Draping + Cutting Terrain/Mesh for Building

Is there an extension that can quickly + intelligently generate a building perimeter plane that can be draped onto a Mesh Terrain so that you can subsequently delete the terrain where the new building sits?

The way I’ve always done this is to either re-draw the outline on a plane or isolate the external walls, intersect with a plane and clean up.

Any help appreciated!


Have you tried the stamp tool?

Hi Box,

Yes, I have. The building is quite complex with sub groups/components^6+. I’ve tried fully bombing/exploding the building and regrouping into one group, but the program ends up crashing… (see below)

If the stamp tool could be a 2-stage process, which allows you to get a footprint plane first, and then let you use that to drape, then my cpu mightn’t crash.

Maybe I’m over simplifying it, but I think you may be over thinking it a bit. You shouldn’t need to isolate the external walls etc.
Here I have used a mix of groups, components and raw geometry all grouped.
One plane through them. Intersect with model.
Move it away.
Double click on the outermost face to select all of its border edges, use Shift to deselect the edges and face you don’t need.
Cut, delete the rest, paste in Place, and you have the perimeter, add any extras as needed.


Hey Box,

It’s a good tip, but my buildings vary through the z axis in height and shape, as it steps down the site, so there is no one horizontal plane that cuts through all that the building-as-a-whole needs. If there were a way to top-to-bottom scan through the group to pick up the outermost extremities and create a flat plane, that’d be cool :smiley:

I guess I could use the intersect trick over a few planes and then mash them together and clean it up

You can have a look at Fredos TopoShaper plugin too, I like the created terrain more that that from the sandbox tools.

Isn’t that what you have already done with the sketches you show above? You as a designer then are responsible for either making a foundation for all the buildings which would be expensive with all the cutting and filling or smaller sections , but in either case how to get from one level to another is part of your design effort. You probably need to make several design concepts for costing and aesthetic looks to make a final decision on approach .

@Cotty Oooooh, yeah that looks great!

@mac7595 I’m talking about how SketchUp users could save time with a new function that creates a perimeter through the whole z-axis. It has nothing to do with my design and foundations.

Sorry I will disagree. You show the flat plane extremities , the relative elevations by inference of each and by reference the elevation you want to fit. You may find this link helpful Vali Architects: Setting up a Project in Sketchup - Part 1 Site Design - YouTube to give you ideas about real design.

That thing I drew (in 20 seconds) was just a made-up diagram to illustrate the point that some buildings are designed to step down a sloping site, such that a single, intersecting horizontal plane will not show the entire footprint that is to make an impression on the terrain. That link you sent taught me nothing new, and has nothing to do with ‘real design’…

I mean, are you trolling me? The workflow I used in SU is to remove the terrain under the entire building and build it up. That has nothing to do with my design in real life… In fact, you have no idea what the real design I have intended is, or for what purpose.

You must be trolling, otherwise you are way out of line with your comments.

That is rather obvious by your posting.[quote=“jwrathall, post:10, topic:14914”]
The workflow I used in SU is to remove the terrain under the entire building and build it up. That has nothing to do with my design in real life… In fact, you have no idea what the real design I have intended is, or for what purpose.

And agin you are 100% correct. In engineering form follows function and the purpose of questions / comments are to try to get an under standing of intent so maybe help or ideas could be provided , but see that will not be possible with comments received.

So… Let’s forget about the trolling that killed this conversation, can I bring this back to life because it is pertinent and I cannot find a satisfactory answer to it?

I think @jwrathall jwrathall and I are having the same issue. When you have a model that follows the contour of a hillside, there arises the need to cut the building outline out of the terrain to nestle the foundation and underground space into the terrain.

Stamp doesn’t do it, it creates unnecessary geometry. Drape will drop every single line onto the terrain. Creating an outline of the building and associated driveway and retaining walls is an option, but it will take significant time.

The geometry seems too complex to use intersect with model, and the building is not a closed volume.

Any suggestions greatly appreciated. I honestly have a lot to learn in Sketchup after 3+ years using it, so don’t assume I know anything complex please.

Thanks! Cheers!

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I have exactly the same problem, and would have thought there was a fairly simple solution. Searching Google so far, it doesn’t seem as though there is. I thought I might have been able to draw the terrain freehand, following the edges of the retaining wall/building, but I can’t see a way to do that – drawing a terrain always seems to want to create a simple rectangle. Does anyone have any ideas how to do this simply?

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