NVIDIA introduced a new SLI antialiasing rendering mode in the ForceWare 77.77 drivers. When enabled, SLI AA exposes two new high quality methods of AA - 8X SLI and 16X SLI. SLI Antialiasing works with Direct3D and OpenGL applications and can be enabled with Coolbits. A future driver release will include SLI Antialiasing as a permanent option in driver control panel.
With SLI AA, the AA workload is distributed between the two graphics processors. However, the sample pattern, which is used to obtain color data from neighboring pixels, is slightly offset between the two GPUs. The final output is produced by blending the frame buffer of each GPU together. By offsetting the sample pattern, addditional pixels are being used as samples, which will increase the color accuracy of the antialiased pixels. The quality of SLI AA exceeds that of 8XS AA.
The following comparison will present a section of a 1024x768 screen capture from Morrowind with the selected method of antialiasing enabled. To better see the effects offered by each of the AA methods, the size of the comparative images was increased by 100% or doubled using a nearest neighbor sampling method.
SLI AA is an extremely effective method of antialiasing. And because 16X SLI AA is derived from the 8XS antialiasing mode, it also carries with it the texture quality improvements that supersampling can provide.
Texture Quality (8X SLI vs. 16X SLI)
The full-size 1024x768 screenshots from Morrowind can be downloaded from the following links: