closed topo curve offset breaking

I have a site that I am making appear to erode by taking a closed polyline, offsetting it, creating a planar surface with that offset, and extruding that surface the height of my topos.

My problem is that some offsets work to the point where they appear to dissolve while others seem to break and the extrude disappears after only a small offset. I know this may be simple but its frustrating me.

Attachments:

EROSION simple.3dm, 102 KB
erosion.gh, 14 KB

Replies to This Discussion

Permalink Reply by Hannes Löschke on February 20, 2013 at 4:05am

Well, Offset will move each subcurve and return only one region inside all the moved curves. So in your second curve, the dent will intersect with the opposite edge, effectively dividing the result into two parts. Only one part will be returned.

Offset will return no meaningfull results if the offset subcurves move past each other so they don't intersect anymore.

Permalink Reply by aaron guilford on February 20, 2013 at 7:42am

I figured thats how it was reacting so i divided the second one into 2 segments to avoid that but still had the same result just a little further down the line. My understanding was that once offset line segments start to cross it no longer creates a closed region and therefore doesnt work. I guess I just need a different solution. Any ideas?

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