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When a mesh is smoothed, every selected vertex is moved towards the average position of its neighbors. Is there a way to do the opposite, given a mesh with bumps, curves and corners, to move selected vertices by small amounts opposite of what mesh smoothing would do?

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  • $\begingroup$ related: if you receive a blender model which has smooth shade enabled, how can you undo this? $\endgroup$ – juFo Sep 24 '14 at 6:57
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Yes. Use the smooth modifier with a negative factor.

Smooth modifier

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  • $\begingroup$ Is the smoothing process perfectly reversible(not considering floating-point error), or will unsmoothing a mesh by the same factor as it was smoothed produce a different mesh? $\endgroup$ – ζ-- May 23 '13 at 1:41
  • $\begingroup$ It appears like it is. I'm not sure, but I tested it with Suzanne, and it appeared to get back to its original geometry. $\endgroup$ – Daniel Pendergast May 23 '13 at 1:44
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    $\begingroup$ This is not the case. Compare before and after. Opening them in different browser tabs and switching quickly shows the effect. $\endgroup$ – ζ-- May 23 '13 at 1:48
  • $\begingroup$ Nice find. Good to know. $\endgroup$ – Daniel Pendergast May 23 '13 at 1:48
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An alternative method to reverse an operation is to add 2 shape keys, enter editmode with with a non-basis shape, edit the mesh (smooth it for example), exit editmode, then slide the shape key to a negative value you can then optionally apply it to the base mesh.

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Unsmoothing with a negative modifier is sufficient for a roughening effect, but not to fully undo a smoothing operation. To test this, I rendered Suzanne and smoothed the mesh(factor 1.0), applied the modifier, and then unsmoothed with factor -1.0.

animated gif

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    $\begingroup$ come on! rerender this with suzanne fitting the window and lit up with more ambient lighting, so much grey..so little suzanne.. $\endgroup$ – zeffii May 24 '13 at 8:13
  • $\begingroup$ @zeffii I was short on time so I basically threw this in a scene with the defaults. When I have some time tomorrow I'll make a better image(animated as a GIF) that shows this. $\endgroup$ – ζ-- May 24 '13 at 10:29
  • $\begingroup$ Would be great if you could find the time, @ ping me in case. I'd like to upvote. $\endgroup$ – Leander May 14 at 12:05
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    $\begingroup$ @Leander added to todo list; hopefully will have time this week at some point. $\endgroup$ – ζ-- May 14 at 12:26
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Another thing to try is the Laplacian Smooth modifier with a negative factor.

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If you're looking to make a model more low-poly, then try using the Decimate modifier.

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  • $\begingroup$ Or maybe the remesh. $\endgroup$ – Róbert László Páli Jun 18 '13 at 9:03
  • $\begingroup$ Please try to answer the question asked. Your answering how to un-subsurf a mesh. The question is asking how to use the smooth tool in reverse. $\endgroup$ – CharlesL Jun 23 '13 at 23:50
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If you're looking to reverse the Subdivision Surface modifier, try the Decimate Modifier on Un-Subdivide mode. I find that you should usually double the subsurf level in the decimate modifier.

One of these Suzannes has been subdivided twice and then un-subdivided four times with the Decimate modifier. How well do you know your Suzannes? Which is which?

Two Suzanne meshes – which is the original?

Also take a look at a smooth-shaded version:

Smooth version of above image

Original face count: 500; processed face count: 699.

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    $\begingroup$ Left is the original, is it not? $\endgroup$ – ζ-- Jun 15 '13 at 23:09
  • $\begingroup$ Yeah, the top of the nose and the top of the mouth are the only real giveaways i see. $\endgroup$ – StarWeaver Nov 27 '14 at 22:08

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