I have tried recomputing normals and tangents, importing the ones from blender, using the Normal and Tangets tools of Modeling mode, but nothing works. I always have artifacts. Why?
Also the normals are facing the right direction. I have a similar square tower but it doesnt show artifacts, only happens with this round one.
Are there any breaks in the vertices where the artifacts occur?
It’s a modular model. The level where the door is is a module in itself and it’s empty from inside, top and bottom. Or in other words, there internal faces (the ones hidden) of the model are empty. In theory all the vertices of the level are connected. But the level is disconnected from the two stripes that surround it from top and bottom. I have a square tower that follows an even more modular design and there are no problems with the light. Maybe it’s because this one is round?
As for the texture that’s giving the bad artifacts is a triplanar projection, not UVs
From the other side it doesn’t look good neither:
The model in blender:
Check if the normal direction are uniform on the mesh (pointing in the same direction, probably out).
If you have a mix of blue and red then do into edit mode and press
CTRL + SHIFT + N to unify the direction (inside or outside) via “Recalculate Normals”
You can pick the direction at the bottom left with the checkbox “inside”.
Yes I know. But all the faces are pointing outwards. It must be something else. Render mode in blender does not show artifacts. It’s in UE only.
Could it be a case of shifted UV maps?
The UVs for the faces of this material are all broken. But they are supposed to be, since I’m using a triplanar projection that creates it’s own UVs procedurally. I attached the screenshot of the material before.In the square tower it works fine, but in this circular one it doesn’t. Could it be something about tangents? I’m not familiar with those.
Could vertex color data have any influence on the shading?
As far as I’m aware I have not used vertex colors.
In blender, in the vertex tab I don’t have anything on color attributes:
I do have custom split normals tho, I’ll check if deleting that works…
edit: ok it hasn’t done anything. I still have artifacts. Check this in the static mesh editor:
It’s like there are two colors, one more yellow and one grey. But it’s the same material.
Not sure how large of an impact this has on the final nodes (haven’t setup an example yet) but in this tutorial the multiply right before the split into texture samples has 0.01 as it’s driving value.
You have 0.005
And do you have smooth shade with and angle set to around 45 for the models shading? Perhaps it’s flat shaded for those faces?
Yes i followed that, but I think that mulitply node is just a scalar for the procedural UVs.
Without auto smooth:
With auto smooth 45:
With auto smooth 90 and above:
45 does look better, but still you can see the division between faces. I’ll try importing it tho. See what happens…
You can clearly see shading artifacts in the viewport of blender (especially on pic 2). See if you don’t have double / duplicated faces.
This is a blender problem not an unreal one 
In edit mode:
In object mode:
Material preview:
In object mode as you say the shading problem is clear, but I do not see exactly what could it be. It’s not duplicated faces, that’s for sure.
One thing I see, the top normals get smoothened, but not the bottom ones:
edit:
shade flat does fix it, but I cannot have such a flat ROUND tower:
Have you considered running merge by distance to check if you have double verts?
I don’t have any. Maybe it’s the way the windows are modelled? I don’t know really.
Could you upload the segment that is wrong? I could analyze it in maya for errors if you want (there are build in tools to detect non-manifold geo and other problems).
Fbx file:
https://file.io/2IJdWwSAMDOX
I have modified the geometry a little and now I have a slightly different result in shading (even though it still looks bad). But it gives away that it is indeed a problem with the model itself.
Ran some fix up functions on it and enforced a shading of 45 deg. Not seeing any artifacts.
tower.fbx (206.1 KB)
You’re uv’s aren’t really well though out though for modular parts. You are spanning well past the bounds of 0,1 uv space per part (they should have self contained uv’s) or keep within their segment of the uv space.
The window area is especially weird as you are in some parts setting the map from vertical to horizontal orientation. Unless you have very specific baked segments in the uv map it wil become messy really fast.
If you are not planning on using the uv map then just strip it from the model.
Here is a version with the triplanar material projection applied
Might take a moment to encode in HD
I know that for a modular design each module should have self contained UVs but it’s very hard to do and preserve the tiling capacity since every module should be a perfect square of the same size or when placing one next to the other the textures of both will not connect well (like a brick wall).
I don’t know if I should just forget about doing things modular and just model every mesh individually.
Well, thanks a lot for your help!
Triplanar can get expensive with a lot of materials. A proper uv unwrap in the 0,1 space should do.
