Splitting complex mesh?

Rhino Rhino for Windows
1

I’m stuck with a huge mesh that I’m trying to split:
it is a huge urban environment derived from a city scale Openstreetmap import, generated with the BlenderOSM addon in Blender, which I imported to Rhino.

Long story short, I would like to split the buildings, I only need a small portion to do solar analysis on the site, but I cannot get to MeshSplit it with a polysurface, as the command results in disappearing geometry.

image
image1639×1115 118 KB

After splitting this is what remains (there is the rectangle on top that I extruded to a polysurface, which was used for splitting):

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image1273×871 75.7 KB

I split the terrain, it is 200x200m wide, I would like to do the same with the purple wired buildings, which are one huge disjoint mesh (I joined everything together so that I can work with them).

This is the extent of it:

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image1640×1116 424 KB

I tried duplicating it and deleting the excess vertices, but that seems to freeze my computer.

In the worst case scenario I can export it to Cinema 4D and do the split there, but I’m looking for a way to handle this in Rhino.

Any ideas?

The .3dm is huge, you can take a look at it at this link.

2

Hello - not a great deal of the mesh comes through the terrain, proportionally, does it mess up your solar calculation to just leave it there?

image

-Pascal

3

Hi Pascal,

the idea is to create one open mesh from the close surroundings.
First get the neighbouring buildings as described above and then trim them with them terrain, then the terrain with them, and join in the end.

I only need them as shading surfaces, so I guess it would work with overlaps like this. I assume it would only be slower, but wouldn’t make a difference.

I’m not there yet, this mesh is still inadequate for this purpose. What I’m not getting is why the disappearing geometry. Splitting only seems to affect the polygons that I’m cutting through. I did try splitting with 4 huge planes that are bigger than the extent of the model, still no luck.

4

Try SplitDisjointMesh command.

5

Yes, that helped!
Thanks, I didn’t know that command, really helpful.