Subtract terrain

Hello Everybody;

I’m super new to Sketchup so please excuse my questions and bear with me.

I have 3d contours and made (tried) its terrain (it’s not even solid yet)

My problem is I want to substract the area that Im not going to use and trying to get a terrain which has exactly the same shape with the contours on it.

On the other hand, the terrain that I got from sandbox tool gives error when I try to make my terrain a solid with vector pushpull. i cant select the edges on my terrain because suddenly my laptop is getting slower and the laptop forces me to switch off the program…

I have been dealing with this thing for a month and I couldnt do anything to reach out a solution.

Hope someone may help with me.



If you attach your model someone may be able to work out what your issue is.

1 create a cube that covers the terrain you want to use
2. select everything and click RMB, select Intersect planes - with model
3 Delete unnecessary geometry (outside the terrain and the top of the cube)
4, Select all geometry and make group and… You have Solid!
5 Tea i smile

@Luxalyn, the best help/sugguestion you could get so far. Without the model to go by it will be most difficult to give meaningful intructions.

No need to post the model multiple times, we can all see each post.

What is it you are trying to create? What is the end use?
Knowing this may help point you in the right direction.
Currently your model is difficult to work with due to the quantity of edges and faces and the small size. I’m thinking you may have a better result by working the contours before making the terrain. If the contours are very complex with lots of segments and quite small then the resulting sandbox terrain can be very complex.
Perhaps by cleaning up the contours first you will get a more workable model.

This is what I mean by needing to know what the end result needs to be, many options, which way to go?

Thank you so much for replying.

What I’m trying to do is to get a solid body of the contours of waterbody without uncessary part (with the exact same shape of contours) so that I can analyze the flow properties in CFD.

I am going to check out what I can do with contours or how i can simplify them.

Can you attach a model with the contours.

Ok, give me some time to look at it.

I’m sure @Box will have a better suggestion but I would use TopoShaper to get the terrain with a skirt. The skirt will be created as a group separate from the terrain surface but that group can be exploded. Trace a bottom edge of the skirt to get the bottom face completed and you will have a solid group.

Thank you so much for your interest Daver.

Yeah I exactly have done the same thing and got the solid but once I imported it to solidworks it was extremly hard to see the path and I was enable to trim the parts that I dont want to put in my analyze in CFD.

What I’d like to have is like in the attachment “model1” but as a solid body.

Sorry. Once you’ve got the solid you should be able to trim away whatever you don’t want with Trim from the Solid Tools.

Is this close enough?

OMG! this is simply amazing!! thank you so very much for your help !!

If it is not so complicated to explain, may i ask how have you done this?

@DaveR is probably right, toposhaper would probably be easier.

But the method I used.
Scale up the contours by 100 so you are working with a reasonable size.
Use Fredo’s Curvizard to Cleanup Contours, then same tool, Simplify contours, this gets rid of any real strays and reduces the complexity significantly while not losing much definition.
I then used Sandbox, softensmooth to get the edges back, removed the parts not wanted.
Then Tigs Extrude tools to pull the border edges down to make the skirt, a bit of cleanup and it was a solid.

As with all things in sketchup there are many ways to do things, I did it this way because I am comfortable with those tools.

Thank you so much Box!
Your helps are completely life saving and they mean a lot!

With your permission I’d like to ask you a last question…

Is there a method that I can apply on for this type of thing that happens after sandbox tools. How can i repair or enchance the surface when this occurs?


Sandbox is a fairly blunt instrument, Toposhaper would probably give you better surfaces.

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Thank you so much Box for everything you have done for me. They mean a lot.

Since my supervisor is not confident with that may you please delete all the cad /skp files that you share with me?

He consistently asking me if I have deleted everything here.

Thank you so much

Sincerely Ali.