FSAA Performance in Direct3D

Because of the lack of any decent benchmarks in Direct3D games, we resorted to using 3DMark in order to illustrate the performance penalty incurred by enabling the various FSAA settings.

There are a couple of interesting points to make here. First of all, anything above 2x2 FSAA (the 4th slider setting) makes the performance of the GeForce2 GTS drop below the 30 fps mark at 640 x 480 which is borderline playable for most users, especially for a $300 card.

At the same time, the high quality 2x2 setting ( 2x2 FSAA (HQ) ), performs almost as well as the regular 2x2 FSAA setting yet looks better which makes it the ideal setting if it works properly in all situations, otherwise the next best choice is the 2x2 setting.

Notice that as the resolution increases, the performance of the various settings seems to level off. This is because of the fact that at the higher resolutions the GeForce2 GTS runs out of memory, forcing it to drop down to a lower FSAA setting. Of course, that means the performance does not change as can be seen in the graphs. The reason it runs out of memory is that it is rendering the image at 4x the resolution in both the horizontal and vertical directions at the highest setting. That means a 16x increase in total pixels - much more than a 32MB GeForce 2 GTS can hold in memory.

We get a similar situation under the Game 2 benchmark of 3DMark 2000, however this time even the 3x3 FSAA setting is still "playable" at 36.2 fps at 640 x 480.

Here you can see the synthetic fill rate numbers. The huge drop in fillrate as the FSAA quality is turned up simply illustrates the additional raw power required to perform FSAA. Fillrate is not actually being lost, but rather it's being devoted to performing FSAA. Once again, we see that 32MB is simply not enough for NVIDIA's highest FSAA settings, forcing the driver to drop back to a lower quality setting.

FSAA Image Quality in Direct3D (continued) Final Words
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