Tone mapping with HDRI

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Heliodor
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Joined: Sat May 21, 2016 10:20 pm

Tone mapping with HDRI

Post by Heliodor » Mon Sep 30, 2019 1:37 am

I have problems with tone mapping, when I'm using just a HDRI map for lighting.
With "Reinhard" I receive some good results. But with different tone mapping as "linear" or "camera" the images are all just black. Even the untonemapped .exr, whatever I change in the camera settings.
The reason I have to use another tone mapping is, I have to test different materials in the same setting. And the tone mapping is all different with Reinhard.

Any ideas?
Thanks!

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thesquirell
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Location: Novi Sad, Serbia

Re: Tone mapping with HDRI

Post by thesquirell » Mon Sep 30, 2019 2:51 am

Got some ideas.

First one.

Did you check on your light emitting values? The power of your source? All black usually means that you don't have enough power on your light sources. The easiest way to check this out is just to input insane large number for exposure time, ev adjustment or ISO of your camera. If that's the case, it's just an easy fix. Increase those parameters, or give your light source more power. To give it more power you could use Emission Scale, or you could change the spectrum type in Base emission to uniform and give it a large value of, let's say 1 000 000, while keeping the hdr texture in Emission (also check the gamma value, it should be 1.0), and that's it!

Best of luck!

Heliodor
Posts: 12
Joined: Sat May 21, 2016 10:20 pm

Re: Tone mapping with HDRI

Post by Heliodor » Mon Sep 30, 2019 3:23 am

Thank you!
In parallel I tried exact this way, with real crazy high values. But is this really the usual way to deal with ISO values or emission multiplicators in a million range?

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thesquirell
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Re: Tone mapping with HDRI

Post by thesquirell » Mon Sep 30, 2019 9:53 pm

Well, even though Indigo is a rendering engine, it still tries to imitate/simulate real life phenomena. So, instead of multiplication on your emission, you should scale it to a physical size, which for the Sun is something around 32,000–130,000 lux, depending on your exposed surface, and time of a day/year. And that being a source that is faaaar away from your scene, passing through all the layers of Earth's atmosphere, etc. And since you're using a HDR source, it will vary depending on your image. Far better solution: change Spectrum type to Uniform, give it a 1 000 000 value, and set it up on a specific light layer, so you can tweak all the lights with light layers (all that being in the Base Emission channel). Observe which light is producing the greatest amount of noise, if you have many, at give it a higher priority (change Emission sampling factor).

Heliodor
Posts: 12
Joined: Sat May 21, 2016 10:20 pm

Re: Tone mapping with HDRI

Post by Heliodor » Tue Oct 01, 2019 3:29 am

This is helpful, too. Thanks a lot!

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Oscar J
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Re: Tone mapping with HDRI

Post by Oscar J » Tue Oct 01, 2019 5:28 am

This question frequently comes up. It is indeed very questionable from a usability point of view having to type a number like 100000000 in order to be able to see anything in your scene, but AFAIK it's the only way to do it.

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