In this paper, we present our networked virtual tennis game that has been developed as a hybrid framework with head-mounted display and fishtank virtual reality systems. The paper reports the findings of a hybrid collaboration task which compared the two systems based on their egocentric and exocentric features. The focus of the study was on the strengths and weaknesses in each system for the given particular task: How do users perform in each system? And how might each system complement the others for teamwork? We report on localization error and correct hit percentage results that were obtained during trials with the two types of systems. These results suggest that head-mounted displays with egocentric features allow more accurate spatial localization and the fishtank displays with exocentric features provide better cues for time synchronization events.

We present a physically-based approach to grasping and manipulation of virtual objects that produces visually realistic results, addresses the problem of visual interpenetration of hand and object models, and performs force rendering for force-feedback gloves in a single framework. Our approach couples tracked hand configuration to a simulation-controlled articulated hand model using a system of linear and torsional spring-dampers. We discuss an implementation of our approach that uses a widely-available simulation tool for collision detection and response. We illustrate the resulting behavior of the virtual hand model and of grasped objects, and we show that the simulation rate is sufficient for control of current force-feedback glove designs. We also present a prototype of a system we are developing to support natural whole-hand interactions in a desktop-sized workspace.