[mapserver-users] Mapserver and projcs in geotiff header

[Jørn Vegard Røsnes]

Hi Frank,

good timing I just finished compiling mapserver 5.6.5, gd, proj, geos,.....


On Thursday 28 October 2010 15:35:54 Frank Warmerdam wrote:
> Jørn Vegard Røsnes wrote:
> > Hi all,
> >
> > just a feature check of Mapserver.
> >
> > Should Mapserver read the projection information in the geotiff header,
> > if PROJECTION is not set in the LAYER def. of the map file?
> >
> > I'm testing with Mapserv 5.1-dev, and it's not working without
> > PROJECTION, only when PROJECTION is set.
> > I will soon try with a recent version of Mapserver (compiling).
>
> Jørn,
>
> MapServer does not ask the underlying data source for coordinate system
> information by default.  However, you can setup a projection block like:
>
>    PROJECTION
>      "auto"
>    END
>
> to automatically read the projection through GDAL.  This is a little
> used feature, so it is possible it is broken now.  

"auto" works.
Not so accurate as the result with proj4 in PROJECTION enabled (map file), but 
it is probably due to the geotiff headers.

Thank you very much.

cheers
Jørn Vegard

> The normal projection 
> block for your coordinate system would look something like:
>
>    PROJECTION
>      "+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +datum=WGS84 +units=m
> +no_defs" END
>
> If it is intended to be "google mercator" then you should use:
>
>    PROJECTION
>      "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0
> +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs"
>    END
>
> Best regards,