Multi-Image Based Photon Tracing for
Interactive Global Illumination of
Dynamic Scenes

Chunhui Yao, Bin Wang, Bin Chan, Junhai Yong and Jean-Claude Paul

Computer Graphics Forum (Proceedings of the EGSR), Vol. 29(4), Jun 2010, pp. 1315-1324.
Photon mapping is a popular framework for global illumination. A promising implementation of photon mapping is the image space approach in which the scene geometry is encoded in a depth image. The image space method has the advantage of simple implementation on GPU without the need of pre-computation of complex acceleration structures, such as KD-trees, therefore allows fast photon-mapping computation. However, existing image-space methods use only a single image for tracing caustic photons, so they are limited to computing only part of global illumination effects for very simple scenes. In this paper we fully extend the image space approach by using multiple environment maps for photon mapping computation to achieve interactive global illumination of dynamic complex scenes. Two key problems due to the introduction of multiple images are 1) selecting the images to ensure adequate scene coverage; and 2) reliably computing ray-geometry with multiple images. We present effective solutions to these problems and show that, with multiple environment maps, the image-space photon mapping approach can achieve interactive global illumination of dynamic complex scenes. The advantages of the method are demonstrated by comparison with other existing interactive global illumination methods.
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We thank the anonymous reviewers for their helpful comments and the great help of Prof. Wenping Wang from the University of Hong Kong. This work was supported by National Basic Research Program of China (Grant No. 2010CB328001), National Science Foundation of China (Grant Nos. 60773143,90818011), and National High- Tech Research & Development Program of China (Grant No. 2007AA040401). Prof. Paul was supported by ANRNSFC(60911130368), and Prof. Yong was supported by the Fok Ying Tung Education Foundation (111070).