Reflected and Transmitted Irradiance from Area Sources using Vertex Tracing
Michael M. Stark
and
Richard F. Riesenfeld
Abstract
Computing irradiance analytically from polygonal luminaires in polygonal
environments has proven effective for direct lighting applications in diffuse
radiosity environments. Methods for analytic integration have traditionally
used edge-based solutions to the irradiance integral; our previous work
presented a vertex-based analytic solution, allowing irradiance to be computed
incrementally by ray tracing the apparent vertices of the luminaire. In this
work we extend the vertex tracing technique to the analytic computation of
irradiance from a polygonal luminaire in other indirect lighting applications:
transmission through non-refractive transparent polygons, and reflection off
perfectly specular polygons. Furthermore we propose an approximate method for
computing transmitted irradiance through refractive polyhedra. The method
remains effective in the presence of blockers.
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Mike Stark (mstark@cs.utah.edu)