Hello all,

I am not able to unroll a mesh surface obtained by "mesh" command on a NURBS one.

In my mind the good process should be : exploding the original nurbs surface in a mesh one (say a lot of planar meshes) then applying UnRollSrf tool on the mesh surface for flat patterning this surface.

But when I run 'UnRollSrf' on command prompt I can't select the mesh surface (instead of this I can select only the nurbs one) and of course command line says : "Unrolling doubly curved surfaces will produce inaccurate results."

Any idea to help me understanding what is wrong in my process please ?



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You cannot currently unroll meshes in Rhino.  You cannot unroll doubly curved surfaces because that would result in significant distortion of the surface.  You can unroll joined flat surfaces, so you could:

1) MeshToNurb the mesh

2) Unroll the resulting polysurface

This has significant limitations, some of which are outlined here. If the mesh is at all complex, the likelihood of getting something useful is pretty low.


Thank you very much for your help in my understanding Helvetosaur, even if the response is not what I dreamed... O:-)

I will study more in depth the tip and the link you gave me, hoping to find a way for my needs.

BTW : could you explain with your words what is in fact the Squish command please ?
My aim is something almost like flat-patterning a kite-surf wing to cut and sew the fabrics to build the wing.

Any advice will be very welcomed, even if it is to buy an other software ! (if you can tell me which one ! ;-)



Hi Guy- Squish will 'unroll' mesh objects. 




As Pascal points out, Squish will unroll a surface or a mesh, whether it is developable or not. I don't see a reason to first convert it to a mesh. Of course if the surface isn't developable (single curvature), then the unrolled surface cannot be exact; there will be some compression or expansion (or both). Squish has a number of controls to help you (e.g., whether the surface is rigid (plywood) or not (cloth)).


Thanks Pascal and Bruce,

What I don't really understand is : will Squish be able to flat pattern my polysurface to make a pattern usable to cut the fabric ?

You say you don't see the reason to convert first in a mesh one... Oh well, I'll try to explain within my poor English writing (I apologize for this) : 

I thought (maybe I'm wrong) the meshed surface is an ensemble of planar surfaces (triangles or rectangles).

So made from a NURBS polysurface, this originally non-developpable surface becomes some planar surfaces (if mesh are in fact a lot of juxtaposed planar triangle/rectangle surfaces) which can be unrolled on a flat pattern just like some flat surfaces shown here : http://v5.rhino3d.com/video/3d-to-2d-to-3d

Well I thought this because in fact I have already done this kind of work with Moment Of Inspiration and SketchUp :
I have modeled a nurbs surface in MoI,
then exported in SU (meshed) format,
then within SU I have unfolded the "nurbs transformed in mesh" surface with the 'UnFold Tool' plug-in.

This worked as well as possible, but I need more fine, clean and precise work and this is why I test Rhino.

Do you think Rhino can give me a good solution for this work ?



(if mesh are in fact a lot of juxtaposed planar triangle/rectangle surfaces)

Mesh quads cannot be guaranteed to be planar.  Only triangles.  That also goes for 4 sided NURBS surfaces, even though their edges may be straight, they can represent a warped surface.  So, unrolling (squishing) quad meshes or surfaces may lead to distortion.  You would have to test all quads for planarity to be sure.


Hi Guy- Squish is not especially suited to any particular material- it is designed to unroll surfaces or meshes that have relatively light double curvature - steel panels for ship hulls for example - that are not strictly developable but not terribly convoluted either. That said, users have been getting useful results for shoes for example. 

Squish will unroll meshes or single surfaces, so for polysurfaces it may pay to create a mesh first- I would make a fairly dense, evenly distributed mesh using the 'Detailed controls' in the Mesh command. But I would also break up objects so that they can be reasonably unrolled. (i.e. don't try to Squish a sphere or even half a sphere but some panels that each make up a sector of the sphere, to take a simple example...




The key is that the surface has to be able to "tear" along boundaries in order to be flattened, unless it is completely developable. In Brian James's video, as has been pointed out, each of the mesh panels was planar, so unrollsrf was able to handle it.


I haven't used Squish on any real-world problems, and I have no idea what your model looks like, so I can't comment on how well it would work. I have tested it against some developable (single curvature) shapes, and it matched exactly with unrollsrf.



Thanks all,

I understand a bit more and more, thank you very much.

So the problem seems to simplify itself : I need to know how to transform a NURBS non-developpable surface in a triangular meshed one, while being able to choose the size of triangulation, and with the ability to "explode" triangles, say break up some parts.
Is there a way to do this in Rhino ?


Hi all,

An update after some learning. 

Helvetosaur : MeshToNurbs could be the solution, but alas the command does not make the job as I need just because it does not triangulate the facets.

Pascal, Bruce : alas Squish both on NURBS or MESH does  not the job as I need just because it deforms the shapes of the non-developable facets, so bad for a fabric flat pattern making.

One solution could be to import from a mesh software like 3DS, SU and so on, but I search a cleaner and simpler way to do this only within Rhino.

In fact I do not need to mesh the surface (it was just my own and dirty work around to make planar triangle facets), I only need to make triangular planar facets from a NURBS polysurface. Say : to transform a NURBS surface in triangular facets.

Is there a tool to do this within Rhino ?



Hi Guy- 


 I only need to make triangular planar facets from a NURBS polysurface. Say : to transform a NURBS surface in triangular facets.

Is there a tool to do this within Rhino ?"

Meshing and then , if triangles are needed, with no quads at all, TriangulateMesh, then MeshToNURB would be the way.... The detailed meshing controls will help you get a tessellation that is not too dense. Then on the resulting polysurface, UnJoinEdge will help you designate edges that are allowed to open up when UnrollSrf unfolds the thing. Use Explode=No in UnrollSrf.

Does that get you anywhere?




This sounds very good, thank you very much Pascal ! :-)

[few minutes after reading...]


Thanks a lot because you save me a lot of time, and you definitively convert me to Rhino O:-)

Best Regards,




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