Gamma control for GI HDRI environment and ...

[Micha_cg]

... reflection environment is very useful.

A gamma control is very important for the HDRI of the environment. Some images ar corrected, other not. But If would use the global gamma control, I would change the gamma of textures from the materials too.

In the past I had the same problem with AIR and have modified the GI light shader. Here an example:



first row - left image: the gamma is to strong, the lighting to contrastful
first row - right image: the gamma of the lighting is good, but the texture is to soft now
second row: global gamma 1.4 and HDRI gamma 2 give me the right mix

[Thomas An._cg]

Gamma control for GI HDRI environment and ...

Micha,

Did you also try the "color mapping tab", or the post processing controls of the "Indirect Illumination tab" ? Do they have the same effects on your textures ?

[Micha_cg]

Gamma control for GI HDRI environment and ...

Thank you. The GI post processing could be do it, I will test it later. But I think a simple gamma option at the evironment tab could be the simpliest way.

[flipside]

Gamma control for GI HDRI environment and ...

The problem indeed is that hdri's are gamma 1.0, and most normal textures have gamma 2.2 or something similar baked in.

If you use the color mapping with 1/0.455, you will create a gamma 2.2 rendering. Your hdri map lighting and reflections will look good. But all your materials and texture maps will look washed out, because they will be double corrected (they are already gamma 2.2, and you put another gamma 2.2 on top of it).

If the whole interface has a gamma 2.2 correction, including all color swatches and color selectors and material preview, you can create materials which will look good when using the gamma color mapping. But still, your textures need to be corrected. In max, you can do this with a color correct map, to convert them to gamma 1.0 again, avoiding double correction. Max also has a display gamma option, which displays all the color swatches etc... gamma corrected. Gijs wrote an interesting page about theis whole issue:
http://www.gijsdezwart.nl/tutorials.php

I've talked with corey about this.

But remember that by simply changing the gamma of your hdri to 2.2, this will not have the same effect as described above! You need to adapt your complete workflow to 2.2.

Here's an example of that, done in max:
Normal workflow, same as you do in rhino now:



Same but hdri is gamma adjusted:



Now the hdri is not gamma adjusted, but all the rest is. I have set display gamma in max to 2.2, adjusted the materials so they don't look washed out. Then I set gamma color mapping with 1/0.455.



The last one is the only correct one. This is the lighting as it was where the hdri is shot.