A computer graphics system generates a pixel value for a pixel in an image, the pixel being representative of a point in a scene as recorded on an image plane of a simulated camera, the computer graphics system being configured to generate the pixel value for an image using a selected ray-tracing methodology in which simulated rays are shot from respective ones of a plurality of subpixels in the pixel, each subpixel having coordinates (s.sub.x,s.sub.y) in the image plane The computer graphics system comprises a sample point generator and a function evaluator. The sample point generator is configured to map subpixel coordinates (s.sub.x,s.sub.y) onto strata coordinates (j,k):=(s.sub.x mod 2.sup.n,s.sub.y mod 2.sup.n), from which a ray is to be shot, in accordance with.sigma..function..sigma..function. ##EQU00001## where "i" is an instance number for the ray generated as i=j2.sup.n+.sigma.(k), where integer permutation .sigma.(k):=2.sup.n.PHI..sub.b(k) for 0.ltoreq.k<2.sup.n for selected "n," where .PHI..sub.b(x) is a radical inverse function given by.PHI..fwdarw. ##EQU00002## .infin..times..function..times. .infin..times..function..times..times..times..infin. ##EQU00002.2## is the representation of "x" in a selected integer base "b". The function evaluator is configured to evaluate a selected function using the strata coordinates generated by the sample point generator, the value generated by the function evaluator corresponding to the pixel value.
This is a continuation in part of U.S. patent application Ser. No. 09/884,861, filed on Jun. 19, 2001, which is a continuation in part of U.S. Provisional Patent Application Serial No. 60/212,286, filed Jun. 19, 2000, and U.S. Provisional Patent Application Serial No. 60/265,934, filed Feb. 1, 2001.
