dges of shapes in images (Pai & Reissell, 1997). At IMSC we are currently working with both the PHANToM and the CyberGrasp, using the Polhemus Fastrak for tracking the position of the CyberGrasp user's hand. The tracking problem has been widely studied in the context of mobile robots at USC (Roumeliotis, Sukhatme, and Beckey, 1999a, 1999b). In the museum application the visitor and the museum staff member will be able to manipulate haptic data jointly, regardless of display type. Thus one of our primary concerns is insure proper registration of the disparate devices with the 3D environment and with each other. Of potential use in this regard is work by Iwata, Yano, and Hashimoto (1997) on LHX (Library for Haptics), a modular software that can support a variety of different haptic displays. LHX allows a variety of mechanical configurations, supports easy construction of haptic user interfaces, allows networked applications in virtual spaces, and includes a visual display interface. We are particularly eager to begin work with the CyberGrasp; to date we have been unable to identify any published work or conference papers reporting research using the device, which we attribute in part to its expense and relative infancy as a haptic display device. Figure 2. Haptic acquisition and display devicesRepresentative applications in haptic acquisition and display A primary application area for haptics has been in surgical simulation and medical training. Langrana, Burdea, Ladeiji, and Dinsmore (1997) used the Rutgers Master II haptic device in a training simulation for palpation of subsurface liver tumors. They modeled tumors as comparatively harder spheres within larger and softer spheres. Realistic reaction forces were returned to the user as the virtual hand encountered the "tumors," and the graphical display showed corresponding tissue deformation produced by the palpation. Finite Element Analysis was used to compute reaction forces correspond...
