SUMMARY: Visiohaptic simulators use well established robust methodologies for visual rendering of volumetric data. Haptic rendering on the other hand uses techniques that are limited in their capacity to render perceptually accurate haptic sensations at interactive rates. Lack of touch feedback that is influenced by the geometry of the volumetric model can create sensory conflicts between the visual and haptic modality, seriously affecting the learning of skills that rely on haptic sensations. There is a need for development of a haptic volumetric rendering algorithm that generates haptic feedback consistent with the geometry and spatial characteristics of volumetric models. This project dealt with the development of an iterative methodology for design and development of a novel haptic rendering algorithm based on the perceptual parameterization of volumes.
METHODS: A generic haptic rendering methodology (the god-object algorithm) was evaluated to study the perceptual effects experienced by the user during haptic interaction with the volume. This yielded the design space for the development of this algorithm. A combination of known spatial volumetric clustering and geometric techniques were used to perceptually parameterize the volume data. The DBSCAN (Density Based Spatial Clustering of Applications with Noise) algorithm was employed to sub-divide the volume into haptically homogeneous sub-volumes that are used to provide stable haptic feedback at fast and interactive rates. Force shading techniques were employed to handle haptic discontinuities encountered across sub-volume boundaries. Geometric properties like surface curvature were modeled to provide shape sensitive haptic feedback.
CONCLUSIONS: The simulation showed adequate performance, while being able to yield accurate and meaningful haptic sensations. Experiments proved the validity of the simulator and provided key insights to the perceptual requirements of haptic feedback. The simulator developed reuses state-of-the-art methods of volume visualization while presenting a novel haptic rendering methodology to provide high quality, stable feedback. Experimentation and testing of the simulator showed that the design goals of speed, accuracy and stability of haptic feedback were met.
ROLE: Researcher, Application Developer
STATUS: Completed (2008)
- [THESIS] Vankipuram M, “Haptic Rendering of Volumetric Data through Perceptual Parameterization”, Arizona State University, (2008); Submitted for completion of M.S. Computer Science degree. [Download PDF]