A Compression Method For Spectral Photon Map Rendering

The photon map method can easily be extended to handle wavele ngth-dependent phenomena such as dispersion, chromatic aberration, etc. Using the computationally effective appr oach of point sampling for this extension, the size of the pho ton map is increased proportionally with the number of samples. In thi s paper we present a solution for modelling wavelength-depe ndent phenomena that keeps variance low, while having a memory usa ge comparable to that of an RGB based renderer. The method is best used for photon mapping, where there is a need to store large amounts of spectral flux directly in the photon map. Our method incurs a slight loss of accuracy for photons in the glo bal map, while photons in the caustics map retain all informa tion. Our tests show negligible loss of accuracy in the image quali ty.