I have a bunch of buildings, and want to get the outer silhouette to perform a set of split operations on the terrain surface. I haven’t seen any good solutions to this problem, am I missing something? [Screenshot 2022-02-04 at 18.32.27] I’m looking for closed curves like the green line (without…

Hi @julian.riise , If you bake your geometry, back into Rhino, and then run the Silhouette command, do you get what you are looking for? – Dale

If you can get curves rather than closed Breps, there’s a tool in Grasshopper called Region Union. I’ve uploaded an example with some internalised Breps. [image] The script takes your Breps, finds the face with the lowest z-coordinate center (so the bottom face), explodes it into its curves, join…

Elegant solution! I had some issues with the Region Union component, it took forever to process, even on a small sample size of buildings… I don’t know if you had that issue? I’m ultimately running the definition on ~350 buildings. Thanks for your help!

You could also use Mesh Shadow. [Canvas at 22;15;34] makeBuildingCut_re.gh (49.7 KB)

[makeBuildingCut_2022Feb6a] makeBuildingCut_2022Feb6a.gh (45.6 KB)

I didn’t have that issue, but I also only tested on the boxes I posted there. I did a quick test and arrayed out the sample boxes. With 3000 closed polysurfaces (so 600x the 5pc example I posted) the script took 2.8s. With 9000, it took 14.7s. [image] (500 closed polysurfaces) [image] (9000 c…

Outer boundary curve from Breps

Grasshopper

HS_Kim February 6, 2022, 1:17pm 5

You could also use Mesh Shadow.

makeBuildingCut_re.gh (49.7 KB)

How to create a silhouette curve?

How to get a polysurface's outer boundary?

Topic		Replies	Views
Find a good way to get the outline of the sliced Grasshopper grasshopper	5	941	August 20, 2019
How to get a polysurface's outer boundary? Grasshopper windows	16	442	November 25, 2025
Closed Curve Silhouette of a Brep Grasshopper windows , mac	5	1260	February 16, 2023
Grasshopper - Finding the outer boundary of a collection of curves Grasshopper windows	14	5009	October 26, 2022
Selection of building footprints, and region union not working Grasshopper curve , surfaceintersection , grasshopper , surface	6	1043	December 19, 2019

Outer boundary curve from Breps

Related topics