Groups > comp.graphics.apps.gnuplot > #390

Re: Can contour surface model be saved to file?

From	Hans-Bernhard Bröker <HBBroeker@t-online.de>
Newsgroups	comp.graphics.apps.gnuplot
Subject	Re: Can contour surface model be saved to file?
Date	2011-06-21 00:12 +0200
Message-ID	<969uv3F8k8U1@mid.dfncis.de> (permalink)
References	<5fcfa1fb-f678-4d88-887e-57fa4303df99@b3g2000vbm.googlegroups.com> <961o1dFmv7U1@mid.dfncis.de> <ca48d1dc-3031-4f81-9d47-6dc2111f822e@d14g2000yqb.googlegroups.com> <966dnbFp3rU1@mid.dfncis.de> <967126Ff39U1@mid.individual.net>

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On 19.06.2011 21:30, Ingo Thies wrote:

> One technical question at this point: How are the contours actually
> calculated in gnuplot?

Like I roughly described in my post 3 days ago.

First, you need a grid dataset.  This is triangulated by adding 
diagonals, and then we run "Marching Triangles" on the triangular mesh. 
  It looks for edges in the triangulation that go from above to below 
the contour plane.  Linear interpolation yields a point on each such 
edge where it can be assumed to cut through the contour plane.  Connect 
these dots triangle by triangle until you either hit a dataset boundary 
or find a complete cycle.  Repeat until all straddling edges are 
accounted for.  Repeat for all contour levels.

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Thread

Can contour surface model be saved to file? Bengt T <bengt_tornqvist@hotmail.com> - 2011-06-16 22:52 -0700
  Re: Can contour surface model be saved to file? Johan B <johan.barne@gmail.com> - 2011-06-17 03:07 -0700
    Re: Can contour surface model be saved to file? Bengt T <bengt_tornqvist@hotmail.com> - 2011-06-17 09:08 -0700
  Re: Can contour surface model be saved to file? Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2011-06-17 21:26 +0200
    Re: Can contour surface model be saved to file? Bengt T <bengt_tornqvist@hotmail.com> - 2011-06-19 00:37 -0700
      Re: Can contour surface model be saved to file? Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2011-06-19 16:00 +0200
        Re: Can contour surface model be saved to file? Ingo Thies <ingo.thies@gmx.de> - 2011-06-19 21:30 +0200
          Re: Can contour surface model be saved to file? Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2011-06-21 00:12 +0200
            Re: Can contour surface model be saved to file? Ingo Thies <ingo.thies@gmx.de> - 2011-06-21 16:00 +0200

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