A Perceptually Driven Investigation of Point-sampled Soft Shadows

Rendering shadows quickly is an active area of computer graphics research. This dissertation improves the practicality of using a small number of point-sampled light sources to approximate soft shadows. Results are presented from two perceptual experiments demonstrating the perceptual efficacy of soft shadows as spatial cues for a specific set of tasks . A third experiment found coarse point-sampled soft shadows to be as effective as smoother pointsampled soft shadows in producing illusory motion. Two computationally efficient methods for improving the discretization artifacts present in point-sampled soft shadows are introduced. The first method modulates intensity across the shadow penumbra, and the second carefully selects an ideal sampling distribution for point light sources. These results are applicable to all implementations for point-based shadow algorithms.