NVidia 7900 Can't Render AA & HDR at once!?

Sup Guys, I was checking the Nvidia vs ATI slugfest on gamespot just now, and it turns out that the 7900 can't perform with the AA & HDR at the same time!? how can this be!? What I also want to know if It's the same in the 7800 Series?

Here's the article.
GameSpot ATI vs Nvidia Slugfest

That comes as no surprise, given that all in all, the G71 (GF7900) is a REFRESH of the G70. (GF7800) Pretty much, it's just a re-design to both increase power by a decent bit, and drastically reduce production costs. No new features.

However, to say that it can't do AA and HDR at the same time is a lie; it only cannot do MULTI-SAMPLE AA, along with OpenEXR HDR, at the same time; use super-sampling, or some other method, and it works fine. This includes the latest nVidia tech demos, which DO use AA and HDR. (note that the HDR in Oblivion, at least the SM 3.0 components, also cannot be used with multi-sample AA on any card, including Radeon X1ks, given that the developers disabled it)

Want to use HDR and AA on a GeForce 6 or 7? (if you have one, that is) Check out RTHDRIBL. It also uses SM 2.0, so it can even be used on GeForce FX 5xxx cards as well. Of course, not that you'd WANT to use it on said cards, given the rather hefty performance cost the thing has.

Anisotropic filtering can be turned on all he way which helps a bit, so is this a driver issue? no HDR and AA? I have heard this before but never really got too worried about it since most of the games I play right now dont use HDR. but I have already invested in 2 - 7800GTX's so I guess I don't really care is it does it or not.

Well, if you want to use "standard" AA with a game using OpenEXR for it's HDR, which includes popular HDR-enabled games like Far Cry, Splinter Cell 3, and the like, then it's impossible with your cards; such can currently only be done with a Radeon X1300, X1400, X1600, X1800, or X1900 card.

However, you can use other forms of AA, such as super-sampling, or "SLi AA," which are both done post-processing, and hence will work no problem. Also, with other types of AA, such as that used in the RTHDRIBL demo mentionmed above, and those used in nVidia's GeForce 6 and 7 tech demos, will work fine with normal "multi-sample" AA.

Well, if you want to use "standard" AA with a game using OpenEXR for it's HDR, which includes popular HDR-enabled games like Far Cry, Splinter Cell 3, and the like, then it's impossible with your cards; such can currently only be done with a Radeon X1300, X1400, X1600, X1800, or X1900 card.

However, you can use other forms of AA, such as super-sampling, or "SLi AA," which are both done post-processing, and hence will work no problem. Also, with other types of AA, such as that used in the RTHDRIBL demo mentionmed above, and those used in nVidia's GeForce 6 and 7 tech demos, will work fine with normal "multi-sample" AA.

so your saying "SLi AA," + HDR is possible?

so you just have to change a driver settings? cause i was gonna buy a 7900GT soon and do want to play games in all their glory. and does the post proccessing Super-AA effect the performance alot? Thank You.

Yep, big time. I'll post links if I can dig them up.

I don't know to be honest. I thought SLI 16X AA was just MSAA an SSAA combined, which I'd think would still have limitations with the method of HDR used in games like Farcry and SCCT. As far as power, I know dual 7900GTX can run 4X Transparency SSAA at 16x12 in Doom3, which single cards don't have the power to do. That was in a [H] review that they found that playable. BUT, TR SSAA is not real SSAA from my understanding, which admittedly is not that great. But Dave B. at B3D said that in the forums. If I can dig up his MSAA and SSAA explanation in my history, I will post it. it was a good one.

In times like this when the technicals go above my knowledge, I say, Grape? where are you?

once my proc gets delivered ill give it a shot and post some Screenies and some Benchmarks.

That's just it. We've discussed this before and no one, not a reviewer, not even people at B3D has ever been able to explain that statement. I think some of it may come from the fact that nV mentiones MSAA and not SSAA, but no one explained how the limitation would work since the only one I've heard sofar is that nV's HDR implementation (use of OpenEXR spec) used in conjunction with MSAA runs out of memory (needs some ridiculous numbers like 2+GB), but why would that be true for MSAA and not SSAA, which to me is more memory intensive, no?

Well that answers the other question I had last time (since people kept saying, no it's not hybrid, it's OpenEXR, etc.).

I'd still love to see this explored, because I'm still stumped as to why it would work for SSAA and not MSAA, unless there's something about the nV AA algo that just mucks things up, whereas the SSAA doesn't have that glitch. Also why not at lower res like 640x480?

To me it's likely to do with the design of the chips/rendering pipepline, but I'd have to revisit the diagrams to even begin thinking about it.

Anywhoo I'm outtie, gotta go get some meds for chect-cold, you know all that cold mountain air flowing through the lungs while bouncing down the mountains. But it's worth it!

If I find anything more I'll definitely share, last time's effort seemed futile since no one seems to have any explanation for this issue.

Super sampling runs the game at a higher resolution and then resizes it for your monitor.

So you essentially restated what I said.

OMFG, Lol, I posted this 2 days ago and didn't had a chance to check it out, and it's gone up ^_^. Well yeah that was my doubt since I'm playing NFSMW and if I'm no mistaken it uses HDR on the sunlight flashes and other things, On wich I have FULL SCREEN AA enabled, and It all works fine.

But my guess that running games at higher resolutions will eventually reduce the use of AA.

got'cha thanx dude ^_^

let me ask this.... do you need aa and af if your running at or over 1600x1200?

I can run call of duty @ 1920x1440 or something like that with over 60fps on a x1900xtx (no aa or af)

I thought AOEIII used bloom rather then HDR.

I have eyes, does that count? There's a few reviews out there, look yourself.

And supersampling for nvidia cards from what I read.

I'd die without at least 2x antialiasing.

I know that, but why would it work at 4X the info for 2X (2X by 2X), but not for MSA regardless of the image size or setting?

If it is indeed just a question of memory size then 2X MSAA at 640x480 should be far less memory intensive than 4X SSAA at 1280x1024, unless like I said it's pipeline dependant which means nV is applying MSAA while using the FP16 results within the pipeline, whereas ATI must apply MSAA seperately to the 8bitInt targets that are held within the buffer.

Actually, there is, but its pretty high.

so bascially were just out of luck theres no way to render true super-sampling and HDR, i doubt nvidia will release a driver workaround(one that instantly works). its not to bad for some reason i kind of hate HDR it kills my 6800 i was playing DOD:Source and it killed my frames, plus it dosent look to good, and kinda interferes with my sight(i know that happens in real life to ). lighting wont be extremely accurate until a couple generations later. Peace.

You can't use super sampling on a 6800.

I'm not going to say "Go ATI!" but I will say X1900>7900.

Well there is if you think about it there is even for SSAA, but the way it's applied matters most. SSAA is still 2X x 2X more pixel at least in buffer space before reduction, but even that 4X+ image increase isn't too hard to handle because the targets are 8bitInt. For MSAA the discussions the probability that it's pipeline FP16 target dependant, and that's does become a space issue, the FP16 target using 4 plane dithered AA / 4X was running out of buffer space in onboard memory. The results were calculating in the 2-4GB range for 1280x1024, so even with the reduction to about 60% for 1024x768 would still require nearly just over 1 gig for 4XAA. Even 800x600 would run up against buffer space limitation on a 512MB board being very close to max.

That SSAA does this post FP blend(s) with 8bit targets instead of fp16 targets in the pipeline would make sense as to SSAA vs MSAA (some nice comparisons at B3D and 3Dlabs IIRC), but the question I'm asking is what particularly is different between ATi MSAA and nV MSAA, it's likely that the ATi cards are saving to buffer in 8bitInt of FX10 mid-pipeline.

I'm having some trouble remembering where everything is and I'm kinda under the weather so limit my online time, but that would explain the difference to me.