Normal map causing material to go dark

[leehenshall]

I have built a normal map using Quixel. When I try to apply the normal map in v-ray is make my mesh display weird like it's inverting the normals.

Any idea what could be causing this?

[Neilg]

Wrong gamma in the normal map import options. change it to either 1, .454, or 2.2. it'll be obvious when it's right.

[leehenshall]

Life saver! Thanks....I think Quixel may have applied a gamma already so a Maya gamma node with a 2.2 curve seems to have fixed it.

[yolov]

I think we can improve that on the vray side in maya, we just need to carefully think it through - not applying the corrections when the texture is a normal map. At least when it comes to the corrections from the Maya color management system that by default applies sRGB to the file node.

[vlado]

Actually, one can define rules on when to apply color corrections or not in the Maya preferences; we don't use those at present but at some point we will have to.

Best regards,
Vlado

[leehenshall]

Adding a gamma of 2.2 gives me a better result but upon further inspection I'm still noticing some strange results. I'll post a screen shot when I'm back in the office.

Regardless of the gamma I use I can see that something odd is happening with the normals. The only way I can get the object to shade correctly is to apply my normal map as a bump map which seems odd to me. It doesn't look terrible as a bump map but I'm gunna guess here that it's not right.

Usually I plug my normal maps into my shader with no gamma correct so that it comes in as linear. Have I been doing it wrong this whole time? This is the first time I've encountered this issue which leads me to believe that it has something to do with the way Quixel is saving the normal maps? Maybe inverted Y axis?

I can't seem to find the same options that MAX has in MAYA for dealing with normal maps. Max has a Slate node that allows you to control normal options like red/green flip etc. That's from memory correct me if I'm wrong.

Is this something the QA team would be interested in investigating? or is it a Quixel Issue?

[yolov]

Sure, we're interested in having a look, always
I need to test a bit how the maya color management system handles normal maps, since there is some built-in logic that maya follows.
As for flipping red/green, I don't know if there's such an option, but you can use utility/maths nodes to do that. I think we even had an example shared in another thread, I need to find it.
I'll keep you posted.

[leehenshall]

I'm going to send something across this week. I only have Ivan & Blagos email. Are those the best guys to send the download link to?

I'm noticing that since 2017 and latest nightlies that gamma feels different....for as long as I can remember v-ray for Maya has required gamma correct nodes or an extra attribute to control colours/linear workflow. I discovered yesterday something that puzzled me. When creating a custom image plane as a work around for maya image planes not being supported yet on the GPU. I noticed that when I applied the usual .454 inverse gamma that my backplate texture looked dark. It wasn't until switched the gamma back to 1.0 that it look correct.

This has never been the case in my experience and it got me thinking whether it had anything to do with why my normal maps looked weird. The only explanation that I can think of is that Mayas Color Management that is on by default in Maya is now supported or at least partially supported by V-ray Nightly builds?

[yolov]

You can also write to me at alexander.yolov@chaosgroup.com
And yes, we have been supporting Maya's native color management system for some time now. V-Ray respects 6 of the correction options to the file node: Raw, sRGB and the 4 gamma-type corrections.

[leehenshall]

I must have had it disabled before. Can't believe I missed that!

That's great that it's supported...Thanks for confirming. So that means no more gamma nodes? that's going to really help speed up shader creation.

I'll send you my file when I get a moment this week.

[damaggio]

Yes I just noticed that Chaos fixed or changed the gamma in 2017, there's no need to create Attributes>Input gamma, that's fantastic guys, honestly that was a bit of pain. ..and it respects the Raw for Normal maps.