Unroll Nurbs surface, problem

[Craigie]

I'm having problems with unfolding Nurbs surfaces.  These were created with 2 Nurbs rails and "ruled" between so they are developable but VW tells me not.  When I import them into Rhino they develop fine.   Any ideas ?

[Benson Shaw]

Don't know whether normals matter, but reverse any that are opposite side from bulk and try Unfold again. ?

 

oops edit. I guess no control of normals for individual sub surfaces in the loft. Tedious, but you could extract each sub surface as planar object. 
-B

Edited October 13, 2021 by Benson Shaw

[Kevin McAllister]

17 hours ago, Craigie said:

I'm having problems with unfolding Nurbs surfaces.  These were created with 2 Nurbs rails and "ruled" between so they are developable but VW tells me not.  When I import them into Rhino they develop fine.   Any ideas ?

 

Are you able to post an example file? That would help us help you to solve your problem.

 

Kevin

 

[Benson Shaw]

@Craigie Is there some reason to assume that a Ruled Loft is developable?

 

I don't know Rhino.  @Kevin McAllister will likely have superior knowledge.

 

This may be vwx specific (working in v2022), but the ruled loft option does not necessarily make a segmented loft with planar sections which would be automatically developable.

Example shows 2 NURBS curves, all non endpoint vertices are curvy variety rather than corner point variety. I lofted them twice.  Bronze loft is ruled. Blue one is not ruled.  Normals appear same direction. CM same in xyz. Area same. (perimeter is missing - didn't that used to be in OIP?)

In this case Ruled seems indistinguishable from not ruled. Neither is perceived as developable for unfold by vwx.

 

-B

 

Unfold NURBS.vwx

[Claes Lundstrom]

Unfolding very much depends on the method used and how good the shape control is. Rhino's variation can sometimes be a bit sketchy and may or may not be all that reliable on more complex shapes.

[Benson Shaw]

I think? guess? suspect?  that vwx can only unfold surfaces which are cylindrical, conical or flat/planar, or continuous aggregations of such areas.  The surfaces can have holes of any shape, the edges can have notches.  These surfaces would be developable in the sense that real world materials do not require any stretching or compression.

 

Other software, eg for design and mfg of automobile body work, shipbuilding, magnet or press formed sinks and cookware, etc can probably predict the least wasteful config for start shape of flat material.  Another unfold context is the various mapping projections - orange peel, cylinder, globe.

 

Can anyone verify or extend any of this?

 

-B

[Claes Lundstrom]

17 hours ago, Benson Shaw said:

I think? guess? suspect?  that vwx can only unfold surfaces which are cylindrical, conical or flat/planar, or continuous aggregations of such areas.  The surfaces can have holes of any shape, the edges can have notches.  These surfaces would be developable in the sense that real world materials do not require any stretching or compression.

 

Other software, eg for design and mfg of automobile body work, shipbuilding, magnet or press formed sinks and cookware, etc can probably predict the least wasteful config for start shape of flat material.  Another unfold context is the various mapping projections - orange peel, cylinder, globe.

 

Can anyone verify or extend any of this?

 

-B

I agree that VW's ability is covering the basics, whereas other more specialised programs are needed for mode complex tasks.

 

I work with these things on a more or less daily basis, but I have to confess that I never use VW for this, mainly because what I do is highly specialised and therefore well above what VW can do in terms of unfolding.

 

 

Edited October 15, 2021 by Claes Lundstrom