Graphics Cards for Every Budget

The reason that films such as Final Fantasy: The Spirits Within; Monsters, Inc.; Toy Story; and Toy Story 2 look worlds better than what PC graphics offer is that they're pre-rendered. By rendering every scene ahead of time, animators can use curved surfaces to make 3-D objects look more realistic. For example, look at your hand. Now, fire up any 3-D game and look at the hand of any character model. Notice how the character model's hand looks blocky and suffers from strange joint anomalies? That's because rendering curved surfaces to properly represent any type of real-world object has to be supported in hardware. Today's 3-D graphics technology considers curved surfaces and polygons to be mutually exclusive, so a typical consumer graphics card can't do both.

ATI's approach is an elegant solution that could give us the best of both worlds. TRUFORM works by taking the triangle information that tells the GPU how to render each polygon and internally converts that information into curved surfaces. TRUFORM then takes the converted information and uses it to draw the polygons on screen.

The details behind this technology are complex, but in a nutshell, to produce curved surfaces, TRUFORM takes each triangle's vertex information and uses N-Patches to form a curved surface mesh on each triangle. It then places additional control points on a separate plane located above or below the triangle. Using these control points, the GPU draws additional triangles until the original triangle is actually a curved surface. Because the GPU's T&L engine computes these calculations, the enhanced visual quality doesn't come at the cost of performance.

So how well does TRUFORM perform? Recent games like Return to Castle Wolfenstein and Serious Sam: The Second Encounter use TRUFORM to "flesh out" character models. By adding polygons to round off joints, RADEON 8500-rendered characters appear to be less blocky than GeForce4-rendered characters-and with no performance hit. Counter-Strike junkies will be glad to know that Valve Software's most recent game patch includes TRUFORM support.

To improve on the original RADEON's performance, the RADEON 8500 uses the new HyperZ II architecture, which is a form of tile-based rendering. Rather than leveraging a true tile-based rendering architecture, ATI takes a three-pronged approach to reduce wasted memory bandwidth. First, the RADEON 8500 uses a technique called Hierarchical Z to determine which pixels are visible and which are obscured when the graphics card renders a scene. The RADEON 8500 culls obscured pixels before they enter the rendering pipeline. Second, the card uses Z Compression to fit more data into the Z-buffer. Third, Fast Z Clear clears the Z-buffer to begin rendering the next frame. Traditionally, graphics cards clear the Z-buffer by overwriting the existing data with zeros. Fast Z Clear just marks the data in the Z-buffer as clear in one pass, which on paper is 64 times as fast as the conventional approach. The benefit? Blazingly fast performance.

Finally, the RADEON 8500 includes an FSAA component dubbed SMOOTHVISION. Rather than taking a multisampling approach to FSAA as the GeForce4 does (see the sidebar, "Inside The GeForce4"), SMOOTHVISION uses the old supersampling method to reduce the amount of jagged edges in a scene. The benefit to using supersampling is that the displayed textures are generally less blurry than those anti-aliased with a multisampling technique. The drawback is the performance hit that comes with internally rendering a scene at a higher resolution than is displayed, which is one reason supersampling was phased out. Luckily for ATI, the RADEON 8500 has enough raw power to perform 2X FSAA using SMOOTHVISION without impacting performance to the point where games are unplayable. However, 4X FSAA results in abysmal performance. As SMOOTHVISION shows, supersampling was put out to pasture for a good reason.

Beyond gaming, the RADEON 8500 also provides several additional functions. The RADEON 8500 features superb TV-out quality, a staple of ATI technology. Even at a screen resolution of 800 x 600, using an S-video connection makes text as readable as it gets on TV screens. For those of you who already have HDTV, the RADEON 8500 features impressive de-interlacing technology that lets it output 480, 720, and 1080 progressive scan (along with 1080 interlace) signals. Just plug a DVI-I to Component adapter between the card and your HDTV's component inputs, and you're set.

Home theater enthusiasts will find a lot to like about the RADEON 8500. By including a hardware DVD decoder (which supports all the expected features, such as motion compensation and Inverse Discrete Cosine Transform-IDCT-to take the load off the CPU), the RADEON 8500 offers a picture comparable to most mid-range DVD players. Because the RADEON 8500 can output a progressive scan signal, the card fares well even against high-end DVD players. Simply put, if you're looking for a video-decoding solution, the RADEON 8500 is an obvious choice.

So what's the problem with the RADEON 8500? In a word: drivers. As anyone who has owned a recent ATI video card can attest, ATI has always been light years behind NVIDIA when it comes to driver development. The original drivers that shipped with the RADEON 8500 were horribly broken to the point that features either didn't work or were intentionally disabled simply because ATI's software engineers hadn't implemented them. Performance was also an issue-with its specifications, the RADEON 8500 should have outperformed the GeForce4 Ti 4600, but it didn't and it doesn't even now. To ATI's credit, later driver releases fixed some issues but performance still lags behind the GeForce4 Ti 4600 in most games.

The RADEON 8500 offers good performance, excellent 3-D technology, and advanced video playback features. Aside from the driver issue, the RADEON 8500 is superior to the GeForce4 Ti 4600 in almost every way. ATI plans to aggressively release beta drivers on a monthly basis, so the product can only get better from here. As it stands, the RADEON 8500 is an excellent product if you're willing to deal with growing pains.

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