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I am wondering if there is a modifier or tool that will essentially undo a subsurf or subdivide command.

PGmath
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TheCycleOfBlend
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4 Answers4

38

You can use the 'Decimate' modifier set to 'Un-Subdivide' mode:

enter image description here

Increasing the number of 'Iterations' will increase the number of times the modifier un-subdivides the object.

This works particularly well with quad based geometry. Below, the monkey on the left (that had a Subsurf modifier applied) has 8,000 vertices, while the un-subdivided monkey on the right (with 2 iterations) has 2000 vertices, with all details preserved well.

enter image description here

Ray Mairlot
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    Lets add a note that unsubdivide is a destructive operation that usually destroys UV maps to unusable state. – beiller Dec 18 '14 at 19:13
18

The Cleanup Menu has an option called ' Limited Dissolve '.

enter image description here

This turns the mesh on the left side into the mesh on the right:

enter image description here

As you see, it treats all surfaces that are adjacent and have a consistent 'normal' direction as one surface and joins them .

zeffii
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13

What I found today is that you can also use Ctrl+E and there's an 'Un-Subdivide' option but I don't know if that's the same as the modifier.

Ray Mairlot
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TheCycleOfBlend
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    http://sv.tinypic.com/r/2vta8gz/8 The left one was un-subdivided in Edit mode with Ctrl+E > U and the right one was un-subdivided by the Decimate modifier. They look identical to me, and they do have the same number of vertices and faces. The advantage of doing it in Edit mode, is that you can un-subdivide only the faces you want, and the advantage of the modifier is that you can undo it more easily if you do not apply it. –  Dec 18 '14 at 22:06
  • Worth mentioning that also the UVs get messed up the same way than with Decimate: http://bit.ly/unsubdivide – Manu Järvinen Dec 19 '14 at 09:18
  • While this is destructive and the decimate modifier is not, this was perfect for my use case. (Too many subdivisions and unable to undo -- it can happen!) – itmuckel Apr 24 '19 at 18:46
1

There's also the option of using Decimate and then the Remesh Modifier. They are both under the Generate section of the Add Modifier drop down.

Duarte Farrajota Ramos
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Rahgnoruk
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