'quincunx’ High resolution Anti-aliasing

A really cool and new form of Antialiasing along with the GeForce3 is now introduced: High resolution Anti-aliasing with 'quincunx'.As soon as all Pixels are processed there is the option the use Anti-aliasing to get rid of the so called 'Jaggies'. With the GeForce3 you can use the existing Multi-sampling FSAA methods or the newer and much faster 'quincunx’ High resolution Anti-aliasing

What is Anti-Aliasing ? - Explaining this completely would mean explaining the whole mathematical sampling theory. It boils down to this. To recover a signal, or image, you need a minimum of samples to be able to give a realistic representation of the image. The problems start with texture maps being either too close or too far away from the viewpoint. If the polygon is far away you only have a limited number of points to show the texture map, so logically you have to drop a lot of the real pixels of your texture map.

This creates some sort of interlace effect : one line is shown and one is not. This can result in weird patterns appearing, and makes the texture map look completely different from the real one. A similar problem if the polygon is close to you. You need more info than there is resulting in the generation of random noise (meaningless values). Most of the time the last problem is solved by MIP-Mapping while the other is solved by the anti-aliasing. Another point where anti-aliasing is used is with straight lines. If you draw a straight line (under an angle) using a paint program and you zoom in, you will discover that the line looks like a stairway. To remove this and make the line look like a line points in different colors are added to the side of the line to make it look more like a real line. Most of the time it is this kind of Anti-Aliasing they are talking about, however quincunx does it slightly different. This system will get you results that can be compared with 4x FSAA while the performance is not bigger than 2x FSAA, a miracle ? Not exactly .. the quincunx system is relatively easy to understand.

What happens is this, a copy of an imaginary 3D scene will be placed over the existing 3D scene. However, the imaginary layer will be moved a half pixel up and a half pixel to the left as you can see in the diagram in the middle. The final color of all pixels will now be calculated  by the color from the five surrounding pixels  in a form much like a dice. This figure is called quincunx. The image quality is most definitely comparable with 4x FSAA which allows us to make use of Anti-aliasing higher resolutions, something we where not able to do with videocards from the past year.