converting polygons to nurbs

[pylo]

Is there a way to convert polygons to nurbs?

I have a curve from Illustrator that I want to extract by "curve to mesh". If I do polygons it´s ok, but in the end I will need nurbs because it should be put into a CAD tool to cut it about of real metal.
The mashine only recognizes iges or step files and both of them only allows nurbs.

I would need a button that says curve to nurbs.

or any other solutions?



I never work with nurbs, so I don´t know its rules.

[Eugen]

One solution for converting polygons to Nurbs is this, but it's a 3ds Max plugin, and it costs 800$... °.°
http://www.npowersoftware.com/NewPowerSubDNURBS.html

Another would be exporting to Rhino. But before you do that, you better work in Rhino altogether... (I don't like it's interface...)

But maybe there's a chance to stay in Softimage... depends on how complex the model is you want to create. If is it a simple extrusion type object, you could as well extrude a Nurbs surface instead of polys.
The problem though will be the capping, especially if it has holes. The whole trim business is somewhat error-prone, and I'm also not sure if the exported IGES will be watertight.

P.S. right, Softimage Nurbs suck badly... we should all nag Autodesk more about it.

[ActionArt]

I believe MoI had a solutions (script I think) for this. You might want to check with Michael on the forum (http://www.moi3d.com).

[pylo]

tried moi but it only imports nurbs...

I already have a detailed polymesh...

Just want to convert it

[Eugen]

You have chosen the most difficult path. You will hardly find a one-click solution for it, because it is a non-trivial problem, and if there is, it's going to be expensive.
Check the price of this Rhino-plugin:
http://www.rhinoreverse.icapp.ch/english/index.html
€1290,-!

Is re-modeling an option?

[pylo]

Not an option.

I tried it now with pro engineer and it seems to work.

I tried it with a simple cube.
Tommorrow i will go for a more detailed model.

[ActionArt]

tried moi but it only imports nurbs...

I already have a detailed polymesh...

Just want to convert it

Yes, but there was a script for it if I remember right (not part of the basic package).

[Mathaeus]

tried moi but it only imports nurbs...

I already have a detailed polymesh...

Just want to convert it

if it's still about original post ( extrusion form curve for machine which wants nurbs), as Eugen already said, I think it's best to redo all work in some specialized NURBS app, Rhino or Moi. There's always chance, something will go wrong with3d print, and exactly that conversion from mesh to NURBS could be a reason. Also, nothing in Softimage is dedicated to real output, SI is DCC app, not CAD app. Forget your detailed mesh, that's it.

Just for info ( which probably helps nothing to original question) there are several ways to fit the nurbs to mesh in SI. One is direct shape key or ICE switch context method, *if* count of points match, *and* mesh is ordered (that is, vertex Ids are distributed nicely, by rows). But, ordered mesh is grid primitive, possibly loft, so on. Extruded mesh from curve, together with caps, bevels. tessellation, definitively not. But it works nicely for fitting the nurbs to some simulated cloth, and similar stuff.
Another way for fitting is deform by UV method. Even 'UV deform on mesh' has *mesh* in name, actually it operates only on points and point normals, so it is able to deform the nurbs surface too. But precision is not the best side of this method, so I think, again nothing for CAD. For example, I'm using it for converting the polygon hair to NURBS stripes for hair styling.

[Daniel Brassard]

Tyr this:
Select your polygon object to convert, run this script:
in jscript
ApplyOp ("PolyMeshPNet", selection(0), 3, siPersistentOperation);

An other way, if the model is not too complex would be to shrink wrap a nurbs object to your polygon object, or several nurbs objects and then merge them.

[Eugen]

... or shrink-wrap the Nurbs object created with "PolyMeshPNet" to the polygon object.
PolyMeshPNet obviously "softens" the shape without need, and it does not have any parameters.

However, it's pretty slow, because there will be 4 subsurfaces per polygon... too heavy probably for practical use.

Nice find, anyway! I think I heard about this one years ago. Shame it was left to rot in the basement, like the other Nurbs tools. Back in those days they were pretty ambitious with them.


Or how about looking for another service provider for your metal prototype that takes care of this conversion nonsense himself?

[Mathaeus]

.... regarding Nurbs assemblies in SI, there's great tutorial by Jeremy Birn for Softimage 3D . Don't know exactly how shrinkwrap works with that assemblies thing - but I do know for lot of problems with them, when it comes to ICE, like non existent PointReferenceFrame attribute on anything but first subsurface, general problem with retrieving location on multiple subsurfaces. Then, broken shrinkwrap (and ICE get closest location) if nurbs is target, on even single nurbs surface after second snip operator. And more.

About ordered mesh, Edy Susanto already made plugin for XSI 5 or 6, I think. I believe the plugin, internally, creates a grid primitive, then matches it to mesh, something like that. I think some feasible method could be 1: breaking the mesh into quad-like pieces 2: creating ordered IDs, probably as some ICE attribute 3. fitting the nurbs surfaces to pieces.
4. assembling, if there's need for that, most likely in another app.

[pylo]

the script works not so good...



shrink wrap works okay for easy models but the logo that I need to convert is quite complex. Many holes.

[caledonian_tartan]

the script works not so good...

and not so bad eighter... for what it is...

just tried on the default man character and it takes some time but does its job.

i'll give it a: cool!