NV Coverage AA question

[GreedIsGood]

According to NVIDIA's webpage, 8xQ mode in CSAA actually is 8x sample MSAA. However there's a guy who keeps saying 8xQ has the same speed as 8x MSAA but with a better quality. I know he's wrong and he used a wrong method to support his opinion, but how can I convince him?
Someone uses nHancer and DX9FSAAViewer to analyze, are there any tools that show even more details in algorithm or IQ?

Thank you in advance.

 

[evilsofa]

According to NVIDIA's webpage, 8xQ mode in CSAA actually is 8x sample MSAA. However there's a guy who keeps saying 8xQ has the same speed as 8x MSAA but with a better quality. I know he's wrong and he used a wrong method to support his opinion, but how can I convince him?
Someone uses nHancer and DX9FSAAViewer to analyze, are there any tools that show even more details in algorithm or IQ?

Thank you in advance.

You can't. He has experienced a critical user error. Your only choice is to RMA your friend for a new one. Sorry!

For those who don't know, in the nVidia control panel 8xQ is indeed nVidia's listing of the standard 8x MSAA, while 8x is nVidia's CSAA which indeed looks better but costs a performance hit. My guess is this guy has done something like enable "Image Settings" in the nVidia control panel to High Quality for one test and had it revert back to the default Quality setting for his second test, and has now convinced himself that he had the same settings in both tests. Maybe not that exact thing, but something like it, and it's going to be difficult to break his conviction.

 

[Forceman]

In real world usage, are you really going to be able to tell that much of a difference between 8x CSAA and 8x MSAA? I have my doubts - particularly when you factor in the performance difference.

 

[Bo_Fox]

There's an excellent article done by XbitLabs.. lemme dig it up for you.. here

http://www.xbitlabs.com/articles/video/display/ati-radeon-hd4850_19.html#sect0

If you compare 4x AA to 8x CSAA, you can see that the barb wires on top of the fence is much slimmer in 8x CSAA than 4x AA. I do not like this because it thins out everything (tree limbs, small characters or details in games like Company of Heroes, wire fences, etc..), making the game look more bland. Plus, if there is not much contrast among the edges, 8x CSAA is hardly any smoother than 4x. CSAA merely uses the color coverage samples to improve anti-aliasing, at the expense of thinning out narrow or small objects.

I would only use CSAA in games that still look awful with 4x, but still cannot perform fast enough at true 8x MSAA, ONLY if I can bear the thinner objects. It's up to you if you want to see the objects at their true sizes or if you do not mind those wires being twice as thin as normal (making them much harder to see).

another excellent site: http://www.behardware.com/articles/644-8/nvidia-geforce-8800-gtx-8800-gts.html by looking at the very distant wires in the background, in front of the distant cliff, with CSAA, the wires nearly disappear completely, while with 4x or 8x, they are nicely visible.

 

[GreedIsGood]

Thanks everyone.

 

[evilsofa]

In real world usage, are you really going to be able to tell that much of a difference between 8x CSAA and 8x MSAA? I have my doubts - particularly when you factor in the performance difference.

I can tell you from personal experience that in Far Cry 2 at 1680x1050, the difference is glaringly obvious; at 8x MSAA, the grass was a shimmering aliasing mess, while at 8x CSAA the grass looked perfect with no aliasing at all.

 

[Forceman]

I can tell you from personal experience that in Far Cry 2 at 1680x1050, the difference is glaringly obvious; at 8x MSAA, the grass was a shimmering aliasing mess, while at 8x CSAA the grass looked perfect with no aliasing at all.

Shouldn't that be the other way around? MSAA should be better, right?

 

[Forceman]

There's an excellent article done by XbitLabs.. lemme dig it up for you.. here

http://www.xbitlabs.com/articles/video/display/ati-radeon-hd4850_19.html#sect0

If you compare 4x AA to 8x CSAA, you can see that the barb wires on top of the fence is much slimmer in 8x CSAA than 4x AA. I do not like this because it thins out everything (tree limbs, small characters or details in games like Company of Heroes, wire fences, etc..), making the game look more bland. Plus, if there is not much contrast among the edges, 8x CSAA is hardly any smoother than 4x. CSAA merely uses the color coverage samples to improve anti-aliasing, at the expense of thinning out narrow or small objects.

I would only use CSAA in games that still look awful with 4x, but still cannot perform fast enough at true 8x MSAA, ONLY if I can bear the thinner objects. It's up to you if you want to see the objects at their true sizes or if you do not mind those wires being twice as thin as normal (making them much harder to see).

another excellent site: http://www.behardware.com/articles/644-8/nvidia-geforce-8800-gtx-8800-gts.html by looking at the very distant wires in the background, in front of the distant cliff, with CSAA, the wires nearly disappear completely, while with 4x or 8x, they are nicely visible.

Hmmm, that is noticeable when you look at it like that, I haven't ever noticed in real usage but maybe now I'll do my own comparison.

 

[evilsofa]

Shouldn't that be the other way around? MSAA should be better, right?

No.

More recently, the GeForce 8 series onwards has introduced CSAA which is Coverage Sampling Anti-Aliasing. This method produces even better quality results than the standard Multisampling (MSAA) approach, at around the same performance as MSAA. Similarly, ATI has introduced CFAA which is Custom Filter Anti-Aliasing, as of the HD2X00 series. This method may also provide better results than standard MSAA depending on the filter used, but can also blur the image slightly.

http://www.tweakguides.com/Graphics_11.html