[Mapserver-users] msProcessProjection(): Projection library error. major axis or radius = 0 or not given

[Pericles S. Nacionales]

Hi Tom,

I'm in the process of updating the tutorial for version 4.  I have no
answer as to why the LAYER projection objects no longer work without the
ellipsoid. However, it should work if you add "ellps=clrk66" to your
projection object.  The original data came in Lambert Azimuthal Equal
Area projection and uses Clarke 1866 as the ellipsoid.

Just so you know, shapefiles themselves don't require projection info. 
You can define a projection for it by adding a projection info (.PRJ)
file (I don't know the format) which ArcView 3.x would gladly use for
reprojection purposes.  If you are fortunate enough to have shapefiles
that come with .PRJ file, it includes ellipsoid (called spheroid) info. 
If the .PRJ file is missing, then you'd better hope to find a metadata
for your shapefile.  The metadata should have a projection info section.

-Perry N.

On Mon, 2003-08-11 at 17:13, Tom H wrote:
> Hi group,
> 
> > > If I comment out "proj=latlong"
> > > 	PROJECTION
> > > 		#"proj=latlong"
> > > 	END
> > > it outputs a map, and there is no error.
> > 
> > Tom,
> > 
> > You need an ellipsoid definition for the projection definition to
> > be valid.
> > 
> > eg.
> > PROJECTION
> >    "proj=latlong"
> >    "ellps=WGS84"
> > END
> 
> in Section 4 Example 1 - On-the-fly Reprojection at;
>  http://terrasip.gis.umn.edu/cgi-bin/mapserv35?map=/data/projects/tutorial35/s4/s4ex1.map&layer=water&layer=states&layer=relief&zoom=1
> 
> in the tutorial for 3.6 there is a projection block for the MAP;
> PROJECTION
>   "proj=laea"
>   "ellps=clrk66"
>   "lat_0=45"
>   "lon_0=-100"
> END
> 
> and then subsequent projection blocks for the layers;
>   PROJECTION
>     "proj=latlong"
>   END
> where there is no ellipsoid definition for each of the layers.
> 
> I downloaded all these tutorial files to my mapserver, which is a binary version 4.0 mapserver 
> on win2000, and im getting the same "msProcessProjection(): Projection library error. 
> major axis or radius = 0 or not given" error with the tutorial files.
> 
> so was there a default ellipsoid definition for earlier versions of mapserver?
> 
> and also; 
> 
> how do I find out the correct ellipsoid definition for shapefiles and their layers?
> 
> Thanks,
> 
> T.
> 
> 
> 
> 
> 
> 
> 
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-- 
Pericles S. Nacionales <nacional at cbs.umn.edu>
University of Minnesota