How to make selected faces flat

Hi There,
I have an object and I would like to make the selected faces flat.

here my object:

here the selection:

here a detail of the irregularity of the selected faces: (that I would like to set flat!)

I tried to do that with the command S+Z+0 but when I apply it the selected faces disappear.

Any suggestion?

Thanks in advance,

you can do that with S (scale) , Z and then 0, keep in mind that Blender will then use the Z axis to make the polygons flat, if you don’t want it completly flat just drag the mouse pointer towards the plane instead of 0

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Hi @GFXManx, thanks for your answer. Actually I already tried it, but when I apply the Scale the selection just disappear.

I share the project here. If you just switch in Edit Mode the faces that I would like to will be flat are already selected!

Enable loup tools addon and in edit mode select your polys , press w then loop tools then flaten.
And voila

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Hi @skuax,
thanks for your contribution!

I already tried to do what did you say, but when I apply the ‘Flatten tool’ all the selection disappear…

If you want to try I attached my Project in the previous comment!


There’s something very wrong with that mesh. When you go to edit mode, the median Z value of the selection is NaN. That’s why scaling doesn’t work. (Median being NaN suggests there’s at least one vertex with coordinate(s) that somehow fell out of range of values that can be represented, it’s “not a number - NaN”). If you select all faces, the median will be NaN for all three axes. Something somewhere went wrong with coordinates. There are also zero-area faces, loose vertices, etc…

There is a way to “fix” it: go to object mode, open the Python Console in one of the editors, type this:

and press Enter. It should print “True”. Now when you go to edit mode, there will be 2530 vertices at the origin with lots of edges stemming out to the model. I think you can just delete those vertices. Whether this ruins some other part of the mesh, I can’t tell. But at least it lets the tools work again.

How did you get this mesh into Blender? Some sort of importer?


Hi, @Stan_Pancakes and many thanks for spend time to answer my question.
Yes, the problem was about the coordinates, with your method I fix the problem!!

The mash is a bit strange because I’m experimenting how to represent a real terrain with the BelnderGIS Addon.

Thank’s a lot,

You’re welcome :slight_smile: Just keep in mind that that is a “nuclear” solution, not something that should be done on a regular basis. Probably best to try and figure out what caused the problem in the first place and fix that issue.

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makeflat.blend (2.7 MB)

I would use a shrinkwrap modifier, set it to project and use another surface to flatten it, this will preserve your mesh and it is useful for those occasions when you need to change the mesh with a non destructive workflow. If you need to, you can also use some weight painting and vertex groups to help with both the shrinkwrap modifier and a smooth modifier to clean up any quirks.

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Okay! But I just checked and the problems for the coordinate Z start when I just imported the file.

Hi @joseph_raccoon,
thank’s for share with me this other solution!! It’s really helpfull!

You are welcome. you can do some animation tricks with this if you need to animate the shift of a river over time.

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