Browsing by Author "Dobashi, Yoshinori"

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    An Efficient Hybrid Incompressible SPH Solver with Interface Handling for Boundary Conditions
    (© 2018 The Eurographics Association and John Wiley & Sons Ltd., 2018) Takahashi, Tetsuya; Dobashi, Yoshinori; Nishita, Tomoyuki; Lin, Ming C.; Chen, Min and Benes, Bedrich
    We propose a hybrid smoothed particle hydrodynamics solver for efficientlysimulating incompressible fluids using an interface handling method for boundary conditions in the pressure Poisson equation. We blend particle density computed with one smooth and one spiky kernel to improve the robustness against both fluid–fluid and fluid–solid collisions. To further improve the robustness and efficiency, we present a new interface handling method consisting of two components: free surface handling for Dirichlet boundary conditions and solid boundary handling for Neumann boundary conditions. Our free surface handling appropriately determines particles for Dirichlet boundary conditions using Jacobi‐based pressure prediction while our solid boundary handling introduces a new term to ensure the solvability of the linear system. We demonstrate that our method outperforms the state‐of‐the‐art particle‐based fluid solvers.We propose a hybrid smoothed particle hydrodynamics solver for efficiently simulating incompressible fluids using an interface handling method for boundary conditions in the pressure Poisson equation. We blend particle density computed with one smooth and one spiky kernel to improve the robustness against both fluid–fluid and fluid–solid collisions.To further improve the robustness and efficiency, we present a new interface handling method consisting of two components: free surface handling for Dirichlet boundary conditions and solid boundary handling for Neumann boundary conditions.
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    An Interactive Modeling System of Japanese Castles with Decorative Objects
    (The Eurographics Association, 2022) Umeyama, Shogo; Dobashi, Yoshinori; Yang, Yin; Parakkat, Amal D.; Deng, Bailin; Noh, Seung-Tak
    We present an interactive modeling system for Japanese castles. We develop an user interface that can generate the fundamental structure of the castle tower consisting of stone walls, turrets, and roofs. By clicking on the screen with a mouse, relevant parameters for the fundamental structure are automatically calculated to generate 3D models of Japanese-style castles. We use characteristic curves that often appear in ancient Japanese architecture for the realistic modeling of the castles.
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    Two-stage Resampling for Bidirectional Path Tracing with Multiple Light Sub-paths
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Nabata, Kosuke; Iwasaki, Kei; Dobashi, Yoshinori; Eisemann, Elmar and Jacobson, Alec and Zhang, Fang-Lue
    Recent advances in bidirectional path tracing (BPT) reveal that the use of multiple light sub-paths and the resampling of a small number of these can improve the efficiency of BPT. By increasing the number of pre-sampled light sub-paths, the possibility of generating light paths that provide large contributions can be better explored and this can alleviate the correlation of light paths due to the reuse of pre-sampled light sub-paths by all eye sub-paths. The increased number of pre-sampled light subpaths, however, also incurs a high computational cost. In this paper, we propose a two-stage resampling method for BPT to efficiently handle a large number of pre-sampled light sub-paths. We also derive a weighting function that can treat the changes in path probability due to the two-stage resampling. Our method can handle a two orders of magnitude larger number of presampled light sub-paths than previous methods in equal-time rendering, resulting in stable and better noise reduction than state-of-the-art methods.