Virtual Environment Rendering

A virtual environment (VE) may represent a simulation of a real environment or of an artificial environment, such as in scientific visualization of data. For haptic interaction with a VE, the simulation has to compute some kind of geometrical relationship between positions of the haptic interface and objects in the VE, and then based on this geomety to compute an interaction force arising from some desired dynamics of the VE. There have been a number of papers on haptic rendering of non-real VE’s, such as the visualization of computational fluid dynamics data (Avila and Sobierajski, 1996; Iwata and Noma, 1993) or of molecular interaction (Brooks et al., 1990), but in this chapter we will restrict the discussion to simulation of real physical environments. Real environments are difficult to simulate well, both because of their great complexity but also because of our own personal experiences which make us discerning critics. In a VE representation of a real physical environment, manipulation of virtual objects with a haptic interface should feel as similar as possible to manipulation of real objects with our hands. The challenge is not just the device limitations of the haptic interface, but also the computational demands in making the VE interactive and realistic. Here is a typical scenario. There is a virtual hand controlled by the haptic interface that represents the user in the virtual environment (Figure 1). The user wishes to pick up a virtual object from a table.