Nice article on SM3

[hans030390]

http://forums.overclockers.co.uk/showthread.php?p=5160067

Found that while doing random UE3 research. It's just a nice article.

And remember....all my opinions/speculations come from the fact that i hardly ever upgrade...thats why SM3 is important to me...just remember that, so don't flame me.

I mean this to be a nice thing

 

[Pete]

Minor, technical nitpick: "HDR" ain't SM3. I say technical b/c currently nV's the only one with SM3 cards and they also happen to support a form of HDR that devs seem to be opting for (namely, using FP16 framebuffers and blends). So, SM3 and HDR are basically interchangable WRT currently available cards.

It's also more of a post than an article, but that probably crosses the nitpick line.

 

[hans030390]

yeah, article, post...sorry. its a nice post.

And yeah, dont know why he put HDR as being Sm3...

 

[gunblade]

FP blending is the technique used in OpenEXR to do HDR. It is one of the way but not the only way to do HDR.

I think people and websites generally refer the FP blending as HDR. After a while, it is then becoming part of the Nvidia's package of SM3 featureset.

 

[kylebisme]

Funny thing is, HDR useing SM2 looks exactly the same in both Splinter Cell 3 and Far Cry.

 

[mwmorph]

funny that B&W2 wil have SM# considering it was built on the B&W1 engine. must be insainely modified to run SM3 on that thing.

 

[hans030390]

Originally posted by: TheSnowman
Funny thing is, HDR useing SM2 looks exactly the same in both Splinter Cell 3 and Far Cry.

Yeah, that is a tad weird. What's also weird is that HDR doesnt kill performance as much in 2.0 as it does in 3.0. Isn't it supposed to be the other way around?
Just a random thought.

 

[biostud]

I read somewhere that it's impossible to use HDR with Antialiasing (in all games).

 

[Drayvn]

Only when using the FP16 buffer to use Tone mapping that you cant use AA in games

 

[SonicIce]

why has this year old argument resurrected lately?

 

[Pete]

Originally posted by: gunblade
FP blending is the technique used in OpenEXR to do HDR. It is one of the way but not the only way to do HDR.

I thought OpenEXR (as it relates to nV's current hardware) simply defined the FP16 precision nV uses? I didn't realize FP blending is OpenEXR-specific, unless it's so just because nV uses the same FP16 precision (for shaders, buffers, and blends?).

Originally posted by: biostud
I read somewhere that it's impossible to use HDR with Antialiasing (in all games).

That's just a limitation of current nV hardware, either because of a transistor budget or simply lack of bandwidth. Yeah, R520 is supposed to allow for AA with "HDR," but I wonder if it'll be limited to FP10 or some lower precision.

 

[Drayvn]

Originally posted by: Pete

Originally posted by: gunblade
FP blending is the technique used in OpenEXR to do HDR. It is one of the way but not the only way to do HDR.

I thought OpenEXR (as it relates to nV's current hardware) simply defined the FP16 precision nV uses? I didn't realize FP blending is OpenEXR-specific, unless it's so just because nV uses the same FP16 precision (for shaders, buffers, and blends?).

Originally posted by: biostud
I read somewhere that it's impossible to use HDR with Antialiasing (in all games).

That's just a limitation of current nV hardware, either because of a transistor budget or simply lack of bandwidth. Yeah, R520 is supposed to allow for AA with "HDR," but I wonder if it'll be limited to FP10 or some lower precision.

Check this out dude, the OpenEXR website.

http://www.openexr.com/

It supports 16 and 32 FP buffers.

About the HDR with AA, i think its because AA is applied to the pixels before the HDR is added, and because HDR is added at the very end of the pipeline AA has to be disabled otherwise there will be conflicts. Tho i cannot be certain about this.

 

[Pete]

Thanks, Drayvn. The OEXR site states that "OpenEXR is a high dynamic-range (HDR) image file format developed by Industrial Light & Magic for use in computer imaging applications." The About page similarly states that

ILM decided to develop a new HDR file format with 16-bit floating-point color component values. Since the IEEE-754 floating-point specification does not define a 16-bit format, ILM created the "half" format.

So it's just a file format. FP blending doesn't appear to an OpenEXR-specific technique, but rather a general one that can be applied to many formats, OpenEXR's among them.

I recall that David Kirk said as much WRT HDR and AA in a recent interview, but the folks at B3D don't think that's correct. IIRC, nV applies AA at the very end of the rendering process, so I'm not sure how HDR affects that. I'm also not sure how the higher-precision/-range variables and frame buffers affect the rendering order, but maybe tone-mapping is a problem.

If Xenos allows for AA with FP buffers, though, then maybe Kirk was just poo-pooing something his GPUs don't yet have (like he did with gamma-adjusted AA or unified shaders)--as a businessman, not as an engineer. We've seen him play a little fast and loose with NV30, so it wouldn't be new. I still believe (but that's all--I'll be the first to admit I'm not fully versed in 3D) it's a question of engineering resources, not the rendering process.