[Proj] Data Plotted at Wrong Location

Ed McNierney ed at topozone.com
Mon Dec 10 11:57:51 EST 2007

Toan -


This is probably a better question for the MapServer list, but you're on
the wrong path.  Put the 42304 definition back the way it was - that's


The EPSG:42304 projection is a Lambert Conformal Conic projection, and I
assume that's what you want to use for your OUTPUT map image.  Its units
are not in decimal degrees, nor can they be.  You have an INPUT data
layer in decimal degrees, and you'd like MapServer to reproject that
data to your output projection.


Your top-level MAP file needs the PROJECTION definition you describe
below, and then you also need to have an appropriate PROJECTION block
inside the LAYER definition for the layer in decimal degrees.  That
tells MapServer that your input and output data are in different
projections, and the data need to be reprojected.


The correct EPSG definition for your input data in decimal degrees will
depend on what datum those coordinates use.


-          Ed     


Ed McNierney

Chief Mapmaker

Demand Media / TopoZone.com

73 Princeton Street, Suite 305

North Chelmsford, MA  01863

ed at topozone.com <mailto:ed at topozone.com> 

Phone: +1 (978) 251-4242

Fax: +1 (978) 251-1396


From: proj-bounces at lists.maptools.org
[mailto:proj-bounces at lists.maptools.org] On Behalf Of Tran, Toan (MCYS)
Sent: Monday, December 10, 2007 11:32 AM
To: proj at lists.maptools.org
Subject: [Proj] Data Plotted at Wrong Location



I wish to plot several points in Canada, but the problem is that the
points are plotted at the wrong location. My data are in decimal degree
stored in a CSV file. I am guessing that Map Server plots the points  in
meters instead of degree.

I used this in my map layer: 

I added this for epsg: 
<42304> +proj=lcc +lat_1=49 +lat_2=77 +lat_0=49 +lon_0=-95 +x_0=0 +y_0=0
+ellps=GRS80 +datum=NAD83 +units=m +no_defs  no_defs <>

I try changing: 
 - <42304> +proj=lcc +lat_1=49 +lat_2=77 +lat_0=49 +lon_0=-95 +x_0=0
+y_0=0 +ellps=GRS80 +datum=NAD83 +units=dd +no_defs  no_defs <> ....
this causes a msProcessProjection(): Projection library error. unknown
unit conversion id error

 - UNITS METERS to UNITS DD in my map file, but that doesn't help. 

Sample DATA: 


Any help is much appreciated 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.maptools.org/pipermail/proj/attachments/20071210/58532031/attachment-0001.html

More information about the Proj mailing list