the IEEE Engineering in Medicine and Biology Society 2012年08月 ポスター発表
  • 高密度3次元形状復元のための単色波線パターンを用いたグリッド能動ステレオ  [通常講演]
    阪下 和弘; 佐川 立昌; 古川 亮; 川崎 洋; 八木 康史
    第15回画像の認識・理解シンポジウム 2012年08月 口頭発表(一般)
  • アクティブ3次元センサを用いた簡易型非接触呼吸計測  [通常講演]
    青木広宙; 宮崎雅樹; 仲村秀俊; 古川亮; 佐川立昌; 川崎洋
    電子情報通信学会技術研究報告 2012年03月 口頭発表(一般)
  • Point Cloud Compression for Grid-Pattern-based 3D Scanning System  [通常講演]
    I. Daribo; R. Furukawa; Hiroshima City; University, Japa; R. Sagawa; u; Advanced; Industrial Science; Technology, Japa; H. Kawasaki; Kagoshima University; United States, Jap; S. Hiura; N. Asada; Hiroshima City; University, Ja
    Visual Communications and Image Processing 2011年11月 ポスター発表
  • Dynamic Compression of Curve-based Point Cloud  [通常講演]
    Ismael Daribo; Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki; Shinsaku hiura; Naoki Asada
    Pacific-Rim Symposium on Image and Video Technology 2011 2011年11月 口頭発表(一般)
  • "A System for Capturing Textured 3D Shapes based on One-shot Grid Pattern with Multi-band Camera and Infrared Projector"  [通常講演]
    Kazuhiro Sakashita; Yasushi Yagi; Ryusuke Sagawa; Ryo Furukawa; Hiroshi Kawasaki
    The First Joint 3DIM/3DPVT Conference 3D Imaging Modeling Processing Visualization Transmission 2011年05月 ポスター発表
  • "One-shot entire shape acquisition method using multiple projectors and cameras"  [通常講演]
    Ryo Furukawa; Ryusuke Sagawa; Hiroshi Kawasaki; Kazuhiro Sakashita; Yasushi Yagi; Naoki Asada
    The 4th Pacific-Rim Symposium on Image and Video Technology(PSIVT2010), pp.107-114, 11.2010 2010年11月 口頭発表(一般)
  • "One-shot scanning method using an uncalibrated projector and camera system"  [通常講演]
    Hiroshi Kawasaki; Ryusuke Sagawa; Yasushi Yagi; Ryo Furukawa; Naoki Asada; Peter Sturm
    IEEE Computer Society Conference on Computer Vision and Pattern Recognition Workshop, Procams2010 2010年06月 口頭発表(一般)
  • "Linear solution for oneshot active 3D reconstruction using two projectors "  [通常講演]
    Ryusuke Sagawa; Kazuhiro Sakashita; Yuya Ohta; Yasushi Yagi; Ryo Furukawa; Ryota Zushi; Naoki Asada; Hiroshi Kawasaki
    5th international symposium on 3D data processing, visualization and transmission (3DPVT2010) 2010年05月 口頭発表(一般)
  • "Shape Rank: Efficient Web3D search technique using 3D features"  [通常講演]
    Masahiro Ishikawa; Hiroshi Kawasaki; Ryo Furukawa; Yukiko Kawai
    11th ACM SIGMM International Conference on Multimedia Information Retrieval 2010年03月 ポスター発表
  • Dense 3D Reconstruction Method Using a Single Pattern for Fast Moving Object  [通常講演]
    Ryusuke Sagawa; Yuya Ohta; Yasushi Yagi; Ryo Furukawa; Naoki Asada; Hiroshi Kawasaki
    In Proc. 2009 IEEE 12th International Conference on Computer Vision (ICCV) 2009年09月 ポスター発表
  • "Super-Resolution of Multiple Moving 3D Objects with Pixel-based Registration"  [通常講演]
    Takuma Yamaguchi; Hiroshi Kawasaki; Ryo Furukawa; Toshihiro Nakayama
    Asian Conference on Computer Vision(ACCV 2009) 2009年09月 ポスター発表
  • One-shot Range Scanner using Coplanarity Constraints  [通常講演]
    Ryo Furukawa; Huynh; Quang Huy Viet; Hiroshi Kawasaki; Ryusuke Sagawa; Yasushi Yagi
    Proc. of international conference on image processing (ICIP 2008) 2008年10月 ポスター発表
  • 実物体のシームレステクスチャ付き3次元モデルの自動生成システム  [通常講演]
    猪瀬 健二; 榎本 和史; 川崎 洋; 古川 亮
    第11回 画像の認識・理解シンポジウム論文集(MIRU2008論文集) 2008年07月 ポスター発表
  • ワンショットスキャンによる動物体の密な3次元形状復元手法  [通常講演]
    古川 亮; 川崎 洋; 佐川 立昌; 八木 康史
    第11回 画像の認識・理解シンポジウム論文集(MIRU2008論文集) 2008年07月 口頭発表(一般)
  • Improved Space Carving Method for Merging and Interpolating Multiple Range Images Using Information of Light Sources of Active Stereo  [通常講演]
    R. Furukawa; T. Itano; A. Morisaka; H. Kawasaki
    COMPUTER VISION-ACCV2007, 8th Asian Conference on Computer Vision, LNCS 4844 2007年11月 口頭発表(一般)
  • Shape Reconstruction from Cast Shadows Using Coplanarities and Metric Constraints  [通常講演]
    H. Kawasaki; R. Furukawa
    COMPUTER VISION-ACCV2007, 8th Asian Conference on Computer Vision, LNCS 4844 2007年11月 口頭発表(一般)
  • Geometrical constraint based 3D reconstruction using implicit coplanarities  [通常講演]
    R. Furukawa; H. Kawasaki
    Proceedings of British Machine Vision Conference 2007 (BMVC2007) 2007年09月 口頭発表(一般)
  • Shape-merging and interpolation using class estimation for unseen voxels with a GPU-based efficient implementation  [通常講演]
    Ryo Furukawa; Tomoya Itano; Akihiko Morisaka; Hiroshi Kawasaki
    Proceedings of the Sixth International Conference on 3-D Digital Imaging and Modeling (3DIM 2007) 2007年08月 口頭発表(一般)
  • Dense 3D Reconstruction method using Coplanarities and Metric Constraints for Line Laser Scanning  [通常講演]
    Hiroshi Kawasaki; Ryo Furukawa
    Proceedings of the Sixth International Conference on 3-D Digital Imaging and Modeling (3DIM 2007) 2007年08月 口頭発表(一般)
  • 詳細形状の保存を考慮した距離画像からの雑音除去  [通常講演]
    原田真治; 古川亮; 川崎洋
    画像の認識・理解シンポジウム(MIRU2007) 2007年07月 ポスター発表
  • 未観測ボクセルのクラス推定を用いた形状の統合及び補間手法とGPUを用いた高速な実装  [通常講演]
    板野友哉; 森栄晃彦; 古川亮; 川崎洋
    画像の認識・理解シンポジウム(MIRU2007) 2007年07月 口頭発表(一般)
  • プロジェクタ・カメラを用いた3次元計測システムにおける複数形状計測時の誤差最小化による精度向上手法  [通常講演]
    榎本和史; 川崎洋; 古川 亮
    画像の認識・理解シンポジウム(MIRU2007) 2007年07月 口頭発表(一般)
  • 全周3次元モデル生成のための複数テクスチャのシームレスな合成手法  [通常講演]
    猪瀬健二; 榎本和史; 川崎洋; 古川亮
    画像の認識・理解シンポジウム(MIRU2007) 2007年07月 口頭発表(一般)
  • 共面性情報を用いた影による自由曲面形状の復元手法  [通常講演]
    川崎洋; 古川亮
    画像の認識・理解シンポジウム(MIRU2007) 2007年07月 口頭発表(一般)
  • 3D acquisition system using uncalibrated line-laser projector  [通常講演]
    Hiroshi Kawasaki; Ryo Furukawa
    International Conference on Pattern Recognition 2006 2006年08月 ポスター発表
  • ラインレーザの自己校正による3次元復元手法 -アクティブ3次元計測における最小構成システムについての提案-  [通常講演]
    川崎 洋; 古川 亮; 中村 泰明
    画像の認識・理解シンポジウム(MIRU2006) 2006年07月 口頭発表(一般)
  • Self-calibration of multiple laser planes for 3D scene reconstruction  [通常講演]
    Ryo Furukawa; Hiroshi Kawasaki
    Third International Symposium on 3D Data Processing, Visualization and Transmission(3DPVT 2006) 2006年06月 ポスター発表
  • Dense 3D reconstruction with an uncalibrated active stereo system  [通常講演]
    Hiroshi Kawasaki; Yutaka Ohsawa; Ryo Furukawa; Yasuaki Nakamura
    LNCS 3851, the 7th Asian Conference on Computer Vision (ACCV06) 2006年01月 口頭発表(一般)
  • Synthesis of Textures with Intricate Geometries using BTF and Large Number of Textured Micropolygons  [通常講演]
    Ryo Furukawa; Masaharu Harada; Yasuaki Nakamura; Hiroshi Kawasaki
    Proc. of Texture 2005, The 4th international workshop on texture analysis and synthesis in conjunction with ICCV2005 2005年10月 口頭発表(一般)
  • 空間コード化法を用いた未校正ステレオシステムによる 密な3次元形状復元  [通常講演]
    川崎洋; 大澤裕; 古川亮
    画像の認識・理解シンポジウム(MIRU2005) 2005年07月 口頭発表(一般)
  • Uncalibrated multiple image stereo system with arbitrary movable camera and projector for wide range scanning  [通常講演]
    Ryo Furukawa; Hiroshi Kawasaki
    Proceedings of the 5th International Conference on 3-D Digital Imaging and Modeling (3DIM 2005) 2005年06月 口頭発表(一般)
  • Dense 3D Reconstruction with an Uncalibrated Stereo System using Coded Structured Light  [通常講演]
    Ryo Furukawa; Hiroshi Kawasaki
    International Workshop on Projector-Camera Systems (PROCAMS 2005) 2005年06月 口頭発表(一般)
  • Combined use of 2D images and 3D models for retrieving and browsing digital archive contents  [通常講演]
    R. Kadobayashi; R. Furukawa
    Proc. Int. Conf. on Videometrics 2005年01月 口頭発表(一般)
  • 回転台を用いた3次元形状の全周リアルタイム獲得システム  [通常講演]
    角野 裕樹; 川崎 洋; 大沢 裕; 古川 亮
    画像の認識・理解シンポジウム(MIRU2004) 2004年07月 ポスター発表
  • 3次元形状データの考古学スケッチ風レンダリング  [通常講演]
    水口 隆介; 古川 亮; 門林 理恵子
    画像の認識・理解シンポジウム(MIRU2004) 2004年07月 ポスター発表
  • Error Analysis of 3D Measurement System based on Sensitivity of Measuring Conditions  [通常講演]
    Ryo Furukawa; Hiroshi Kawasaki
    Proc. of 6th Asian Conference on Computer Vision(ACCV2004) 2004年01月 口頭発表(一般)
  • Interactive Shape Acquisition using Marker Attached Laser Projector  [通常講演]
    R. Furukawa; H. Kawasaki
    Proc. of 4th International Conference on 3-D Digital Imaging and Modeling (3DIM2003) 2003年10月 口頭発表(一般)
  • Removal of Shadows and Shadings from Texture Images for Archiving Historical Ruins  [通常講演]
    R. Furukawa; Y. Kiuchi; R. Kadobayashi
    Proc. of ISPRS Internatnional Workshop by WG V/4 & IC WG III/V "Vision Techniques for Digital Architectural and Archaeological Archives" 2003年10月 口頭発表(一般)
  • Image-based approach for modeling, deformation, and synthesis of real objects  [通常講演]
    Ryo Furukawa; Hiroshi Kawasaki; Ryunosuke Kawatsu; Masao Sakauchi
    画像の認識・理解シンポジウム(MIRU2002) 論文集 2002年07月 口頭発表(一般)
  • Appearance Based Object Modeling using Texture Database: Acquisition, Compression and Rendering  [通常講演]
    R. Furukawa; H. Kawasaki; R. Kawatsu; D. Miyazaki; K. Ikeuchi; M. Sakauchi
    Rendering techniques 2002, Eurographics Workshop Proceedings 2002年06月 口頭発表(一般)
  • Acquiring Bidirectional Texture Function for Image Synthesis of Deformed Objects  [通常講演]
    R. Furukawa; H. Kawasaki; K. Ikeuchi
    Proc. of Fifth Asian Conference on Computer Vision(ACCV2002) 2002年01月 ポスター発表
  • 白内障手術シミュレーションシステム  [通常講演]
    田中純; 仁井谷 智恵; 児島 彰; 古川亮; 藤野 清次; 中村 泰明
    画像の認識・理解シンポジウム(MIRU2000) 論文集 2000年07月 ポスター発表
  • Spatio-temporal Data Management for Moving Objects Using the PMD-tree  [通常講演]
    Y. Nakamura; H. Dekihara; R. Furukawa
    Proc. of the International Workshops on New Database Technologies for Collaborative Work Support \& Spatio-Temporal Data 1998年07月 口頭発表(一般)
  • ATMIQ: Active Tubes in Multiscale Image Queue  [通常講演]
    R. Furukawa; M. Imai; T. Uno
    Proceedings of 13th International Conference on Pattern Recognition 1996年08月 ポスター発表
  • Robust Algorithm for Motion Analysis Based on Active Tubes  [通常講演]
    R. Furukawa; M. Imai; T. Uno
    Proceedings of WorkShop on Motion of Non-Rigid and Articulated Objects 1994年11月 ポスター発表

所属学協会

  • 2009年度 情報処理学会CVIM研究会 運営委員   電子情報通信学会   情報処理学会   The Institute of Electronics, Information and Communication Engineers   Information Processing Society of Japan   

共同研究・競争的資金等の研究課題

  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2020年04月 -2025年03月 
    代表者 : 川崎 洋; THOMAS DIEGO; 佐川 立昌; 小池 賢太郎; 古川 亮; 巻 俊宏; 岩口 尭史; 高松 淳
     
    水中での形状計測や解析に対する関心が高まっていることから、本研究では、高密度・高精度に広範囲の水中の3次元形状を計測する手法を開発する。提案手法では、ROVやAUVなど水中ロボットに開発する計測装置を搭載し、移動しながら水中の3次元形状を取得し、これらを位置合わせすることで、GPSの使えない水中においても広範囲の形状を計測する。
    具体的には、本研究を通して、水中3次元計測の課題である、①屈折の影響や光量の減衰やベースライン不足による精度低下、②電波が届かず見通しの悪い水中での自己位置推定の難しさ、さらに③複数の3次元形状を統合することや計測結果の解析の困難さの解消を目指す。
    初年度は、上記課題を解消するため、主に水中アクティブ3次元センサの基礎アルゴリズム開発および検証実験を実施した。具体的には、水中では中心投影カメラモデルが成り立たないため、ライトフィールドによる補正手法や、大きな歪に対応した近似モデルの2つの手法による解決を実現した。また、プロジェクタの光量の減衰については、i)ラインレーザを用いる共面性復元を水中で使用するできるように変更するための理論構築および実装し実験した。これにより、従来のレーザ復元手法では、1本のラインレーザしか使用できなかったのに対し、共面性による本手法では、より多くのラインレーザを用いたグリッドパターンにより、高精度かつ高密度に3次元復元することができることを確認した。また、並行して、水中ロボットに3次元センサを設置して水中で広範囲の形状計測を実現するための水中ロボット開発やロボットに設置する3次元復元計測装置の開発、およびそれらを用いた実験を実施した。具体的にはROVに、現在開発を進めている水中3次元アクティブセンサを設置して、プールや港湾にて計測テストや精度評価を実施した。これら成果を査読付き会議へ投稿した他、九州大学から特許出願の予定である。
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2018年04月 -2023年03月 
    代表者 : 古川 亮; 田中 信治; 佐川 立昌; 岡 志郎; 川崎 洋; 宮崎 大輔; 馬場 雅志; 日浦 慎作
     
    2020年度には、「(3)形状解像度,距離精度の向上」「(4)(深層学習による)複雑な対象形状への対応」を進めるための方策として,2019年度から継続して,格子パターンの抽出結果から格子グラフを作成し,グラフに対して作用するグラフ畳み込みネットワークを適用することでグラフのノードごとに格子点のIDを推定するアルゴリズムを開発した. さらに,そのようなグラフ畳み込みネットワークの学習を行うために,CGで学習用データを生成し,CGデータから学習用データを生成する手法を開発した.このような手法では,CGによって学習用画像を生成すると共に,例えばノードごとに対応IDを色で表現した画像をレンダリングすることによって,各ノードについての正解ID値をCG画像からサンプリングすることができる.また,大腸など,非常に複雑な対象形状への対応の準備として,大腸に似せた形状モデルに対して,パターン投影画像のCG描画を行う実験を実施した.研究成果の一部は,国際学会EMBCで発表された. また,投影パターンから,深層学習によって画像特徴(パターンの格子構造,コード情報など)を取得する際,大量の学習データを作成する必要があるが,このようなデータもCGで作成することは解決策の一つである.今年度は,CGで作成されたパターンで深層学習モデルの事前学習を行い,実際の少量のデータで実データに適合させる方法を開発した.その成果は,情報処理学会研究報告で報告された. また,3次元内視鏡に関する研究の一部を,2020年度に出版した大学院向けの教科書に掲載した.
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2016年04月 -2019年03月 
    代表者 : 川崎 洋; 辻村 誠一; 日浦 慎作; 古川 亮; 小野 智司; 三鴨 道弘
     
    本研究では、(A)符号化したアパーチャをプロジェクタのレンズに設置することによるライトフィールド・プロジェクタを構築し、被写界深度の拡大を実現し、さらに、これを実システムで使用するため、(B)ライトフィールド・プロジェクタのキャリブレーション手法を開発し、加えて、複数台のプロジェクタを用いて(C)合成ライトフィールドを生成することで遮蔽物の多いシーンにおける密な3次元復元を実現するシステム、および(D)空間中の任意の平面に任意のパターンを描画するシステムを開発した。成果は著名な国際会議に採択され発表した他、特許出願した。
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2015年04月 -2018年03月 
    代表者 : 古川 亮; 田中 信治; 川崎 洋; 佐川 立昌; 吉田 成人
     
    内視鏡の鉗子孔に通すことが可能な、超小型、高輝度化、長焦点深度のパターン光源を開発した。さらに、生体組織のように、パターン光源を照射した時に、散乱、鏡面反射によるハイライト、パターン中の輝点による露出過多の起きる物体でも、安定した計測が可能な能動ステレオ方式の形状計測手法を開発した。これらの成果を通常の内視鏡と組み合わせることで、豚の消化管内部の形状を、実際と同じスケールで計測することに成功した。
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2015年04月 -2018年03月 
    代表者 : 日浦 慎作; 宮崎 大輔; 古川 亮; 馬場 雅志; 水本 憲志; 橋本 修平
     
    複雑な反射特性を有する物体の形状と反射特性を効率よくモデル化・レンダリングする手法を開発した.見えの計測と圧縮については,負値を取り扱う必要がないNMF(非負値行列因子分解)を用いることで,レンダリングの高速化にも寄与することを示した.また形状の計測については,照明の方位が不明でも陰影変化から物体の形状を求めることができる未校正照度差ステレオ法に関する研究を行った.
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2009年 -2011年 
    代表者 : 佐川 立昌; 古川 亮; 川崎 洋
     
    本提案の目的は、超高速な形状計測センサの開発および、計測した形状データを用いた応用の研究を行うことである。提案する形状計測手法は、プロジェクタから固定したパターンを投影し、観測対象上に写ったパターンをカメラで観測することによって形状を復元する。単一画像から形状データを得られるため、ハイスピードカメラを用いることにより、高速な事象の観測が可能な手法を開発した。これまでの実験により、1000~32000コマ/秒で撮影された、複雑かつ高密度な形状の計測に成功した。
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2007年 -2009年 
    代表者 : 古川 亮
     
    プロジェクタとカメラを利用して、テクスチャ付きの全周囲3次元形状モデルを作成するシステムを構築する研究を行った。この研究により,(1)複数形状の位置合わせを精密に行う手法、(2)複数形状を統合した単一の全周囲モデルを高速に生成する方法、(3)多数の光源条件下で撮影された画像集合から、反射特性パラメータを推定し、統合されたテクスチャを生成する方法、(4)プロジェクタでパターンを投影することで運動する物体を計測することが可能な形状計測方法が開発された。
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2006年 -2006年 
    代表者 : 中村 泰明; 内田 智之; 古川 亮; 坂田 勝巳
     
    近年、脳神経外科領域では、頭蓋底手術の技術発達、微小手術解剖の詳細な検討により、脳神経、脳血管、頭蓋底構造物などの複雑な手術立体解剖の知識と多くの手術経験が要求される深部病変への手術が行えるようになってきた。一般に、脳神経外科医は経験をもとにCT(コンピュータ断層画像)、MRI(核磁気共鳴画像)、脳血管撮影により得られた情報と腫瘍の解剖学的見地を加味することで頭の中で立体構造をイメージし、頭の中で手術シュミレーションを行ったうえで手術到達法を作成する。本研究課題では、より安全な外科的治療を提供できる脳神経外科医の育成に寄与するため、仮想現実感(VR)技術を応用した触覚を伴った東部神経外科手術支援・シミュレーションシステムの開発を行う。平成18年度は以下のテーマについて研究する予定であった。 1.CT、MR画像からの精細な頭部3次元ソリッドモデルの構成 2.柔軟で変形可能なボリュームモデルの構築 3.CR、MR画像の高精度化 4.組織.器官の触覚モデルの作成 5.3次元ソリッドモデルの高速表示 6.CT、MR画像の領域分割アルゴリズムの検討研究 7.3次元空間における対話操作のためのデータ管理方式の研究 しかし、本年度からスタートした研究課題である上、9月末に研究全体を統括する研究代表者の急な退職により、研究打合せ等も十分であったとは言えず、実質的な研究成果はこれまでに継続していた研究の延長線上にある「どのボクセルに操作が適用されているのかを高速にハンドリングするための新しい空間データ構造であるMVR+木の開発に関する成果のみであった。
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2005年 -2006年 
    代表者 : 古川 亮; 中村 泰明
     
    本研究の目的は,物質表面の微細形状や質感をモデル化し、表現するための手法の研究である. (a)立体形状を持つ物体をサンプリングし,CGとして再現するためには,物体の形状と見え(appearance)を,同時にサンプリングする必要がある.このための手法として,従来からラインレーザによる光切断法を用いてきたが,そのために必要なラインレーザの校正手法は,非常に複雑なものであった.本研究では,プロジェクタ,あるいはラインレーザを用いて物体の計測を行うために,光源の位置や方向などについて校正を行うことなく形状データを計測することができる手法を開発した.この手法については,3次元データ解析および可視化についての国際会議であるIEEE International Symposium on 3D Data Processing, Visualization and Transmission(3DPVT)と,国内最大のコンピュータビジョンの会議である、画像の認識・理解シンポジウム(MIRU)で発表された. (b)物体の見えのサンプリングを行い,CGとして描画可能なデータを得るための工程を行うためには,物体のサンプリング,サンプリングされた画像からのテクスチャの切り出し(レクティフィケーション),球面調和関数によるテクスチャデータの近似,テクスチャの統合など,複雑な処理を必要とする,これらの処理を行うために,従来はユーザが逐一パラメータと処理を指定していたが,その処理の煩雑さゆえにユーザに対する負荷が大きく,専門的能力を必要とした.そこで,これらの処理を,インタラクティブに行うことの出来るユーザインターフェースを開発した.
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2004年 -2005年 
    代表者 : 中村 泰明; 内田 智之; 古川 亮
     
    ネットワークカメラにより送られて来る映像情報から、移動オブジェクトを抽出・追跡し、移動物体に関する情報を初期イベントとして、監視制御システムに転送する。監視制御システムは、イベントの時系列を表現するイベントグラフにより表現された危険状態を保持し、送られてきたイベントから危険状態を判定する。今年度は、移動物体抽出、イベント生成、監視制御システムを統合したプロトタイプシステムを試作し、駐車場監視システムを適用した。移動オブジェクトとしては、車、人間、その他とし、監視空間(駐車場)内の駐車スロットごとに危険領域を設定した。危険状態として、移動オブジェクト同士の衝突、駐車スロット内への人間の長時間滞在を設定した。ビデオ映像から移動オブジェクトのおよその3次元位置、大きさ、色情報を抽出し、<オブジェクトID、時刻、位置、高さ、幅、色>をイベントとして、監視制御システムに転送する。2次元画像処理では映像上で重なっている移動オブジェクトは衝突と判定されるが、3次元位置を検出することで、3次元空間で衝突していない場合を判定可能とした。監視制御システムでは、危険領域(駐車スロット)を20個、通常監視領域を1個設定した。駐車スロットに対しては、人間の滞在時間により警報を発生させることとした。危険領域、通常管理領域とも、移動オブジェクト同士の衝突を危険状態として設定した。通常監視領域には、さらに、車の長時間滞在を危険状態として設定した。移動オブジェクトが、いずれかの状態に陥った場合、警報を発生させるものとする。映像からの移動物体の検出では、長時間の監視を行うため、背景の緩やかな変化に対応できる差分方式を提案し、実験により有効性を示した。監視制御システムでは、移動オブジェクト同士の衝突、指定領域内に含まれるオブジェクトの効率的な検索を実行するために時空間データ構造であるPMD木を応用した。実験より3次元位置を使うことで車同士の衝突の検出、衝突なしのすれ違いの検出がほぼ可能であった。
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2002年 -2003年 
    代表者 : 中村 泰明; 古川 亮; 内田 智之
     
    技術設計のデータベースにおいては,各設計間での参照関係が存在する.また,ある設計を一部修正して別のバージョンの設計とすることがしばしばである.設計データベースにおいては,図面が重要な役割をはたす.図面データを効率的に管理することが設計データベース管理システムでは要求されるが,各バージョンに対応した図面間では,一部しか変化していないにもかかわらず,全データをデータベースに格納されることが多く,データ量の増大をもたらす.そこで,本研究では,図面間の差分を効率的に管理し,変化しない部分を共有化する方式を提案した.すなわち,複数バージョンの図面データから重複部分を除くことで,効率的なバージョン管理構造を発案した.シミュレーション実験によれば,従来のもっとも単純な方式に比べ,必要なメモリー量を1/3に削減することが可能となった.しかも,データ検索効率は,従来法とほとんど同等の性能であった. また,HTML文書などの半構造化データを木構造で表現し,頻出する構造を検出することで,木構造を圧縮する手法を提案した. さらに,図面などの幾何構造データの接続関係,トポロジーを保存した可逆圧縮方式を提案し,グラフ文法で表現することが可能であることを示した.プラントソフトウェアの構造表現に,この方式を応用し,グラフ表現とソフトウェア構造を対応させることで,監視制御システムソフトウェアの半自動合成法を提案した.
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2000年 -2001年 
    代表者 : 古川 亮; 内田 智之; 中村 泰明
     
    原子力プラント、発変電所、駐車場などの屋外の施設や屋内の重要施設では、24時間の監視が要求される場合がある。現状では、ビテオカメラの映像を監視員がテレビモニターを目視することよるチェックが普通であるが、こういった業務は肉体的な疲労と精神的なストレスを伴う。本研究では、このような監視業務を支援するシステムに関する研究を実施した。具体的には以下の研究を行った. 1.パンチルトカメラにおいて,カメラ旋回中においても背景/フレーム間差分塗を利用するために,円筒面への投影画像を作成し,その画像における複数のテンプレートマッチングの結果を多数決にかけることで背景の移動量を推定し,補正することで差分法を利用できるようにするアルゴリズムを開発した. 2.PMD木というデータ構造を用いることで,監視対象において生じる時空間イベントを効率よく記録/検索することを提案し,その実相の性能評価を行った. 3.監視対象の施設を高い臨場感で再現するために,ウオークスルー可能な写真を用いた仮想3次元環境を構築する手法と,写真画質で変形可能な仮想オブジェクトを構築する手法について研究した. 4.時空間におけるイベントのパターンを学習,分類するために,位置情報を加えたグラフ表現を提案し,そのグラフデータの表現と検索方式,また,学習アルゴリズムを開発するためのパターンの抽出に関する研究を実施した.
  • 日本学術振興会:科学研究費助成事業
    研究期間 : 2000年 -2001年 
    代表者 : 中村 泰明; 菅野 洋; 古川 亮; 内田 智之
     
    従来,ポリゴンで構成されていたCG(コンピュータグラフィックス)モデルを内部の詰まったソリッドモデルで構成し,このソリッドモデルに対して,変形,切開などの操作を可能とした.また,ソリッドモデルの高速な表示アルゴリズムを考案し,実験により実用性を評価した.実際のシステムにソリッドモデルを適用するために,CT画像からのソリッドモデルへの変換方式を提案した.さらに,平成12年度に開発されたボリュームグラフィックスボードを購入し,汎用のPCにおいても,高機能ワークステーションと同程度のスピードでの描画性能を実現した.仮想的3次元空間中のオブジェクトに対する操作を実現するためには,メスと頭部表皮との交差判定や内部判定(以下,干渉チェックと呼ぶ)を高速に実現する必要がある.このためには,空間中のオブジェクトを効率的に管理し,距離に基づく検索を高速・確実に実行しなければならない.空間オブジェクトの管理と検索,さらにオブジェクトの時間的な変化の効率的管理方式として,PMD木というデータ構造を開発し,その性能評価を実施した.PMD木を用いることで,膨大な空間オブジェクトの時間的な変化や位置変化の履歴管理が可能であることを示した.CT画像や実写画像から変形可能な3次元モデルの作成方式に関する研究では,複数の実写画像と3次元地図から仮想3次元空間を構築し,その中をウォークスルーできるシステムの実現方式を提案した[8].さらに,オブジェクトをあらゆる方向から撮影することで,写真品質での変形可能な仮想オブジェクトを構築する方式を提案した.位置構造をもつグラフデータの表現と検索方式,パターンマッチシグ方式に関する研究を実施した.

産業財産権

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