WMS GetMap not using Lat/Lonprojection

McGraw, Joanne mcgrawj at AGR.GC.CA
Tue May 3 11:58:10 EDT 2005

Hi Frank,

Is simply copying this file enough? Or, do I also need to add some
indication that the grid shifts should be used somehow? 

The reason I ask is that I tried just copying the file and it hasn't had
any effect. I was reading the "nadgrids - Grid Based Datum Adjustments"
section at http://proj.maptools.org/gen_parms.html and was wondering if
I should be creating a new definition (with the +to NAD27 from NAD83) in
the epsg file and using that as the projection definition.

Is the use of this data file something that has been introduced
recently; that is, post-MapServer 4.4.0? Perhaps, it is just not being
referred to in the version I have?


-----Original Message-----
From: Frank Warmerdam [mailto:fwarmerdam at gmail.com] 
Sent: Tuesday, May 03, 2005 10:50 AM
To: McGraw, Joanne
Cc: MAPSERVER-USERS at lists.umn.edu
Subject: Re: [UMN_MAPSERVER-USERS] WMS GetMap not using

On 5/3/05, McGraw, Joanne <mcgrawj at agr.gc.ca> wrote:
> 1. In my map file, I added a config line within the map object:
>     config      PROJ_LIB /usr/local/proj-4.4.5/nad/
> And have verified that the epsg data file actually exists there. The
NAD83 still does not appear when I try to display the layer in map mode.
There is no error or anything, just a blank display as though the
contents simply don't fall within the extents of the map (I have triple
checked this possibility).


The critical item for the layer in question is whether the
ntv1_can.dat file (or better yet ntv2_0.gsb) exists 
in the directory /usr/local/proj-4.4.5/nad.  This is not
installed by default with PROJ.4 - you need to separately
download the datum shift files and unpack them before 
configuring and installing PROJ.4.   

Assuming you have the ntv1_can.dat file on your development
server, you can just copy that one file over to your corporate
server if you want.  

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam,
warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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