| Re: Problem: Filled contour Plots [message #16534] |
Wed, 04 August 1999 00:00 |
R.Bauer
Messages: 1424
Registered: November 1998
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Senior Member |
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amit99@my-deja.com wrote:
> I have been trying to make contour plots where some of the levels are
> filled either with lines or with a solid color, with limited success.
>
> I am using map_set to define a grid and plot gridded data over the
> globe. My plotting instructions are as follows:
>
> contour,indata,lon,lat,/overplot,nlevels=3,c_orientation=[45 ,45,0]
>
> sometimes it works and sometimes I get the error message:
>
> Internal error: Border sort.
>
> With some of the datasets I try to plot, even though all my datasets
> have exactly the same format. I also get the same error message if I
> try to specify the levels I want to plot with levels=[...]
>
> Any Insights ?
>
> Amit amit@physics.utoronto.ca
>
> Sent via Deja.com http://www.deja.com/
>
> Share what you know. Learn what you don't.
The online help says:
CELL_FILL
Set this keyword to produce a filled contour plot using a "cell filling"
algorithm. Use this keyword instead of FILL when you are drawing filled
contours over a map, when you have missing data, or when contours that
extend off the edges of the contour plot. CELL_FILL is less efficient
than FILL because it makes one or more polygons for each data cell. It
also gives poor results when used with patterned (line) fills, because
each cell is assigned its own pattern. Otherwise, this keyword operates
identically to the FILL keyword, described below.
------
Caution
In order for CONTOUR to fill the contours properly when using a map
projection, the X and Y arrays (if supplied) must be arranged in
increasing order. This ensures that the polygons generated will be in
counterclockwise order, as required by the mapping graphics pipeline.
Caution
Do not draw filled contours over the poles on Cylindrical map
projections. In this case, the polar points map to lines on the map, and
the interpolation becomes ambiguous, causing errors in filling. One
possible work-around is to limit the latitudes to the range of -89.9
degrees to + 89.9 degrees, avoiding the poles.
R.Bauer
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