Haptic Volume Rendering with an Intermediate Local Representation

In medical applications volumetric data sets are widely used. Therefore a strong desire for haptic volume rendering exists in this community. Established force-feedback approaches are limited to surface-based data and cannot satisfy the needs of volume rendering. Particularly in the medical field, where physicians are used to examine objects with their sense of touch, a combination of volume visualization with haptics would be desireable. We present an approach where volumetric data is locally transformed into a surface representation. For our research, we use a PHANToM force-feedback device with the GHOST v2 library. In our approach, the voxel data in a neighborhood of the current interaction point is used to generate isosurfaces through points with similar density values. The isosurfaces are then passed to the GHOST library and used as an intermediate representation between the volumetric data and a surface-based haptic rendering. As the surfaces are generated on the fly and no preprocessing is needed, it is possible to change transfer functions or the volume data itself during the haptic interaction