Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!evax!utacfd!letni!texsun!csccat!larry
From: larry@csccat.cs.com (Larry Spence)
Newsgroups: comp.graphics
Subject: Re: curve represenation
Keywords: bezier or b-spline
Message-ID: <4012@csccat.cs.com>
Date: 15 Nov 90 20:33:57 GMT
References: <1990Nov14.160528.10333@progress.com> <1990Nov14.193732.570@watcgl.waterloo.edu>
Reply-To: larry@csccat.UUCP (Larry Spence)
Organization: Computer Support Corporation. Dallas,Texas
Lines: 30

In article <1990Nov14.193732.570@watcgl.waterloo.edu> rhbartls@watcgl.waterloo.edu (Richard Bartels) writes:
>In article <1990Nov14.160528.10333@progress.com>
>as@progress.COM (Amitabh  Shukla) writes:
>>
>>What I want to know is what is the industry standard to store information about
>>curves? The choices being bezier curve or uniform/non-uniform
>>b-spline represenation.
>>
>Given those choices, the answer would have to be Bezier.

The table below doesn't mention rational vs. non-rational curves.  An important
point is that non-rational cubics cannot exactly represent conics.  Of course,
Mr. Bartels knows this, but Mr. Shukla may not.

>Thus it is that one sees Bezier representation as a frequent industry
>choice for representation and interchange.

I'm not a CAD guru, but I had the impression that many CAD systems are using 
NURBS as an exchange format (i.e., IGES format).

>   [non-uniform splines]
>   The evaluation algorithm is more complicated than the one for Bezier
>   splines.

And NURBS are even nastier. %)

-- 
Larry Spence
larry@csccat.cs.com
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