An incremental photon-mapping algorithm for fast walk-through animations

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 apply photon-mapping to generation of such animations because of its high computational cost. This paper proposes a new algorithm to accelerate the generation of walk-through animations using photon-mapping. The proposed algorithm stores diffuse radiances, which do not depend on the camera position, and reprojects these radiances onto the screen when rendering the subsequent frame. The algorithm uses photon-mapping incrementally only when required. The pixel intensities not determined by the reprojection 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 algorithm. The algorithm can also render the scenes with participating media that photon mapping can efficiently handle. The experimental results indicate that the proposed algorithm can achieve significant acceleration of generating a walk-through animation based on photon mapping without remarkable degradation of visual quality.