UV mapping problem with some Normal maps

[SSmolak]

There is issue with some linearized normal maps while using UV map generated by Automated UV Packing because UV polygons islands are randomly rotated. The problem is only with normal maps that are linearized :

Problem is gone when these maps are converted to sRGB 2.2 gamma.

Unfortunately Octane doesn't support gamma changes for normal maps. The only way is to use OSL script :

So please add support for changing Normal maps gamma or Color Space as it is for regular texture images.

[bepeg4d]

Can you share an example scene with assets that shows the issue?

ciao,
Beppe

[SSmolak]

Here is scene with two materials - UV map Normals BAD and OK

Problem with OSL version is that OSL doesn't have Transform node connection and Power of the texture but it generate correct shading.

[bepeg4d]

Hi,
if you enable the Invert option it sems pretty similar.
On the left Normal texture, on the right OSL version:

ciao,
Beppe

[SSmolak]

Hi,
if you enable the Invert option it sems pretty similar.
On the left Normal texture, on the right OSL version:

C2BEBF17-345F-4FF8-B935-8AB1FCA1D1FE.jpeg

ciao,
Beppe

But after that bump effect is inverted too this can interfere with bump channel texture.

[SSmolak]

Unfortunately shading generated by normal map using standard cubic or box UV looks different even if we use OSL version of image node compared to UV Packed version of model. Please see new scene version - Left model has Automatic UV Packed, right one - box UV. ALso as I said there is no way to increase power of OSL normal map. I tried multiply but it only change shading not strenght.

Inverting generate totally different "heights" on the surface.

[SSmolak]

Problem is serious with normal map color spaces - please see attached videos.

Also I was wrong - problem is with Non-Linearized Normal Maps. Making AutoContrast in Photoshop works the same as changing ColorSpace.

[jobigoud]

Why are these normal maps saved in non-linear sRGB in the first place? This is non-color data, save them linear.

[SSmolak]

Why are these normal maps saved in non-linear sRGB in the first place? This is non-color data, save them linear.

These are orginal from many texture vendors that I have. Some of them are correctly linearealized some are not. Octane should have option to change normal map color space like it is for other texture types. I don't know why this is locked for normal maps.

For example I noticed that CG Axis ones needs to have inverted Normal map Y green channel ( they are directx versions probably ) and Exorbitart needs to have inverted X red channel and some of them are not linearized.

So this is generally texture vendors incompatibility but it would be great to have possibility to repair them directly in Octane.