I am trying to figure out why Rhino doesn’t make simple plane out of this 4 sides surface, with the control turned down to simple.

Planer Surface.3dm (96.6 KB)

I am trying to figure out why Rhino doesn’t make simple plane out of this 4 sides surface, with the control turned down to simple.

Planer Surface.3dm (96.6 KB)

I don’t understand the question. There is one mesh and one planar surface in that file. That surface is a simple plane trimmed to its edges.

Something is a bit odd about your surface. If you DupBorder your planar surface, you will see that there are actually 10 edge curves, not 4. The joints along the edges correspond with the mesh facets. If you simplify the border, you can get it down to 5 curves, but there is still a break point left on one of the long sides. This looks like a bug to me, as it should simplify down to 4 linear borders.

The only way I could get a simple mesh out of it was to remake the surface using either the fixed edge curves or 4 corner points.

–Mitch

Correct. If create a mesh from planer surface I would expect to get a single face mesh, not an 8 faced mesh like I got, which I included for reference.

Yeah figured that out the edge problem after I posted this. I didn’t create the surface so not sure how they got so many segments in edges. I tried the DupBorder, SimplyCrv, PlanerSrf method, but came to the same conclusion you did. Where is still has 5 edges. I am not sure why it didn’t simply that one edge. It looks like the end points are the same and direction of the curve is the same, so it seems like it should have simplified it into one curve. I even tried drawing and new curve the full length of the edge and direction matches the others. If you take the start point and end point creating an new full length curve the direction is still the same.