Re: [cgmo-webcgm] Error in nurbs01 test

[Lofton Henderson <lofton@rockynet.com>]

Rob,

Checking this out...

At 02:03 PM 3/8/2006 -0700, Robert Orosz wrote:
>[...]
>
>There is an error in the nurbs01 test in the test suite.  It appears that
>the interpreter/viewer used to generate the reference PNG image ignored the
>weights in the NURBS element.

I just looked on the FTP site, and there is no NURBS01.PNG there!

So for starters, what are you looking at for the reference PNG?

In my working directory, I have a NURBS01.PNG that looks pretty 
circular.  Dave has just sent me an earlier version that looks lopsided 
circular -- there is a little extra bulge at 0, 90, 180, 270.  I have 
attached a reduced-size (400x400 instead of 2300x2300) version.

Does that look right to you?

If not, what do you *think* the PNG should look like?

Regards,
-Lofton.

>To illustrate my point, I've generated an
>equivalent file (without the boilerplate text labels) containing a NUBS
>element which is unweighted by definition.  The knot vector is identical to
>the nurbs01 test, and I've placed the control points at metrically
>equivalent positions in VDC space.  This file views identically to the NURBS
>element in the NURBS01.cgm file as depicted in the PNG image.  Applying
>weights to the spline should significantly alter the shape of the curve.
>
>You could do an equivalent test by using your convert program to remove the
>weights in the NURBS element (i.e. set them all to 1.0) in the NURBS01.cgm
>file.  You will see similar results.
>
>Regards,
>
>Rob
>
>  <<NUBS01_rob.cgm>>

NURBS01lh_sdi-small.png