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Seam Issues

Hey guys, I’m new to Unreal, I’ve been using Unity for years but finally getting tired of Unity currupting my scenes.
So I’m moving my current game to Unreal to see if it works out better.

However I’m having a seam issue that I never had in Unity.
Well I’ve had this issue in Unity when I had overlapping seams, etc.

But this isn’t the case for that, this is a ZBrush Unwrap and it’s always worked beautifully
ever sense I’ve used it.

But in Unreal, I’ll just take a photo and show you.


2420a969bea51f1f9a2866c6ede5981d97600de2.jpeg

Textures are painted in Substance Painter if that means anything as well.
I Included the Main Albedo Unwrap so you can see it as well.

As you can see the dark spots on the top of the head and the middle of the next on the bottom of image.
However if you look - the center of the head has a seam but it’s not getting that darkening shadow effect on it.

I’m notcing that the UV Channel 1 inside Unreal moves over to the right about half an inch, not sure if it’s supposed to do that or not?

EDIT -

Turns out it is my Normal map

Is there something special I need to do with the Normal map?
I mean if I disable it I can see see the seams, but it’s not from darkening, just from a seam in general.

So it has to do with the Normal Maps.
Does Unreal have something special I need to do with the normal maps?
#EndEdit.

#2NdEdit
I got it guys!

But now I’m running accross another issue, when I look at my character model Frame must drop dramatically because game will freeze for like 3 seconds then get really glitchy with model in view.

Has like 33K Polys.

#EndEdit

For normal maps make sure you use normal map compression otherwise they will not render correctly.

Hey thanks bud, I finally figured it out last night before bed.

Well I think I did.
I mean it works,
but I changed it to something like TC_Normal and Somethign WorldNormal. And it works.
But not sure if that’s the right way to do it lol.

Yeah, this is the issue with Tangent Space Normal maps.

Ok, so you know that the renderer is looking to the R, G, and B values to determine the angle of the surface, and shade accordingly. But tangent means that these values are relative to the texture’s X,Y space, and NOT the object’s world space (which creates the problem you saw).

The result is that Tangent space normals can cause issues on seams, because on one side of the boarder, it’s reddish, and the other side of the boarder is greenish, which creates this border of light and shadow when rendered.
If you need to use Tangent space normal maps (which most cases do) then that means you need to re do your UV unwrap of the problem area.

Methods:
Vertically split the UV by laying down a UV seam along the vertical axis in your 3d application, to create a mirror like effect.
Or, instead of trying to create a perfect mirror, try to have the two hemispheres of the model face the same direction in the UV in wrap.

This issue is amended by better seam placement, and arranging the UV’s differently.

Btw, this is an issue that plagues professional games all the time, look at the characters fingers in any random AAA game, look at the inner sides (in-between the fingers) that most people lay seams down, and you’ll see dividing lines of light and shadow EVERY time.