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New Nurbs features


Kaare Baekgaard

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I am very pleased with the new modelling features in version 10.5. Here are a couple of wishes for nurbs in 11:

1. The ability to change a planar nurbs curve into a surface - and the edges of any nurbs surface into curves. I can do both of these today, but it takes several clicks.

2. The ability to chose method of conversion when extracting a nurbs curve from a solid: When I try to extract very simple curves, I get very complex results with lots of anchorpoints - a lot more than is required to describe the shape of the curves.

(To prove this extrude a simple planar nurbs curve and extract its egde: the three or four control points have now become dozens!)

I would like to be able to chose between methods of extraction or choose the acuracy af the resulting curve, so I can get some control over the complexity of the curve. (Or you could just fix the problem :-)

3. Hypernurbs!

4. Speed! ? Working with nurbs has become frustratingly s l o w!

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The HyperNURBS in C4D are actually nothing more that a polygon tesselator. Same thing exists in LightWave, Max, Maya, XSI and a lot of other applications. It has nothing to do with NURBS. Great tool for producing visuals, but not usable for design (where precission is required).

One piece of software capable of doing such a thing with mathematical precision is Maya (another one would be the higher end versions of StudioTools). Maya has (at least) 3 geometry types: polygons, NURBS and Subdivisions. Subdivisions (or subdivision surfaces) use a polygonal grid to produce a resolution independant smooth surface, which can be converted to NURBS. This can actually be used to model production-oriented geometry.

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> The HyperNURBS in C4D are actually nothing more that a polygon tesselator. Same thing exists in LightWave, Max, Maya, XSI and a lot of other applications. It has nothing to do with NURBS. Great tool for producing visuals, but not usable for design (where precission is required).

I, for one, would still like to see the functionality of C4D's HyperNURBS inside VW. I've been studying this online tutorial (http://www.7thchamber.com/tutorials/Chev/) on how to model a car using C4D and am very much impressed with the ease on how the shapes were modeled and reformed.

It would be interesting to see how a VW modeler would approach the same problem.

Ariel

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I personally like the idea of having extra modeling options in VW.

But incorporating C4D's HyperNURBS in VW would actually be a step backwards. VW has a more advanced modeler than C4D: first of all, VW can use polygons (faces) with more than four points, while C4D can only handle 3 or four points per polygon. Second, VW uses NURBS as well as polygons, while C4D can only use polygons.

Unlike the name suggest, HyperNURBS have nothing to do with NURBS surfaces. HyperNURBS are just a method to tesselate a polygon surface in an organic way. Granted, C4D's subdivision system is pretty good given the internal limits of the application - not every app is capable of applying point, edge or face weight. But from a technical point of view, it's still rather limited.

Maya, OTOH, is much closer to VW than C4D. Maya also knows NURBS (but uses a different kernel) and can also handle n-gons (polygons with more than 4 points). Maya knows two subdivision systems: one that operates on polygons refered to as smoothing, and one that produces what is know as Subdivision surfaces. The former is comparable to what you know in C4D. The latter is however much more advanced: it can use a polygon "Cage" to produce resolution independant surfaces. It combines the advantages of polygons - ease of use - and the advantages of NURBS - C2 surfaces. Introducing this in VW would be a real asset.

To summarize: I stand behind the idea of having a Subdivision modeling system in VectorWorks. But using C4D's system as a (technical) reference is not such a good idea. Maya's sub-D's would be a much better base.

Cheers,

BaRa

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Thanks for clearing that up BaRa.

Personally I could live happily ever after with the lack of acuracy of a polygon tesselator (weird term).

I suppose it would be no different from the inherent inacuracy of mesh objects, which worked fine with me until recently.

But if it could not be converted into true nurbs surfaces, it would be somewhat like a one way street with a dead end.

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