Z-Buffer on a Transputer-Based Machine

Abstract

This paper describes the parallel implementation of the Z-Buffer algorithm on a distributed memory machine. The Z-Buffer is one of the most popular techniques used to generate a representation of a scene consisting of objects in a 3-dimensional world. We propose and compare two different parallel implementations on a network of Transputers. In the first approach, the description of the scene is distributed among the processors configured as a tree. The picture is processed in a pipelined fashion, in order to output parts of the image during the computation of the remainder. In a second approach, both the picture and the scene description are distributed to the processors. interconnected in a ring. We have therefore to redistribute dynamically the tiles among the processors at the beginning of the computation. We show thlat the two approaches are complementary : for small pictures or large scenes, a tree-based algorithm performs better than a ringbased algorithm, but for large pictures or small scenes, it is the other way round. We obtain substantial speedups over the sequential implementation, with up to 32 processors.