Gaussian Quadrature for Photon Beams in Tangled

We implemented the recent Photon Beams algorithm in Photorealistic RenderMan to efficiently render artistically-directed volumetric lighting effects for the feature-length animated movie Tangled. With the knowledge that most fall-off functions defined by our artists would be polynomial-smooth, we use Gaussian Quadrature to accurately and efficiently estimate the lighting contribution of these camera-containing beams.