[postgis-users] NAD conversion problem

Sat Jan 29 15:06:29 PST 2011

Thanks!

Copying the directory \share\contrib\postgis\proj from the zip to
program files (C:\Program
Files\PostgreSQL\9.1alpha1\share\contrib\postgis\proj ) and restarting
postgres helped.

I have to admit, that I installed postgres and postgis by hand.

Though I actually can't remember where I could have missed that copy
step. And I could'nt think share\contrib\ would be a place where
runtime programs would look into since typically there are sql files
in there which need to be loaded by hand while doing a db or template
setup.

Yours, S.

2011/1/29 Paragon Corporation <lr at pcorp.us>:
> Stefan,
>
> Our apologies.  We'll clarify the instructions.
>
> The batch script doesn't copy the files in the share/contrib folder.  I'm
> debating if it should or not, part of me thinks it should but most of me
> thinks not since people often have newer versions of those.
>
> For windows install, the nad shift files are hard-coded to first look in
> share/contrib/postgis as you probably guessed.
>
> I guess our fear was if you were installing on an existing PostgreSQL with
> another version of PostGIS, we really didn't want to override that folder.
>
> If anyone else has thoughts on the matter, please let us know.  At anyrate
> we should clarify the instructions.
>
> Thanks,
> Regina and Leo
> http://www.postgis.us
>
>
>
>
>
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Stefan
> Keller
> Sent: Saturday, January 29, 2011 4:33 PM
> To: PostGIS Users Discussion
> Cc: Frank Warmerdam
> Subject: Re: [postgis-users] NAD conversion problem
>
> Hi,
>
> I'm having problems with grid shift files and I suspect it's an installation
> or compilation-config. problem:
>
> This works:
> # SELECT ST_AsText(ST_Transform('SRID=900913;POINT(977705
> 5981192)'::geometry, 21781))
> But this...
> # SELECT ST_AsText(ST_Transform('SRID=900913;POINT(977705
> 5981192)'::geometry, 4326))
> .. gives following error:
>> FEHLER:  transform: couldn't project point (977705 5.98119e+006 0):
>> failed to load NAD27-83 correction file (-38)
>> HINT:  PostGIS was unable to transform the point because either no grid
> shift files were found, or the point does not lie within the range for which
> the grid shift is defined. Refer to the ST_Transform() section of the
> PostGIS manual for details on how to configure PostGIS to alter this
> behaviour.
>
> I installed Postgres 9.1alpha and PostGIS 2.0 on Windows XP (experimental
> binaries) using the makepostgisdb.bat ( from
> http://postgis.refractions.net/download/windows/pg91/experimental/postgis/po
> stgis-pg91-binaries-2.0.0svn.zip).
> Below you see the contents of srid=900913 in my spatial_ref_sys  table
> (should be the most recent).
>
> That's what I observed: Looking at the contents of this zip there is a
> directory ".\share\contrib\postgis\proj". But looking at makepostgisdb.bat
> this directory (and its content including files calles nad*) is ignored.
> There is consequently also no proj files under program files bin, lib, share
> (e.g. C:\Program Files\PostgreSQL\9.1alpha1\ ). Under linux you wrote
> elsewhere that the appropriate location of these files should be
> /usr/local/share/proj and /usr/share/proj.
>
> => How can I make this transformation EPSG:900913 => 4326 work under
> Windows?
>
> => To me, either .\share\contrib\postgis\proj should be deleted from .zip
> delivery (because it's compiled into dll?)
>     or makepostgisdb.bat should install/copy this proj directory somewhere
> into %PGBIN% or %PGLIB%.
>
> Yours, S.
>
> ---
> SELECT srid, auth_name, auth_srid, proj4text, srtext FROM spatial_ref_sys
> WHERE srid=900913; 900913;"spatialreferencing.org";900913;"+proj=merc
> +a=6378137
> +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +units=m +k=1.0
> +nadgrids=@null +no_defs";"PROJCS["Popular Visualisation CRS /
> Mercator (deprecated)",GEOGCS["Popular Visualisation
> CRS",DATUM["Popular_Visualisation_Datum",SPHEROID["Popular
> Visualisation
> Sphere",6378137,0,AUTHORITY["EPSG","7059"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY
> ["EPSG","6055"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree
> ",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4055"]],UN
> IT["metre",1,AUTHORITY["EPSG","9001"]],PROJECTION["Mercator_1SP"],PARAMETER[
> "central_meridian",0],PARAMETER["scale_factor",1],PARAMETER["false_easting",
> 0],PARAMETER["false_northing",0],AUTHORITY["EPSG","3785"],AXIS["X",EAST],AXI
> S["Y",NORTH]]"
>
>
> ---
>
> 2009/9/28 Frank Warmerdam <warmerdam at pobox.com>:
>> Peter N. Schweitzer wrote:
>>>
>>> So my hypothesis--please help me understand how wrong this is--is
>>> that the @null has the effect of keeping proj going when I project a
>>> point that is not in the areas covered by the nad27-to-nad83 conversion
> tables.
>>
>> Peter,
>>
>> Yes, this is the expected behavior of including null in a list of
>> nadgrids. It is a fallback for quietly doing nothing if no other
>> matching grid is found.  BTW the @ prefix means it's ok for the grid
>> to not be found at all.   So if you wanted conus to be used for the
>> continental US, and do nothing outside that region you could use
>> +nadgrids=conus, at null while +nadgrids=@conus, at null means if the conus
>> grid does not exist it is ok to do nothing everywhere.
>>
>>>I have
>>>
>>> to admit, as you probably suspect already, that I really don't know
>>> this stuff very well.  And since the data are not highly accurate in
>>> any case, the difference won't matter much in any analysis of the
> converted data.
>>> But this is what I'm thinking.  Your counsel would be welcome!
>>
>> OK, as long as you understand the potential for error involved.
>>
>> 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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