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enter image description here

Is the smoothing option meaningless since the displacement map is meant to be extracted from high polygons?

So what is the correct way to create a greyscale bump map?

And here is my blend file

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  • $\begingroup$ can you detail how exactly are you baking from 1 to 2? $\endgroup$ – m.ardito Nov 16 '17 at 13:24
  • $\begingroup$ Well ... I baked the sphere to the plane to get a dome-shaped bump map. So I do not have to overlap two spheres. The reason for capturing the two spheres is to show you that the blender ignores the shade smooth option when baking works. I modified the attached image to help you understand. $\endgroup$ – J. SungHoon Nov 16 '17 at 13:26
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    $\begingroup$ I mean, which render engine? which kind of bake, how can I reproduce exactly? can you share the file (use blend-exchange.giantcowfilms.com then paste the provided link text iediting your question)? Anyway I guess yuor bake reflects object geometry, and shading doesn't alter that. $\endgroup$ – m.ardito Nov 17 '17 at 9:15
  • $\begingroup$ I apologize for posting duplicate questions. I made my question more clear. And I attached the blend file according to your advice. I baked it in BI and then rendered it in Cycles. Could you check my file? $\endgroup$ – J. SungHoon Nov 17 '17 at 9:54
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Now it's much more clear and you put your "real" question.

It seems you wish to bake displacement (ie: geometry) from shading (ie lighting): it will never work imho.

Use a real "smoothing" option, like more subsurf

enter image description here

so, why "Shade Smooth" doesn't work when baking a displacement map, unlike the "normal map" (that works)?

because "smooth shading" is, in fact, just a shading trick: it alters the normals, to let the object appear smooth (as if it had more geometry, which it has not), so the normal baking takes it into account.

the "displacement baking" instead needs to bake the geometry "height levels" into color levels (the baked image), but since "smooth shading" leaves the geometry untouched, you get the same identical result as without the smooth shading...

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  • $\begingroup$ Thank you. This is a nice solution. But I'm studying the theory now, so I wonder why Shade Smooth doesn't work when baking a displacement map, unlike the normal map. My guess is that shade smoothing is meaningless because a single polygon has a size of less than 1 pixel on the image to be baked, because the original displacement map baking feature was intended to be extracted from the high polygon model. Am I making the right guess? $\endgroup$ – J. SungHoon Nov 17 '17 at 10:29
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    $\begingroup$ I edited the answer to explain why (imho)... $\endgroup$ – m.ardito Nov 17 '17 at 11:04

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