oeLangOetan
Newcomer
any proof to back that up?bigz said:
HDR Method used in Splinter Cell: Chaos Theory
- Thread starter bigz
- Start date
No. 16-bit int gives an HDR range of 256-1 at 8-bit precision. FP16 gives an HDR range of approximately 2 billion to one at 10-bit precision (note: could be a little bit off on the dynamic range depending on the exact specifications of the format, but 2 billion-1 is an absolute minimum it could be).arrrse said:
If you want to model real-world situations, you'll frequently be working with dynamic ranges of thousands or tens of thousands to one.
Last time I spoke to the author of RTHDRIBL was a good while back, so my memory isn't 100% clear on this but the rendering went along the lines of render to a FP surface, next pass sample this surface for appropriate effect; if necessary render to a new FP surface and repeat. He had mentioned that with all the effects running, the demo is taking up to 40 passes per frame.
Mintmaster
Veteran
IMO the easiest thing to do is just do all blending after tonemapping into an 8-bit per channel buffer. It's not perfect, but it's very easy and should give 90% of the HDR look. You may want to tweak the textures of all blended objects, but it's not necessary.Chalnoth said:
This method fails most noticeably for transparent things reflecting bright light, e.g. windows and water. I guess implementing the ping-pong method for a special case like water won't be that annoying.
Man, ATI would have been so much better off if they tackled blending like NVidia. For their 16-pipe cards, knock off 8 blend units since you don't have the bandwidth anyway, and add FP blending to 4 of the remaining pipes.
Chalnoth said:
In the context of games you're unlikely to see a dynamic range anywhere near that. 256 will be more than enough for most situations. In fact, MDR (medium dynamic range) is probably enough most of the time, letting the range go up to 4 or 8 or so.
Also, by storing a range in alpha you can get pretty darn good results with RGBA16 even with extreme values.
tEd said:
Oh, I wish more people did. Some of you may have noticed that I'm not posting as frequently in this forum as I used to. I think most of my posts are in the General and Politics forums these days. Not because I prefer to, but because I've been misinterpreted a number of times, even after being extremely careful about how I word things.
Well, the thing is, you can get away with lower dynamic range if you're tuning your rendering algorithm for a single scene. But true HDR allows you to not have to worry about the overall light level, and just let the tonemapping pass take care of it.Humus said:
For example, one of the most fantastic places in FarCry for HDR was when I was exiting a cave. I thought it caught the effect of moving from a dark area to a very bright area quite well. That's something you just can't do without either true HDR, or hardcoding the effect. I don't think it makes much sense to hardcode that sort of thing, because it'll lead to spotty implementations.
Skinner-BH71
Newcomer
Humus said:
A mini comparision (benchmark/ I.Q.) in my system.
HDR SM3 (16-bit floating point, openEXR format) vs HDR SM2 (16-bit integer?? 8-bit integer??)
http://www.adrenaline.com.br/forum/showpost.php?p=794117&postcount=1650
1024x768+SS+PM+HDR SM3 ->6800gt
1024x768+SS+PM+HDR SM2 (3d-Analyse 2.36b) ->6800gt
ps: See brazilian threads about you, Humus:
http://www.adrenaline.com.br/forum/search.php?searchid=294532
Last edited by a moderator:
tEd said:read his sig.
I know he's not speaking for ATi
But no matter what's in his sig, one can't simply completely ignore the fact that he does work at ATi and there may be influences there in both directions. Nevertheless, his comments do point to the possibility of ATi doing only what's "necessary" with respect to HDR - just like they did with FP24 shader precision for the past few generations. Can't say I'd be surprised either.