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Overexposure

Posted: Thu Mar 11, 2010 12:33 am
by Meelis
Hi

Direct sun light burns over (pure white), but shadows are quite dark.
When i lower sun gain too mutch then not overburned areas don't look correct and skylight / sun balance is off.
Reinhard don't burn over but there is noo photoreal contrast.

Sun comes from window holes but there is no windows and curtains. Window holes are 2x1,1m & 0,67x1,1m. Room is ~14 square meters.

Is there point restarting rendering with sorter explosure, or is it same like lowering iso (what didn't help).
Should i maybe remove exit portals.

Re: Overexposure

Posted: Thu Mar 11, 2010 1:12 am
by StompinTom
Lowering the ISO and increasing shutterspeed (reducing exposure) will do the exact same thing. Removing light portals shouldn't have any effect other than slowing down your rendering.

Take a photo of a sunlit room, you'll see a fair bit of contrast. My solution has been to render out different exposures, including a Reinhard one, and mix them slightly in Photoshop to preserve details both in light and shadow. It's much like taking a couple exposures with a tripod and mixing them up.

Re: Overexposure

Posted: Thu Mar 11, 2010 2:04 am
by Meelis
Thanks

Is it like HDR, i guess Gimp doesn't support tone mapping.
Is there any free or demo programs for that.

Re: Overexposure

Posted: Thu Mar 11, 2010 2:22 am
by Psychotron80

Re: Overexposure

Posted: Thu Mar 11, 2010 3:45 am
by Meelis
Psychotron80 wrote:maybe this one?

http://www.hdrlabs.com/picturenaut/
Thanks :D

Re: Overexposure

Posted: Thu Mar 11, 2010 7:36 am
by suvakas
What Indigo version?
You can pick a different camera profile. There are plenty of them to choose from.

Re: Overexposure

Posted: Thu Mar 11, 2010 9:07 am
by Meelis
suvakas wrote:What Indigo version?
You can pick a different camera profile. There are plenty of them to choose from.
2.2.12 stable
I tried different camera profile and adjusting iso, ev, and light layer gain. No perfect one.

I go with multible images and mix to HDR. But i havn't done it before.
*I can get good average datails with reinhard,
+ i want some beautiful natural soft sun highlight that bumps up more than reinhard, but nice looking medium highlights come with overburned direct sunlight. Soo i need to reduce pure white effect when mixing.
+ I need to bring out shadow details, shadows are very unreally dark, but its going to overburn direct sunlight even more. There i need to reduce even more pure white effect when mixing.
+ Getting out details from direct sunlight with camera tone maping will produce large areas of black, soo i need to reduce black effect when mixing.

Can i mix Indigo tonemaped exr 3x16bit files, where are they saved now.

Now i need to render long time because it goes like 13k s/sec with my slow cpu.
I post it here if something comes up.

Re: Overexposure

Posted: Thu Mar 11, 2010 10:33 am
by galinette
I would say that reinhard is the most suitable tonemapping for doing this, as it is meant to compress the high dynamic range pictures to low dynamic range, without too much cropping. That's exactly what you want to do.

You have to play with the three parameters. To compress more, let the post gain to something not too high (1 or 1.5), increase the pre gain ( try large values, from 5 t o20, maybe more) and increase the burn (also 20)

Etienne