Help me understand ATI's AA options!

[thecremeegg]

I'm playing with the SF4 benchy at the moment and seeing what effect each AA setting in the CCC has on the score.

With 8x Box AA I get the lowest framerate and with Edge Detect I get the highest.

When I add adaptive AA on quality the frame rate gets higher still.

What do these options do?

Cheers

 

[drunkenmaster]

adapative, I can't remember exactly, it alternates between say 4x and 2xaa rather than just 4xaa, its more technical than that but this late, tired, sleeping pill thats as good as it gets


box is supposed to be the bog standard style, narrow/wide tent are supposed to increase accuracy and I think edge detect is supposed to be the most accurate however if its faster for you, its probably due to the game not supporting edge detect or something so its reverting to something else, maybe just no aa.

I think its as stands, normally theres 2/4/6/8xaa options, essentially using say narrow tent with 2xaa is really giving you effectively a reduced quality(slightly) 4xaa effect, its somewhere inbetween. Wide tent increases the quality a little more to 6xaa(ish) and edge detect takes it to roughly 8xaa. So the 24xaa option you see talked about is actually the 8xaa option with edge detect enabled.

http://www.anandtech.com/video/showdoc.aspx?i=2988&p=14

Its damn hard to tell the difference even more so in the pics/zoom/size they used, but its the best I could find.

In reality 8xaa box should be faster than 8xaa edge detect, but its perfectly possible the game/driver is bugging and reverting to say 2xaa with edge detech which should be comparable in quality but faster. Adaptive should make things faster still normally.

Again depends on the game, if you want to test it out and "try" to see the difference I'd suggest an older, well patched, popular game that likely has had any/all kinks worked out by now .

 

[kylew]

Adaptive AA is for smoothing the edges of alpha textures, so on things like fencings, where it's a simple image with 'holes' you can see through. Before adaptive AA they appeared quite rough and jagged.

Box AA is where samples are taken from around the jagged edges, a 'box' template is applied over the area and pixels are sampled and blended to smooth the edges.

Edge detect smooths the edges of visible polygons only, it's in theory supposed to increase performance quite a bit, when it first came about it didn't seem to work, but now it has quite a good result, it's faster and achives higher levels of AA. There seems to be a trade off though that not all the edges of textures are smoothed, so you may get some jagged edges in odd place. I suppose in theory the best result would be a mix of Box AA and Edge detect AA.

Wide-tent and narrow-tent are methods of sampling over different areas than the others. Generally though I think these end up with a pretty poor result unless the drivers have added benefits made for specific games. In general though all they seem to do is blur the image where there are jagged edges. This works in some games without losing image quality, but others it can give the appearance of running a game at a res much lower than the screen's native res.

 

[Final8y]

Adaptive AA is for smoothing the edges of alpha textures, so on things like fencings, where it's a simple image with 'holes' you can see through. Before adaptive AA they appeared quite rough and jagged.

Box AA is where samples are taken from around the jagged edges, a 'box' template is applied over the area and pixels are sampled and blended to smooth the edges.

Edge detect smooths the edges of visible polygons only, it's in theory supposed to increase performance quite a bit, when it first came about it didn't seem to work, but now it has quite a good result, it's faster and achives higher levels of AA. There seems to be a trade off though that not all the edges of textures are smoothed, so you may get some jagged edges in odd place. I suppose in theory the best result would be a mix of Box AA and Edge detect AA.

Wide-tent and narrow-tent are methods of sampling over different areas than the others. Generally though I think these end up with a pretty poor result unless the drivers have added benefits made for specific games. In general though all they seem to do is blur the image where there are jagged edges. This works in some games without losing image quality, but others it can give the appearance of running a game at a res much lower than the screen's native res.

+1