Normal map seams on UV seams

thedigitalguerrilla

Hello,
I have this problem with models where the highlights break where the UV layout has a seam. Please have a look at the full resolution image. No matter what I do I keep getting this issue.
I've tried to:

• making the low-poly (LP) matching the high-poly (HP) or making it smaller so just the edges touch the HP;
• different amount of dilation, resolution, frontal and rear distance;
• single smoothing group (SG), 1 SG per UV shell;
• exporting the fbx with/without the SG;
• exporting the fbx with/without the tangents;
• Baking in MAX, XNormal and mostly in Substance Painter

At this point I'm really stuck, seems to me that I've tried every trick in the book and that the problem is not in the map itself cause it is resolution-independent but more in the combination map+mesh.
Here are the meshes http://bit.ly/1T1uMGt
Any help will be greatly appreciated!

peanut™

First thing i see is that the Lowpoly has 2 UV maps. The placement of those UVs aren't really good either. A good place to start is to delete one of the maps you have. Im not too sure about 3dsmax but your modeling program may not like 2 maps for one single object (i know Modo will not like it).

thedigitalguerrilla

Thank you, but the second channel is disregarded by substance painter and the UV are automatic, just to have something. Even getting them more packed wouldn't change much I guess, I've tried with different resolutions. 

Son Kim

thedigitalguerrilla said:

Thank you, but the second channel is disregarded by substance painter and the UV are automatic, just to have something. Even getting them more packed wouldn't change much I guess, I've tried with different resolutions. 

Are you targeting UE4? If so try turning on Use "Full Precision UV" by double clicking on your mesh in the content browser. Sometimes I see seams in SP/Toolbag but they show up in UE4, even though both are sync to MikkT. So it's always a good idea to check in your target engine.

Your Mesh in UE4(don't notice any seams,2K normal map):





I create hard edges base on UV island boundary edges, in Modo, baked in Modo targeted for UE4. You can reduce any seam by baking at a higher resolution(i.e. 4K) then reduce it to target res(i.e. 2K) in Photoshop. When I brought the same mesh and normalmap into Toolbag2 I noticed the seams.

thedigitalguerrilla

Yes, I should have said it before, the pipeline I'm studying is MAX>Substanca Painter>UE4. This is the forum page where I'm reporting this. After trying what you kindly suggested I noticed a small improvement, but still the issue is there and I'm using a 4K map with full precision UV. (Maybe is not clear after the compression but the line is there and breaks the highlights and the reflections)
Going back to a simple mesh I noticed that the problem is gone (both with single SG and 1 SG per UV island). I don't understand why and I start wondering if this is just how it should be and I'm just too picky...

Here I don't have that nasty issue even up-close but the normal map gradient is kind odd: it gets darker before reaching the flat parts...
Anyway thank you again for taking the time to check it!

Son Kim

The seams in your UE4 screenshot is barely noticeable. You are correct, once you apply a diffuse map , you won't even notice the seam..so I won't stress out too much about the seam "issue".  In short you are indeed being too picky  

Other things you can try, bake to 16-bit image file.  Take that into photoshop and changing it to 8-bit, Photoshop will add some dithering which might help or not(been awhile seen I done this) with this issue.

I always noticed extra seams in Substance Painter but they never show up in UE4. Might be  a precision issue with SP.


edit: you probably know this already but make sure "Compute Tangent Space per fragment" is ON, in SP when you bring in your mesh.

ryanonline

Did you solve this as I am "too picky" and really hate seeing my uv's!