Clean up Model Nurbs Or Meshes



Hello All,

I’ve got a model in dwg that I need to adjust. At the moment it looks like this, they are all meshes.

I’m a complete newbie but I want to use this project to learn Rhino. I want to clean my model up first: deleting all the unnecessary lines, joing the different meshes and so on.

First question: would it be best to convert all the meshes to nurbs first (with meshtonurbs) and then cleanup the polysurfaces, or would it be better to keep working with the meshes?

Second: If I keep working with the meshes : what command to use for cleaning up meshes: weld doesn’t seem to help. Repairmesh doesn’t have the option I need. Ay thoughts?

Lastly: is there a way to have an overview of all the meshes/groups and thier hierarchy?


(David Cockey) #2

Rhino is NURBS based, and mesh tools are basic. I would not use Rhino for more than occasional mesh editing and repair. MeshToNURBS converts each mesh face to a NURBS surface The result will not be useful to you…The number of NURBS surfaces will be the same as the number of input mesh faces, and the result will be faceted along the curved portions, just like the mesh.

The preferred approach in Rhino would be to create a new NURBS surface model using the mesh as a reference. This shape can be modeled in Rhino using about 25 NURBS surfaces. Creating the NURBS model using the mesh as a reference should be a straight forward and simple task for a knowledgeable Rhino user. However it is not a good task for the “complete newbie” to start learning Rhino with.

A good way to start learning Rhino is to go through the Rhino User’s Guide and work throught the exercises there. To learn more go through the Level 1 and Level 2 training manuals and examples.

Do not assume any knowledge of other modeling software is directly transferable to Rhino.

(David Cockey) #3

Meshes in Rhino generally result from NURBS surfaces and curves. The basic Rhino geometry includes points, lines. curves, surfaces and extrusions. Curves, surfaces and extrusions all use NURBS aka Non-Uniform Rational B-Splines, and can have degrees from 1 to 7 or more with degree 3 (cubic) being the most common and typicall the default degree. Lines and polylines can be considered as degree 1 curves.


Just for your example, I would use Dupborder on this one…it would duplicate the internal and external borders which you could then select and extrude to obtain what you are showing here without all the mess from a imported mesh.

done easily, and you could use this on any FLAT mesh you import. Once you get into more complicated meshes then you will have to either meshtonurb and clean up, or sometimes just converting to quads will do wonders. For hierarchy if your mesh is a .obj file you can send the groups to different layers, it may be worth your time to convert your mesh first before you import so you can do so, as I know not all imports will allow you to do so.