Contour Plots, Delaunay triangulation, and Plotmtv

[John Smith]

A summary of my progress:

I collected plotmtv 1.4.1 from a mirror of ftp.x.org. 
(a 1.4.3t version exists but I have not tried it)
It compiled cleanly, comes with a good manual, and generates bright and
bold contour plots (and many other 2D and 3D graphs). Well worth a look.

Given some data not sampled from a rectangular grid (mine came on a polar
grid), plotmtv can triangulate the data and draw contours on the
triangular mesh. My experience was that the meshing algorithm was poor.
The code's documentation admits that meshing is not perfected yet.
I replaced it with Steve Fortune's 2D Delaunay meshing algorithm
(indirectly available from www.voronoi.com), and generated a much better  
mesh. The substitution was a simple hack. An example of one of these
contour plots is at

         http://www.arrows.demon.co.uk/plotmtv/mtv_example.html

Ted Harding provided a simple framework of Octave code to drive plotmtv
(see previous emails), which is dispite its simplicity, must be worthy of
wider distribution.

I am happy to say that with Octave+Fortune+Plotmtv I now generate better
plots than with Matlab! A reversal of the position 4 days ago.

Thanks to everyone,
  John Smith




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