linear 1.0 with caterpillar scene

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doreamon
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linear 1.0 with caterpillar scene

Post by doreamon » Thu Feb 12, 2015 4:46 pm

I assumed that linear 1.0 in tonemapping means linear image with no tonemapping applied. I think I misunderstand that setting.
F stop at 32 and exposure to 1.0 in linear 1.0 the scene is very dark Ithought it would brighten up.
So this scene can't be rendered with linear tonemap and really have to use camera tonemap? What if I wanted to render out an non tonemapped image?

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Re: linear 1.0 with caterpillar scene

Post by galinette » Thu Feb 12, 2015 9:40 pm

Yes, it works at you think.

What explains the dark results in the caterpillar scene, is the amount of light from the environment, which is tiny and unrealistic. So the problem is the scene and not your exposure settings.

If you have a photometrically correct lighting set-up, such as the sun+sky or a calibrated envmap, linear tonemapping to 1.0 and correct camera settings (FStop and Shutter), the exposure will be as expected. Only difference is the dynamic, which is poor with linear tonemapping. Real cameras have a non-linear curve to improve the dynamic, and this partially reproduced by camera tonemapping.
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Re: linear 1.0 with caterpillar scene

Post by Zom-B » Fri Feb 13, 2015 1:18 am

doreamon wrote:What if I wanted to render out an non tonemapped image?
In your exporter there should be a option to save untonemapped EXR file.
This one is identical to Linear @ 1 but full 32bit depth, while all other saved EXR files are clamped to 8bit.

The untonemapped EXR is a great start to do your post processing.
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doreamon
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Re: linear 1.0 with caterpillar scene

Post by doreamon » Fri Feb 13, 2015 1:29 am

Thanks. I usually render in linear and was confused why linear 1.0 with that scene is pure black and even cranking it up was not enough to brighten the caterpillar. So I thought this wasn't a linear hdr scale.
So 2.2 value here is like srgb? I just do renders in linear with gamma 2.2 for reference but do the actual tonemapping in post. The caterpillar scene got me confused a bit. :D

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Re: linear 1.0 with caterpillar scene

Post by Zom-B » Fri Feb 13, 2015 1:33 am

doreamon wrote:So 2.2 value here is like srgb? I just do renders in linear with gamma 2.2 for reference but do the actual tonemapping in post. The caterpillar scene got me confused a bit. :D
This linear setting is not gamma, but only a linear multiplier in the case its needed like for scenes that aren't arranged to real world light settings...
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doreamon
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Re: linear 1.0 with caterpillar scene

Post by doreamon » Fri Feb 13, 2015 1:59 am

Zom-B wrote:
doreamon wrote:So 2.2 value here is like srgb? I just do renders in linear with gamma 2.2 for reference but do the actual tonemapping in post. The caterpillar scene got me confused a bit. :D
This linear setting is not gamma, but only a linear multiplier in the case its needed like for scenes that aren't arranged to real world light settings...
So how do we see a pure linear render and temporarily add gamma 2.2 for reference?

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doreamon
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Re: linear 1.0 with caterpillar scene

Post by doreamon » Sat Feb 14, 2015 5:54 am

So we can view a pure linear render on the indigo viewport while its rendering without having to save an untonemapped exr? Then add gamma 2.2 to the viewport for reference?

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