NVIDIA GeForce 6600 GT
by Marc Prieur
Published on September 7, 2004
Anti aliasing and anisotropic filtering
We verified that the algorithm used by NIVIDA for the GeForce 6600 GT and the GeForce 6800 were identical on anti-aliasing or anisotropic filtering. We couldn’t find any fault with these two functions and anti aliasing is clearly better than with the GeForce FXs because of the Rotatet Grid in AA 4x.
To get an idea of the difference in practice, here are a couple of images from UT 2004, Colin McRae 04 and Far Cry in 1600*1200 with 4x anti aliasing and 8x anisotropic filtering forced via the driver (the original non compressed versions except for Far Cry are available here). Of course these are frozen images and the overall quality can only be evaluated in motion. The images are in the following order; GeForce 6800GT (65.76), GeForce 6600GT (65.76) and Radeon 9800 Pro (4.8) :
The following table shows the impact of 4X anti-aliasing and anisotropic filtering on performance with Colin Mc Rae. Anisotropic filtering is forced via the driver and optimizations were left activated. Results compared to those without AA / Aniso are expressed in percentage:
Logically, the GeForce 6600 GT registers the biggest drop in performance due to 4X anti aliasing activation, however not as much as we thought. The most surprising result was regarding anisotropic filtering. The GeForce 6600 GT was the card with the smallest drop in performance in this mode!
It’s difficult to understand this result as the 6600 and 6800’s algorithms are similar. This might be due to better cache and the presence of 4 ROPs for 8 Pipelines. Anisotropic filtering requires more work from the 8 pipelines than a simple “optimised” trilinear filtering.
In conclusion, activating 4X anti aliasing and the 8X anisotropic filtering requires more effort from the GeForce 6600GT, but thanks to excellent performance with anisotropic filtering the difference is reduced. This first result is a great start and foretells excellent performance in game tests.
