Mesh2NURB multiple surfaces problem

Rhino Rhino for Windows
1

Hi guys,

Did a MeshToNURB command on a high resolution quad mesh, and the output resulted in 15744 individual surfaces. Is there any solution or workflow to merge these surfaces into one while keeping a great degree of accuracy with regard to the original shape? even if it would be a tedious process, I’m open to any suggestions. Thanks!

mesh
mesh1220×633 470 KB

2

MeshToNURB converts each mesh face into a NURB surface. It’s primary use is with low density meshes.

There is no simple command that I am aware of to convert a polysurface to a single surface.

There are many ways to create a NURBS surface from a high density mesh. The “best” method depends on a number of factors including:

  • Topology of the shape. Can the shape by represented by untrimmed NURBS surfaces?
  • How smooth is the shape.
  • How accurately does the NURBS model need to conform to the mesh.
  • Density of the mesh.
  • Topology of the mesh. Is the mesh quad only cells arranged in rows and columns or does it have a more random arrangement
  • User knowledge.

One method I frequently use for shapes which can be represented by an untrimmed NURBS surface is Patch with a starting surface.

Typical workflow:
DupBorder on mesh
Point to create points at corners of border polycurve
Split border polycurve using corner points
EdgeSrf to create a starting surface
Patch with mesh as object to fit to. Check Select starting surface.
Select the starting surface. Make sure Preserve edges is checked.
Complete Patch command.
Added: Experiment with values of Stiffness for the starting suface. I typically use 0.1. Patch can be run several times using the previous result as the starting surface.

The resulting surface can be simplified if desired using the usual tools.

3

Hello - depending on what you’ve got there, we can only see a little of it, I wonder if it would be worth a try using V7 beta to get there ‘around the horn’ so to speak: First ToSubD the mesh, and then ToNurbs the SubD… ToNurbs will be able to combine multiple subD patches into single surfaces - it seems at least worth a shot to see how far it gets.

-Pascal