Dont affect colours - Different gamma values effect AA - which?

[Morne]

Hi all

I've been using LWF for a while now and I'm saving linear to EXR and I have "Don't affect colours" ticked. In VFB I have the sRGB button ticked.
In color mapping I have linear miltiply and gamma set to 2.2. Everything works fine and as expected. I've noticed some people however use here gamma 1.0 instead of 2.2 and I've tried that in the render looks exactly the same. So then why 1.0 or 2.2?

I then for a test used gamma 100 (yes hundred) to see what this gamma value does. The colours looks the same and light intensity is the same. The render is the same EXCEPT for AA. On 100 gamma I get rough edges on object and shadows.

So then this made me think. Have I been using the 2.2 incorrectly all this time and that's why my multimattes dont have 100% correct edges? Am I suppose to use 1.0 Gamma and that will result in correct AA also for my multimattes?

[rivoli]

nope, 2.2 is correct. it let vray knows that you're rendering with a gamma correction, so that it can do the correct sampling all across the image. of course colours won't change, that's what the "don't affect colours" is for, you are previewing the linear image via the srgb switch.
some problems with render elements may come from the fact that not every part of the image need the same sampling, and in some cases vray might undersample what it doesn't consider to be worth spending more time on. you can try forcing a more even sampling with a higher number of minimum samples, like 2 or 3 for example.

[vlado]

I then for a test used gamma 100 (yes hundred) to see what this gamma value does. The colours looks the same and light intensity is the same. The render is the same EXCEPT for AA.

Yes, this is the whole point of having the "Don't affect colors" option. The gamma should affect AA sampling, but not the final image, under the assumption that you will be doing the gamma correction later on in a post-processing application.

Best regards,
Vlado