David Kirk on HDR+AA

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Here we go again with our HDR/AA topic of the week

Some interesting info here, I hope this has not been posted already:

(From Bit-Tech interview)

Using AA with HDR

For those of you with super-duper graphics cards, you will have come across a problem: you can't use Anti-Aliasing when using HDR lighting, for example in Far Cry. In these cases, it's a situation where you have to choose one or the other. Why is this, and when is the problem going to get solved?

"OK, so the problem is this. With a conventional rendering pipeline, you render straight into the final buffer - so the whole scene is rendered straight into the frame buffer and you can apply the AA to the scene right there."


"But with HDR, you render individual components from a scene and then composite them into a final buffer. It's more like the way films work, where objects on the screen are rendered separately and then composited together. Because they're rendered separately, it's hard to apply FSAA (note the full-screen prefix, not composited-image AA! -Ed) So traditional AA doesn't make sense here."

So if it can't be done in existing hardware, why not create a new hardware feature of the graphics card that will do both?

"It would be expensive for us to try and do it in hardware, and it wouldn't really make sense - it doesn't make sense, going into the future, for us to keep applying AA at the hardware level. What will happen is that as games are created for HDR, AA will be done in-engine according to the specification of the developer.

"Maybe at some point, that process will be accelerated in hardware, but that's not in the immediate future."

But if the problem is the size of the frame buffer, wouldn't the new range of 512MB cards help this?

"With more frame buffer size, yes, you could possibly get closer. But you're talking more like 2GB than 512MB."

 

[AndrewM]

Dear god, that was terrible. Why doesnt he just explain it correctly?

 

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Correctly being...?

 

[Colourless]

Not dodging the question.

 

[AndrewM]

Correctly being...?

ie. not like a moron..

Shader Model 2 HDR? uhhh.. yeah ok

 

[Geo]

Is it just me. . .or does David Kirk have a biological clock that wakes up every three years or so and makes him say something he's really going to regret? (as opposed to run-of-the-mill oopsies we'd all like back from time to time). Last time it was how 128-bit bus was still just peachy. . .

Edit: Tho if he's right about it being "expensive" to do in hardware, that might get us a fair piece down the road in explaining 16 pipes for R520 on 90nm.

 

[Jawed]

Well, one thing's for sure, Digi and WaltC are both gonna have fun today.

Jawed

 

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Geo: don't forget that he MUST insert enough marketing for the own comany and against the competition in every interview. Perfectly normal IMHO.

 

[AndrewM]

On the first page, he mentions that he didnt have anything to do with the chip (7800), also.

 

[_xxx_]

Well, one thing's for sure, Digi and WaltC are both gonna have fun today.

Which means that we're gonna have fun reading that, so that's nice

Although I'll be @ Napalm Death concert today, so I guess I'll have even more fun...

 

[_xxx_]

On the first page, he mentions that he didnt have anything to do with the chip (7800), also.

No, he had nothing to do with the launch as I get it.

 

[JF_Aidan_Pryde]

Can someone provide a "correct" / "non-dodge" answer then? I thought Kirk's answer made sense. Although I am not sure why you can't just AA each part of the composited frame or just SSAA the final frame.

 

[_xxx_]

You can SSAA the final frame anytime, methinks.

EDIT:
And he didn't say "You can't", he just said "It would be too expensive".

 

[Xmas]

"But with HDR, you render individual components from a scene and then composite them into a final buffer. It's more like the way films work, where objects on the screen are rendered separately and then composited together. Because they're rendered separately, it's hard to apply FSAA (note the full-screen prefix, not composited-image AA! -Ed) So traditional AA doesn't make sense here."

Sometimes I get this feeling that Mr Kirk completely switched to the PR department. That, or he really doesn't know what he's talking about.

 

[nAo]

Sometimes I get this feeling that Mr Kirk completely switched to the PR department. That, or he really doesn't know what he's talking about.

PR/damage control stuff..

 

[Jawed]

I actually thought he was suggesting that to do HDR on NVidia hardware you had to ping-pong between render targets and that was why you got no AA

Jawed

 

[Mindriot]

slightly OT:

Are the SSAA modes of the GF7800 gamma corrected?

 

[Geo]

Geo: don't forget that he MUST insert enough marketing for the own comany and against the competition in every interview. Perfectly normal IMHO.

Well, sure, and his touching defense that R520 is really worse than NV30 as a company failure warmed the cockles of my heart (well, something got warm anyway). But his answer on HDR AA, when he must know that ATI has it on tap for R520, is just a disaster --possibly worse than the previous 256-bit answer for NV30 three years ago. Talk about trade-offs and priorities, if you like (ATI certainly has in the past), but making it sound undoable right now just makes you look like a fool when someone then does it shortly after.

And he's not a fool --he can't be.

 

[nAo]

he was suggesting we have to revert to ordered grid SSAA and shut up

 

[jb]

Sometimes I get this feeling that Mr Kirk completely switched to the PR department. That, or he really doesn't know what he's talking about.

Could be both. Remember as Rev said ALL NV answers from Tech people are ran though the PR department first. So no idea what they changed/added/tweaked...