nVidia GeForce GT200 Series Anti-Aliasing Investigation

Combined Mode Anti-Aliasing (xS)

nVidia also offers full scene super-sampling on their single GPU configurations in the form of combined modes (xS). These modes combine traditional multi-sampling with ordered grid super-sampling to further enhance image quality. The super-sampling component in these modes is obtained by rendering the entire scene bigger and then scaling down.

The notable advantage of super-sampling is that it anti-aliases all parts of the scene including shaders and textures, something pure edge-based schemes like MSAA and CSAA can’t do. Another advantage of super-sampling is that it stacks with anisotropic filtering and can increase the clarity of texture filtering. We’ll see an example of this later.

nVidia has a range of super-sampling modes, but here are the three that make the most sense:

There are eight, sixteen and thirty two blue dots representing the multi-samples, while multiple green dots (shader/texture samples) confirm super-sampling is in operation. 32xS has a truly extraordinary sample count, but we can also see it has the same super-sampling component as 16xS.

The components of these modes are as follows:

8xS = 8xMSAA + 2xSSAA.
16xS = 16xMSAA + 4xSSAA.
32xS = 32xMSAA + 4xSSAA.