Cycles bake - high-> lowpoly bake triangle orientation is mixed for texture coords in shader normals. #45463

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Vilem Duha · 2015-07-16T23:06:02+02:00

Vilem Duha commented

2015-07-16 23:06:02 +02:00

System Information
win 8.1 32gb
nvidia 880m 8gb

Blender Version
Broken: 2b5e150
Worked: probably never

Short description of error
generated noise texture is wrongly mapped in other direction, when baking selection to active in the provided file. The artifacts are quite gentle, and only happen to normals of the shader(not baked normals). Also, if the texture is mapped to color of shader, the color is ok.
the bug doesn't happen when triangulate modifier is added to the target object.
This happens for me on many objects, this is just one example.

Exact steps for others to reproduce the error
open the file, hit bake.
add triangulate to the "test" object, voila, problem gone.

bakebug_triangulate1.blend

**System Information** win 8.1 32gb nvidia 880m 8gb **Blender Version** Broken: 2b5e150 Worked: probably never **Short description of error** generated noise texture is wrongly mapped in other direction, when baking selection to active in the provided file. The artifacts are quite gentle, and only happen to normals of the shader(not baked normals). Also, if the texture is mapped to color of shader, the color is ok. the bug doesn't happen when triangulate modifier is added to the target object. This happens for me on many objects, this is just one example. **Exact steps for others to reproduce the error** open the file, hit bake. add triangulate to the "test" object, voila, problem gone. [bakebug_triangulate1.blend](https://archive.blender.org/developer/F207510/bakebug_triangulate1.blend) ![pasted_file](https://archive.blender.org/developer/F207497/pasted_file)

Vilem Duha commented

2015-07-16 23:06:02 +02:00

Changed status to: 'Open'

Vilem Duha commented

2015-07-16 23:06:02 +02:00

Added subscriber: @VilemDuha

Bastien Montagne commented

2015-07-17 19:34:53 +02:00

Added subscriber: @mont29

Dalai Felinto was assigned by Bastien Montagne

2015-07-17 19:34:53 +02:00

Bastien Montagne commented

2015-07-17 19:34:53 +02:00

Dalai, maybe you can check this one? Thanks.

Vilem Duha commented

2015-07-17 20:56:57 +02:00

Just a comment - it looks very similar to other artifacts you can get in other bugs, but it's not a duplicate. All somehow manage to mix something up, but they are all different by the specific conditions in which they happen.

Vilem Duha commented

2015-07-21 16:44:07 +02:00

Upadte - this also happens with highpoly objects, so even if the lowpoly object has triangulate, it can still happen.
When both objects have triangulate, then it's ok.

Upadte - this also happens with highpoly objects, so even if the lowpoly object has triangulate, it can still happen. When both objects have triangulate, then it's ok.

Vilem Duha commented

2015-07-21 16:54:06 +02:00

just uploaded a file for the above comment - you can see half a triangle has an artifact, it's probably because of the triangulation of both objects acting over each other. Here the artifact is again quite subtle, but I guess it's visible how the coords are rotated. again, add triangulate to the object which gets baked from to fix the artifact and see the difference
artifact_highpoly.blend

just uploaded a file for the above comment - you can see half a triangle has an artifact, it's probably because of the triangulation of both objects acting over each other. Here the artifact is again quite subtle, but I guess it's visible how the coords are rotated. again, add triangulate to the object which gets baked from to fix the artifact and see the difference [artifact_highpoly.blend](https://archive.blender.org/developer/F211352/artifact_highpoly.blend) ![pasted_file](https://archive.blender.org/developer/F211349/pasted_file)

Bartosz Moniewski commented

2015-07-22 15:42:06 +02:00

Added subscriber: @BartekMoniewski

Dalai Felinto commented

2015-08-10 22:25:01 +02:00

I'm not sure I can see the artifact here. Also it's a strange report because 'internally' we add a triangulate modifier to the highpoly object, exactly to prevent triangulation issues.

Dalai Felinto commented

2015-08-11 16:52:20 +02:00

I simplified the file a bit, and I can confirm that there is some difference when triangulating (or not) the low poly object. File: bakebug_triangulate2.blend

Original:
Triangulated:

I simplified the file a bit, and I can confirm that there is some difference when triangulating (or not) the low poly object. File: [bakebug_triangulate2.blend](https://archive.blender.org/developer/F223458/bakebug_triangulate2.blend) * Original: ![bake-original.jpg](https://archive.blender.org/developer/F223459/bake-original.jpg) * Triangulated: ![bake-triangulate.jpg](https://archive.blender.org/developer/F223460/bake-triangulate.jpg)

Dalai Felinto commented

2015-08-11 18:37:03 +02:00

Added subscriber: @brecht

Dalai Felinto commented

2015-08-11 18:37:03 +02:00

@brecht do you think this can be caused by the differentials calculation?
The differential calculation that we do is based on the image space and the low poly object uv.

The differentials are relative to the UV/image space, so the highpoly differentials
are the same as the low poly differentials

Since the issue shows up when using bump map, and is sensitive to the low poly object geometry, I believe it's related to the differentials.

@brecht do you think this can be caused by the differentials calculation? The differential calculation that we do is based on the image space and the low poly object uv. ``` The differentials are relative to the UV/image space, so the highpoly differentials are the same as the low poly differentials ``` Since the issue shows up when using bump map, and is sensitive to the low poly object geometry, I believe it's related to the differentials.

Brecht Van Lommel commented

2016-02-14 12:31:01 +01:00

Changed status from 'Open' to: 'Resolved'

Brecht Van Lommel closed this issue

2016-02-14 12:31:01 +01:00

Brecht Van Lommel commented

2016-02-14 12:31:01 +01:00

I can confirm this bug in 2.75 and 2.76, but in latest master this seems to be all fine. There were various fixes regarding triangulation consistency, which I suspect fixed this, but did not try to find the specific commit that did it.

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Cycles bake - high-> lowpoly bake triangle orientation is mixed for texture coords in shader normals. #45463