Problem with mesh join

Grasshopper
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1

Hi all,

I’m trying to turn a terrain mesh into a closed solid. Steps:

  1. Take the terrain mesh, copy it and move on -Z for the bottom.
  2. Extract naked edges of the top, loft to the bottom boundary, convert to mesh.
  3. Merge top + bottom + sides → Mesh Join → Weld / Combine & Clean.

Is Mesh Closed always returns False. I think the vertices along the seams don’t match between the lofted sides and the terrain boundary, but I can’t figure out the clean way to fix it.

Script attached — any help appreciated!

  1. mesh join problem.gh (635.7 KB)
2

Here’s a solution without pufferfish

image
image2697×1362 319 KB

mesh join no puff.gh (649.7 KB)