Anti-aliasing in form factor computation and precise determination of shadow boundaries are important issues for radiosity method. A-buffer is a technique introduced by L. Carpenter (1984) for anti-aliasing in hidden surface removal. In this paper, we propose a method based on the A-buffer to replace the Z-buffer in the computation of form factors using the Hemicube for anti-aliasing. The method directly computes shadow boundaries in contrast to the adaptive re-meshing approach. Though the processing of shadow boundaries is not fast, only one discontinuity meshing (no iteration) is required. We implement the method in an infrastructure building design system.

This paper studies the impact of the architecture features of the Cray-1 and the Cray X-MP and related compiler optimizations on machine performance. We develop a methodology for evaluating the effectiveness of the Cray Fortran compilers in coping with the architecture features and limitations of the Cray-1 and the Cray X-MP. As examples, the effects of vector register reservation and vector index misalignment on the performance of Livermore Fortran Kernels (LFKs) are presented. The causes of the performance differences of two Cray Fortran compilers, CFT1.14 and CFT77.13, on the vectorized LFKs are described and some areas for further improvement are suggested.