X-bit labs

ATI RADEON X800: R420 Totally Exposed (page 17)

Category: Video

by Tim Tscheblockov , Alexey Stepin , Anton Shilov

[ 05/04/2004 | 06:42 AM ]

Full-Screen Anti-Aliasing

The anti-aliasing algorithms implemented in R3x0 have been fully inherited by the new RADEON X800. The newcomer supports rotated-grid multisampling. We have already told you about the idea of multi-sampling, the samples gamma-correction from ATI and about the advantages of rotated-grid multi-sampling in our articles called On the Way to Ideal Picture: Anti-Aliasing by Contemporary Graphics Cards and NVIDIA GeForce 6800 Ultra and GeForce 6800: NV40 Enters the Scene. That is why let’s not go deep into details, but just compare the anti-aliasing quality of polygon edges on ATI RADEON X800 XT Platinum Edition, RADEON 9800 XT, NVIDIA GeForce 6800 Ultra and NVIDIA GeForce FX 5950 Ultra.

As an example, just like in our GeForce 6800 Ultra review, we will take a Max Payne 2 scene:

The white squares mark those image fragments, which we are going to draw your attention to: the polygon edges there have the most interesting angles there.

The ATI based graphics cards worked in 2x, 4x and 6x AA modes. NVIDIA based solutions worked at 2x, 4x and 8x AA modes.

Well, this is the first image fragment: the polygon edges are almost horizontal. The screenshots should be read as follows: ATI RADEON X800 XT Platinum Edition, RADEON 9800 XT, NVIDIA GeForce 6800 Ultra and NVIDIA GeForce FX 5950 Ultra.

FSAA 2x

FSAA 4x

FSAA 6x/8x

In 2x mode all graphics cards show almost identical AA quality, but when we shift to 4x mode, the graphics processors using rotated-grid (and these are all of them except NVIDIA GeForce FX 5950 Ultra) show better anti-aliasing quality.

In 6x/8x modes the polygon edges anti-aliasing quality is very similar, though ATI based graphics cards use gamma-correction to sum up the subpixels colors and hence the half-tones on the polygon edges they provide are subjectively more natural thus making much nicer overall picture.