Shading with linear light sources

A new shading model for linear light source is presented. It accounts for both diffuse reflection and specular reflection of the illuminated surface. By regarding a linear light source as a directional rectangular light source with infinitesimal width, a simple formula is derived for calculating the diffuse reflection component. The specular reflection component is represented by an integration taking Phong's specular model as the kernel and evaluated by a linear approximation. Finally, an efficient shadow detection algorithm for linear light source is proposed. The images rendered with the shading model are very photo realistic.