The parallelization of the perspective shear-warp volume rendering algorithm

Abstract

The shear-warp algorithm for volume rendering is among the fastest volume rendering algorithms. It is an object-order algorithm, based on the idea of the factorization of the view matrix into a 3D shear and a 2D warp component. Thus, the compositing can be done in sheared object space, which allows the algorithm to take advantage of data locality. Although the idea of a perspective projection shear-warp algorithm is not new, it is not widely used. That may be because it is slower than the parallel projection algorithm and often slower than hardware supported approaches.In this paper, we present a new parallelized version of the perspective shear-warp algorithm. The parallelized algorithm was designed for distributed memory machines using MPI. The new algorithm takes advantage of the idea that the warp can be done in most computers' graphics hardware very fast, so that the remote parallel computer only needs to do the compositing. Our algorithm uses this idea to do the compositing on the remote machine, which transfers the resulting 2D intermediate image to the actual display machine. Even though the display machine could be a moderately equipped PC or laptop computer, it can be used to display complex volumetric data, provided there is a network connection to a high performance parallel computer. Furthermore, remote rendering could be used to drive virtual environments, which typically require perspective projection and high frame rates for stereo projection and multiple screens.