New FSAA and Anisotropic Filtering Methods, 3Dc+
As you know from our reviews, NVIDIA implemented a transparent texture antialiasing technique in its G70 chip. ATI also developed an analog for the RADEON X1000 and called it Adaptive Antialiasing. Improving the visual quality of transparent textures in such objects as wire fences, foliage, etc., Adaptive Antialiasing can be used in combination with all the other types and modes of antialiasing the RADEON X1000 architecture supports, including Temporal AA and Super AA. This is also accompanied with full HDR support.
The anisotropic filtering algorithm from the previous ATI products has also undergone some improvements. The new mode, Quality AF, uses the so-called Area-Aniso algorithm to achieve a better texture filtering quality than before. However, as we have repeatedly argued in our reviews, it’s difficult or near impossible to see a slight image quality improvement in modern dynamic 3D games. While the difference between tri-linear and anisotropic filtering is obvious, the difference between 8x and 16x AF is hardly discernable. We will show you below how the new anisotropic filtering algorithm improves the visuals in a real game and will also measure the performance hit the new graphics cards suffer with enabled Adaptive AA and Quality AF.
One more technology which directly affects the image quality has also been improved further in the new RADEONs. We mean the normal map compression (3Dc). Its new version has acquired a plus sign in the name and can compress textures that are used, for example, as lighting and shadow maps, HDR textures, material properties, etc. 3Dc+ provides a compression coefficient of 2 to 1 with such textures and 4 to 1 with two-channel textures. If you don’t know what it’s all about, here’s its purpose in brief: the 3Dc (and now 3Dc+) technology helps to improve the level of detail of 3D models by using high-resolution normal maps rather than increasing the number of their polygons. Why 3Dc but not something else? The DXTC technology, for example, provides an 8 to 1 texture compression, but it doesn’t suit for normal maps where per-pixel precision is necessary. The quality of the final rendering would suffer.