Re: [Gnuplot-info] splot pm3d advice

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Anirban Banerjee wrote:

> The issue I am facing is while trying to plot a 3d graph with splot 
> using pm3d. I have  data file with data in the following format

> x y z
> x1 y1 z1
> .
> .
> .
> and so on ...

The problem starts here, already.  This format is not useful for 
plotting as a pm3d map.  It lacks information about which points are 
supposed to be connected to which other ones, in the surface you're 
plotting.

> x ranges from 1 to 500 , y from 1 to 6 and z from 1 to 100 .
> 
> when I use splot "data" u 1:2:3 w lines/points I can see that the scale 
> on the z axis is 0 to 100, but as soon as I type
> 
> set dgrid3d
> splot "data"  u 1:2:3 w pm3d
> 
> the resulting graph seems to get the z axis scaled down to 0 to 18 or 30 
> if I use set dgrid3d 30,30 .. why is this so..why is the z axis being 
> scaled???

It isn't the z axis that's being rescaled --- it's your data.  That's 
what dgrid3d does: it averages data z values, so the z range of its 
output will typically be smaller than that of the input.  Now, if only 
your data were in proper gridded format, you wouldn't need dgrid3d, and 
this whole problem wouldn't exist.  So I strongly suggest you read 'help 
glossary' and 'help splot datafile' about grid structure.