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Problem baking normal map with hard edges


I'm a beginner, and I have made a wheel in blender, that I would like now to texture in substance painter.
This is my low poly, it is about 5k tris. 

The back of the wheel in wireframe

The bottom, where I  placed my seams for the cylinder like shapes

The front, every hard edge (marked sharp) is also a seam.

Everything is turned smooth, with Auto-Smooth activated, and a weighted normal with keep sharp edge has being applied.

For the High poly, it is the same mesh, with only quads, supporting loops on the hard edges and a subdivision surface modifier (set on 2 subdivisions and Catmull Mark).

The unwrap look like this, it is far from being perfect, but it should work, I think.

In substance painter, I'm baking a 2k textures, And I get this

The problem being on the crevasses of the wheel, where I get strange result.

I get all these weird reflections on the hard edges. 
It can be seen from far enough for me to think there is a problem , although it might be just me.

I did triangulate both of my meshes before exporting. I've tried reducing the front and back max distance in baking options of SP, it gets a bit better, but still there, visible. Likewise, I have put antialiasing on 8x8, and even put the texture in 4k for testing, and it always appears enough to annoy me.
I've also tried not using seams and hard edges, but just split hard edges manually, and I get the same result.

My though were that the rays coming from the faces facing each other in the crevasses was intersecting the other face across the crevasse, as they are pretty close, but this should be fixed with reducing the max front and back distance, and it is not working.

So, is it me trying to get a perfect result where it is not needed, or is there a mistake in the way I make things work?


  • gnoop
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    gnoop polycounter
    For such a low res model with so many hard edge splits  you don't need hi res model at all .   All the normal map could be baked on low res itself using  bevel shader in Blender to round hard edges.

  • AlexandreT
    Okay, no need for high poly then, and so when do I need a high poly in this type of modelling? Can I just use the low poly for all of my mesh, or there are part that needs, in function of his topology, high poly in order to bake well?
    Thanks a lot for the help!
  • AlexandreT
    I have just realized that I needed the high poly for the other maps, so I do need the high poly, but not to make the normal, which could be made with bevel shader in blender. I guess baking a normal map with high poly is for higher resolution mesh, with the high poly mesh having sculpted detail on it.
    Anyway, thanks for the help, problem solved!
  • poopipe
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    poopipe godlike master sticky

    baking a cylinder is a crap idea as a rule , ther'es basically no situation where you don't get some sort of shitty artefact.

    Bake the cylindrical part flat and your mesh normals will take care of the rest 

    also tidy up the UVs - it's worth the extra 20  minutes to straighten everything up
  • CloudChiller
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    CloudChiller polycounter lvl 8
    Baking with hard edges are always a crapshoot, in my experience. Soft edges and bevels, if the poly count allows it.
  • Mink
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    Mink polycounter lvl 4
    Baking a cylinder can and has worked before, but not with subsurf. The reasons for this are documented so many times here that I'm not going to explain it again. You can still use bevels for a high poly though, I recommend you give your UV Islands some space, and actually try smoothing your hard edges in the lowpoly.. It's just gonna be impossible to do a high=>low poly cylandir with that adds segments around the circumference of the cylinder. Will never work.
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