Merge Co-planar surface

Let’s say I have a bunch of co-planar surfaces/trimmed surface that can be joined together, how do I merge all of them into one trimmed surface without interior edges? For example, lets say I have a bunch of square surfaces laid out in a grid, how do I turn them into one large square with no edges in the middle of it. What I am trying to get to is to be able to merge co-planar faces in a polysrf (similar to the way reduce mesh can merge mesh faces that are in plane).

Hi Lawrence - Join, then MergeAllFaces.


Thanks Pascal

My objective is to convert a mesh into a brep. The form is relatively simple, but because there are circles and arcs, the mesh gets pretty dense, even on the planar regions, which means that MergeAllFaces gets pretty slow. What is the best way to do this aside from remodeling it?

Hi Lawrence- Join, DupBorder, then PlanarSrf on the resulting curves should do it.


I couldn’t quite get dupborder to work on this model. Mesh to Brep.3dm (311.7 KB)

Your mesh is closed so it does not have any borders, which is the reason DupBorder does not work. DupBorder only duplicates the borders of surfaces/polysurfaces/meshes, not interior edges joining adjacent surfaces/meshes (Revised for clarity).

I tried a brute force approach.
MeshToNURB to create NURB polysurface from the mesh facets.
MergeAllFaces to merge the co-planar surfaces. This took a long time.
Mesh to Brep_DC.3dm (2.6 MB)

Hi Lawrence - try this macro:

Weld Pause 10 Enter Enter
SelNone SelLast
Explode DupBorder
SelNone SelLast
PLanarSrf SelNone
SelLast Join


I tried your method and it does a good job of simplifying the planar surfaces. However it does not work with curved regions of the mesh. Is there any sort of command that just turns mesh into a clean simple nurbs?

Nope - you need to do that by hand. Circle > 3Points and ChamferEdge should help here.