MergeAllFaces - limit?

Is there a limit of faces for MergeAllFaces. I have converted a STL file to nurbs and try now to simplify these for redesign it. But I have a spinning ball forever with 3000 faces or less. Is there al limit of faces for that?
Andreas (1.5 MB)

I don’t know if there is a working limit the number of faces you can attempt to merge, although as you can see there is a practical one - how long it can take to complete.

You could try the ReduceMesh command with the ‘planar faces only’ option toggled before you convert the STL to a polysurface.

Thanks David. I have reduce before with Quatriangulate. Now I can playing around with that to optimize. But MergeAllFaces kill me Rhino. Can`t do anything but force quit.

Hi noetzig,

Thanks for your note.

MergeAllFaces can indeed be slow when input lots of faces. The algorithm it uses merges 2 faces at a time to ensure accurate result . Two adjacent faces might be coplanar within tolerance, but with a big set of faces, the overall accumulated deviation can easily exceed tolerance yielding invalid result.

At some point, we tried to update MergeAllFaces to take the overall boundary and replace with one face, but it proved to unreliable and we reverted from that solution. We can still improve the speed with threading and new revision of the algorithm and this is on the list.

Thanks Rajaa - It’s so strange I got only 12polysurfaces and it’s been taking 15minutes.

In general, for these objects, “it is advisable” to draw the basic curves and to make the polysurface from 0 (this file is full of open edges to be placed). The total time is not different from the working time of MergeAllFaces (which will take a few seconds extracting the few zones that have flat surfaces using the MergeAllFaces command, rather than using the command with the entire polysurface)