RAY CASTING AND THE ENCLOSING-NET ALGORITHM FOR EXTRACTING SHAPES FROM VOLUME DATA

One of the most useful applications of virtual reality is to let doctors view the inside of the human body non-invasively and in real time. In this paper, we first survey the area of virtual reality and volume-visualization techniques. We discuss our ray casting implementation for viewing the medical data which is available as a set of slices from NMR and CT scans. Next we present a new method, the enclosing-net algorithm, for extracting iso-surfaces from volume data. A simple implementation of our technique is described. Since the topology of the extracted surface is well defined and non-ambiguous, the enclosing-net algorithm eliminates a major problem of surface extraction techniques. In addition, the number of polygons representing the surface can be controlled to obtain a finer shape. Therefore real-time interaction is feasible on both low-end and high-end graphics machines, making the enclosing-net algorithm suitable for virtual reality experiments.