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660811 No.660811 [Reply] [Original]

Is it possible to reverse bake? Specifically in Blender.

I have a generated normal map that I would like to apply to geometry for the purpose of 3D printing.

What is the easiest way to go about this? I figure the easiest way would be to subdivide my model enough to get the normal details to appear from a displacement modifier and apply that, but that would create an insane level of geometry if I am not mistaken.

Pic related, but not the normal map I am dealing with.

>> No.660828

>>660811
There is no depth information at all present in a normal map so it's not possible.

One could write an algorithm to extract depth from a normal map but you would have to deal with a lot of ambigous difficult to define cases to make it work.
All the information in a map like that is about what angle the surface has locally, there is no way to tell if that blue pixel ontop of one of them bumps is elevated or not.
you would need to calculate the slope rise of surrounding pixels, in maps with different geometry that would lead to inconsistencies making the same pixel be on different elevation
depending on where it was approached from.

What you need is a traditional bump map that is a black and white texture where black means low and white means high. They're know by several names depending on their intended use,
displacement map, height map, z-Depth map or bump map (tho that one is often used for normals these days by confused devs).


TL:DR - Normal maps are for pixel shaders to fake surface geometry on a flat surface, not to be used for any actual geometry displacement.

>> No.660830

>>660828
Ah ok, I made the normal in substance, so making it output as a bump map instead of a normal shouldn't be too difficult.

>> No.660850
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660850

>>660811
You can convert a normal map into a displacement map with Knald or Crazybump. then you can apply it onto a mesh.

Here's a couple meshes I made from normal maps.

>> No.660879

>>660828
Nah. You're right It's not possible to do it exactly but you can definitely get an approximation.

>>660850
Substance Designer can do it too with a Normal to Height node.

>> No.660922

>>660811
download zbrush and apply it as a noise layer there

>> No.660923

>>660811
Convert normal to bump (or re-bake as bump) use bump for displacement, and that's it.

Yes the mesh will be extremely dense but at that point you can just decimate it before printing

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