How do I plot measured data (was: GnuPlot; Contour + Contour + Plot)

[Cameron Laird]

On Mon, Sep 25, 2006 at 05:29:48PM +0200, Stefan de Konink wrote:
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> I want to plot two contours and a plot with datapoints on top of
> eachother. I got the contours to work with hold on; But when I want to
> plot on top of it with the original datapoints I get the following error:
> 
> gnuplot> sp '/var/tmp/oct-zU9WJn' u 1:2:3 t "line 1" w lines 1,
> '/var/tmp/oct-vzTH1t' u 1:2:3 t "line 2" w lines 1, '/var/tmp/oct-UCFB0C'
> u 1:2 t "" w dots 3,   '/var/tmp/oct-xwitFD' u 1:2 t "" w dots 1
> 
> ^
>          line 0: 2 columns only possible with explicit pm3d style (line 5)
> 
> Ofcourse I tryed the explicit style which produced a beautiful gradiant,
> but that is not what I want ;)
> 
> How is this possible?
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This is interesting to me.  While I can't help at all with your
question, perhaps you can help me.

As I read the gnuplt and especially pm3d documentation, I thought
that contours can only be drawn for parametrized data ("filled-out"
matrices), rather than sparse measurements.  I've tried all sorts
of
  splot "mine.dat"
without ever seeing anything useful in case 
  set pm3d at st
Does anyone have an example of measured data plotted as color levels,
a 3D graph, contours, surfaces, or anything *other* than individual
points-in-space?