Ray casting for collision detection in haptic rendering of volume data

A haptic exploration adds an additional dimension to working with 3D data: a sense of touch (figure 1). This is especially useful in areas such as medical training and pre-surgical planning, entertainment, CAD and others. Each haptic rendering frame consists of three stages: collision detection, collision response and force-feedback generation. In order to feel the 3D data smoothly, an update rate of at least 1 kHz is required [Brooks Jr. et al. 1990]. Unaddressed practical problems for almost all haptic rendering methods are that no guarantees for collision detection could be given and/or that a special topological structure of objects is required. Here we present an approach which does not have these drawbacks. Furthermore our algorithm has nearly constant time complexity independent of data resolution and does not require any additional precomputed structures. We focus on volumetric voxel data, since that is the direct input from the scanning devices. Other data types could be transformed to this one, if necessary.