THE POWER OF CURRENT CONSUMER GRAPHICS HARDWARE increasinglyallows the integration of truly volumetric graphics into applications with very high real-time demands. Computer and video games are certainly the prime example. In many traditional volume-rendering applications, such as medical volume rendering, frame rates between 10 and 20 frames per second are usually considered to be sufficient. In games, however, the overall frame rate needs to be much higher than that, including all the simulation and rendering for the entire scene, of which volumetric effects are but a small part.