VR-Desktop Initiative
The VR-Desktop Rationale:
The VR-Desktop Initiative is an effort to make the benefits of projection based VR more generally accessible for everyday users than has been the case with many canonical, first generation, projection based VR systems. We refer to this goal as "lowering the bar and extending the reach" for the use of VR in everyday teaching and research.
Systems like the Fakespace CAVETM
and ImmersadeskTM, Mechdyne
SSVRTM and MD TableTM, I-walls, VR theaters and similar products of various configuration from various vendors, have been with us for about a decade. The design of these systems continues to evolve and mature in ways that are increasingly useful, durable, etc., for the international high performance research clientele they typically have served. Until very
recently, such systems could almost uniformly be characterized by:
- Large-screen (often multi-screen) stereoscopic projection
- Tracked user interaction and viewpoint
- Typically driven by SGI Onyx class computers
- Employing C/C++ and OpenGL for graphics programming, in conjunction with any of several VR development libraries, toolkits, or scene graph APIs such as CAVElibsTM,
VRJuggler, DIVERSE,
WorldToolKitTM,
PerformerTM, etc.
Such systems enjoy considerable acceptance among high performance computing research groups around the world. The CAVERNUS Users Group maintains a partial list of such facilities. These are great systems for those who can afford to acquire and maintain them and who either have or have
access to the often formidable skills required for their effective use.
However, it seems a fair assessment at this writing that projection based VR has not achieved widespread use among everyday users outside of the high performance community. We believe that the lack of acceptance by general users is due to 1) a dearth of VR enabled applications to which such users can easily transition, 2) a challenging programming environment for those who would attempt to use VR systems to develop unique applications, and 3) the relatively high cost of purchasing and maintaining such facilities. It has been our experience that for many potential users in our university community,
the effort and resources required to bring VR techniques to bear on everyday research and teaching are simply too great.
The design point for the VR-Desktop is to provide VR systems that will meet a wider range of potential users closer to ``where they are" in terms of 1) existing computing skills and work methods, 2) budgets and 3) physical proximity. In short, we want to make it as easy, cost effective and convenient as possible for everyday computer users (as well as potential VR lab administrators) to realize whatever benefits ``big screen VR" can bring to their respective disciplines and organizations. Continuing improvements in the price/performance of desktop graphics systems and related technology have made these goals reasonable, as evidenced by recent commercial and academic development efforts. Visbox and Georgia Tech's NAVE projects are representative of commercial and academic projects in this spirit (though certainly not the only examples).
The VR-Desktop Current Implementation:
Graphics host: Our first VR-Desktop is a single screen system driven by an IBM Intellistation, running Windows 2000, with an ATI FireGL4 graphics adapter. The key features required from the graphics adapter are good OpenGL acceleration and support for quad
buffered frame sequential stereo display with flexible display resolutions and scanning frequencies. We like that the ATI cards offered vendor supported drivers for both Windows and Linux. We are using a 3Dlabs Wildcat 5110 for the dual-screeen display in the VR-Desktop system in the ITS/SALA Immersive Environments Lab as the Wilcat drivers allowed Windows to recognize individual graphics displays when in dual-headed mode (as opposed to one logical, albeit dual-headed display), which was a requirement for one of our key applications in that lab.
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Projection System: The heart of our projection system is the Cyviz xpo.2 stereo convertor (acquired under research partnership with Cyviz AS of Norway). The xpo.2 accepts the frame sequential stereo signal that is supported by existing active stereo viewing devices (e.g. StereoGraphics CrystalEyes or similar products) and converts it to separate
display signals for the left and right eyes to allow polarized passive stereo display. These separate signals are fed to two projectors. The dual images of which are precisely aligned (using adjustable stacking racks provided by CyViz) and superimposed onto a single polarization preserving screen (we've used rigid, rear projection screens available from VREX). Polarized filters are placed in the projection path (immediately in front of the projectors) and inexpensive polarized glasses are worn by viewers to maintain the separation of left and right eye images that is required for stereopsis.
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Software Environment: Since the system is built around a Windows desktop, many general computer users can do VR work within the desktop computing environment with which they are familiar. Since the xpo.2 stereo convertor uses the de-facto standard CrystalEyes stereo display format (which is supported by a number of existing commercial applications), many users can derive the benefit of large format stereoscopic display within applications with which they are familiar, and they will have most (if not all) of the functionality of those applications at their fingertips.
In addition to using off-the-shelf applications that inherently support stereo display, we've also developed (using some open source components) basic applications for loading, viewing and navigating geometry exported from existing applications in industry standard 3D formats (VRML97 and 3DS). This latter effort has been particularly helpful in allowing Architecture students using a VR-Desktop system deployed in the ITS/SALA Immersive Environments Lab to load and navigate designs they have been developing in FormZ, for example, to allow a more human
scale involvement with their designs than would otherwise be available on their computer monitors.
Interactive Devices: Here we will put stuff about using off-the-shelf interactive devices. Including a pix of the new joystick.
The VR-Desktop Future Development: Multi-screen, tracking, networking, etc.
Please send questions or suggestions about this web page to vizgroup@psu.edu
ASET | ITS | Penn State
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