Obscurances for ray-tracing

We present a powerful method to create realistic-looking pictures of scenes with objects that have diffuse and non-diffuse properties. The method recreates the obscurances technique, introduced some years ago, with a new approach based on ray-tracing. The first version of the obscurances technique was used only for diffuse environments. It is already working successfully in some widely known video games because it is able to avoid the high cost of radiosity techniques in the interactive and real-time game environments. Soft shadows, nice colour reflection effects, visually pleasant rendering of corners and other partly occluded surfaces of the scene are reproduced at a small fraction of the cost of radiosity. We extend here obscurances to handle non-diffuse environments via ray-tracing. Instead of computing the obscurance of every patch in the scene, we will compute view-dependent obscurances. The direct illumination is separately handled and diffuse color albedo functions are used for obscurance computation. Ray-traced obscurances can be useful in animation, both in the editing phase and/or in final images, and in ray-traced games, when the use of future graphics cards will decrease dramatically the cost of tracing a ray.