Real-time haptic rendering of volumetric data during shape changes

Abstract

Virtual reality-based applications for medical training mimic physical phenomena which occur in deforming, cutting and bleeding with soft tissue, as well as milling with hard tissue. Real-time interaction plays an important role in these applications to acquire enhancements of medical skills and dexterity. Therefore, both visual and haptic cues should be properly provided not only to convey deliberate intention of the operators but also to improve their visual-spatial skills. Considering surgery simulation with real-time interaction, the topological changes of physical representation is one of inevitable components. This paper investigates a haptic rendering algorithm with shape changes in interactive virtual environments. While we primarily focus on asymmetric contact model such as Voxmap-PointShell, and its improved method using a distance field, some of the presented approaches could be transferable to haptic rendering algorithms with volumetric data. To be specific, the focus of our development is on collision model update and contact resolution engaged in topological changes. We contributes to efficient and stable contact resolution for haptic-enabled virtual environments with topological changes by employing pointless full octree as well as a normal estimation method based on adaptive sampling of a local distance map. The results of real-time tooth probing and cutting simulations support the benefits of our approach.