Normal map shading issue around the seams.

ValkanPavlov

Hey folks, if it is a lame question, please do not judge me too hard, I did try my best to find a solution in Google, but just could not find the same situation.

Let me present you with the case:

I have a model that have the Unwrap seems visible in 3DsMax (I know that the choice of it is not the best, I also know that the issue will disappear when just make seams on other - less visible place. But I had this issue from quite some time, and never been able to solve it in its essence) here is a preview of the Unwrap  UVW seems:

Now  the situation is this: the area of the seems have same smoothing group of 1, it is same object, the vertexes are welded. Shading in Max is correct, but when I apply the normal I get strange result, around the seems.

It looks pretty much OK in Substance Painter:

What I have tried:

- I did make sure that it is all one object, and no unwelded vertexes are present on this area.

- I did try with "Compute Tangent Space per fragment"  in SP

- Manually inverting the green channel.

- The issue is around a loop, but still tried it with triangulation export.

I am kind of dry on ideas, and will appreciate any suggestion. Thank you!

Noors

If it looks fine in substance, it may be a tangent space mismatch between the 2 softwares.
But considering what you've already tried, I feel there's a wrong gamma correction applied to the normal map in max. Albedo maps should be gamma corrected, but not "mathematical maps" like normal/displacement maps, which should stay linear.
https://coronarenderer.freshdesk.com/support/solutions/articles/5000675886-a-normal-map-appears-to-be-using-input-image-with-incorrect-gamma-this-can-cause-shading-artifacts-
In which software would you like to visualize your object in the end ?
Because if it's Unreal or Toolbag, you don't really care about Max rendering it wrong.

ValkanPavlov

Hey Noors, that you very much for the suggestion! My gamma/LUT correction in Max are disabled. The model is for Microsoft Flight Simulator. Unfortunately I do not have it in my PC, but I got feedback from the client, that the issue is there too. However I will try to dig more about that "tangent space", since I do not understand very well what is it.

Noors

The tangent space is just the coordinate system used to calculate/display a normal map (where each pixel is coding for a direction).

But softwares don't always use the same approach to define this coordinate system, hence the classic artefacts when you bake in one software and display in another.
Eventhough they now all tend to use a same standard called "MikkTSpace".

Now maybe you should get in touch with some flightsim modder to know what option to set.

gnoop

if it looks ok in Substance Painter  export triangulated mesh from  Painter and use it

ValkanPavlov

Hey folks, many thank for your help, especially to Noors! It turns out that the normal maps need to be processed with certain software to work properly with their material, also textures needed to be flipped vertically.

Noors

Hey, just noticed this in Max Preference Settings/General !

Sorry I assumed MikkTSpace was the default mode but you have to check it.
Tbh i never display normal maps in max.