The Voodoo5/GeForce2 Anti-Aliasing Wars
Jun 11 '00 (Updated Nov 03 '00)
Well, once again, it seems that a segment of the computer industry is going to advance the least common denominator instead of true innovation, ala Windows. What I'm talking about here is all the hype over Full Scene Anti-Aliasing(FSAA). Instead of taking the logical step of promoting graphics acceleration at higher and higher resolutions to reproduce realism, let us settle for the low resolution we're dealing with now and attempt to make that pretty.
Problems with aliasing have been around for some time now. Aliasing is the creation of nasty looking visual anomalies during the rendering process that usually take the shape of jagged edges where smooth lines should exist. This problem mainly exists because, at lower resolutions, there simply arent enough pixels present on screen to accurately reproduce smooth lines.
Since the dawn of consumer graphics, there has been a need to eliminate visual anomalies created by low resolution images. Here we are some years later with much the same problem because our current 3d accelerators have only just now reached a speed at which they are truly playable across the board in high quality mode in every game available. But the problem still remains that these cards don't do quite as well at super high resolutions that would eliminate virtually all visual quality problems while games, and monitors, simply havent caught up in being able to support these types of resolutions.
What this has created is a short term need to make our unacceptably low resolution images look as pretty as the very high resolution images we need to be seeing. The current generation 3dfx and nVidia accelerators set out to do just that. However, they go about this process in a slightly different manner.
3dfx:
3dfx cards that enable FSAA include the Voodoo4 and Voodoo5 series. 3dfx utilizes a FSAA solution which renders a scene a number of times and stores them in a hardware buffer, each time rotating the scene on an axis slightly, and blending those scenes together to produce an average scene. Call this what you will, or argue that the result is better, but plain and simple, what this method does is merely blur the scene so that the sharper edges are smoothed out. This results in the virtual elimination of jagged, pixelated edges, but at the same time, can eliminate sharp detail from the scene completely. This seems to be a seldom mentioned side effect of this method, but I've seen the screen captures to prove it. Textures will get blurry and, especially in first person shooters, some people may experience a type of "motion sickness" because their eye will be unable to focus on a given image while they're "moving"
Fortunately for 3dfx, this blurring isnt noticed in most games, nor by most game players, but it does actually occur, since that is essentially what this method of FSAA does. 3dfx has two levels of FSAA, 2x, which uses two renderings to determine the blend, and 4x, which uses 4 renderings. The more renderings used, the smoother the blend, and the better it looks. Unfortunately, the more renderings used in blending, the slower the scene is rendered. Compared to nVidia's FSAA, most people seem to think this method looks slightly better. According to benchmarks, performance with FSAA is about equal to nVidia-based cards.
nVidia:
nVidia based cards that enable FSAA are based on the GeForce2, however, GeForce cards are also able to utilize the FSAA enabled drivers. What nVidia does is render the scene in hardware at a higher resolution, and then scales it down to the monitor resolution. This results in an approximation of what the scene would look like at a higher resolution, but does not involve any type of blurring like the 3dfx method. Details stay sharp and unchanged, however, it seems that the quality appears as slightly less than that of equivalent 3dfx FSAA. Unfortunately, graphics cards based on the GeForce2 shipped with broken FSAA in their drivers. The fixed version of these drivers is currently available at nVidia's website. The upcoming GeForce2mx will shipping with FSAA fully enabled in it's drivers. Either way, nVidia's method is API dependent, and may not work with all games, especially older ones. With the fixed drivers, nVidia supports 2x and 4x FSAA in OpenGL and 2x, 4x, 9x, and 16x FSAA in Direct3D. It should be mentioned that anything above 4x FSAA is completely useless with the current generation of 3d accelerators. And, just like 3dfx, the better the FSAA quality, the slower the 3d acceleration.
Conclusion:
Out of the box, 3dfx wins this war because their method is faster, most people think it looks better, and it works with almost all games. With the fixed drivers, both brands' flagship accelerators benchmark about the same with FSAA enabled. With the reference drivers on nVidia's site, nVidia based cards are going to win this battle because the Geforce2 is not only a better non-FSAA accelerator than the Voodoo5, but in many cases, it can also be found for less money.
Near Future:
3Dfx's new Rampage chip is due sometime between Christmas and Spring. It should be a very powerful processor with hardware T&L at least on par with the Geforce2. You can count on FSAA being a major feature when it's released.
nVidia's next generation chip is planned to be released around Spring of next year, should feature a hardware buffer, like 3dfx, and is supposed to offer FSAA with virtually no performance hit.
Expect drivers from both companies to continue to improve, and performance while using FSAA to improve with them.
Long-Term Future:
However, hopefully we can expect FSAA to be a short term solution, and move on to satisfying gaming at resolutions above 1600x1200 pixels that won't really have any need for anti-aliasing to begin with.
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Member: Curtis Burdette
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