Hva er AA?

[lobfredd]

Jeg vet hva det står for, men hva gjør det?

Om jeg tar på 8x får jeg mye mer lagg enn om den står på disable.

[Olavxxx]

AntiAliasing..

Det er så du ikke får så "skarpe kanter"..

 

Det krever mer av kortet ja..

 

http://en.wikipedia.org/wiki/Anti-aliasing

[guezz]

- AA (Anti-Aliasing)

The screen consists of a lot of pixels (a square entity) and because of its shape aliasing happens, which also produces crawling (when aliasing moves). This isn’t a problem for lines which are vertical or horizontal since they then will follow the pixel’s sides. Anti-aliasing will reduce the problem by making the transition between pixels smother by replacing the light intensity of the pixel. This is done by creating sub-pixels which samples how the actual luminance (colour) is within the pixel which then creates a final pixel colour. More samples will ensure an even smother transition between the pixels.

 

There exist two main solutions:

 

MS (Multi-Sampling)

This method only works on polygon edges. Think about polygons as something which has a skeleton (called mesh). Not everything on screen is made up by polygons - it will therefore not catch everything (e.g. vegetation). It requires a lot of memory bandwidth and memory.

4xRGMS (D3D FSAAViewer)

Pink = sub-pixels

Green = texture sample

 

SS (Super-Sampling)

It’s a “catch all” method. The normal implementation is by making a higher resolution version (4x = 4xresolution!) of the frame which is then down-sampled to the correct screen resolution. This ensures that everything on-screen get anti-aliased. It requires a lot of fill-rate, memory bandwidth and memory.

 

Ordered Grid vs. Rotated Grid

Ordered grid = samples follows the shape of the pixel

Rotated grid = same as the above but now on a angle (see picture above)

RGSS is seen to have one basic advantage over OGSS: More effective anti-aliasing near the horizontal and vertical axes, where the human eye can most easily detect screen aliasing (jaggies). This advantage also permits the use of fewer sub-samples to achieve approximately the same visual effect as OGSS.

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