In this paper, we quantify the effects of two physical affordances on user interaction in an augmented virtual environment: the grounding of datasets on a workbench and the augmentation of a Magic Lens interface tool. We investigated the effects of these affordances on subjects' performance and behavior in an information gathering task. Our results indicated that grounding had a significant main effect and that there was significant interaction between grounding and interface factors. Specifically, subjects tended to perform better with some level of affordance than none at all, although performance with grounded datasets decreased in the presence of augmented Magic Lens. Further, both affordance factors influenced behavior by reducing head mobility.

We have previously developed a collaborative infrastructure called SCAPE - an acronym for Stereoscopic Collaboration in Augmented and Projective Environments - that integrates the traditionally separate paradigms of virtual and augmented reality. In this paper, we extend SCAPE by formalizing its underlying mathematical framework and detailing three augmented Widgets constructed via this framework: CoCylinder, Magnifier, and CoCube. These devices promote intuitive ways of selecting, examining, and sharing synthetic objects, and retrieving associated documentary text. Finally we present a testbed application to showcase SCAPE's capabilities for interaction in large, augmented virtual environments.

This paper presents a multi-user collaborative infrastructure, SCAPE (an acronym for Stereoscopic Collaboration in Augmented and Projective Environments), which is based on recent advancement in head-mounted projective display (HMPD) technology. The SCAPE mainly consists of a 3'/spl times/5' interactive workbench and a 12'/spl times/12'/spl times/9' room-sized walk-through display environment, multiple head-tracked HMPDs, multi-modality interface devices, and a generic application-programming interface (API) designed to coordinate the components. The infrastructure provides a shared space in which multiple users can simultaneously interact with a 3D synthetic environment from their individual viewpoints. We detail the SCAPE implementation and include an application example that demonstrates major interface and cooperation features.

A head-mounted projective display (HMPD) consists of a pair of miniature projection lenses, beam splitters and displays mounted on the helmet and retro-reflective sheeting materials placed strategically in the environment. This has recently been proposed as an alternative to existing 3D visualization devices. In this paper, we first briefly review HMPD technology, including its featured capabilities and the recent development in both display implementations and applications. Then the implementation of a testbed for playing a "Go" game with a remote opponent in a 3D augmented environment is described. The testbed not only demonstrates the capabilities of virtual-real augmentation and registration, the natural occlusion of virtual objects by real ones, interaction with augmented environments and networking collaboration, but also embodies part of our long-term objective to develop a collaborative framework in 3D augmented environments. Through the testbed, major calibration issues, such as accommodation/convergence considerations and determination of viewing transformations, are studied and discussed in detail. Both calibration methods and results are included, which are applicable to other applications. Finally, experimental results of the testbed implementation are presented.