Erasing, digging and clipping in volumetric datasets with one or two hands

Visualization of volumetric datasets is common in many fields and has been an active area of research in the past two decades. In spite of developments in volume visualization techniques, interacting with large datasets still demands research efforts due to perceptual and performance issues. The support of graphics hardware for texture-based visualization allows efficient implementation of rendering techniques that can be combined with interactive sculpting tools to enable interactive inspection of 3D datasets. In this paper we report the development of three 3D interactive tools, eraser, digger and clipper, which specify regions within the volume to be discarded from rendering. Sculpting is accomplished by running special fragment programs that discard fragments based on geometric predicates. The interaction techniques we proposed were implemented using the virtual hand metaphor. The tools were evaluated by comparing the use of a 3D mouse against a conventional wheel-mouse for guiding volume and tools manipulation. Two-handed input was tested with both types of mouse and the results obtained indicate a preference for a combination of 2D and 3D mouse.