What is the difference between NURBS and PolyNURBS

Cyrill Wälchli

Dear Community

I am a mechanical engineering student at RPTU and currently writing my master thesis in the field of topology optimization.
During the literature research it could not be clearly clarified what the difference between NURBS and PolyNURBS of the software Altair Inspire is. 

Would someone be so kind as to tell me the difference based on the excerpt from Altair Website which is attached. Support with pictures would be very helpful as there has been no difference in presentation between NURBS and PolyNURBS.

I would greatly appreciate your assistance and look forward to your explanation.

Sincerely yours
Cyrill Wälchli

What is the difference between NURBS and PolyNURBS.JPG

Antonio Flores_21377

Hi Cyrill,

Here is another definition:

PolyNURBS

Create polygonal surfaces that can easily be converted into NURBS surfaces.

PolyNURBS combines the ease and simplicity of polygonal modeling with the precision and flexibility of NURBS, allowing you to quickly create free-form solid geometry that is smooth and continuous. A PolyNURBS object represents geometry as a NURBS surface surrounded by a transparent, quad-only, polymesh cage.

 

The difference between a Nurbs and a PolyNurbs is that a PolyNurbs is made of many Nurbs patches automatically generated and aligned in order to generate a continuous and fluent shape with ease and being able to edit it easily through a control cage that doesn't have the huge complexity of dealing with the control points of the many patches but that has very few points. This approach in terms of cage is identical to polygonal modeling, so most of the techniques that are used in polygonal modeling are available on PolyNurbs geometries acting on its cage. Polynurbs makes easy to create and control shapes that would be very hard to model and control with Nurbs only.

I hope that this clarifies a bit the nature of PolyNurbs.

Regards,
Antonio