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normal map artifacts
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System Information
OS: Windows 7 64bit
GPU: NVIDIA Quadro K4000 (driver: 331.82)

Blender Version
Broken: Blender 2.69 r61235
Worked: dont know

Short description of error
there are 2 things

  1. is the bleeding of normal maps supposed to have these very strong variations of color? i would expect them to flow with the same color and not abruptly change but that might be because i dont understand the maths behind that.

  1. when baking on a low resolution texture every edge gets visible in the normal map and the faces look like they are inset. and when having a reflection map on the object the reflection does not go in the same direction over the object but switches direction over each face when rotation the object. which leads me to believe that there might something wrong here but then again i dont know the math so...

Exact steps for others to reproduce the error

  1. issue:
    • bake a normal map from a highres to a low res object and make sure to have some uv islands that are diagonal

  1. issue:

  • bake a normal map from a high res mesh to a low res mesh
  • if you dont see the artifacts with the normal map enabled continue
  • decrease the texture size and bake again
  • at some resolution the artefacts should become visible all over the mesh



Event Timeline

dan grauer (kromar) set Type to Bug.
dan grauer (kromar) created this task.
dan grauer (kromar) raised the priority of this task from to Needs Triage by Developer.
Brecht Van Lommel (brecht) triaged this task as Needs Information from User priority.

For 1), please attach a .blend file for this issue so we can reproduce it. It looks wrong but I can't tell from the screenshots where these color variations might come from.

For 2), this is a known issue basically, this should be solved by adding antialiasing / extra samples for baking, it does 1 sample per pixel now, but with a small texture map this will miss geometry detail. This is planned to be added as part of the game development project, the workaround is to bake a bigger image and scale it down.

for 1) here is a blend file for the first problem, just bake from highres to lowres with uv - islands that are diagonal in the uv space.

for 2) are there any details to this "the game development project"?

Brecht Van Lommel (brecht) claimed this task.

Looked into the diagonal issue, it has the same cause as the other, lack of antialiasing gives uneven colors on the borders, which then get extrapolated giving these lines.