Anti-aliasing with Stratified B-spline Filters

A simple and elegant method is presented to perform anti-aliasing in ray traced images. The method uses stratified sampling to reduce the occurrence of artifacts in an image and features a B-spline filter to compute the final luminous intensity at each pixel. The method is scalable through the specification of the filter order. A B-spline filter of order one amounts to a simple anti-aliasing scheme with box filtering. Increasing the order of the B-spline generates progressively smoother filters. Computation of the filter values is done in a recursive way, as part of a sequence of Newton-Raphson iterations, to obtain the optimal sample positions in screen space. The proposed method can perform both anti-aliasing in space and in time, the later being more commonly known as motion blur. We show an application of the method to the ray casting of implicit procedural surfaces.