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Temporal AA

A new anti aliasing mode that ATi is introducing is something they call temporal AA. It is an interesting concept - instead of strictly using more samples to achieve better quality, temporal AA switches the AA pattern back and forth between a high and low sample to simulate a higher sample pattern with the performance of a fewer samples.

-Temporal AA can cause visible artifacts if the frame rate drops too far below the display refresh rate. To avoid this issue, temporal AA will be temporarily disabled if the frame rate drops below 60 frames per second for more than a few seconds. In this case, the driver will revert to using standard AA. Temporal AA will be automatically re-enabled if the frame rate spends more than a few seconds above the threshold. For this reason, we recommend using an on-screen frame rate display when testing temporal AA to ensure the frame rate stays above 60 fps.

-Because temporal AA using alternating sample patters from frame-to-frame, the effect cannot be seen in the screenshots that capture only a single frame.

The first point highlights the main issue with Temporal AA - the framerate has to be sufficiently high to be able to take advantage of this feature. This will work well on the R420 series at 1024 and above but on the R3xx based cards it might be a bit of a stretch to have it going at 1024 with AA and above. Yes that was correct - temporal AA is not a new hardware feature but will work on the R3xx architecture also.