VR poses a true challenge for the underlying software environment, usually referred to as the VR operating shell. Such a system must integrate real-time three-dimensional graphics, in large object-oriented modelling and database techniques, event-driven simulation techniques, and the overall dynamics based on multithreading distributed techniques. The emerging VR operating shells, such as Trix at Autodesk, Inc., VEOS at HIT Lab, and Body Electric at VPL, Inc., share many design features with the MOVIE system. A multiserver network of multithreading interpreters of high-level object-oriented language seems to be the optimal software technology in the VR domain.
We expect MOVIE to play an important role in the planned VR projects at Syracuse University, described in the previous section. The system is capable of providing both the overall infrastructure (VR operating shell) and the high-performance computational model for addressing new challenges in computational science, stimulated by VR interfaces. In particular, we intend to address research topics in biological vision on visual perception limits [Farell:91a], [Verghese:92a], in association with analogous constraints on VR technology; research topics in machine vision in association with high-performance support for the ``non-encumbered'' VR interfaces [Krueger:91a]; and neural network research topics in association with the tracking and real-time control problems emerging in VR environments [Simoni:92b].
From the software engineering perspective, MOVIE can be used both as the base MovieScript-based software development platform and the integration environment which allows us to couple and synchronize various external VR software packages involved in the planned projects.
Figure 17.19 illustrates the MOVIE-based high-performance VR system planned at NPAC and discussed in the previous section. High-performance computing, high-quality three-dimensional graphics, and VR peripherals modules are mapped on an appropriate set of MovieScript threads. The overall synchronization necessary, for example, to sustain the constant frame rate, is accomplished in terms of the real-time component of the MovieScript scheduling model. The object-oriented interpreted multithreading language model of MovieScript provides the critical mix of functionalities, necessary to cope efficiently with prototyping in such complex software and hardware environments.
Figure 17.19: Planned High-End Virtual Reality Environment at NPAC. New
parallel systems: CM-5, nCUBE2 and DECmpp are connected by the fast HIPPI
network and integrated with distributed FDDI clusters, high-end graphics
machines, and VR peripherals by mapping all these components on
individual threads of the VR MOVIE server. Overall synchronization is
achieved by the real-time support within the MOVIE scheduling model.
Although the figure presents only one ``human in the loop,'' the model can
also support in a natural way the multiuser, shared virtual worlds with
remote access capabilities and with a variety of interaction patterns
among the participants.
The MOVIE model-based high-performance VR server at NPAC could be employed in a variety of visualization-intensive R&D projects. It could also provide a powerful shared VR environment, accessible from remote sites. MovieScript-based communication protocol and remote server programmability within the MOVIE network assure satisfactory performance of shared distributed virtual worlds also for low-bandwidth communication media such as telephone lines.
From the MOVIE perspective, we see VR as an asymptotic goal in the GUI area, or the ``ultimate'' user interface. Rather than directly build the specific VR operating shell, which would be short-lived given the current state of the art in VR peripherals, we instead construct the VR support in the graded fashion, closely following existing and emerging standards. A natural strategy is to extend the present MovieScript GUI sector based on Motif and three-dimensional servers by some minimal VR operating shell support.
Two possible public domain standard candidates in this area to be evaluated are VEOS from HIT Lab and MR (Minimal Reality) from the University of Alberta. We also plan to experiment with the Presence toolkit from DEC and with the VR_Workbench system from SimGraphics, Inc.
Parallel with evaluating emerging standard candidates, we will also attempt to develop a custom MovieScript-based VR operating shell. Present VR packages typically split into the static CAD-style authoring system for building virtual worlds and the dynamic real-time simulation system for visiting these worlds. The general-purpose support for both components is already present in the current MovieScript design: an interpretive object-oriented model with strong graphics support for the authoring system and a multithreading multiserver model for the simulation system.
A natural next step is to merge both components within the common language model of MovieScript so that new virtual worlds could also be designed in the dynamic immersive mode. The present graphics speed limitations do not currently allow us to visit worlds much more complex than just Boxvilles of various flavors, but this will change in coming years. Simple solids can be modelled in the conventional mouse-based CAD style, but with the growing complexity of the required shapes and surfaces, more advanced tools such as VR gloves become much more functional. This is illustrated in Figure 17.20, where we present a natural transition from the CAD-style to VR-style modelling environment. Such VR-based authoring systems will dramatically accelerate the process of building virtual worlds in areas such as industrial or fashion design, animation, art, and entertainment. They will also play a crucial role in designing nonphysical spaces-for example, for hypermedia navigation through complex databases where there are no established VR technologies and the novel immersion ideas can be created only by active, dynamic human participation in the interface design process.
Figure 17.20: Examples of the Glove-Based VR Interfaces for CAD and Art
Applications. The upper figure illustrates the planned tool for
interactive sculpturing or some complex, irregular CAD tasks. A set of
``chisels'' will be provided, starting from the simplest ``cutting plane''
tool to support the glove-controlled polygonal geometry modelling. The
lower figure illustrates a more advanced interface for the
glove-controlled surface modelling. Given the sufficient resolution of
the polygonal surface representation and the HPC support, one can
generate the illusion of smooth, plastic deformations for various materials.
Typical applications of such tools include fashion design, industrial
(e.g., automotive) design, and authoring systems for animation. The
ultimate goal in this direction is a virtual world environment for
creating new virtual worlds.