[mapserver-users] Re: display isolines with raster data

[windfreak]

I tested gdal_contour and it actually looks ok. I think I can use that as a
pre process for mapserver.
My eye immediately fell on gdal_polygonize because I think that can create
polygon shapefiles. I haven't got gdal_polygonize running yet because of
some compatibility errors (gdal.Polygonize() not available) but will try to
find that out.

Thanks for your help



2010/2/1 Frank Warmerdam [via OSGeo.org] <
ml-node+4495096-771874491 at n2.nabble.com<ml-node%2B4495096-771874491 at n2.nabble.com>
>

> windfreak wrote:
> > I am wondering if it's possible to present isolines from raster data. I
> have
> > NETCDF/GRIB/HDF5 data and want to plot lines. Until now I haven't found
> any
> > examples like that.
> >
> > If it's not possible, I think the best workaround is to create an
> > application that generates shapefiles from raster data. Then I can use
> these
> > shapefiles to plot lines with mapserver. Do you have suggestions for
> better
> > workarounds?
>
> Windfreak,
>
> MapServer does not support computing isolines on the fly, though you might
> get a vaguely similar effect by defining a class for each iso level with
> different colors.
>
> You can use the GDAL/OGR gdal_contour utility to produce iso-contours from
> a raster file. Be aware that it produces very fine isolines with one
> segment
> for each pixel crossed so some simplification might be appropriate before
> using the results for map rendering.
>
> Best regards,
> --
> ---------------------------------------+--------------------------------------
>
> I set the clouds in motion - turn up   | Frank Warmerdam, [hidden email]<http://n2.nabble.com/user/SendEmail.jtp?type=node&node=4495096&i=0>
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