X-bit labs

ATI RADEON X800: R420 Totally Exposed (page 13)

Category: Video

by Tim Tscheblockov , Alexey Stepin , Anton Shilov

[ 05/04/2004 | 06:42 AM ]

Now we will enable anisotropic filtering (not the heaviest mode, of course) in addition to the tri-linear one. It will be AF 4x. the testing conditions remained unchanged. The cards go in the same order as before: ATI RADEON X800 XT Platinum Edition, RADEON 9800 XT, NVIDIA GeForce 6800 Ultra and NVIDIA GeForce FX 5950 Ultra:

ATI RADEON X800 XT Platinum Edition, RADEON 9800 XT and NVIDIA GeForce 6800 Ultra show very similar images, where we can clearly see “inconvenient” angles: the color stripes of the highlighted MIP-levels get closer to the camera. NVIDIA GeForce FX 5950 Ultra doesn’t have clearly visible “inconvenient” angles for anisotropic filtering, which you can see on the screenshot.

Now let’s enable the maximum level of anisotropic filtering. For ATI graphics processors and GeForce 6800 Ultra from NVIDIA, this is 16x AF, while GeForce FX 5950 Ultra supports the maximum of 8x AF. The anisotropic filtering quality in the drivers is set to the maximum, tri-linear filtering is on. You can see a screenshot for ATI RADEON X800 XT Platinum Edition in the upper left corner, the one for RADEON 9800 XT in the upper right corner, the screenshot for NVIDIA GeForce 6800 Ultra is on your lower left, and the one for NVIDIA GeForce FX 5950 Ultra – on your lower right:

ATI RADEON X800 XT Platinum Edition, RADEON 9800 XT and NVIDIA GeForce 6800 Ultra again produced very similar images, differing from what GeForce FX 5950 Ultra showed us.

It is interesting that if we compare the image quality obtained in the most favorable conditions, then NVIDIA GeForce FX 5950 Ultra will lose to all other graphics cards tested: you can clearly see it from the MIP-levels location, for instance, at the horizontal surfaces available in the test scene. However, if we compare the texture quality in the most unfavorable conditions, then GeForce FX 5950 Ultra will outperform all other graphics cards, because the algorithms they are using have a few “inconvenient” angles, where the texture clarity gets significantly worse than what we see by GeForce FX 5950 Ultra with 8x anisotropic filtering. You can clearly see it from the screenshots: the stripes of MIP-levels on ATI RADEON X800 XT/9800 XT and NVIDIA GeForce 6800 Ultra move much closer to the camera than those by NVIDIA GeForce FX 5950 Ultra.

The situation will never be changed, actually, because these “inconvenient” angles where the textures get less clear-cut is the price you have to pay for high performance of the new anisotropic filtering algorithms.