Rendering Caustics on Non-Lambertian Surfaces

This paper presents a new technique for rendering caustics on non Lambertian surfaces The method is based on an extension of the photon map which removes previous restrictions limiting the usage to Lambertian surfaces We add information about the incoming direction to the photons and this allows us to combine the photon map with arbitrary re ectance functions Furthermore we introduce ba lancing of the photon map which not only reduces the memory requirements but also signi cantly re duces the rendering time We have used the method to render caustics on surfaces with re ectance func tions varying from Lambertian to glossy specular