Normal artifact on flat surface from Substance normal map.

MechWarrior99

I am getting a strange artifact on the surface on the top of a simple table model I did.


It is a bit hard to see on it's own, but shows up easily when tiled. It is the light spot in the middle to be clear.


And this is what it looks like in Substance Painter for reference.


Regarding the model. I used blender to make it. I turned on the "Shade Smooth" object option, and that is it as far as normal editing goes. The highpoly is the same model, but all the edges are beveled.

If any more info would help, please let me know. If anyone has any ideas, they would be greatly appreciated.

Eric Chadwick

Is the lowpoly table top a simple box with no bevels? What does it shade like with no textures (just a gray material)?

MechWarrior99

Eric Chadwick said:

Is the lowpoly table top a simple box with no bevels? What does it shade like with no textures (just a gray material)?

Yes, the lowpoly is just simple boxes. None of the individual box vertices are connected either.

Here it is in blender.


And here it is in unity with just a plain material, no texture, normal map, or smoothness.

Eric Chadwick

You're not using a synched workflow, and your vertex normals are bent too far, so your normal map can't fix the shading.

This sticky topic in Technical Talk is worth your time:
https://polycount.com/discussion/107196/youre-making-me-hard-making-sense-of-hard-edges-uvs-normal-maps-and-vertex-counts/p1

MechWarrior99

Eric Chadwick said:

You're not using a synched workflow, and your vertex normals are bent too far, so your normal map can't fix the shading.

This sticky topic in Technical Talk is worth your time:
https://polycount.com/discussion/107196/youre-making-me-hard-making-sense-of-hard-edges-uvs-normal-maps-and-vertex-counts

Thanks for the link! Sorry that I didn't think to look at the stickies first, before posting.

I had to read through it and watch the video a couple of times, but I think I understood it after some trial and error.
So I separated out each face in to it's own uv island. And that seems to give pretty good results. Though of course, a lot more vertices (from 106, to 168).


Looks a bit odd on the corners, but I suppose that is to be expected. There is only so much a normal map can do.


I have two questions now if that is okay.
1. Is this the proper way to do it? Is there a more efficient way?
2. Kind of a broad question. But is there an recommendations you have of things to do/try, or any videos/posts to watch regarding normal maps, and setting models up? 

Eric Chadwick

Try to figure out what tangent basis your renderer (Unity) uses, then get your baking tool (Substance Painter) to sync it.

If you can't get a sync, then you'll always see some errors. But you can reduce them by splitting UVs wherever you have vertex normal  splits (see sticky linked).

For the second question, see the other stickies in Technical Talk. A gold mine of normal mapping info!

jRocket

https://medium.com/@bgolus/generating-perfect-normal-maps-for-unity-f929e673fc57