NX 12.0.0.27 - Extruded surface creates a convergent body 3

[tryitagain]

Hi NX 12 users,

attached a small surface where I used the extrude command with "face edges" to create a solid body. The feature turns out as an unuseable convergent body.

Does anyone within the NX community has a workaround for it?

Thanks in advance.

 

[BubbaK]

> Yep. Different entities on each body type. Ignore all those other facts concerning tessellations
> and different calculations - they don't matter, right?

Yes, different surface types generally require different calculation approaches. Computations on spheres, NURBS, and mesh surfaces are done differently, for sure. Does it matter? Sometimes, yes. When you intersect NURBS surfaces, you'll generally get icurve edges, and there are a few things you can't do with icurves -- you can't extrude them, for example. When you intersect mesh surfaces, you get polyline edges, and there are some things you can't do with polylines, today.

> Why even refer to each body type using different words if there are no fundamental differences?

That's a good point. I think the "convergent" terminology is marketing -- to emphasise that something new and cool is happening. But the new things are a new surface geometry type (mesh) and a new edge geometry type (polyline), not a new body type. Since we don't have a new body type, we don't need a new name. So, I predict that the terminology will change, because it doesn't really make sense, except maybe in a brochure.

> I don't have to convert it to do additional modeling tasks to it.

And (someday soon), you won't have to do any conversions on bodies that include mesh surfaces, either. You can already do booleans and offsetting, replace face, delete face, etc. Blending will be hard, but I expect it will come. Move face will probably never work very well, for the same reasons that it sometimes doesn't work very well with NURBS faces.

> The faceted representation would be fundamentally different - zero NURBS, zero spheres, zero center points,
> all faceted and edges would be polylines and all calculations are different.

What about a body that has some mesh faces, some spherical faces, and some NURBS faces. Do you regard that as fundamentally different from one that has zero mesh surfaces? Not a trick rhetorical question; I'd really like to know how you think.

> Probably won't respond to further replies

Me neither. I've already explained this as well as I can, and I'm starting to repeat myself.

> Have a happy Thanksgiving, Bubba.

I'm not American, so I don't celebrate Thanksgiving. But thanks, anyway. Enjoy your turkey.

 

[Xwheelguy]

But the new things are a new surface geometry type (mesh) and a new edge geometry type (polyline), not a new body type. Since we don't have a new body type, we don't need a new name.

So what’s a Convegent Body then? Certainly wasn’t around prior to all the allowable faceted modeling. Once you try to do anything with a faceted body the body type changes to a Convegent Body which today is still faceted all over. All facet body conversion commands give only options for different types of faceted bodies, none give the option to go to a traditional solid. If anything, they might add this to the Convert Solid as that’s the only hard evidence outside of the vision press releases up to this point of how to go back and forth between the two. If that’s how they plan to tackle it, then that is just more evidence pointing to two different bodies. The vision hasn’t been fully realized, if it even can be given the challenges they’ll eventually run into with blends and continuity control.

What about a body that has some mesh faces, some spherical faces, and some NURBS faces. Do you regard that as fundamentally different from one that has zero mesh surfaces? Not a trick rhetorical question; I'd really like to know how you think.

As far as I know that type of body doesn’t exist - Mr. Allen’s PDF even says that (all faces are all one or the other, not a mixture). A moody with mesh surface type is a Convegent Body which is 100% facets - every post on Siemen’s forum refers to convergent as faceted and the GTAC employee performed Booleans on a Convegent model with a traditional solid as the tool and the target remained faceted all over. It was still a Convegent body.

If the vision is ever fully realized to have a mixture between facets (mesh surface) and analytic surfaces, I would expect the software to still distinguish between a faceted model/"hybrid’ mixed face type and a traditional solid because not every user/customer is going to be very happy with facets on a body without being aware of it. Quite a few industries would have to buy into the concepts that facets are OK on the "master" math. Right now, I don’t see that happening across the board - too many styling types would object to the facets no matter what is presented or claimed as being just as good. You can’t even get them to openly settle on using just blending tools - they believe the blend surfaces have to be simpler and have the poles aligned to a ridiculous extent.

No matter what comes of it or what bodies are what, I can’t deny that being able to do any modeling tasks to a faceted is a pretty big accomplishment.

Tim Flater
NX Designer
NX 11.0.1.11 MP8
GM GPDL 11-A.3.4.2
Win7 Enterprise x64 SP1
Intel Core i7 2.5GHz 16GB RAM
4GB NVIDIA Quadro K3100M