NVidia : A closer look At CSAA

[LambChop]

CSAA (Coverage Sampling Antialiasing)

In summary, CSAA produces antialiased images that rival the quality of 8x or 16x MSAA, while introducing only a minimal performance hit over standard (typically 4x) MSAA. It works by introducing the concept of a new sample type: a sample that represents coverage. This differs from previous AA techniques where coverage was always inherently tied to another sample type. In supersampling for example, each sample represents shaded color, stored color/z/stencil, and coverage, which essentially amounts to rendering to an oversized buffer and downfiltering. MSAA reduces the shader overhead of this operation by decoupling shaded samples from stored color and coverage; this allows applications using antialiasing to operate with fewer shaded samples while maintaining the same quality color/z/stencil and coverage sampling. CSAA further optimizes this process by decoupling coverage from color/z/stencil, thus reducing bandwidth and storage costs.

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http://www.nvidia.com/docs/IO/37516/sample_coverage.gif

CSAA can be enabled in one of the two following scenarios:

When the application specifically enables CSAA.
When CSAA is turned on in the control panel by the end user. The control panel offers users one of two options:
“Enhance” mode: All application-created MSAA surfaces are converted to CSAA surfaces using the control panel-specified CSAA mode.
“Override” mode: The control panel forces a CSAA-enabled backbuffer. Note that this mode only works for applications that render directly to the backbuffer.

It is recommended that applications enable CSAA directly. The process of implementing CSAA is incredibly simple (almost exactly the same as implementing MSAA), and the benefit to your users is enormous; they get much higher image quality at almost zero performance loss, without the fuss and hassle of manipulating the control panel.

Think this explains in detail just how good CSAA is over MSAA. Unlike others, NVidia simply gives detailed information on CSAA without using it in benchmarks to get better scores as its a more efficient form of AA.

Spoiler

http://4d663a369f9f03c3c61e-870e77779efd63f7bd6c2ee08d8cfae6.r2.cf1.rackcdn.com/images/YQ0AFrrpRBi2.png

Spoiler

 

[Dicehunter]

CSAA has been removed from Maxwell hasn't it ?
Only 8x appears in the drivers now which I'm guessing is MSAA.

 

[triss]

I dont know about maxwell but one the latest drivers with a 780 i can still choose upto 32xCSAA in Nvidia control pannel

 

[pgi947]

I'm sure I had something like 64x or 128x csaa available the last time I looked? Or is that to do with sli?

 

[almighty15]

With native DSR now available in the last 3 generations of Nvidia cards MSAA and all the variants is now pointless.

On most of the newer games it's actually much better from a performance point of view to run with MSAA turned off and FXAA+DSR turned on.

Higher IQ from DSR is just a nice bonus.

 

[Gregster]

CSAA is fantastic and been around since 2008? AMD caught up 4 years later and had EQAA. nVidia don't tend to make a song and dance about it mind and prioritise other techs. Good info Lambchop

 

[rtho782]

With native DSR now available in the last 3 generations of Nvidia cards MSAA and all the variants is now pointless.

On most of the newer games it's actually much better from a performance point of view to run with MSAA turned off and FXAA+DSR turned on.

Higher IQ from DSR is just a nice bonus.

Would be nice if DSR would work with SLI+GSync :/

 

[Gregster]

Why create a thread now? Cant help but think its because a lot of AMD talk atm? I wonder

Not sure if you have been reading the threads lately, but there has been a lot of talk about EQAA, MSAA and CSAA and I wasn't sure of what was what on performance against frame hits, so it was good that someone created a thread with a simple explanation of what it does and how it performs. You didn't need to post anything really and citing jealousy kind of made you look silly.

 

[LambChop]

Hopefully I'll get windows installed on my new rig tonight or tomorrow, be good to run some benchmarks with CSAA on and MSAA on and see whats what ?

 

[Gregster]

Hopefully I'll get windows installed on my new rig tonight or tomorrow, be good to run some benchmarks with CSAA on and MSAA on and see whats what ?

Yer it would be. I am on a crappy 14:00-22:00 shift, so not much time for gaming but 6-2 next week, so will have a play and compare some screen shots.

 

[David Bisset]

Pretty sure this thread is because of the EQAA thread (EQAA and CSAA being to all intents and purposes the same thing, if marginally different in execution - the nVidia one predates the AMD one, but neither are new) and that thread in turn was because certain well known accounts were complaining that AMD cheated/were cheated (think both camps of over-eager users got involved in this part) in a benchmark thread by using different settings even though they were using the (fractionally) harder EQAA instead of MSAA.

Personally I've never been able to see the difference between EQAA, CSAA, MSAA (at same level) which makes it harder to care I know it's good both companies come up with better aliasing techniques (DSR/GPU scaling is awesome when you can afford the hit) but sometimes it's hard to get excited by some of the technologies

 

[Wizzfizz]

All sounds like a new crime drama or disease to me

 

[LambChop]

Pretty sure this thread is because of the EQAA thread (EQAA and CSAA being to all intents and purposes the same thing, if marginally different in execution - the nVidia one predates the AMD one, but neither are new) and that thread in turn was because certain well known accounts were complaining that AMD cheated/were cheated (think both camps of over-eager users got involved in this part) in a benchmark thread by using different settings even though they were using the (fractionally) harder EQAA instead of MSAA.

Personally I've never been able to see the difference between EQAA, CSAA, MSAA (at same level) which makes it harder to care I know it's good both companies come up with better aliasing techniques (DSR/GPU scaling is awesome when you can afford the hit) but sometimes it's hard to get excited by some of the technologies

Ok, so let's say you cant notice the difference between EQAA, CSAA and MSAA. Then you can run either EQAA or CSAA and have less of a performance hit. That's one benefit.

 

[David Bisset]

true enough LambChop

 

[shankly1985]

Ok, so let's say you cant notice the difference between EQAA, CSAA and MSAA. Then you can run either EQAA or CSAA and have less of a performance hit. That's one benefit.

EQAA or CSAA needs MSAA for it to work without MSAA its nothing.

 

[Rroff]

CSAA is fantastic and been around since 2008? AMD caught up 4 years later and had EQAA. nVidia don't tend to make a song and dance about it mind and prioritise other techs. Good info Lambchop

Approx 2006 IIRC it came out with the 8000 series? nVidia have backed off it as it doesn't really produce that much in the way of benefits and most users can't tell the difference between it and the same level of MSAA (minus the coverage samples) ingame without using side by side comparisions.

 

[Final8y]

Pretty sure this thread is because of the EQAA thread (EQAA and CSAA being to all intents and purposes the same thing, if marginally different in execution - the nVidia one predates the AMD one, but neither are new) and that thread in turn was because certain well known accounts were complaining that AMD cheated/were cheated (think both camps of over-eager users got involved in this part) in a benchmark thread by using different settings even though they were using the (fractionally) harder EQAA instead of MSAA.

Personally I've never been able to see the difference between EQAA, CSAA, MSAA (at same level) which makes it harder to care I know it's good both companies come up with better aliasing techniques (DSR/GPU scaling is awesome when you can afford the hit) but sometimes it's hard to get excited by some of the technologies

true enough LambChop

Which it cant be because EQAA is (fractionally) harder which you said but Lam is claiming that its easier which it is not because it needs MSAA as the base to build on top of.

 

[LambChop]

Which it cant be because EQAA is (fractionally) harder which you said but Lam is claiming that its easier which it is not because it needs MSAA as the base to build on top of.

Yes but you will not need to double up and get the performance hit.

i.e. you will use say x4 MSAA and x8 CSAA which in theory if one cant tell the difference will equate to X8 MSAA I believe but not having the performance hit of a true x8 MSAA unless I'm mistaken ?

 

[Final8y]

The problem is that NVs naming solution is there upper equivalents with lower base AA, so the assumption is that AMD is doing the same which is not the case.

EAQAAx8 has an AAx8 base so it will have a MSAAx8 performance hit plus a bit more, while CSAA8 may have an AAx4 base which gives the visual equivalent of MSAAx8 but is less of a performance hit than MSAAx8 because its only using AAx4 base.

CSAA16 or 32 or 64 are not using 16, 32, 64 AA base they are the visual equivalents.

EAQAAx8 has an AAx8 base which has the visual equivalent of MSAAx16 but AMD didn't name it EAQAAx16 which would give less hit then real MSAAx16 if EAQAA naming was an equivalent which it is not, EAQAAx16 has the visual equivalent of MSAAx32.

 

[David Bisset]

the namings are inconsistent, and not all levels exist for both sides solutions which is true.

From Anand