Cg source hdr exposure issue.

[thanulee]

Hi, I have this dumb issue and cant seem to find what i am doing wrong or if im too picky.
I have some hdrs from cg source and they are far different from what i see in their website as u will see in the images attached. These are supposed to match 1:1.

So, i created a similar scene, added a dome at 1.0, added a vrayhdr with default values and gives me much less direct light than it should. If i crank up the inverse gamma of the hdr to 0.85 i get give or take the amount that i want, but the clouds start blowing out. In any case, i am not supposed to mess with the gamma.

Thoughts or solutions?
ty

ps. images are side by side comparison with their web, one image im at inverse gamma 1.0, the other one at 0.85.

[crazy homeless guy]

Hmm... CG-Source are my favorite HDR's to use. I find them more reliable than any others I have used. I wonder if you can ask them if they will share the test scene setup with you so you can learn more about how to properly use them.

As a side note... don;t assume anything is plug and play... for example.. to use Guthrie's HDR's effectively you need to use Reinhard color mapping at 0.1-0.2 otherwise they will blow out like no tomorrow.

[thanulee]

Thanks a lot for the reply. Well, ya i know and i always fix things in post and find my way around, but this has been bugging me everytime i use this image, cause they have it like this on the website and people say that these are the best hdrs out there as well. It shouldnt require any fiddling. Same thing that goes on with cg source ones, goes with jorgens as well. Not as they are in the previews. All of em need the inverse gamma down a bit. PG's hdrs are a complete other story yea.
I d ask em, but there is no contact in cg source site, or im missing it

[squintnic]

turn the light multiplier up
feels like you are being a bit particular
try them on a proper scene

[thanulee]

Thanks buddy for the tips. Unfortunately light mult up is not the option. The proper way is the inverse gamma without blowing the image out. Same time i wanna stay linear for comp and not clamp down my highlights.
Its not a matter of another scene, already tested many times with the exact same result.

As said i might be picky, but this is not the result i am after. If i have to comp the sky, i see no reason for using those hdr in exteriors. I also bought the timelapse scene from them, cause of a project and i d appreciate if it could spare me some serious post work

edit: i also noticed just of now, the shadows in the reflections. Mine are smudgy, theirs crispy sharp. Might be low sampling on my side, but i dont think this is the case cause rest reflections are as they should. So definitely im missing something in this setup!

[Komposer]

hey, since years, I´ll start a thread like that....but...
The same here, again and again, with HDRI´s from all you can get there (as I know´s
When I saw one of the thousands tut´s there, the inverse gamma thing works much better in Max (for me in Maya...
In 100% of all samplerenderings, I was here the same crap like You. Very frustating.
A few month before I found this:
http://www.hyperfocaldesign.com/
Their images are dramatically other than all I saw and test before. Don´t know why, but unclamped seem´s to be one point, and much smaller high lights one more...
There is a test-hdr and you will see a good step forward I think.
The final images, not too cheep in my eyes, comes in 2 versions.
One small one (200-400K) only for lighting, and a second version with 60-100?Mb for reflection.
Both seem´s to have different fstops! (I´ve no idea how I can precise that)
They spoke about more physically correct results and I can absolute confirm that.
Rebuild most of my old scene in this weeks with their HDRI´s (bought at first the bestseller set)
http://www.hyperfocaldesign.com/hdri-skies-best/
WOW!
...and no, it´s not my company

[thanulee]

Thanks a lot Komposer! I ve test em waaayy back, i ll give em a second look since u feel me over here!

[Pixelab]

One small one (200-400K) only for lighting, and a second version with 60-100?Mb for reflection.

I might be wrong but I think it's an outdated method. Vray already rescales the map during the render for MIS (Multiple Importance Sampling).

[joconnell]

I'd say the images that are on the site were using vray's old method of colour calculation (CIE) whereas vray is now (from 3.3 onwards I think?) doing everything in srgb so there'll be a slight difference.

[suurland]

Hi thanulee

I'm the owner of CG-Source.. The missing contact information is on the site on the about page, and when you made your purchase you received confirmation emails you can reply to if you have any questions.

I can't say for sure what you are doing wrong, but you said: "Same time i wanna stay linear for comp" so I assume you have set your color mapping to linear, and my example scene is using exponential as you can see on https://cg-source.com/sky_info.php If you are rendering HDR maps, mine or others, then with linear color mapping all bright areas will always look very blown out, just as when you open it in photoshop for example. If you want to stay linear then you can do that but then you should do some color mapping on the end result to stop bright areas getting blown out.

/Thomas

[joconnell]

Just curious thomas, do you capture the full range of the sun in your hdrs? As in you had to put on some kind of nd to underexpose the sun?

Cheers!

[suurland]

Yeah, I'm using a ND filter.

[joconnell]

Super, will pick up some of your images then

[crazy homeless guy]

Same time i wanna stay linear for comp and not clamp down my highlights.

Then you will likely need to do Rinehard adjustments or something similar in post to clamp down your highlights. At the end of the day it is the pixels that we see on the screen that matter most. You can get to that end in a variety of ways.

[joconnell]

Very true, pretty much every stills or film camera tone maps images, our eyes see in logarithmic colour too so it's useful to do as a last step if you're trying to do something photographic.