九州大学 研究者情報
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岩口 尭史(いわぐち たかふみ) データ更新日:2023.11.27

助教 /  システム情報科学研究院 情報知能工学部門


原著論文
1. Takafumi Iwaguchi, Takuya Funatomi, Hiroyuki Kubo, Yasuhiro Mukaigawa, Light path alignment for computed tomography of scattering material, IPSJ Transactions on Computer Vision and Applications, 10.1186/10.1186/s41074-016-0003-2, 8, 1, 2016.12, [URL], We aim to estimate internal slice of the scattering material by Computed Tomography (CT). In the scattering material, the light path is disturbed and is spread. Conventional CT cannot measure the scattering material because they rely on the assumption that rays are straight and parallel. We propose light path alignment to deal with scattering rays. Each path of disturbed scattering light is approximated with a straight line. Then the light path in the object corresponding to a single incident ray is modeled as straight paths spreading from incident point. These spreading paths are aligned to be parallel, so that they can be used directly by conventional reconstruction algorithm..
2. Xingji Zeng, Takafumi Iwaguchi, Hiroyuki Kubo, Takuya Funatomi, Yasuhiro Mukaigawa, Estimating parameters of subsurface scattering using directional dipole model, 16th NICOGRAPH International, NICOInt 2017
Proceedings - 2017 NICOGRAPH International, NICOInt 2017
, 10.1109/NICOInt.2017.20, 41-48, 2017.09, [URL], Acquisition of parameters for the Bidirectional Scattering Surface Reflectance Distribution Function (BSSRDF) has significant meanings in the study of computer graphics and vision research field. In this paper, we present an inverse rendering approach combined with a newly developed BSSRDF model, directional dipole model, for parameter estimation. To validate our algorithm, we estimate parameters from spheres with a wide range of radius in a simulated and real environment, respectively. According to the observations from both simulated and real experiments, we find that surface curvature significantly affects the estimation results..
3. Hiroyuki Kubo, Suren Jayasuriya, Takafumi Iwaguchi, Takuya Funatomi, Yasuhiro Mukaigawa, Srinivasa G. Narasimhan, Acquiring and characterizing plane-to-ray indirect light transport, 2018 IEEE International Conference on Computational Photography, ICCP 2018
IEEE International Conference on Computational Photography, ICCP 2018
, 10.1109/ICCPHOT.2018.8368461, 1-10, 2018.05, [URL], Separation of light transport into direct and indirect paths has enabled new visualizations of light in everyday scenes. However, indirect light itself contains a variety of components from subsurface scattering to diffuse and specular interreflections, all of which contribute to complex visual appearance. In this paper, we present a new imaging technique that captures and analyzes these components of indirect light via light transport between epipolar planes of illumination and rays of received light. This plane-to-ray light transport is captured using a rectified projector-camera system where we vary the offset between projector and camera rows (implemented as synchronization delay) as well as the exposure of each camera row. The resulting delay-exposure stack of images can capture live short and long-range indirect light transport, disambiguate subsurface scattering, diffuse and specular interreflections, and distinguish materials according to their subsurface scattering properties..
4. Takafumi Iwaguchi, Hiroyuki Kubo, Takuya Funatomi, Yasuhiro Mukaigawa, Srinivasa Narasimhan, Acquiring short range 4D light transport with synchronized projector camera system, 24th ACM Symposium on Virtual Reality Software and Technology, VRST 2018
Proceedings - VRST 2018
24th ACM Symposium on Virtual Reality Software and Technology
, 10.1145/3281505.3283377, 2018.11, [URL], Light interacts with a scene in various ways. For scene understanding, a light transport is useful because it describes a relationship between the incident light ray and the result of the interaction. Our goal is to acquire the 4D light transport between the projector and the camera, focusing on direct and short-range transport that include the effect of the diffuse reflections, subsurface scattering, and inter-reflections. The acquisition of the light transport is challenging since the acquisition of the full 4D light transport requires a large number of measurement. We propose an efficient method to acquire short range light transport, which is dominant in the general scene, using synchronized projector-camera system. We show the transport profile of various materials, including uniform or heterogeneous subsurface scattering..
5. Takafumi Iwaguchi, Takuya Funatomi, Takahito Aoto, Hiroyuki Kubo, Yasuhiro Mukaigawa, Optical tomography based on shortest-path model for diffuse surface object, IPSJ Transactions on Computer Vision and Applications, 10.1186/s41074-018-0051-x, 10, 1, 2018.12, [URL], We tackle an optical measurement of the internal structure of a diffuse surface object—we define as an object that has a diffuse surface and its interior is transparent, like grapes or hollow plastic bottles. Our approach is based on optical tomography that reconstructs the interior from observations of absorption of light rays from various views, under the projection of the light. The difficulty lies in the fact that a light ray that enters changes its direction at the interaction of the surface, unlike X-ray that travels straight through the object. We introduce a model of light path in the object called shortest-path model. We acquire the absorption of light rays through the object by the measurement upon the assumption of the model. Since this measurement acquires insufficient observation to reconstruct the interior by conventional reconstruction algorithms, we also introduce a reconstruction method based on a numerical optimization that a physical requirement of the absorption is taken into account. Our method is confirmed successful to measure the interior in a real-world experiment..
6. H. Kubo, S. Jayasuriya, T. Iwaguchi, T. Funatomi, Y. Mukaigawa, Programmable Non-Epipolar Indirect Light Transport: Capture and Analysis, IEEE Transactions on Visualization and Computer Graphics, IEEE Transactions on Visualization and Computer Graphics, 2019.10.

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