Antialiasing - Image Quality
Serious Sam: Second Encounter is a decent test to evaluate antialiasing performance. Using the Technology Test level from the demo, the curved arches are a nice test of AA quality and I chose a zoomed section of the base image to display the quality, focussing on an intersection between arch and building edge.The images use Quality mode in the driver. Time constraints stop me from evaluating AA quality in Performance mode, I'll update the review with Performance shots as soon as possible.
Click on each zoomed sample of AA quality to see the full 640x480 .png version. Each is around 450KB in size.
No antialiasing first for a base image.
No antialiasing, zoomed section, click for full 640x480 image
There's no anisotropic filtering so texture quality isn't brilliant on the building side, but geometry aliasing is very evident in the base image and that's what we're looking for.
2X mode now.
2X antialiasing, zoomed section, click for full 640x480 image
Antialiasing is clear to see, the 45° sample rotation doing a decent job of simple antialiasing of our geometry edges.
2XQ mode next, the 2X RGMS+Quincunx DAC filtering method.
2XQ antialiasing, zoomed section, click for full 640x480 image
Urgh. And to think I used to quite like Quincunx AA. Anyway, we get arguably better edge antialiasing on the arch and building edges, compared to the base 2X mode, but things are obviously blurry, especially the texture on the building's front face. It's decent for edge AA, but the overall image quality reduction isn't something you want to see on a leading-edge graphics accelerator.
4X mode now, the first really new mode that NV40 does, compared to GeForce FX.
4X antialiasing, zoomed section, click for full 640x480 image
It's a noticable jump in quality from 2X (no Quincunx) and if you check the full screenshot, things look good.
The 8X RGMS+SS mode to round things off.
8X antialiasing, zoomed section, click for full 640x480 image
To best see the difference between the 4X and 8X modes, look at the reflection on the arch curve. The extra texture sampling in the 8X mode means that the texture is antialiased too, since there's no physical geometry that defines that reflection, just clever per pixel lighting effects. Edge AA, at least in the zoomed section, isn't noticably improved, although the edge angles hide any massive differences.
Feel free to use ATI's Compressonator tool to do your own comparison analysis between 4X and 8X AA modes, using the full size .png images. The texture sampling quality will show its face.
In any case, the 8X mode's texture sampling performance hit may render the mode unusable in most cases, despite good quality. Let's see why.
