Why SSAA and DX10 cen't work together In HD58X0 ?

[ronpe]

Hi all, i'm reading here for a long time but registered only now because i think its the only place to get the right answer.

“Older games” is an important keyword here, as there is a catch to AMD’s SSAA implementation: It only works under OpenGL and DirectX9. As we found out in our testing and after much head-scratching, it does not work on DX10 or DX11 games. Attempting to utilize it there will result in the game switching to MSAA

why ?
This is hardware or software problem ?

So far I've seen some games that use DX10 (crysis/bioshock) run with SSAA on nvidia cards but I do not know for sure if they really run on DX10 at that Time.

this is a problem with ssaa and dx10 for both ATI and NV or ATI only ?

Thank you very much

 

[tabs]

The way I understand it is that DX10 gives developers added control over AA which interferes with user enabled (forced) SSAA.

 

[ChrisRay]

Bioshock can run and capable of running SS in DX10 mode for Nvidia cards.

Cant answer your other questions

Chris

 

[phenix]

With the reintroduction of SSAA, AMD is not dropping or downplaying their existing MSAA modes; rather it’s offered as another option, particularly one geared towards use on older games.

“Older games” is an important keyword here, as there is a catch to AMD’s SSAA implementation: It only works under OpenGL and DirectX9. As we found out in our testing and after much head-scratching, it does not work on DX10 or DX11 games. Attempting to utilize it there will result in the game switching to MSAA.

When we asked AMD about this, they cited the fact that DX10 and later give developers much greater control over anti-aliasing patterns, and that using SSAA with these controls may create incompatibility problems. Furthermore the games that can best run with SSAA enabled from a performance standpoint are older titles, making the use of SSAA a more reasonable choice with older games as opposed to newer games. We’re told that AMD will “continue to investigate” implementing a proper version of SSAA for DX10+, but it’s not something we’re expecting any time soon.

http://www.anandtech.com/video/showdoc.aspx?i=3643&p=14

 

[ronpe]

so it's only a software limitation, right ?

 

[fellix]

SSAA vs. MSAA frame sequence comparison (screen-shots taken from [H]'s review).

2x Samples:

4x Samples:

8x Samples:

All SSAA modes in a progressive row:

 

[compres]

Why so blurry? Am I missing something?

 

[Ailuros]

Why so blurry? Am I missing something?

Use a third party tool to offset the LOD. For 4xSS roughly -1.0 LOD should be fine.

 

[homerdog]

Why so blurry? Am I missing something?

It's a bug.
http://www.anandtech.com/video/showdoc.aspx?i=3643&p=14

Unfortunately, in our testing of AMD’s SSAA mode, there are clearly a few kinks to work out. Our first AA image quality test was going to be the railroad bridge at the beginning of Half Life 2: Episode 2. That scene is full of aliased metal bars, cars, and trees. However as we’re going to lay out in this screenshot, while AMD’s SSAA mode eliminated the aliasing, it also gave the entire image a smooth makeover – too smooth. SSAA isn’t supposed to blur things, it’s only supposed to make things smoother by removing all aliasing in geometry, shaders, and textures alike.

As it turns out this is a freshly discovered bug in their SSAA implementation that affects newer Source-engine games. Presumably we’d see something similar in the rest of The Orange Box, and possibly other HL2 games. This is an unfortunate engine to have a bug in, since Source-engine games tend to be heavily CPU limited anyhow, making them perfect candidates for SSAA. AMD is hoping to have a fix out for this bug soon.

Apparently Source is not the only engine that's affected.

 

[no-X]

Yes, the SS method makes polygon edges soft. That's not correct.

 

[Silent_Buddha]

Well, briefly tested out SSAA on the 5870 myself. My brief notes from trying it in Eve Online (DX9).

1. Introduces a slight overall blurr that makes small text a bit difficult to read. Similar to most SSAA implementations around the time of Voodoo 5/GF2/GF3/GF4.

2. 4x SSAA helps reduce shader/specular aliasing significantly but doesn't not remove it altogether. Still see some shimmer/crawling when in motion but much less pronounced and less noticeable than 4xMSAA box.

3. Appears to very slightly dull the effect of some HDR effects. Not always noticeable but sometimes some effects seem less "bright." Could just be a by product of my tired eyes at the time I tested, will have to revist this.

It's not something I'd use all the time or probably most of the time, but there's a few games I'd probably use it on. Mass Effect for one assuming it would run well with SSAA (don't have it installed at the moment so can't check) since it has tons of shader/specular aliasing and no small font text.

Overall it's a nice option to have, but definitely not a fulltime replacement for MSAA. The removal/reduction of shader aliasing is a huge bonus for some games. In other games, it's not worth it due to the slight blur that is incurred.

Ghostbusters from the screens above would be a hard choice for me, but I think I like the SSAA shots better overall. There's far more elements that are AA'd far better with it. The blur is a bit of a downer though but far less distracting that crawling due to aliasing.

Oh, and it appears Edge Detect is faster. But that could just be purely due to the fact that this card is faster than my 4890.

Regards,
SB

 

[no-X]

Could you make screenshots of SS 2x/4x/8x in the Tommti Systems tester?

z - switches to the FSAA testing mode
v - switches to full-screen
s - saves screenshots

I have many samples in my archive, we could made a comparision (if you retain "z->v->s" order, the sreenshots should be directly comparable).

 

[SirPauly]

Well, briefly tested out SSAA on the 5870 myself. My brief notes from trying it in Eve Online (DX9).

1. Introduces a slight overall blurr that makes small text a bit difficult to read. Similar to most SSAA implementations around the time of Voodoo 5/GF2/GF3/GF4.

2. 4x SSAA helps reduce shader/specular aliasing significantly but doesn't not remove it altogether. Still see some shimmer/crawling when in motion but much less pronounced and less noticeable than 4xMSAA box.

3. Appears to very slightly dull the effect of some HDR effects. Not always noticeable but sometimes some effects seem less "bright." Could just be a by product of my tired eyes at the time I tested, will have to revist this.

It's not something I'd use all the time or probably most of the time, but there's a few games I'd probably use it on. Mass Effect for one assuming it would run well with SSAA (don't have it installed at the moment so can't check) since it has tons of shader/specular aliasing and no small font text.

Overall it's a nice option to have, but definitely not a fulltime replacement for MSAA. The removal/reduction of shader aliasing is a huge bonus for some games. In other games, it's not worth it due to the slight blur that is incurred.

Ghostbusters from the screens above would be a hard choice for me, but I think I like the SSAA shots better overall. There's far more elements that are AA'd far better with it. The blur is a bit of a downer though but far less distracting that crawling due to aliasing.

Oh, and it appears Edge Detect is faster. But that could just be purely due to the fact that this card is faster than my 4890.

Regards,
SB

Have you tried to add some negative lod -- should get rid of the blur for ya?

 

[Cypher]

SSAA vs. MSAA frame sequence comparison (screen-shots taken from [H]'s review).

Uh, am I alone in thinking "Why on earth are you doing image quality comparisons using a dithered 256-colour GIF?" ?

 

[Ailuros]

It's a bug.
http://www.anandtech.com/video/showdoc.aspx?i=3643&p=14


Apparently Source is not the only engine that's affected.

It's not a bug. Due to the way AMD implemented Supersampling I wouldn't be surprised if no LOD offset comes automatically with it. If that's the case then it's not a bug but merely a restriction based on the implementation (which I could of course be wrong too).

In other cases where full screen SSAA is used there's a typical -0.5 LOD offset for each 2x SSAA samples. In other words:

2xSS = -0.5
4xSS = -1.0
(6xSS = -1.5)
8xSS = -2.0

Now if it is implementation specific and AMD can't change it all you have to do as a user whenever you want to use Supersampling is to offset the LOD through a third party utility by roughly the values as above.

 

[no-X]

Ailuros: The issue isn't in LOD. The new SS method blurs polygon edges - that's it. I have no idea, if the problem is bug-related (e.g. uncorrect resolving filter), or if the problem is kind of compromise to make the SS method faster. I any way, it isn't correct.

None of the box-filtered SS methods I saw in past blurred polygon edges. 3Dfx, nVidia (GF2), ATi (R1xx/R2xx), Kyro I/II...

I have some screenshots taken on these cards:


Radeon 9600 - MultiSampling 4x:



Radeon 9000 - SuperSampling 4x (Cat. 3.10):



It's clearly visible, that SS doesn't blur-out polygon edges when compared to MS.

Catalyst 4.2 (or some version between 3.10 and 4.2) enabled automatical correction of LOD, when enabling of SS:

Radeon 9000 - SuperSampling 4x (Cat. 4.2):



Again, edges are unaffected...

 

[homerdog]

It's not a bug.

As it turns out this is a freshly discovered bug in their SSAA implementation that affects newer Source-engine games. Presumably we’d see something similar in the rest of The Orange Box, and possibly other HL2 games. This is an unfortunate engine to have a bug in, since Source-engine games tend to be heavily CPU limited anyhow, making them perfect candidates for SSAA. AMD is hoping to have a fix out for this bug soon.

http://www.anandtech.com/video/showdoc.aspx?i=3643&p=14

So, with Source it's a bug but in other games there is some other problem?

 

[Dave Baumann]

We're looking into it. HL2 appears to be fine, except for EP2 - when Anand reported it on EP2 we did find a few other titles where something similar occurs.

 

[no-X]

That's great! I'm looking forward to better results, thanks!

 

[AlNom]

I'd really like to see some Mass Effect Screenshots. Those parallax staircases in particular. T_T