Image Quality: Anisotropic Filtering
With this next set of screen shots, we followed a similar procedure to evaluate the effect of the GeForce 7800 GTX's anisotropic filtering technique on a given scene. The screenshots below are from Half-Life 2's "background 4" map. We've again compared similar settings using the GeForce 7800 GTX, GeForce 6800 Ultra, and Radeon X850 XT Platinum Edition. For this set of screen shots, anti-aliasing was disabled.
When browsing through the screen shots above, pay special attention to the lower left portion of the scene. The detail in the road is affected most by enabling anisotropic filtering. In the "No Aniso" shots at the top, which have only trilinear filtering enabled, the blurring in the road is clearly evident.
However, with 8X anisotropic filtering enabled, the detail in the road is dramatically enhanced. If you open each of the shots individually and skip through them quickly, you're likely to notice a bit more detail in the shots taken with the GeForce 7800 GTX, disregarding artifacts produced by the JPG compression used to make the pics "Web-friendly." (The file names make it easier to track which image you're looking at, should you open multiple images at once.)
We got a similar impression looking at the 16X aniso shots. Of course, image quality analysis is objective by its nature, but based on these images, we think the GeForce 7800 GTX has the best image quality as it relates to anisotropic filtering. The GeForce 6800 Ultra and Radeon X850 XT Platinum Edition produce similar images, but the GeForce 7800 GTX seemed to product better visuals in our opinion.
Whenever it introduces a new family of GPU, NVIDIA historically introduces a few technology demos to highlight the new features available with its new GPU as well. With the launch of the GeForce 7800 GTX, NVIDIA is introducing two new demo characters: Luna and Mad Mod Mike. Luna is NVIDIA's typical siren, with a highly detailed suit and realistic hair and facial characteristics. The Luna demo makes use of Pixel Shader 3.0 effects, displacement mapping, translucency, and real-time hair that's shadowed based on the number of hairs between each pixel and the light source. Luna's suit and real-time refraction on an eyeball shot featured in the screen shot above, require more than 300 instructions with per-pixel branching and are computed in 64-bit color.
Mad Mod Mike, who strikes us as a combination of Paul Sr. (From "American Chopper"), Santa Claus, and Ty Peddington (From "Extreme Home Makeover"), make use of similar shader model 3.0 effects, along with Radiant Lighting and Depth-of-Field effect.