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Bart Rammeloo

NURBS tessellator in VW

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Hi guys,

Correct me if I'm wrong, but I believe that VectorWorks and Rhino use the same NURBS kernel (SMS's SMlib).

However, VW doesn't give you the same control level as Rhino - in different situations. Below you'll see an iges model, imported in both VW and Rhino.

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In the next image, you'll see the result form an export command in both applications. On the right you see the mesh produced by Rhino. On the left, the mesh produced by VectorWorks.

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I speak from experience when I say that re-using your model in a non-NURBS-supporting software package is a hell when it comes from VW, because you don't get square-ish tessallation, which is needed to get proper surface behavior and avoid render artifacts.

As it seems that SMLib offers the tools to control the tessallation algorithm, wouldn't it be a good idea to implement them in VW? Or is my reasoning totally off?

Cheers,

BaRa

[ 02-17-2004, 01:05 PM: Message edited by: BaRa ]

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Hi Chris,

I do agree with what you say. After all, VW is a hybrid of 2D graphics, 2D CAD and 3D NURBS-based modeling. So it's quite unique in its own.

However, as far as I know (and correct me if I'm wrong), VectorWorks and Rhino use the same NURBS foundation, namely SMLib. They didn't develop their own NURBS kernel, it was licensed from another manufacturer (just as the RenderWorks technology isn't "made" by NNA).

Rhino has better NURBS tessellation options than VW - or at least, offers more control. There can be two reasons for this: either is has been developed by the Rhino guys, or it's a feature included in SMLib.

I'm guessing here, but I think the latter is true. And if that's the case, then it's really a matter of implementing it in (and not developing it for) VectorWorks.

B.T.W.: Rhino is cheaper than VW, so it can't be price related.

Cheers,

BaRa

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BaRa

Sorry to be slightly off string, but you sound knowledgeable. How would you say that Rhino and VW compare? Which is good where, and visa versa which is bad where?

How do you think Amapi, FormZ & Ashlar compare?

After your post, I took a look at the Rhino site, ........very interesting!

I am freelance and much as I love VW, I am looking for something a little less constraining than VW, but it must be accurate, quick to learn and suit a free lancers pocket.

Thanks

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Hi Christian,

Rhino exists only for PC - not for Mac. It's mainly a surface modeler, whereas VW is also capable of performing very good solid operations (and it keeps the construction history of those operations, whereas Rhino doesn't). Rhino has a pretty good interface, although it's not really mainstream.

Rhino cannot handle 2D operations. Which means that, if you want to create 2D projections and sections from your 3D model, you're stuck.

I don't think it can be a replacement for VW. In the current situation, it can be an interesting addition, especially since you can use the IGS format to exchange data between both packages.

Form-Z has (IMO) a rather clumsy interface. VectorWorks is easier to use than Form-Z, and has better (more stable) NURBS than Form-Z. I would never trade in VW for Form-Z. But that's only my opinion, of course [smile]

I never used the Ashlar line-up, but it's more of an industrial design tool. For what it's worth: according to the grapevine Xeon, Cobalt and Co. used to be quite unstable. Don't know what it's like nowadays.

Cheers,

BaRa

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BaRa, since your essentially exporting polygons, you could export STL from vectorworks...there is a tesslation setting there. I've imported stuff into form_Z this way with reasonable success.

I see a lot of confusion regarding form_Z, Rhino,and VW. Here's my 1 cent. Personally, I use all 3. Vectorworks primarily for drawing creation (it's a CAD program), but am using it more for 3D as the 3D power pack develops. Rhino I use for organic modeling (ps. it is a nurbs surface modeler, but mathematically, a solid is a volume enclosed by surfaces, so Rhino can export SAT solids all day long). VW can't touch Rhino nurbs at this point. Form_Z is a little complicated to learn at first, but once you learn it's tool set, it is really a powerful modeler. Vectorworks is the tool of choice if you have to produce drawings. If you're doing 3D visualization and producing renderings, then Rhino or Form_Z, and if you're doing visualization on a Mac, then form_Z is the 3D modeler with the best tools (at this point). I'd have to disagree with BaRa about form_Z nurbs tools though, they work great for me. Check out the respective galleries for form_Z and Vectorworks to get an idea of what's getting modeled on each platform.

[ 05-05-2004, 01:26 PM: Message edited by: tom kyler ]

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Actually, Rhino, VW, and a couple of other 3D modelers all use SMlib as a NURBS kernel. So technically speaking, they're all capable of doing the same type of stuff. As far as I know, Form-Z uses another kernel. The stuff that bothers me with form-Z are the selfintersecting roundings. They frequently fail. VectorWorks has less problems with that.

Before the NURBS functions in VW, there wasn't a doubt that Form-Z was better at 3D. But now, everytime I meet form-Z users and show them what is possible, they all are very impressed. I have no problem whatsoever of using the Form-Z tutorials in VW. It's not a one on one translation (their internal logic differs), but it gives the same final result.

About the STL: not really an option for me, because it doesn't support anything else than geometry. It's all very well if it's an object in one piece, but the VW to C4D exporter supports material categories, so for most models, this method is a better solution, if it weren't for the incontrolable tessalation.

Cheers,

BaRa

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I know that lightworks, which licenses it's rendering routines to vectorworks and form-Z comes with different levels of rendering routines. I might guess that even though Rhino and VW uses the same kernel, it could be that Vectorworks doesn't license the complete set of modeling routines that Rhino does. Since VW incorporates so much more functionality though, that would explain it's higher price currently. Also, each developer is responsible for programming it's own "front-end" for the modeling routines. I would hope that VW is incorporating more of the features from SMlib in the future. I know Rhino has some NURBS tools I would love to have in VW. Time will tell.

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Hi Tom,

It would be helpful for us to know the list of features that you think are missing in VW when compared to Rhino.

Thanks.

--Biplab

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Biplap, one features that comes to mind is "offset surface" or "extrude suface"...like a curved nurb surface extruding in the normal direction at each point on the surface

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Tom,

We do thcikening of surface - using the Shell tool - which uses offset surface.

--Biplab

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