Recent approaches to realistic image synthesis split the rendering process into two passes. The first pass calculates an approximate global illumination solution, the second produces an image of high quality (from a user selected view point) using the solution obtained in the first pass by applying the local illumination model to each surface point visible through each pixel.
This paper presents two new methods to compute the local illumination quickly. Instead of recalculating form factors and visibilities the information computed by a hierarchical radiosity solution algorithm is reused. The image generation time is reduced significantly by using stochastic methods.