Improved Illumination Estimation for Photon Maps in Architectural Scenes

The photon map algorithm provides a number of advantages for fast global illumination algorithms. In order to calculate the illumination at each point in a scene, the photon density needs to be estimated. Standard estimation methods will have problems with typical architectural scenes, as walls and corners will lead to undesirable light and shadow leaks. We introduce a new method for estimating photon density in photon maps, that is especially suited for calculating global illumination in architectural scenes. By providing additional information using a limited number of ray-casts, shadow and light leaks can be significantly reduced, thereby resulting in a significant improvement in the speed and accuracy of global illumination algorithms based on photon maps.