Soft shadow rendering using spherical reparameterization scheme

Rendering realistic soft shadow under all-frequency lighting environment is receiving more and more attention in recent years. 2D Haar wavelet has been recognized superior at approximation of all-frequency signals such as very keen-edged shadows. Nevertheless, rotating scene objects efficiently under wavelet basis has yet remained a troublesome problem. In this paper, we present a spherical reparameterization scheme under which spherical functions, as lighting, BRDF and visibility, are mapped onto the spherical polar coordinates. Rotating scene objects can thus be eased by a single linear transformation in our approach. Furthermore, a technique for efficiently projecting visibility is proposed. To accelerate shadow computation, we make full use of the computational resources of modern graphical hardware to perform our algorithm.