I have a very detailed mesh (terrain surface), looking like this:

enter image description here

enter image description here

That I would like to give some volume to. A little bit like this:

enter image description here

However, I'm super new to Blender (especially in the modeling department), and I'm wondering if there a any modifier that would take care of this. Once again, the mesh is very detailed, so I would like to use a solution that would use few vertices, hopefully.

If no modifier exists for this kind of operation, how would one model this surface into a volume?


  • $\begingroup$ Simple way with modifier is Solidify. Note that if mesh itself is highpoly adding thickness to it will mean even more polygons. $\endgroup$
    – Mr Zak
    Feb 27 '18 at 15:41

It's actually possible with just 4 verts. Select the corner verts.

selected corners

Extrude them down with EZ.

Scale them to the same height if needed using SZ0RETURN

extrude down

Turn them into a face using F.

face it

Select everything with AA and hit F again.

face it again

The fill tool is smart enough to fill the holes separately and only generates 4 more ngons.

While my mesh was fine, you can play it safe and hit CTRLN to recalculate the normals. Make sure to give kheetor's comment an upvote.

  • 1
    $\begingroup$ Remember CTRL-N to ensure proper normal alignment. $\endgroup$
    – kheetor
    Feb 27 '18 at 15:48
  • $\begingroup$ At least in my mesh, the normals were all fine without recalculating them. But yeah, it's safer. $\endgroup$ Feb 27 '18 at 15:54
  • $\begingroup$ This is absolutely perfect and idiot-proof, that you so much @Haunt_House!!! $\endgroup$
    – Lucien S.
    Feb 27 '18 at 15:56
  • 1
    $\begingroup$ @Rodolphe Blender surely has its moments, hasn't it? $\endgroup$ Feb 27 '18 at 16:08

Start by extruding the corner vertices. Locate them at the same height by selecting the extruded vertices and then Scale Z, 0. This decreases the Z difference between the vertices to 0. Then change the absolute z-value of the corner vertices to 0 if you want to start the model at sea level.

enter image description here

Create a bottom face by selecting the extruded edge vertices and using the Fill command (F).

If you have a terrain model with many faces, then using the Select All Vertices > Fill approach takes very long. It is much more feasable if you use Blender's Edge Loop Selection Tool for each side of your model:

  1. In Edge Mode, use ⇧ Alt + ⇧ Shift + Left Mouse Button to ring select the edges by selecting the formerly created vertical and horizontal edges
  2. At last, select one of the outer edges of the terrain model.
  3. Fill the selection

enter image description here


If your goal is to make the surface have a thickness that results in a uniform (flat) bottom then there is a fairly simple way you could accomplish this. I did it with a really simple plane for an example.

Manual Method

Simple plane

  • Select All (Edit Mode > A ) so that everything in your mesh is highlighted
  • Extrude (E). Cancel the extrude but do not cancel select.
  • Translate (G) along Z axis only (if your mesh is up with respect to Z)

After Extrusion

  • With the new bottom selected, Scale on Z (S, then Z) to 0 Flat bottom 1 Flat bottom 2
  • I would also reccomend adding a loop cut (CTRL + R) around the sides if you plan to edit the top and bottom independently or modify the topology etc. You can make that loopcut parrallel to the bottom by scaling it to 0 on the Z axis like you did with the bottom

As @Haunt_House Suggests in the comment below, you can also align a loopcut with the following method

You can align the loopcut to the bottom by hitting E for even and F for flipped after deciding on the edges to cut. CTRL-R, LMB, E, F, RETURN

Loop cut

Solidify Modifier

You can do almost the same thing with the solidify modifier, but if you do it this way, you can't garuntee that the edges are perfectly flat.

  • Start with a plane like you have, choose the solidify modifier (Generate > Solidify)


  • Choose a thickness that you like, exit edit mode and apply the modifier.

Solidify applied

  • You can then flatten the bottom by selecting it all and scaling it to 0 along the axis representing the height (Z in my case) similiar to the above method.

Final result of solidify

As you can see, the sides are not perfectly flat but if you dont need or want flat sides, this will work fine too.

  • 1
    $\begingroup$ You can align the loopcut to the bottom by hitting E for even and F for flipped after deciding on the edges to cut. CTRL-R, LMB, E, F, RETURN $\endgroup$ Feb 27 '18 at 16:05
  • $\begingroup$ Thanks Haunt, I will add that in courtesy of you. $\endgroup$
    – VampyreSix
    Feb 27 '18 at 16:07

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