WMS GetMap not using Lat/Lonprojection

[Frank Warmerdam]

On 5/3/05, McGraw, Joanne <mcgrawj at agr.gc.ca> wrote:
> 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?

Joanne, 

I think just copying it should be fine. 

Internally +datum=NAD27 is defined as:

+nadgrids=@conus, at alaska, at ntv2_0.gsb, at ntv1_can.dat

That is, it searches for the conus, alaska, ntv2_0.gsb and then
ntv1_can.dat files till it finds a file overlapping the region to 
be converted.  So you shouldn't need to do anything special
to use this file. 

If it still isn't worked, I am somewhat confused.   I am assuming
that MapServer is able to load the epsg file which is the
same directory, so it shouldn't be a permissions problem on
the directory path, though you might want to check the permissions
on the ntv1_can.dat file itself. 

My next suggestion would be to test interactively with
shp2img.

eg.
shp2img -m pei.map -o out.png

If you set the PROJ_DEBUG environment variable to a 
value (any value) then you should get detailed reports
from the PROJ.4 library on files that it tries to open.   This
might provide a clue. 

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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