Abstract: An Apparatus for use in producing lighting effects comprising a plurality of graphic processing units, each graphic processing unit for jittering a first ray, having a direction, to result in a second ray, the second ray having a direction not the same as the first ray; and each graphic processing unit having a plurality of threads for processing rays for computing lighting effects such that the first ray is processed by a first thread and the second ray is processed in a thread adjacent to the first thread; and a memory for providing data for use in computing the lighting effects for the first ray and the second ray.