An Incremental Photon-Mapping Algorithm for Fast Walk-Through Animations

K. Ikeda, H. Takizawa, and H. Kobayashi (Japan)


photon-mapping, diffuse cache, walk-through animation, reprojection


A photo-realistic walk-through animation is required for entertainment and industrial uses. Although photon mapping is an effective approach to photo-realistic image synthesis based on global illumination, it is difficult to ap ply photon-mapping to generation of such animations be cause of its high computational cost. This paper proposes a new algorithm to accelerate the generation of walk-through animations using photon-mapping. The proposed algo rithm stores diffuse radiances, which do not depend on the camera position, and reprojects these radiances onto the screen when rendering the subsequent frame. The al gorithm uses photon-mapping incrementally only when re quired. The pixel intensities not determined by the repro jection are preciously recalculated by photon-mapping. As the cost of the reprojection is much lower than that of the recalculation, the algorithm can generate the subsequent frame much faster than the standard photon-mapping algo rithm. The algorithm can also render the scenes with partic ipating media that photon mapping can efficiently handle. The experimental results indicate that the proposed algo rithm can achieve significant acceleration of generating a walk-through animation based on photon mapping without remarkable degradation of visual quality.

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