[Mapserver-users] Using MapServer as a general graphing engine

[Stepan Kafka]

I have tried this approach, but without success. I got an error message:

msLoadMap(): General error message. Undefined overlay symbol ...

It seems that mapserver does not support http://.. symbols in current
version (4.0b). What version does it support?

Stepan Kafka

> -----Pùvodní zpráva-----
> Od: mapserver-users-admin at lists.gis.umn.edu
> [mailto:mapserver-users-admin at lists.gis.umn.edu]za uživatele Daniel
> Morissette
> Odesláno: 28. èervence 2003 21:29
> Komu: Tyler Mitchell
> Kopie: mapserver-users at lists.gis.umn.edu
> Pøedmìt: Re: [Mapserver-users] Using MapServer as a general graphing
> engine
>
>
> Tyler Mitchell wrote:
> >
> > I'm thinking more along these lines:
> >
> > - I have x,y data where these are two non-geographic values
> that I want to
> > graph.  I have z which is the magnitude, count, etc. that I
> want to graph.
> > - Use a simple coordinate system to map the "location" of the
> x,y pairs and
> > draw the symbol based on the z value.
> > - z may be a value used as a radius for a circle or there may
> be a z- and
> > z+ which defines the vertical offsets of the extents of a bar/rectangle.
> >
>
> Actually, instead of a full integration with GDChart as suggested in my
> previous message, we could add support in MapServer for symbols that
> come from an URL, and this URL could contain [field] replacements,
> similar to what we can do with query template URLs already.
>
> So you could define a layer like this:
>
>    LAYER
>      CLASS
>        ...
>        SYMBOL
> "http://127.0.0.1/cgi-bin/owtchart?type=pie&numpts=3&vals=[VALUE_A
]![VALUE_B]![VALUE_C]&xlabels=A!B!C&w=400&h=400"
     END
   END

This wouldn't be very fast, but would work fine for relatively small
number of symbols.  When MapServer encounters a symbol name that starts
with http:// then it would do the field value replacements ([VALUE_A],
[VALUE_B] and [VALUE_C]), and then call the URL to download the symbol,
a chart in this case.

Another benefit of this approach is that you could link to about
anything that can dynamically generate images, not just charts.

Daniel
--
------------------------------------------------------------
  Daniel Morissette               morissette at dmsolutions.ca
  DM Solutions Group              http://www.dmsolutions.ca/
------------------------------------------------------------

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