Plug-ins to translate files from and to SW

Title says it all:

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Never tried any, don't know how good/ useful they are. HIH JM

Reply to
Jean Marc
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basically we need a 2008 iges version.

Reply to
vinny

Yep, seems they all use the same base stuff.

though

Agreed. Actually to a big degree.

Uncertain. After all, what better math exists beyond

I read an article explaining how nurbs suck. Kinda eye opening. If I find it ill post it.

It has to be computable ... and,

Reply to
vinny

I don't understand half of what you wrote, maybe you should of put it in your own words.lol

There's a good article on it ill try to post tommorrow, but I will throw a few things out there now. disclaimer(never took calculus or even advanced algebra, so I am not trying to be a spline expert.)

Nurbs are a good thing for lots of reasons. the main reason is its become a standard, even though there's different levels of nurbs, for the most part its standardized. The second thing and reason it was invented was to have surface patches blend to each other on the edges. There's an old wives tale that says Ford invented the form patch for hoods on their cars, so different outsourced hoods would match. problem came when they added hood scoops, the hood scoop was a patch, and the edges weren't smooth or didnt blend smooth. So they invented coons patches. a way of blending multiple form patches on the edges. that was the standard for a long time. Cam systems used these surface formulas for a while, till surfcam began using nurbs.

The benefit of nurbs over coons patches is the defining geometry need only be two edges. However, those 2 edges need the same amount of control points. problems show up when one edge is simple and one edge is complex. It can make unexpected surfaces if they are too different.

the real problem with nurbs is trimming. trimming is bad. Trimming turns your simple geometry into complex geometry. For years on cam systems, once a surface has been trimmed, its stuck that way. Cant do anything to that edge. Cant retrim it, cant extend it, etc... The surface is basically broken at that point.

Another problem is for the nurbs surface corner to be accurate it needs to touch 4 surfaces. Without that the surface could be different. If you make a hood, without the surfaces touching it the corner could be wrong and not be smooth to the rest of the car where it meets the hood.

I have no idea what Im talking about by the way. I half understand it, but always endup walking away saying who gives a rats ass. lol

nurbs holds us to 4 sides. If your software makes a 3 sided surface its because it added a tiny fillet in one corner making it 4 sided. Nurbs needs

4 sides to be smooth to other patches. Because it is an "approximation". Nurbs are used to make patches. Problem is there's more to a surface than just the edges.

There's a new math for splines...called nss. basically surfaces are built from curves, not control points. All thats needed is 2 curves, they can be different in complexity, in fact they can be any curve, even one from the edges of many surfaces. So what about ruled surfaces? they are not nurbs. Nurbs surfs need 4 sides/ nss surfs need 2 minimum. One curve can be a boundry from 10 surfaces.

Hell, im way over my head. I will hunt down that article and post it. If anything I said was wrong, feel free to correct me. Im half trashed and all holloweened out.

Reply to
vinny

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