ATI’s Radeon 9700 (R300) – Crowning the New King

Fixed Anisotropic Filtering, Finally

The R300 fixes another issue that many complained about with the R200, and that is in regards to its anisotropic filtering. With the Radeon 8500, ATI introduced their adaptive anisotropic filtering algorithm that determined the number of samples that should be taken based on the rotation along the x and y axes with respect to the user. The end result of this method was that in situations where the highest degree of anisotropic filtering was necessary, the GPU would take the maximum amount of samples set in the driver (16X was the max you could set on the slider).

The only problem with ATI’s algorithm was that they did not take into account what would happen if there was rotation along the x, y and z axes. In most cases, with rotation along the z axis also thrown in, the GPU would default to the lowest filtering method supported – bilinear – which looked pretty bad.

The R300 not only supports trilinear alongside anisotropic but they also fixed the z-rotation issue. Once again, we will have to spend some more time with a card in order to get a better idea if the problem is truly fixed or not, but from what we can tell, they have done a solid job.

We’ve already encouraged NVIDIA to offer a similar form of anisotropic filtering, since the difference between ATI’s adaptive algorithm and NVIDIA’s approach where everything is anisotropically filtered is negligible in most cases; the main difference is that ATI’s method incurs a noticeably smaller performance hit.

According to ATI, there’s no performance hit with bilinear filtering enabled and 16X anisotropic filtering on the R300 and a small performance hit with trilinear enabled. We didn’t have enough benchmarking time with the card to define what a “small performance hit” was but based on our experience with the R200, we would estimate 10%, at most.