Is there a difference in printing quality between polys vs. NURBS for Maya 3D models?

Question

I've been reading a lot about the many differences, pros and cons between NURBS and polys, but is there a difference when it comes to 3D printing?

Answer 1

The printed model is typically polygonized before printing - it's easier to do things like watertightness checks and so on using triangle meshes. A nurbs model can be polygonized at various resolutions, so it should be possible to get a higher quality, smoother looking print by starting with a NURBS model and using a very generous tesselation at printing time. The tesselation may not always produce a watertight mesh - depending on the software used to do the printing that might cause problems which need to be fixed up by hand.

So, overall the main advantage of a nurbs model in this context is that you can work with a more efficient, lightweight representation of the data up until its time to print: the final printed mesh may be impractically dense for most ordinary applications (millions of triangles).

Answer 2

To add to @theodox answer. The other reason is that CAD/CAE applications do not really like polygon models, and treat them as a second class citizen at best. So if you need to do some analysis on the model and do some extra operations or send it to a engineer the NURBS model is MUCH better. For the engineer it allows to optimize production paths so if they are using high end printers or CNC machines instead it allows them to do a much better job. If you do not use a NURBS model the engineer will just most likely reverse engineer your model and throw your data away.

Maya on the other hand is not a very conductive engineering application. But as a upside you can just use subdivision surfaces and get both a NURBS model and benefits of polygon modeling.

PS: For a engineering application making the model watertight is no problem whatsoever if your gaps are not too big.

Answer 3

Depends what you mean by polys. Most of the time, what people mean is you model a poly and then smooth it (by hitting '3' or turning it into a subd).

If you're doing that, nurbs have absolutely no advantages over subds for 3d printing in terms of smoothness.

Answer 4

NURBS surfaces created with Class A technical surfacing may be considered "airtight" surface meshes. B-spline mathematical surfaces include physical science dynamic compression/tension surface characteristics as "structurally loaded" systems model architectures. G-Code file formats now apply b-spline data in vector based tool path manufacturing. Raster based polygon smooth function is contrary to accurate modeling for functional engineered prototypes of zero tolerance accuracy. Smooth function provides unpredictable mesh as is undefinable approximation. Professional 3D Print solutions employ NURBS geometry G-Code directly and do NOT create polygon tessellated mesh as seen in common STL file formats.The future of 3D modeling and additive manufacturing is clearly vector based b-spline NURBS surface product architecture.