Fast re-rendering of volume and surface graphics by depth, color, and opacity buffering

A method for quickly re-rendering volume data consisting of several distinc t materials and intermixed with moving geometry is presented. The technique works by storing depth, color and opacity information, to a given approxim ation, which facilitates accelerated rendering of fixed views at moderate s torage overhead without re-scanning the entire volume. Storage information in the ray direction (what we have called super-z depth buffering), allows rapid transparency and color changes of materials, position changes of sub- objects, dealing explicitly with regions of overlap, and the intermixing or separately rendered geometry. The rendering quality can be traded-off agai nst the relative storage cost and we present an empirical analysis of outpu t error together with typical figures for its storage complexity. The metho d has been applied to the visualization of medical image data for surgical planning and guidance, and presented results include typical clinical data. We discuss the implications of our method for haptic (or tactile) renderin g systems, such as for surgical simulation, and present preliminary results of rendering polygonal objects in the volume rendered scene. (C) 2000 Else vier Science B.V. All rights reserved.