Visible Seams on 3D Scan
We would like to use Shadermap to generate a normal map for scanned products. A fine normal map gives the model detail and the model looks much better. The normal map from the High poly model does not contain such details. The problem that we have in many cases are visible seams after applying a normal map to a model generated from Shadermap.
I chose a jacket model as an example
Model without normal map
Model with normal map from Shadermap
Visible seams
What causes these seams?
Is it possible to adjust the Shadermap so that the seams are not visible?
Could you advise how to proceed so that the seams are not visible on the model?
Data with the model, Albedo and Shadermap project are available here:
example.zip
Comments
If I had to guess, this is caused by the differing orientation of texture islands that share a seam. See the image below. The islands that share the UV seam are rotated to different angles. The Normal from Displacement map uses height gradients to generate normals. It could be that the orientation shift from one island to another is enough to cause the filter to generate slightly different normal angles.
Generating normals from a high polygon model has the advantage because it casts rays at a uniform surface even though the output normals may be placed in different locations on the final map. When generating normals from 2d maps, it's best to use fewer islands that represent larger areas of the surface uniformly.
There may be a way to overcome this problem by creating a new Normal Map type that takes both displacement and 3d model as sources. This would give the map access to UV data which it could then use to sample the displacement map. Would you mind if I keep your example files to test with future maps?
Thank you for answer.
I also thought that the problem must be in the orientation of the islands.
Here is a model that has preserved the vertical orientation of the islands in UV and 3D.
Verticaly aligned UV
But what is interesting is that the left and right side of the chest are very different.
Have you ensured that islands are not flipped horizontally? That might also cause variation of normals where islands share edges.
They are not flipped
But as you can see, the problem is not just the seam itself, but the area to the left of the seam. Its like the seam in the left island lay lower. But there is no problem with the seam between the islands to the right of the zipper.
Sure
Verticaly aligned UV
I found the offending property.
The Auto Edge parameter in the Displacement Map is causing the problems. Auto Edge uses a series of accumulative blurs which are done in Image Space and not aware of UV edges. Setting Auto Edge to 0 (Zero) removed the artifacts from the output Normal Map.
Thanks for the help.
It's a pleasure to use your software.