3 Accelerated IsoContouring of

With the increasing size of typical 2D and 3D data, e cient computational methods are becoming increasingly crucial for achieving desired levels of interactivity. Computation of isocontours from scalar data is a particularly critical task for comprehensive visualization of volume data. In the case that the volume is discretized by a mesh of volumetric cells, the extraction of an isocontour consists of two primary phases: triangulation of a particular cell and the search for all intersected cells. In this chapter we will review and contrast the primary algorithmic approaches which have been suggested in the literature. Isocontouring is a widely used approach to the visualization of scalar data and an integral component of almost every visualization environment. Computation of isocontours has applications in visualization ranging from extraction of surfaces from medical volume data [Lor95] to computation of stream surfaces for ow visualization [van93]