Adaptive density estimation using an orthogonal series for global illumination

In Monte-Carlo photon-tracing methods energy-carrying particles are traced in an environment to generate hit points on object surfaces for simulating global illumination. The surface illumination can be reconstructed from particle hit points by solving a density estimation problem using an orthogonal series. The appropriate number of terms of an orthogonal series used for approximating surface illumination depends on the numbers of hit points (i.e. the number of samples) as well as illumination discontinuity (i.e. shadow boundaries) on a surface. Existing photon-tracing methods based on orthogonal series density estimation use a pre-specified or fixed number m of terms of an orthogonal series; this results in undesirable visual artifacts, i.e. either near-constant shading across a surface which conceals the true illumination variation when m is very small or excessive illumination oscillation when m is very large. On the other hand, interactive user specification of the number of term...

• Type: Journal
• Year: 2005
• Where: CG
• Authors: Kam Wah Wong, Wenping Wang
• Keywords: CG 2005, Computer Graphics, Density Estimation, Orthogonal Series, Surface Illumination