Anti-aliasing with Stratified B-spline Filters of Arbitrary Order

A simple and elegant method is presented to perform anti-aliasing in computer-generated images. The method uses stratified sampling to reduce the occurrence of artifacts in the image and features a B-spline filter, of some desired order, 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 method is currently used to anti-alias images generated by ray casting of implicit procedural surfaces.