X-bit labs

ATI RADEON X800: R420 Totally Exposed (page 24)

Category: Video

by Tim Tscheblockov , Alexey Stepin , Anton Shilov

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

6x Temporal Anti-Aliasing

Judging by the screenshots, the use of temporal anti-aliasing really does ensure better smoothing of the polygon edges. What should we keep in mind to achieve better effect?

First of all, the frame rate should be high enough to make the “trembling” of the polygon edges invisible to the human eye. ATI claims that the standard frame rate values of the regular monitors (50-60Hz for LCD and 70-85Hz for CRT monitors) should be more than enough for that. I got the impression that it would be better to set the maximum frame rate in this mode, that is 100, 120 or even 150Hz. Otherwise, you will still notice the “trembling”. All in all, the higher is the frame rate on the monitor and the more frames the graphics card can display, the better. It is remarkable that if the graphics card cannot process more than 60 frames per second, temporal anti-aliasing gets automatically disabled, in order not to irritate the user with the blinking lines.

Secondly, video synchronization should be enabled. Without it, the frames calculated with different samples location may not get into the frames sequence displayed on the monitor. For instance, while there is the current even frame displayed on the monitor, the graphics card can have enough time to process a few next frames in a row, so that the monitor will again be displaying an even frame.

And finally, if you are using an LCD panel, the effect should be much more stable: you can count not only on the inertia of the human eye but also on the slowness of the LCD matrices.

Unfortunately, we didn’t manage to check if the use of temporal anti-aliasing loads the graphics accelerator even more. When this mode is enabled, the performance measurements we got differed by 2-3 times, which can only be explained by the unfinalized driver version. Another proof to this point is the fact that the driver control panel doesn’t even allow enabling temporal anti-aliasing, and there is a special utility for that.