Picking Boundary Breaks Terrain

Hi All,

I’m building a model of a mountainous island from a dwg file with contour lines and elevation data. The aim is to 3D print this model.

After making terrain from contour lines the model looks fine (screenshoots 1 & 5). (Model units set to km to be more manageable, thus the small cell size numbers).

I’ve made a boundary from the island outline, and curve is recognized as closed (screenshot 2).

After using Pick Boundary, selecting terrain and then selecting curve as boundary, the terrain boundary is successfully cut, BUT also rectangular holes are cut in the interior of the terrain (screenshots 3 & 5).

Is this a known behavior and is there a solution to keep the terrain mesh intact after cutting boundary?
Do you have any tips for alternative workarounds? I’ve tried extruding the curve and using Trim to cut the terrain instead of Pick Boundary, but the terrain is not recognized as a mesh.

Grateful for any pointers in the right direction!


Update: Seems to be working when I offset the boundary curve to lay slightly outside the original contour line used for making the terrain.

I see, too many coincident points and lines, I guess. It looks like a bug in the clipping algorithm when managing particular cases, or a tolerance problem in the best case.

Thanks for report it and point the solution.