[postgis-users] NAD conversion problem

[Richard Greenwood]

On Mon, Dec 8, 2008 at 12:19 PM, Peter N. Schweitzer
<pschweitzer at usgs.gov> wrote:
> Richard Greenwood wrote:
>>
>> On Thu, Dec 4, 2008 at 1:19 PM, Peter N. Schweitzer
>> <pschweitzer at usgs.gov> wrote:
>>>
>>> Hello,
>>>
>>> I have two PostgreSQL installations.  One uses 8.3.3 with PostGIS 1.3.3,
>>> GEOS 3.0.1, and PROJ 4.6.1 (with proj-datumgrid-1.4).  With it I am able
>>> to
>>> run a command like
>>>
>>> update county set nad27_geom=ST_Transform(the_geom,4267);
>>>
>>> My newer installation uses 8.3.5 with PostGIS 1.3.4, GEOS 3.0.3, and
>>> PROJ 4.6.1.  With this system I get the error message
>>>
>>> WARNING:  transform: -38 (failed to load NAD27-83 correction file)
>>> ERROR:  transform: couldn't project point: -38 (failed to load NAD27-83
>>> correction file)
>>>
>>> I know that proj-datumgrid-1.4.zip must be unzipped in the nad/
>>> directory of proj-4.6.1 PRIOR to running configure.  I have done this.
>>> I have also recompiled and reinstalled proj, GEOS, and PostGIS in that
>>> order, running ldconfig at the end of each step.  The directory
>>> /usr/local/share/proj on each of these systems is identical.
>>>
>>> I've tried recreating the database cluster, starting and stopping
>>> the database instance, rebooting the machine, dropping and rebuilding
>>> the spatial database, all to no avail.
>>>
>>> So I'm looking for some setting that I may have missed, some environment
>>> variable, or some trick to tell libproj.so.0.5.5 where its transform
>>> files should go.
>>>
>>> Both systems run Slackware 12.1.
>>>
>>> I'm at wit's end.  Any clues?
>>>
>>> Pete
>>
>> PROJ_LIB is an environment variable that points to the directory
>> containing grid shift files and EPSG parameter files.
>>
>> The grid shift files are binary and platform specific. Is it possible
>> that you are using Windows grid shift files on a Linux system?
>>
>> You could also rule out issues related to the different versions of
>> Postgres and PostGIS on you two systems by testing at the command line
>> with the cs2cs utility which is a part of Proj.
>
> Rich,
>
> Thanks for your counsel.  The example using cs2cs from its documentation
> worked the same on both systems, executed from the command line.
>
> I believe the grid shift files are slightly different, even though I
> thought I had installed the same versions.  As a test, I copied the
> /usr/local/share/proj directory from the older system (the one that
> does the datum shift without complaint) to the newer one, and the
> ST_Transform completes without error.  So I believe that is the source
> of the problem.
>
> But there is only one link on http://trac.osgeo.org/proj/ for the datum
> shift file package.  If the package is OS-specific I would
> expect to see more than one.  So I am puzzled and worried that next
> time I may face the same problem again.
>
> Peter

The files in http://svn.osgeo.org/metacrs/proj/trunk/proj/nad/ are
ASCII. In the nad directory, you need to do:
  ./configure
  make
  install
to create the binary grid shift files that proj actually uses. (Proj
doesn't read the ASCII files). And I'm not sure that the
config-make-install of the proj program does the nad directory.

Rich

-- 
Richard Greenwood
richard.greenwood at gmail.com
www.greenwoodmap.com