3D Animation Workshop: Lesson 11: Today's 3-D Workstation | 3 | WebReference

3D Animation Workshop: Lesson 11: Today's 3-D Workstation | 3


Lesson 11 - Today's 3-D Workstation - Part 3

3-D Previews

The dominant reason for the 3-D hardware monopoly once held by Silicon Graphics was in its display technology. The MIPS microprocessor used in SGI workstation as the main processing engine is certainly an excellent chip, but SGI workstations used to be unique in offering a separate specialized processor to run the 3-D display. Just as the critical distinction between Intel and Apple computers evaporated when Microsoft implemented the Windows interface, so a similar thing has happened to SGI. A number of companies are now making 3-D graphics processing hardware that can be inserted into a PC. A PC running with such hardware has the 3-D display capabilities comparable to a SGI workstation.

By display, I mean the ability to render shaded, color previews of 3-D objects and scenes so quickly as to permit the illusion of complete interaction. The user builds a model of a boat, for instance. The preview of the boat, (though far lower quality than a final render) is properly colored and reveals the lighting of the scene accurately. If the boat (or the camera view of it) is moved or rotated in the scene, the display is redrawn so quickly that the user has the sense of manipulating a physical object or a navigating a scene in real time. If the display can draw fast enough, keyframed animations can previewed in the same way, thus avoiding the time-consuming process of creating test renders. In short, high quality, responsive previewing is essential to professional 3-D work.

Anyone who has ever used a VRML browser has a very good general sense of interactive, real-time 3-D rendering, and can imagine how important it is for developing 3-D art and animation.

What in the Hell is OpenGL?

Silicon Graphics developed a library of standard procedures for drawing colored, shaded 3-D images on the screen, and made it available as a standard. Microsoft implemented the OpenGL standard as part of the Windows NT operating system last year. This makes it possible for applications to simply call the OpenGL routines in the operating system to draw the screen, rather than having to write and include these instructions in the applications themselves. This approach, however, in which the operating system software draws the display, is generally too slow and clumsy for most practical use (as those who have used VRML browsers can surely imagine).

The Hardware Solution

To speed up the OpenGL display, the OpenGL procedures are hardcoded onto a specialized processor. When we speak of an OpenGL card, we mean a graphics card with such a processor, or in the case of very expensive ones, many such processors. The shaded previews are drawn very quickly because there is a specialized processor, using its own dedicated memory, executing the OpenGL commands directly. Softimage makes the most extensive use of OpenGL of any application, and for that reason, the XERT folks stress the importance of using the most powerful graphics engine one can afford when using this application. Lightwave 3D added OpenGL previewing only in 1996, with its version 5.0, and did not make as extensive use of its capabilities as it might have. The new Lightwave 5.5 (due out in June) makes much more extensive use of OpenGL, including the ability to display textures on previewed objects. Thus the XERT folks anticipate that Lightwave users will begin to need more powerful graphics processing than they may be currently satisfied with.

3D Studio MAX went its own way, refusing to adopt the OpenGL standard and implementing their own previewing technology, called HEIDI. MAX is such a major player that it could get away with this, and all the high-end graphics processors support HEIDI in the same way that they support OpenGL.

Do not confuse graphics boards that truly support the OpenGL and HEIDI standards with boards (some of them very good) that provide other types of 3-D support, generally for games. 3-D professionals typically speak, specifically, of an "OpenGL card."

Making a Decision

Choosing your 3-D graphics card option is undoubtedly the hardest part of the equation. 3D Labs, the makers of the powerful Glint graphics processor, have been pushing a chip called Permedia in order to seize what they believe is a huge potential market for lower priced, medium quality 3-D acceleration. XERT's more affordable systems feature graphics boards incorporating the Permedia processor and 8 MB of SGRAM (sychronous graphics RAM), and these are reportedly satisfactory for many users (though never for Softimage). The step up to boards incorporating the Glint processor, or to the well-known Oxygen line from Dynamic Pictures is an expensive one. This is just the place where expert, up-to-date advice is critical from people who understand this complex field and who are familiar with the precise applications you are using. You can't buy a graphics subsystem from an advertisement, or by simply looking at specs. No one knows more about this forbidding subject than the folks at XERT. Visit their web site at www.xert.com and review the extensive information they have compiled there about 3-D graphics card options. And once you are properly oriented, drop them a line with your questions.

The Easy Stuff

Thank God not everything is as difficult as the graphics card issue. Here are some simple guidelines from XERT concerning the rest of the system.

64 MB of RAM is the minimum and 128 is recommended. Professional 3-D animation packages are memory-intensive far beyond any other kind of program you may be familiar with using. The moment you run out of RAM and start swapping out to your hard drive, things become unbearably slow.

If RAM is important, cache memory is even more so. All of XERT's Pentium Pro systems include 256KB of Level 2 cache per processor. The new Pentium II systems will have 512KB.

Your hard drive should be ultra-wide SCSI. Speed is very important here to improve the inevitable swapping from "virtual memory" and for screen playback of animation files.

A 21 inch monitor is obviously far superior to a 17 inch one because professional 3-D applications necessarily divide the screen into multiple windows for simultaneous viewing from different positions. But a 21 inch monitor still costs $1,000 more than a 17 inch one, and even if you have that money, you may want it for a second processor or a beefier graphics card. On the other hand, you can't simply "upgrade" a monitor in the way you can add more RAM or a second Pentium. In any event, look for a refresh rate no slower than 75Hz. Intensive hours of 3-D graphics work can be hard on the eyes, and noticeable flicker on the screen promotes fatigue.

A Final Word

Staying on top of hardware developments is very tough, and it's easy to naively assume that you understand much more than you do. Developments in 3-D generally are moving so rapidly that yesterday's news is already old, and the whole subject is inherently complex. The practical and professional 3-D artist or animator has his or her hands full with software problems and creative work. When facing hardware choices, he or she simply has find a source on which to rely. The relationship is very much like that with a doctor or an auto mechanic. You must learn enough to ask the right questions, and then find a source to get you the right answers. The folks at XERT have been very generous in sharing their knowledge for this tutorial, and I'm honored to recommend them to my audience. Take some time to look through their website, and especially at the way they've configured standardized systems with an eye to specific applications. There's a lot of solid education there that's not easy to find. And feel free to contact them with your questions.

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Created: June 2, 1997
Revised: March 6, 1998

URL: http://webreference.com/3d/lesson11/part3.html