Intergraph and Omnicomp offer different routes to speedy 3-D
Greg Loveria
Most of us would love to navigate through complex virtual 3-D scenes on our desktop PCs. But functions such as real-time 3-D animation and Gouraud shading are tough jobs for even the swiftest CPU. Most desktop PCs have enough floating-point capability for the initial geometry calculations required by 3-D modeling, but you need specialized 3-D rendering hardware to quickly turn those internal geometric representations into realistic-looking images on the 2-D surface of your monitor.
The combination of lower-cost 3-D hardware and 3-D APIs -- such as Silicon Graphics' OpenGL -- is making that reality more affordable. OpenGL is particularly important because it's built into Windows NT and will eventually be part of Windows 95. Cards t
hat support OpenGL will run lots of 3-D applications.
Here we evaluate two promising approaches to 3-D acceleration: a $2385 PCI card from Omnicomp that works with several currently popular 3-D APIs, including OpenGL; and a $23,850 Intel-based workstation from Intergraph.
Omnicomp's 3Demon cards are the first graphics adapters to use 3DLabs' new Glint 3-D accelerator, which promises good 3-D performance at a low price. (Glint-based cards from Elsa, Fujitsu, and others should be available by now.)
Intergraph's new TDZ-40 system belongs to a family that delivers workstation-level 3-D performance on the Intel x86 platform. The TDZ-40 also proves that a good 3-D chip is not enough in itself for great 3-D performance (see the sidebar "A Whole Lotta Buffers").
The dual-Pentium TDZ-40 is a turnkey acceleration system for MicroStation, a CAD package from Intergraph subsidiary Bentley Systems. It uses Intergraph's two-card GLZ2, an OpenGL accelerator that works in conjunction with Intergrap
h's MOGLE (MicroStation OpenGL Extensions) 3-D API. Omnicomp's 3Demon adapters, while aimed at improving speeds of existing 3-D and CAD applications using various 3-D APIs, can also accelerate MicroStation performance speeds using MOGLE.
3-D Demon
Omnicomp's 3Demon adapters all use the Glint 300SX 3-D graphics chip. Board models in the 3Demon series range from the $1995 SX44 (4 MB each of VRAM and DRAM) to the $3535 SX816 (8 MB of VRAM, 16 MB of DRAM). We tested a $2385 SX48, which has 4 MB of VRAM and 8 MB of DRAM. (Omnicomp plans an October release for its 3Demon TX series, which uses the new Glint 400TX processor to accelerate texture mapping.) The SX44 and SX48 use the 64-bit IBM525 RAMDAC for color conversions, while the SX816 has a wider 128-bit IBM528 RAMDAC. The three-quarter-size 3Demon cards use DRAM for 32-bit Z-buffering.
Jumperless and self-configuring, the SX48 installs easily alongside any existing VGA card, which is required for boot-up purposes. The SX48
supports display resolutions of 640 by 480 pixels with 24-bit color up to 1280 by 1024 pixels with 8-bit color. It also supports 24-bit-color, double-buffered, 3-D model acceleration at display resolutions of 640 by 480 pixels up to 800 by 600 pixels.
GLZ Sizzler
Available only in its TDZ line of workstations, Intergraph's PCI-based GLZ series of OpenGL graphics accelerators supports 24-bit color depth
only
. The GLZ1 adapter, which has 12 MB of VRAM, supports resolutions as high as 1152 by 864 pixels. The two-slot GLZ2 tested here supports resolutions of up to 1600 by 1280 pixels; it has 24 MB of onboard VRAM. Housed in an external cabinet, and packed with 34 MB of VRAM and 32 MB of DRAM, the truly scary GLZ6 supports real-time, fully texture-mapped, photo-realistic model walk-throughs. Other 3-D accelerators in this series include the GLZ3 through GLZ6. All GLZ boards are fully compliant with OpenGL and MOGLE and have built-in VGA support.
Prices for TDZ works
tations, all with GLZ 3-D acceleration, start at $9900 for a single-Pentium TDZ-30 system (less monitor) and climb to $136,800 for the six-Pentium TDZ-60DS with GLZ6 accelerator, a 3- by 2-GB RAID system, 256 MB of system RAM, and 27-inch InterVue display monitor. Our test system -- a 100-MHz
dual-Pentium TDZ-40
, configured with the GLZ2 accelerator, 64 MB of RAM, 2-GB hard drive, and superb InterVue 21-inch monitor -- costs $23,850. TDZ workstations ship with a quad-speed CD-ROM drive and a keyboard with built-in microphone and Altec Lansing speakers.
3-D Performance
Several factors affect 3-D graphics performance: the host CPU and system bus, operating system, 3-D API, and an application's ability to perform multithreaded and multiprocessing operations. As a PCI-based system, Intergraph's TDZ-40 made a good base for testing the 3Demon card; it eliminated many of these variables. We compared the 3Demon to the TDZ-40's own GLZ2 adapter, also a PCI card, under
Windows NT Workstation 3.5, with both MOGLE- and OpenGL-based benchmarks.
We also compared the 3Demon with a Matrox Millennium card, both running in the same Micron 120-MHz Pentium system. Though the Millennium accelerates 3-D, it didn't yet have OpenGL drivers and thus represents a very fast 2-D graphics accelerator for comparison purposes.
To test OpenGL 3-D performance, we used
the Viewperf benchmark
, developed by the OpenGL Performance Characterization Committee. It gauges 3-D performance with lines, solids, shaded solids, and textures. We tested both cards at resolutions of 640 by 480 pixels and then 1024 by 768 pixels with 24-bit color. We also tested static model rendering with MOGLE using MicroStation v5.00.95 and two 3-D DGN files ("bearing cutaway" and "pool architectural" drawings). The MicroStation command functions tested on both adapters consisted of wire mesh, hidden line, filled hidden line, and constant and smooth shading renders.
To put the 3-D per
formance of these products in perspective, the 3Demon board in its 12-bit color mode ran the Viewperf tests three to four times faster than the Matrox Millennium in its 8-bit mode at both 640 by 480 pixels and 1024 by 768 pixels. With both cards using 24-bit color, the 3Demon was only one-third to two times faster at a resolution of 640 by 480. At 1024 by 768, the 3Demon's 4 MB of VRAM wasn't enough to double buffer, and the two cards produced almost identical Viewperf results. For rotating and animating shaded models at a resolution of 1024 by 768 (or higher) with 24-bit color, you should consider the 3Demon SX88 or SX816, which have more VRAM.
Just as the 3Demon beat the Millennium, the Intergraph GLZ2 beat the 3Demon with both boards running Viewperf in the TDZ-40--at least during most tests. In 12-bit color mode, the 3Demon speeded up and averaged roughly the same as the GLZ2 (always in 24-bit mode), but that's an unfair comparison.
The size and complexity of the MOGLE pool model made real-t
ime Gouraud-shaded walk-throughs impossible on the SX48, though wireframe-mode pans and zooms were fluid. The GLZ2 was only 20 percent to 50 percent faster than the SX48 when first running the MOGLE tests. However, on second runs, with display-list caching in its spacious RAM, the GLZ2 ran an amazing three to ten times faster than the SX48 with the MOGLE pool model.
During model-rotation and walk-through tests, the GLZ2, like the SX48, showed motion lags in the more complex pool model when doing Gouraud-shaded pans and zooms. But in wireframe and flat shaded modes, motion was fluid. Rotations of the MOGLE bearing-cutaway model at both resolutions and using Gouraud shading were less jerky with the GLZ2 than with the SX48. With the GLZ2, rotations were as smooth as glass in wireframe and flat shaded modes.
Though a bit pricey, an Intergraph TDZ workstation with GLZ acceleration technology is the top professional 3-D solution if you want the software compatibility provided by an Intel-based system.
For budget-conscious people running existing 3-D applications on a PCI-based system, Omnicomp's 3Demon add-in boards are an excellent low-cost solution.
Product Information
TDZ-40 $23,850
(with two 100-MHz Pentiums, 64 MB of
RAM, 2-GB hard drive, 21-inch monitor)
Intergraph Computer Systems
Huntsville, AL
(800) 763-0242
(205) 730-5441
http://www.intergraph.com
3Demon SX48 $2385
(4 MB of VRAM, 8 MB of DRAM)
Omnicomp Graphics Corp.
Houston, TX
(713) 464-2990
fax: (713) 827-7540
omnicmp@phoenix.phoenix.com
http://phoenix.phoenix.net:80/omnicmp
illustration_link (11 Kbytes)
Viewperf measures shaded-model rotation rates in frames per second using three multicolored, multitextured 3-D models: a Stealth F117 jet fighter (a mesh consisting of 172 primitives and 708 vertices per frame), a human skull (3778 primitives and 14,172 vertices), and a simple sphere (2448 primitives and 9792 vertices).
A single Viewperf frame consists of the model moving or rotating from one rendered x,y,z axes position to the next interpolated, rendered position in a 360-degree rotation about any axis.
photo_link (37 Kbytes)
Intergraph's Pentium-powered TDZ-40 system combines workstation-level 3-D performance with Intel x86 software compatibility. The Omnicomp 3Demon SX48 board (perched atop the monitor) provides good 3-D performance for tighter budgets.
Greg Loveria writes and consults on animation and 3-D graphics from Binghamton, New York. You can reach him on the Internet at
gloveria@spectra.net
or
loveria@bix.com
.
3-D Graphics Go Zoom
