Learn antialiasing techniques in computer graphics (Part 4)

(8x AA 32x CSAA's often compared to nVIDIA)
antialiasing mode sampling covered with CSAA technology NVIDIA and AMD EQAA
With the launch of the GeForce 8 series cards, NVIDIA has introduced a new technique in handling aliasing is aliasing sampling coverage (CSAA - coverage sampling anti-aliasing). Basically CSAA is MSAA samples can get more coverage next defense. Sample coverage will make the check for any polygon that lies in its position or not, then performs the calculations to determine the final pixel color.

nVIDIA introduces the principle of CSAA for card GF100 - Fermi
The sample covers relatively easy to collect, and it can help enhance image quality, but just take a little performance when compared with MSAA. Simply said CSAA 4x MSAA equivalent to 2x, 8x CSAA with MSAA 4x and weighs the same.

We can track the following illustration, square pixel color is purple, red the MSAA sample positions, yellow is the location of sampling coverage. At 2x MSAA mode, we have added two equivalent samples covered four sampling sites of the CSAA, the picture quality results than traditional 2x MSAA.

Sampling principle EQAA coverage, similar to Nvidia's CSAA
AMD also introduced aliasing processing technology similar to Nvidia's CSAA, called antialiasing mode enhancements (enhanced quality anti-aliasing - EQAA ), in line Radeon HD 6900 card. However, the rest of the graphics card AMD (including the Radeon HD 6800) can not afford EQAA, so most users can not use AMD EQAA be. In contrast, the card supports NVIDIA's CSAA very widely, from GeForce 8000; 9000 to 200 yards 300 yards 400 yards 500 and now 600.

Naming confusing < br /> nVIDIA cause problems and misunderstandings with the method naming his antialiasing. Sometimes the number x represents the number of MSAA samples, x is sometimes combined MSAA samples and samples covered. For example, we see 8xQ case, the Q suffix represents the number of MSAA samples tradition, but then again 16xQ including MSAA 8x and 8 coverage samples. Thus some cases lead to game and Forceware drivers do not understand each other, set the driver back in the game 8x understood as MSAA 4x + 4 sample coverage.

CSAA NVIDIA settings, rather problematic and difficult to understand
AMD Naming of simple and more understandable, the level x of AMD is the number of MSAA samples, while EQ prefix is ​​added to cover the samples. For example, AMD's 8x MSAA sample is 8, while 8XEQ is 8 by 8 MSAA sample pattern coverage.

Comparison of equivalence between the level of antialiasing GeForce and Radeon
Compare images of the antialiasing mode sampling covered
To be able to more easily visualize, please see the animations comparison of antialiasing mode 2 AMD Radeon graphics card nVIDIA GeForce and following.


$ ("# galleria_129174098"). Galleria (
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The sampling coverage is generally limited improve the image quality a little bit on both GeForce and Radeon cards. It is clear that more samples will MSAA image quality has been improved, but the more samples may be covered not lead to quality improvement at all. And by way of nVIDIA name, image quality with 16x brings not 8xEQ of AMD, the company may focus on the numbers in order to bring better advertising.

References TomsHardware (continued)