Preserving Sharp Edges with Volume Clipping

Volume clipping is a useful aid for exploring volumetric datasets. To maximize the effectiveness of this technique, the clipping geometry should be flexibly specified and the resulting images should not contain artifacts due to the clipping techniques. We present an improvement to an existing illumination model for volume clipping to allow sharp edges in the data to stay visible. These sharp edges often originate from material transitions in the volume or structures being partially cut by the clipping geometry. The focus is on high, industrial image quality and flexibility of the algorithm; techniques for using high-resolution polygonal meshes as clipping algorithms and removal of artifacts are presented. Features of the latest consumer graphics hardware are exploited to provide the visualization at an interactive framerate without the need for multipassing. We have validated the techniques presented here by implementing them in the context of a professional volume rendering application at Philips Medical Systems, and comparing our results with current results produced by existing solutions.