Built up a terrain but want to subtract areas from it, how?

terrain
subtract

#1

I have built up a terrain (I tried) but now want to cut areas out the top of it, to show areas of the land that will be cut out. I have the shape i want to subtract but can’t do it because the terrain I have isnt classed as a solid.

What can I do?
I can attach the file if need be.


#2

That’s pretty easy to do. See step by step below on large terrain that needed to “cut” out the areas of the existing terrain and replace with proposed grading contours/mesh.

Step 1 - You’ve already got this step but I’m showing it as you this is the proposed terrain/grading that I want to insert or cut out of my existing slope.

Step 2 - Draw in 2D the boundary that you want to clip or cut out of you existing terrain. Here I used a combination of proposed grades and retaining walls to create the extent of proposed changes.

Step 3 - Extrude and group the new face created from your extent of changes. Then copy and ‘paste in place’ INSIDE your terrain group. Then select everything while inside the group and right-click and select ‘intersect with selection’. Then hide or freeze your extrusion and delete the areas around your proposed grading mesh.

Step 4 - Do the same thing for your existing terrain. In this example the resulting pink area was the existing to be re-graded so I grouped that and froze it (as you never know when you need to go back and grab something from existing grades).

Step 5 - Move the proposed grades down into place in hole that you clipped out of the existing terrain mesh. Here I’ve left the existing and proposed in together so you can see cut vs fill required.

Finally, here is what the proposed terrain looks like with existing (pink) frozen. Now I can drape and drop trees, buildings, illustrative plan, etc…


#3

Thank you so much!


#4

No problem. Feel free to post screenshots of your result so we can see how it turns out :wink:


#5

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Native “Sandbox tools” can cut out certain parts of a terrain.
But to use solid tools, you can use fredo’s vector push/pull to make a quick solid of the terrain and then use other cutting shapes to subtract from it.