# Resulting in a single untrimmed surface

Hello,

For the purpose of my script, I wish to have a single untrimmed surface out of three separate ones [FILES ATTACHED].

Surface.gh (25.4 KB)
Wall_.3dm (598.9 KB)

The original geometry comes from Revit and is stored in Rhino as meshes.

1. I’ve been trying to recreate the shapes in Rhino from scratch, but I resulted with a brep combined from three surfaces (one of which was trimmed)

1. In grasshopper, I also tried to convert meshes to surface. However, I got either a brep or a trimmed surface.

I need an untrimmed one since I use the Divide Surface component for the formation of a curtain facade.

I’ve been wondering whether there is any other way to get a single surface of the three (or six Revit meshes) that I have.

Best,
Aga

This is a very good question.
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For the surface lying on the ground, I think a normal extrude will do.
If this one bakes into Rhino, it will also be a single untrimmed surface.
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For the one that is on the 2nd floor, a normal loft will cause an open brep.
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To solve the problem above, you can use something like “ruled surface”.
This will ensure a single untrimmed surface in GH, but a brep once baked in Rhino.
Also, the curve control point weight is not constant 1 in the bottom curve, because there are arcs involved, but the top curve has the same weight as 1, this will cause some problems in the surface structure as you can see in Rhino, and the pic below

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So this is the final approach with some special treatment to knots and weights.
There are some geometry tricks dealing with control points and plane alignment.
If curve A’s all control points C are on plane B, the entire curve A is on plane B, whatever plane B is.

1 Like

Here’s a solution using your meshes as input that produces untrimmed surfaces in GH:

Note: this uses the Pufferfish plug-in.

If you bake these surfaces into Rhino they will become split at kinks (polysurfaces) - unless you turning off `CreaseSplitting` before the bake in Rhino which is not recommended.

Surface_re.gh (33.9 KB)

-Kevin

1 Like

Thank you, @11165 and @kev.r, for the solutions and explanations!
I employed the two solutions in the end.

Best!