ATi Radeon 4000 Series Anti-Aliasing Investigation

Image Quality (AAA)

The tree is actually a transparent texture, likely a result of the game’s LOD system optimizing performance by reducing workload at distances. Because MSAA and CFAA (edge detect) only affect polygon edges, none of them impact the tree. So now I’ll enable AAA and see how it affects the tree. Note that I could’ve used another scene with more alpha content, but by using the same scene, it becomes clearer how these AA techniques all come together as a total package.

0xAAA

2xAAA

4xAAA

8xAAA

24xAAA

Even with just the thumbnails you can clearly see changes to the color gradients at each level of AAA, but feel free to load the larger images if you like. Furthermore, the internals of the tree are being impacted, and the edges aren’t being fattened up like we saw in the last article. This would suggest that in this instance, ATi is applying super-sampling AAA.

Interestingly, there’s a difference between 24xAA and 8xAA when there shouldn’t be given the base level of MSAA is the same in both modes (8x). This suggests that edge detect CFAA may be sampling adjacent pixels with alpha textures when AAA is enabled.