The super-plane buffer: An efficient form-factor evaluation algorithm for progressive radiosity

Abstract

An efficient algorithm for form-factor evaluation is presented with curved surface geometry being accounted for. By adopting two separate plane buffers, namely the form-factor buffer and the shadow buffer, to serve the distinct purposes of form-factor evaluation and visibility determination independently, the new approach inherits most of the computational advantage of hemi-cube algorithm, while avoiding its limitations to progressive radiosity solution. With the use of form-factor buffer, the computation of form-factor from a source patch to a receiving sample point is reduced to a summation of delta form-factors defined over regularly shaped pixels and aliasing is mostly eliminated. By exploiting the spatial coherence of environment, the shadow buffer offers a simple "yes" or "no" answer to a visibility test with less computational cost. As an attempt to extend the progressive radiosity to nondiffuse environment, a specular reflection buffer is provided to facilitate the measurement of light energy transfer from the source patch to a receiving sample point via specular reflections. Theoretical analysis and experimental results demonstrate great potentials of this algorithm. © 1992.