Combining Two Terrains

I’ve got a sketchup model that has two terrains next to each other. They are in different groups and they have a slight gap in some places (on z plane). Is there a way that i can combine them and fix the gaps?

One method would be with Vertex Tools extension.
Another with Fredo Curviloft extension.
And there are several other methods as well.


try to be a bit more articulate. the sandbox is 7 tools.

Without extensions Yavus, you could use either the move tool (native), or the Add detail tool from the sandbox.

extensions will probably make it easier.

please show us which tool exactly you call the sandbox, again, the sandbox is a set of 7 tools. One would do the trick (Add Details), 6 wouldn’t.

not really no. but it’s your preference, you do you.

Mihai recently made a video showing how to merge two terrains using various extensions. The result is sound.

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1.skp (7.8 MB)
Here is the model, if anyone can show me just a bit of how to do it with either extensions or native sketchup i would do the rest and would appreciate a lot!

I chose the following method:

  • create a duplicate of terrain, select all faces > delete (using Selection Toys extension);

  • the remaining edges are the roads and border edges. I made them 2D (with Vertex Tools);

  • I then erased all the lines that were the border edges of those separate plots of terrain;

  • with Sandbox Tools > From Scratch I created a 2D surface slightly larger than the initial terrain.

  • with the MCAlignEnds extension I draped the surface (from Sandbox) on the existing 3D terrain (the one consisting of several separate plots);
    :bangbang: It is best if you drape border edges before using AlignEnds.

  • the result was the new terrain made from a single surface;

  • having in separate groups the perimeter (border edges) of the original 2D terrain, the 2D roads and the new 3D terrain;

  • drape one by one border edges group, then roads group and you will have the clean new terrain in one piece (surface) with the roads.
    :bangbang: It is best if you drape border edges before using AlignEnds.

I also tested before and even if it is possible, the method with Vertex Tools involves much more work.


You are a lifesaver!!! Thanks for explaining in detail and caution. Unfortunately i’ve aligned the terrains one by one with Vertex Tools yesterday (and belive me, it took a loooong time) xD. But i’ve gotta do this again for another file so i’ll use the other method that you’ve showed. Thanks again!

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Hello, there is a very quick way using Fredo6 's toposhaper extension, but it is not free anymore. You may start a trial though.

Select the whole group and go to tools > fredo6 Collection > topo shaper > generate quadmesh terrain (it will take approx 1min to analyse)
then calculate terrain
then generate terrain.

You’ll get this :
1(1).skp (5.3 MB)
(green surface is the result)
You’ll then have to drape all your roads on it again.
Good thing about toposhaper is that you can also label heights, recreate contours etc.

speaking of this, another quick way would be recreating contours from your group. You can use free Tig’s contour maker extension SketchUp Plugins | PluginStore | SketchUcation.
once installed, select the whole group and go to extension > contours. Set up the spacing (the narrower the more precise the result will be) and validate.
You’ll still have gaps where your different surfaces failed to join, but it does not matter : the native “from contours” tool, out of sandbox tools will ignore that and create a smooth surface.
use it on the newly created contours

here is the result with a 1m spacing :


I’ve fixed the issue, the topography is now fixed but a new issue got in the way. So i’ve sliced the terrain (in order to do that i’ve had to erase the roads) and wanted to drape them but it has been running for 15 hours and it still haven’t finished.

When i checked some faces were reversed, can that be the issue? I’ve tried everything, tried to optimize the performance by toggling profiles,edges etc. in the styles section but it still hasn’t finished yet. Is there a way i can make it work?