Need help to understand antialiasing etc...

[Gnosis]

Hi everyone!

I just bought myself a new videocard (a X800 pro ) and
I only just realized that I have no real idea of what
"anti-aliasing, bilinear/trilinear-filtering and anisotropic filtering
really does.

I know - of course - that "more is better" and that it has to do
with improving image quality and smothing edges but that's
also about it.

If anyone could take the trouble to explain what the different
functions do and which one provides the biggest image improvment
and also which one to take away first when the frame rates
begin to drop it would be much appricated!

 

[Schadenfroh]

AA
AF

 

[Marsumane]

AA basically straightens edges that should have straighter lines. It takes samples of the color values (texel values) from around the given jaggy area and blends them together to form a straighter look (the final pixel color). The higher the number (ex 2x, 4x, etc), the more samples that are taken.

Bilinear/Brilinear/Triliner filtering adds a more smooth transition from one texture level to the next by adding a more gradual change between going from one texture level to another. In other words, for example, if you look at the ground in a typical fps game, and can see a huge difference between one area and another, adding these filtering algorithms to the scene will make it a more gradual change instead of being to dramatic.

Af blends blurry levels between texture levels. What i mean by this one, is that the area between the texture level boundries are "averaged" to make the line between one area and the next, less noticable.

AF and texture filtering (the 2nd paragraph) are often used in combination for best results in respect to texture filtering.
I reccomend using Trilinear filtering before af due to the little performance hit.

If im wrong on any of this, or my specifics are a little off (they may be cuz im doing this quickly in a class) then someone plz correct my errors

 

[Gnosis]

OK - great!

So if I get this right you could say that in general:

1. Choose a resolution that suits your screen and game (maybe 1024x768 for a 17'' etc)
2. AA is always good if you think the edges are to rough
3. Use trilinear instead of bilinear if you can
4. If you still have GPU-power to spare - crank up the AF

Then of course their are differences game-to-game. I've
read - for example - that in DOOM3 it looks better to
turn upp the resolution than to use a lot of AA. Because
of the darkness and shadows.

Think I got some better understanding of it now!

 

[Blastman]

Couple good shots of AA..AF ...

http://www.cygaming.net/index....showcontent&id=65

 

[edmundoab]

yeah don't have to play with jaged edges that distorts images during gameplay.
its a luxury these days don't you think?
we get to enjoy smooth images without having the FPS affected too much like before.
Of course for Doom 3 is another issue...

 

[reallyscrued]

funny story, after i got my 6800, i decided to start up an old game of mine, Infiltration- Mod of UT, and everything looked the same as it was on my old radeon. Of course, it was maxed out. so i cranked up FSAA to 16xS and 16x Aniso. WOW. NO MORE JAGGIES AND NO BLURED TEXTURES. and no framerate drops. this really does make it a ton better.

 

[BenSkywalker]

Schaden-

That link to an AA definition is for SSAA, only the NV mixed modes support that, everything else is MSAA now(certain elements such as curing pixel popping is not true for MSAA). The link you have posted for anisotropic filtering is absolutely horrible(they don't mention at all what AF does). Don't have time to go in to it now.