High Dynamic Range Rendering - ATi's

[Alkali]

I was wondering if you guys could help me clarify my knowledge on this subject.

I got into a conversation with a guy on an (nVidia/ATi impartial) forum about HDR. He maintains that nVidia's HDR technology is actually a 'higher level' HDR than ATi's. I would like to clarify with you guys my knowledge of ATi HDR technology.

Please refer to this thread for screenshots of HDR rendering in FarCry on an nVidia 6800 Ultra. (If you ignore the fud about ATi cant do HDR etc in the thread, you can see the bits where he and me are chatting about HDR.)

As much as I understand it, ATi's HDR implementation has remained the same spec since the 9700 card was unleashed. And it seems to me after looking at these demos, and the movies like Half-Life 2's famous HDR video, that ATi has it right. In the discussion I am having with this guy in this thread, I think he is saying that ATi only have an 8-bit (i.e 255 variations per pixel) implementation, while he maintains that nVidia use a higher level.

Can anyone set me straight on this subject, because I'm not sure if I'm mistakenly mixing up FP24 with this subject.



EDIT: The thread has been deleted from their forums
Its a shame, it had over 40,000 views, and was popular, but alas, its gone And all that good discussion that was in it...

[Intensive Purpo]

Sorry guys i have to explain what i said previously!
OpenEXR is 16 bit float buffer format (fp16) - 64 bits per pixel.
RGBE8 is RGB + Exponent format - 32 bits per pixel.

Quality and range with RGBE8 isn't as good as fp16 because it's possible to encode just 256 values for the exponent. If we try to increase the lighting range mach banding becomes noticeable (lighting precision isn't good enough).

Not sure what he's talking about, but FP16 is on ATI cards, and definitely possible for HDR.

He speaks BS.

[JadeDragon]

Yes the later Radeon line has this technology!!
Just look at the old 9700 Debevec RNL Demo!! Here

The scene in this demo is a real-time implementation of Paul Debevec's 1998 Siggraph paper "Rendering with Natural Light." The original version of this was rendered offline on a UNIX rendering farm. Each frame took around 20 minutes to render.The demo is being rendered entirely with image-based lighting - this is a technique for using light captured from the real world to illuminate virtual objects in a virtual scene. In this example, the synthetic objects are illuminated with real light captured in UC Berkeley's eucalyptus grove.

The Radeon 9700 was the first visual processor with the high range and precision required to implement this technique.

The educational modes in this demo showcase two of the features used in the construction of the final scene. High Dynamic Range Textures and post process Light Glows.

[TIKtak]

since he comes from a forum thats mostly nvidia, you already know what to expect.

[JadeDragon]

Originally posted by TIKtak
since he comes from a forum thats mostly nvidia, you already know what to expect.

Pretty much

[Alkali]

Ok, my mistake, I thought it was impartial... hum... Anyway, does anyone have an idea of what exactly HDR for the ATi implementation does?

[Intensive Purpo]

Originally posted by Alkali
Ok, my mistake, I thought it was impartial... hum... Anyway, does anyone have an idea of what exactly HDR for the ATi implementation does?

Its pretty identical to the 9800, however, HDR on the X800 series have MUCH stronger mathematical calculations.

And when compared to the 6800 Ultra, the X800 is also better at mathematical calculations.

EDIT: For example, when the "dribble" demo is run on various graphics cards, which is focused on HDR, here are the scores:

9800 XT: 45.11
5950 Ultra: 24.80
X800: 131.29
6800 Ultra: 58.62

[Alkali]

Ok, its starting to become clearer now...

Was it that program called ShaderMark where people were shocked at how much of an advantage the X800 cards had on the 6800Ultra? I seem to remember at least one website being awed at the sight of the X800's dominace in a shader-related benchmark...

[Crawdaddy79]

First good HDR Demo to come out : http://www.daionet.gr.jp/~masa/rthdribl/index.html


How ATi's X800 Performs compared to NV40:

http://www.hexus.net/content/reviews...JsX3BhZ2U9MTY=

[Skynet]

I didn't realize the NV40 did so poorly with this bench, quite pathetic I'm dissapointed.

[ReDeeMeR_RR]

Wow, NV40 really is crap

[Dave]

60.40 drivers used. would like to see it with latest drivers...

[AlphaWolf]

Originally posted by Dave
60.40 drivers used. would like to see it with latest drivers...

Here is a 6800Ultra with the 60.72 drivers.


<edit> actually it says hexus also used 60.72 drivers

[tEd]

Originally posted by Alkali
I was wondering if you guys could help me clarify my knowledge on this subject.

I got into a conversation with a guy on an (nVidia/ATi impartial) forum about HDR. He maintains that nVidia's HDR technology is actually a 'higher level' HDR than ATi's. I would like to clarify with you guys my knowledge of ATi HDR technology.

Please refer to this thread for screenshots of HDR rendering in FarCry on an nVidia 6800 Ultra. (If you ignore the fud about ATi cant do HDR etc in the thread, you can see the bits where he and me are chatting about HDR.)

As much as I understand it, ATi's HDR implementation has remained the same spec since the 9700 card was unleashed. And it seems to me after looking at these demos, and the movies like Half-Life 2's famous HDR video, that ATi has it right. In the discussion I am having with this guy in this thread, I think he is saying that ATi only have an 8-bit (i.e 255 variations per pixel) implementation, while he maintains that nVidia use a higher level.

Can anyone set me straight on this subject, because I'm not sure if I'm mistakenly mixing up FP24 with this subject.

what the guy meant i guess is that the nv40 supports fp16 blending. It means you can use a fp16 framebuffer format where the r420 only can use 32(8bit per pixel)bit integer as a final output.

It doesn't have much meaning as a fp16 framebuffer today is very slow and not useful for games anytime soon.

[Alkali]

Originally posted by tEd
what the guy meant i guess is that the nv40 supports fp16 blending. It means you can use a fp16 framebuffer format where the r420 only can use 32(8bit per pixel)bit integer as a final output.

It doesn't have much meaning as a fp16 framebuffer today is very slow and not useful for games anytime soon.

Ah thankyou! Thats what I needed to know

[Jawed]

As a photographer, all of the "effects" of HDR are actually entirely undesirable.

Just like the fad for "lens flare" in games from 10 years ago, equally entirely undesirable.

Both of these effects are what cheap lenses/film/digital cameras do - the good gear is expressly designed to remove these artefacts.

What a waste of programming talent and transistors.

Jawed

[Alkali]

Jawed, I think the whole point of HDR is not to reproduce what a bad camera can take, but what the human eye sees. If you look at a silouette of a tree against a sunrise, you will see a blooming effect against the tree from the bright sun...

So rather than trying to copy an undesirable effect in photography, the point is trying to capture exactly how a human eye sees the scene.

Photography obviously tries to eliminate these effects because they simly make a better picture - but to face the fact is to realise that although the scene may look better without blooming, it is not realistic without blooming.

[Jaillum Malord]

Excellently put my friend. Well done.

[movieman]

Both of these effects are what cheap lenses/film/digital cameras do - the good gear is expressly designed to remove these artefacts.

Huh? HDR effects are a limitation of the contrast range of film or the human eye... no camera will change the fact that at a certain brightness level you've gone as far as the film, CCD or human eye can handle. All a photographer can do is try to control the lighting so it never reaches that level.

Try looking at the real world sometime with your eyes, and you'll notice that at high intensities everything becomes white. That is what HDR is emulating.

[movieman]

what the guy meant i guess is that the nv40 supports fp16 blending. It means you can use a fp16 framebuffer format where the r420 only can use 32(8bit per pixel)bit integer as a final output.

It's true that ATI can't display an fp16 image natively (or, at least, my 9500 Pro can't), but, most likely, that just means that everything is rendered to an fp16 texture and then downconverted to 32bpp afterwards.

Can NV40 really display fp16 natively as a framebuffer format? I didn't think any card could do that at the moment.

[FiggyG]

Beyond 32-bit in the frame buffer? New to me...

[tEd]

Originally posted by movieman

Can NV40 really display fp16 natively as a framebuffer format? I didn't think any card could do that at the moment. [/b]

yes it can , it's first card to have support for it.

[bandit55]

Heh, gotta love my 9600XT … score …

9800XT … 45.11
9600XT … 36.0
5950 … … 24.8
5700U… …10.0

[Jawed]

Originally posted by movieman
Huh? HDR effects are a limitation of the contrast range of film or the human eye... no camera will change the fact that at a certain brightness level you've gone as far as the film, CCD or human eye can handle. All a photographer can do is try to control the lighting so it never reaches that level.

Try looking at the real world sometime with your eyes, and you'll notice that at high intensities everything becomes white. That is what HDR is emulating.

As it happens, I know the human eye suffers from bloom, as does film and lenses (the eye's much better generally speaking). What bugs me is:

1) it's exaggerated in all these demos

2) there's a ton of things that are more important in graphics than HDR. e.g. shadows like D3 - unlike the crappy shadowing we've seen in the HL2 demos. The shadowing in HL2 is so 1999 it's embarrassing.

HDR is up there with lens flare and depth of field for utterly useless effects when gaming - great for cinematics, useless for gaming.

Jawed

[Alkali]

Originally posted by Jawed
As it happens, I know the human eye suffers from bloom, as does film and lenses (the eye's much better generally speaking). What bugs me is:

1) it's exaggerated in all these demos

2) there's a ton of things that are more important in graphics than HDR. e.g. shadows like D3 - unlike the crappy shadowing we've seen in the HL2 demos. The shadowing in HL2 is so 1999 it's embarrassing.

HDR is up there with lens flare and depth of field for utterly useless effects when gaming - great for cinematics, useless for gaming.

Jawed

1. I totally agree. I hope the users are able to change HDR effect using a slider (I will have it set to low effect - so I get it, but its not overbearing )

2. I happen to think differently on this - I classify HDR as a pretty important graphical enhancement. I always found lens-flare annoying... As for shadowing, I dont see much wrong with the new sft-shadowing effects the X800 uses in its Ruby demo, and the 6800Ultra used in the Unreal 3 tech demo.

[Monrad]

So... the guy at Guru3D is claiming that this effects can be done with 6800U, and he also says that ATI's X800 will not be able to have THAT good quality... look for yourselves.



He also says that he has a patch to do this... and he got it from a friend that works on Crytek or something like that. He doesn't want to share this patch with us of course... because he has no permission. That's ok... but... why is he posting this pictures on a X800 Screenshot thread? Why don't he post it in the NV section?

This sounds weird to me. I think he is fooling on us. If you can, just read the thread at Guru3D. The user name is Turisto, maybe if you read there, you could provide us with more useful information about HDR on X800.

Thanks a lot.

[Alkali]

Anyone tried increasing the light intensity from the FarCry config screen?

Config -->> Advanced -->> Custom -->> lighting (end tab)

There are options there for exposure and stuff, maybe its just that? I cant test because I am on only a GF2GTS...

[Monrad]

Originally posted by Alkali
Anyone tried increasing the light intensity from the FarCry config screen?

Config -->> Advanced -->> Custom -->> lighting (end tab)

There are options there for exposure and stuff, maybe its just that? I cant test because I am on only a GF2GTS...

I'll try it

[Monrad]

Nop, that options doesnt' modify the lighting on the walls. They only modify the lighting on the gun.

[Monrad]

A quote from the guy...

Hmm. That's strange. May be i cannot explain clearly
1. i said before that FarCry doesn't use 1.4 shaders. Is that clear?
2. FC is using just 1.1 and 2.0/2.x pixel shaders. is that clear?
3. 80-90% of all the shaders used for indoor scenes are lighting shaders. Just search in your shaders cache folder all .cgps files with string ps_2_0. I have 300 ps_2_0 shaders here. So FarCry heavily uses 2.0 shaders, but only in indoor scenes. It's not mainly SM1.0/SM1.4 game (1.0 isn't used in FC at all btw). It's mostly SM2.0 game and 1.1 is using only for compatibility with previous generation hardware.

4. fp16 HDR implementation on ATI is possible only if blending is not used at all or with using trick with 2 fp16 buffers (very slow).

5. NVidia about fp16 buffers:
fp16 textures and render targets should be faster or the same speed as int16 textures and targets, so fp16 is the preferred format.

P.S. would be interesting to see how people can make such effects in photoshop if it's clearly visible on screens that different lights have different range. That's cannot be emulated by any post-processing filters...

What I'm trying to do here is to confirm... This information must be truth because I read it somewhere else, what I don't know is if crytek is going to implement HDR on Farcry... and more important, if it'll be possible to do HDR with a X800 on farcry.