Michael, Could you pleas make some Converter to convert from Polygon models to Nurbs. Now I use Nvil simple polygonal modeller to model base shapes that is practically impossible to model in MOI and then import it in MOI through T-Spline.
I know that make something like T-Spline is very hard task for you, but may be this converter is not so hard to make? This converter will infinitely expanded capabilities of MOI and it will be the GREATEST feature ever...

This is how it works:

Hi Andrei,

> Michael, Could you pleas make some Converter to convert from Polygon models to Nurbs.

I'd love to have something for that in the future, but it will involve quite a lot of work. Things that involve a large intensive amount of work are difficult for me to schedule.

In areas where a sub-d mesh is all quads and only has 4 edges coming out from a single vertex the conversion is actually an easy one.

The difficulty comes in handling structures other than that where more than 4 edges are coming from a single vertex, a sub-d surface has a different structure than a NURBS surface in such areas and so some kind of approximation mechanism has to be used. It can be quite difficult to make such a mechanism that has good quality.

- Michael

There are some high end tools like Geomagic and RapidForm that can do this (both owned by 3d Systems) and it will cost you about $15,000.

To be fair, these companies have a larger development staff, and that's in part what you are paying for.

T-Splines, if I recall correctly is extremely limited in the # of polys it can handle. Its not designed as a poly to nurbs converter (although if you have a low poly object it can do that conversion). T-Splines was designed as a tool to manipulate the nurbs surface via a polygonal "cage". Power Nurbs (Power Surfacing) works in a similar fashion.

There is a plugin for Rhino called RhinoResurf from Resurf3d that can do a conversion like Geomagic Studio, for far less $$$. I tried a demo of it in the Rhino demo version, but had some issues that were related to the demo versions.

Andrei you might be interested in this which is a much cheaper alternative (unless you're looking for a reverse engineering application to go from scans to solids). It does take the investment in Modo but modo is simply awesome
http://community.thefoundry.co.uk/store/Power_SubD-NURBS/

Fusion 360 free a year for students and enthousiasts ?
https://fusion360.autodesk.com/pricing

http://www.resurf3d.com/Objmesh2solid.htm

Works alright if you only have a few vertices but bogs down quickly on large files. Smoothing is OK.

Yeah, I tried ObjMesh2Solid, but it was was only useful for very low poly objects in my experience as well.

I bought the Mesh to Single Nurbs from Resurf, and it works OK with larger meshes, but its only useful if your object is more or less one sided, and does not have huge amounts of detail. You could use it to go completely around an object, by rotating the object to do it in sections. Then you would have to trim and join the sections together.

RhinoResurf can handle larger meshes, with more detail. I would just like to get a demo that is useable to be able to thoroughly test it. Unfortunately, every time it builds the nurbs surface it forces the Rhino demo to use a save, which does not go very far for testing purposes.

Michael, understood.
Guys thanx for all your help :)

I have to say that T-Spline is the best converter. I us eit to convert only base shapes. Now I'm working on this helicopter I made it in Nvil (3 hoours work) and now convert it to MOI.
As you can see cage is very tight, but T-Spline treat it very well! I use this tight cage becouse in Nvil as you can see I used Creas and to save these edges I have to make tight cage.

Looks liek I take the best from Poly and Nurbs. The fastest workflow made organic base shape in poly and then finish it in MOI.

Andrei, looks like there are about 30,000 triangles in the helicopter.

What is the largest # of triangles you have been able to process though T-Splines?

This is Resurf it convert OBJ to Iges, but you have only one Setting.

Step 1: load your OBJ mesh into software;

Step 2: click menu 'Surface> Blend mesh to NURBS' , the software will create NURBS surfaces from your OBJ mesh automatically. The NURBS surfaces are water-tight and exact G1 transition.

Step 3: save the NURBS surfaces as .igs file. Since the surfaces are water-tight, they can be sewed as solid without changing any geometry by other software.


http://www.resurf3d.com/Objmesh2solid.htm

Chrisd , really do not know did not tested this yet.

zarkow, I tested it, and unfortunately the result is not as good as T-Spline.

Viacad are working on the a add on tool to viacad which will have some mesh to nurbs tools, I'm waiting for the beta to have a play with it.

>>.. make some Converter to convert from Polygon models to Nurbs.

It's very interesting for me :) I'll think about it. But I won't promise anything at the moment.

Just came across this while looking for something else.

ViaCAD Pro 9 which was recently released includes sub division mesh modelling tools.
There is a future addon (coming) called Power Pack Pro which includes a convertor from mesh to nurbs. Looks like it does a pretty good job with even high poly models.
http://www.masterviacad.com/powerpack/page9/page36/page36.html

Unfortunately, it hasn't be released yet but sounds like they are about to start alpha testing.
http://forum.punchcad.com/showthread.php?t=4906&highlight=power+pack&page=5

Exciting technology anyway and worth keeping any eye on.

I may be a bit biased, but I think T-splines have the best subd to nurbs converter.. :)

The cheapest way to get this conversion right now is through fusion 360. It's free for students and hobbyists, and about $40/month otherwise. It can open OBJ files and export IGES, which should open in MoI without issue.

Hello,

T-splines along with the VSR (now Autodesk) tools for tweaks is a great combination. Hoping TS v4 for Rhino comes out soon, it makes round trip very easy being able to directly copy between applications.

T-Splines, PowerSubdNurbs, and other "converters" that have been referenced here are quite limited in the number of polys they can process into a nurbs surface. These tools are intended to be able to manipulate a nurbs surface based on a polygonal "reference" surface. The "conversion" is a by product.

If anyone has found something that can handle millions of polys, please indicate what it is. In my experience, the only applications that can fit a nurbs surface to millions of polys are Geomagic and RapidForm.

I am particularly interested in Resurf3D with their RhinoResurf application, which looks like it can handle more polys. Unfortunately I have not been able to test it because the Rhino trial and the RhinoResurf trial don't play well together.