Efficient point-based rendering techniques for haptic display of virtual objects

Computer haptics, an emerging field of research that is analogous to comput er graphics, is concerned with the generation and rendering of haptic virtu al objects. In this paper, we propose an efficient haptic rendering method for displaying the feel of 3-D polyhedral objects in virtual environments ( VEs). Using this method and a haptic interface device, the users can manual ly explore and feel the shape and surface details of virtual objects. The m ain component of our rendering method is the "neighborhood watch'' algorith m that takes advantage of precomputed connectivity information for detectin g collisions between the end effector of a force-reflecting robot and polyh edral objects in VEs. We use a hierarchical database, multithreading techni ques, and efficient search procedures to reduce the computational time such that the haptic servo rate after the first contact is essentially independ ent of the number of polygons that represent the object. We also propose ef ficient methods for displaying surface properties of objects such as haptic texture and friction. Our haptic-texturing techniques and friction model c an add surface details onto convex or concave 3-D polygonal surfaces. These haptic-rendering techniques can be extended to display dynamics of rigid a nd deformable objects.