ng and delivery tools that take enough of the pain out of building VR systems to make them a practical proposition for businesses.
Corporate developers can build VR applications that range from simple to complex for single users or client/server environments. The trade-offs among these systems are like those for any traditional development platform: The tools that are easiest to use produce the most basic applications. But the choice of products lets you put together the right package of tools for your needs.
Virtual Windows
Typical of the new generation of VR authoring tools is Datapath's RealiMation, a software suite for developing VR systems on platforms ranging from low-end PCs up to networks of workstations. As its name suggests, RealiMation combines the attributes of rea
lity and animation for VR, simulation, and game applications. RealiMation has the concepts of time and motion built into it so that, in addition to defining and traversing an interactive virtual world, you can define motions and
trajectories
for the objects in that world and capture the results as animation for later replay.
RealiMation consists of three main components. The RealiBase database contains descriptions of the appearance and behavior of objects in your virtual world; RealiLib is the API via which you can write C programs to manipulate the virtual world and create custom applications; and RealiMationSTE (Space Time Editor) is the tool that brings database entries almost to life. This space and time editor lets you interactively create and modify RealiBases and also acts as the run-time support to deliver finished systems: You can create a complete walk-through or simulation using just the STE with no programming involved. The STE is not a 3-D modeling tool, but you can
import objects created with other tools, including 3-D Studio and AutoCAD DXF, as well as Virtual Reality Modeling Language (VRML) files.
Tools like RealiMationSTE show how far VR has grown since its early days in research labs. Instead of proprietary and arcane systems, developers now have development kits that run on general-purpose OSes and processors. For example, RealiMationSTE is a 32-bit program that runs under Windows 95 or NT, and it supports hot links that let you attach data and behavior to 3-D objects.
Why is this imporant? Say you want a client to walk out onto the terrace of a building you've designed, and in addition to the look of the space you want to simulate the rush of urban life whirring around the building. Hot links trigger WAV sound files and a video clip as the client "walks" through the door to this virtual terrace. Hot links can activate any executable program, another RealiBase (allowing a "tunnel" between worlds), or even a uniform resource locator (URL) so you can cr
eate 3-D Web browsers.
Another nod to the real world is the fact that RealiMation is a portable and distributed system. RealiBases are processor-independent, so you can view the same world on anything from an x86-based PC to an SGI Indigo. You can develop an application on a single PC and then run it as a client/server system with the application running on one machine and one or more remote RealiMation servers performing the image generation.
You just relink your application to the RealiNet library: There is no need to recompile it. Further, each RealiMation server can support multiple channels into the same RealiBase, and each channel can show a different viewpoint. This lets you hang multiple monitors or headsets off the machine, which greatly simplifies the development of multiuser training simulations and games.
RealiMation supports third-party rendering hardware, so it's independent of any display technology. This should ensure early support of the new 3-D accelerator chips, such as
GLINT and nVIDIA, that will soon flood the market. At present, the program supports OpenGL, Criterion RenderWare, and Intel 3DR, with Microsoft's DirectX, Apple QuickDraw, and Argonaut BRender support in the works. You can even hot-swap render engines at run time, and the display instantly changes to reflect the new algorithm.
If you develop entirely within a Windows environment, there is an OLE developer edition that turns RealiMation into an OLE automation server. Thus, you can build 3-D visualization systems that use existing data-analysis tools, such as Excel and Mathematica.
Virtech, based in Fife, Scotland, used RealiMation to help quell fears that a proposed parking lot for a Loch Ness visitor center would ruin the landscape. Historic Scotland commissioned a RealiMation-based virtual walk-through to show local residents how the lot's appearance would blend in with the surrounding area. To add to the challenge, the historical agency needed the simulation in just 14 days.
Virtech us
ed the RealiMation API to build a front end that reads in survey files and turns them into virtual worlds. Historic Scotland had been quoted prices of up to $330,000 by other firms, but Virtech did it for a fraction of this figure. "Building models manually used to be slow and expensive, but nowadays we can always find some way to automate the process using the [RealiMation] API," says John Kelly, technical director of Virtech. "And we can deliver [the simulation] on a PC rather than on an SGI [machine]."
Client/Server Worlds
While Windows and less-expensive x86 hardware can now support VR, some VR pioneers, including Ford, Gulfstream, McDonnell Douglas, and the U.S. Army Research Lab, need scaled-up platforms that work in a highly distributed client/server environment. For these applications, Division
offers dVS
, a Unix-based OS layer that supports VR systems on parallel and distributed hardware. Division makes its own parallel graphics accelerator hardware, but
the firm has also ported dVS as a software-only product onto Silicon Graphics and Hewlett-Packard graphics workstations. Division has also just completed a Windows-hosted version of dVS to allow interworking between PCs and Unix workstations.
A distributed client/server system, dVS breaks down the task of supporting a virtual world in a more fine-grained way than RealiMation does. The dVS system contains several independent servers, called
actors
. You can run each actor on a different processor or processors. Separate actors are responsible for image generation (i.e., geometry and rendering), spatializing stereo audio, collision detection, Newtonian physics (i.e., implementing the laws of gravity, friction, and elasticity on moving objects), and input and output device control. The latter actor supports a variety of VR headsets and 3-D pointing and tracking devices.
Because dVS is a multiuser system, it enables several networked users to work together in the same virtual world. A separ
ate actor, called the Body Actor, provides an interface to each participant in such a shared virtual environment. The Body Actor, assisted by Input and Collision Actors, monitors each participant's position and boundary attributes in real time. This multiserver architecture means that you can run user applications in parallel with the virtual environment. You can, for example, feed continuous data streams into dVS while visualizing them in real time.
The dVS system offers three choices for building applications. One tool is dVISE, an interactive authoring environment that runs on top of dVS and lets you build virtual worlds without programming; it comes with data-exchange interfaces for AutoCAD, 3D Studio, Wavefront, and MultiGen 3-D modelers.
The company sells extra converters for leading industrial CAD packages, such as Intergraph EMS, CADDS 4, IGES 5, and Dassault's CATIA. These converters enable you to directly import engineering drawings to build virtual models. The dVISE tool also contains
an immersive VR editor that lets you go inside a virtual world, move objects around, and paint them. Using the editor, you can adjust attributes, such as sound and visibility, by selecting from a virtual menu of floating tool icons. You also can set conditional triggers for events.
Rather than building VR applications interactively in dVISE, you can write Virtual Data Interchange (VDI) scripts to define virtual worlds (you use traditional text editors and VDI notation to create the scripts). Finally, you can link your own C programs with Division's VC library, which gives you direct access to the dVS actors.
Bob Stone runs one of Europe's oldest VR firms, VR Solutions, which uses dVISE to deliver maintenance-verification systems to Rolls Royce and Vickers (for aircraft engines and nuclear submarines, respectively). These applications help designers check whether engineers can reach parts in confined spaces. "Vickers used to check clearances by building a one-fifth-scale plastic model, which wa
s phenomenally expensive," Stone says.
The fully immersive VR systems cost, depending on development time, about $395,000 to $495,000. By contrast, the cost of a model ranged between $6.6 million and $13.2 million (even at one-fifth scale, they fill an airplane-hangar-size building). Using dVISE simplifies maintaining and managing the VR systems themselves. "I don't consider myself to be a programmer, but I can alter a model in dVISE," Stone says.
High-End VR
At the top end of the market, Multigen's new Smartscene delivers one of the most interactive VR authoring systems in the world. Multigen produces 3-D modeling tools for Silicon Graphics workstations and professional simulation systems from Evans & Sutherland and Lockheed/Martin. Its current customers include some of the world's biggest manufacturers, including Boeing, BMW, Chrysler, General Motors, and Volvo.
Smartscene is an advanced editor for assembling 3-D scenes from prefabricated parts. It's reminiscen
t of a fully immersive version of SimCity.
To use Smartscene, you wear a head-mounted VR display and a pair of special
"Pinch Gloves,"
which have touchpads on each fingertip that act like mouse buttons when touched by the thumb. The two-handed interface allows you to interact with the objects inside Smartscene using the same kinds of hand movements and grips you would use for real-world objects. Your natural eye-hand coordination also comes into play.
The basic component tool sets that you work with appear as 3-D trays--which look somewhat like TV dinners--that you can hold in your hand while you search for the parts you need. Unlike in the real world, however, Smartscene objects all have 3-D handles that allow you to stretch and scale them or change their color or texture. There are also "hyper-real" shortcuts in this world: If you want to see the far side of something, you don't have to rotate the object manually. You just cross your arms, and the distant side turns to fa
ce you.
Don the VR display, and you see sets of prefabricated parts, called Smartkits, that appear to be attached to stalks, like the plastic components of a model-airplane kit. You select the part you need and then use the gloves to stretch and color the part to your requirements. Such parts have built-in intelligence, called ModelTime behavior; thus, when you place them roughly into position, they snap together in the right place. A tree, for example, will plant itself in a lawn and not atop a nearby roof. You can run scenes created in Smartscene under Silicon Graphics Performer software, and Multigen claims that Smartscene is a full order of magnitude faster at creating 3-D worlds than conventional editors.
An Interactive Future
Smartscene-style interactivity is currently available only on Silicon Graphics Indigo Impact workstations, but within a year or two you may see this level of graphics performance on Pentium Pro-based PCs with the new generation of 3-D acceler
ated graphics cards. Previously expensive peripherals, such as headset displays and data gloves, are beginning to fall in price, driven by the games market. Lightweight headsets, such as Virtual i-O's i-glasses, already sell for under $500.
Once this sort of power is available at PC prices, we will see VR applications bloom. Attendees at the CeBIT show earlier this year saw Vierte Art's VuppetMaster application, which captures your facial expressions using a head-mounted video camera and merges them in real time onto any 3-D object displayed on an SGI workstation screen. If grafted onto a multiuser, immersive VR system, technology like this could revolutionize the effectiveness of VR as a tool for diverse uses, such as remote teaching, technical support, or phobia therapy, not to mention recreation.
Where to Find
Datapath, Ltd.
Derby, U.K.
Phone: +44 1332 294441
Fax: +44 1332 290667
Division,
Inc.
Redwood City, CA
Phone: (415) 364-6067
Fax: (415) 364-4663
Multigen, Inc.
San Jose, CA
Phone: (408) 261-4100
Fax: (408) 261-4101
HotBYTEs
- information on products covered or advertised in BYTE
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As the basic building blocks of VR systems mature, applications are no longer bound to proprietary hardware platforms.
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Proprietary Pinch Glove technology in Multigen's Smartscene lets you manipulate VR objects almost as if they were real-world objects.
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RealiMation supports multiple cameras, which you can instruct to travel through a virtual scene on preset trajectories.
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Division's dVS lets companies verify parts clearances by using immersive VR systems rather than multimillion-dollar scale models.
Dick Pountain is a BYTE contributing editor based in London. You can reach him by sending e-mail to
dickp@bix.com
.
VR Meets Reality
