Sunday, October 3, 2010

Interactive Global Illumination of Indoor Scenes with Photon Mapping - A Brief Overview

Efficiently and realistically rendering the nuances as represented by direct and indirect lighting effects of indoor scenes has always been a challenging task in computer graphics. Especially, scenes with moveable light sources
and camera position deserve particular attention as rendering those scenes efficiently would enable animators and designers to quickly inspect architectures from different perspectives and lighting settings.

Based on this requirements, I propose a fast, robust and realistic renderer with global illumination capabilities specifically for indoor scenes, by coupling kd-tree and coherent grid acceleration structures. The renderer uses regular ray-tracing for direct illumination and reflection, and uses photon map final gathering for indirect illumination. The scene comprises mostly static background objects and limited moving objects. Whenever a change in light sources or camera position is required after a given time point, spatio-temporal coherence is exploited so that only a fraction of the work done for the previous frame is needed for rendering a new frame. 

To best utilize kd-tree's fast look-up property and coherent uniform grid's fast reconstruction property, we use the former for static background scene and the latter for moving objects. To improve rendering responsiveness, interim rendering results are displayed during the final gathering process; moreover, photon mapping pre-computation could be used. This should dramatically reduce the required final gathering samples. Lastly, CUDA will be utilized to better parallelize the rendering process. This project is an extension to and further research on my previous work on efficient ray-tracing. Built on the framework of my existing photon tracer, this high quality renderer should be able to deliver impressive scene fly-by experiences and speed up the workflow of creating and rendering indoor architectures.

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