Black Lines on Edges after Normal Baking in Houdini

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Hello everyone,

I'm trying to baking tangent space normal map for a cube.

The methods I've tried on low poly mesh before baking:

- Labs auto uv SOP, method set to UV Unwrap.
- soften_normals SOP with Harden UV Seams toggle On and off.
- when soften_normals doesn't work, I used facet SOP with post-computed normals and cusp polygons option on and off.
- divide SOP to triangulate the mesh after setting normals.
- tangent SOP(polyframe) after setting normals before divide SOP.

When I exported the mesh into Unreal4.27, I realized that tangents and normals were different from another mesh exported from blender. I used tangent SOP to solve this issue but it didn't work either.

For High poly mesh:

- remesh to grid SOP.
- to try another method, watched high res to low res rebelway video, so I used ray SOP to get UV attr from lp to high poly and used bake texture SOP with Unwrap Method set to UV Match.

and I got nearly correct normal map results with the methods listed above, except for black lines on far sided egdes and dark side from some angles.

As for Baker:

- I've tried Labs Maps Baker SOP as well.

I've got the same results with simple_baker and baketexture so I'm sharing the simple one.
Also followed Procedural Sci-fi Crate tutorial Part 3, and I couldn't get the correct results in Unity either.

So, I would be very grateful if you could help!

Here are the results I got in Houdini and Unreal:



Edited by rnorca - Feb. 20, 2024 06:21:40

Attachments:
Screenshot 2024-02-20 135018.png (72.4 KB)
Screenshot 2024-02-20 135049.png (521.4 KB)
Screenshot 2024-02-20 135143.png (160.9 KB)

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I forgot to include normal maps.
With facet and soften_normals SOPs, respectively:

Attachments:
normal.png (208.3 KB)
normal_1.png (94.1 KB)

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that's pretty much what you expect with a normal map. The geometry is showing parts of the mesh that have normals facing away from camera that would normally be unseen on the high res mesh. There are shading techniques to fix this, such as normal clamping. I would expect an advanced engine such as unreal to have such fixes built into their lighting pipeline.
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jsmack
that's pretty much what you expect with a normal map. The geometry is showing parts of the mesh that have normals facing away from camera that would normally be unseen on the high res mesh. There are shading techniques to fix this, such as normal clamping. I would expect an advanced engine such as unreal to have such fixes built into their lighting pipeline.

Hi, thanks for the response. There is this NormalClamp [www.sidefx.com] VOP node, but it's exclusive to Material Network I believe, so before delve into it, I gotta learn how to use it first.

Also, I found a temporary solution by adding Bevel SOP to low poly geo.

Here's some info that I think might help: https://www.svartberg.com/tutorials/article_normalmaps/normalmaps.html [www.svartberg.com]
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