I am running GDAL (1.9.2-2) and PROJ4 (4.8.0-0) installations on Windows 7. I have two installs of the latest release one through the osgeo4w setup and another with my PythonXY install.
With osgeo4w the files are in : C:\OSGeo4W\share\gdal (contains csv files, and pci_datum.txt seems to contain references to grid shift files but not to EPSG codes) C:\OSGeo4W\share\proj (contains an epsg file and the grid shift files with few lines containing the +nadgrids=@null parameter) When I run cs2cs -v +init=epsg:4267 I still do not understand how the +nadgrids=@conus,@alaska,@ntv2_0.gsb,@ntv1_can.dat parameter is being generated as I cannot find it within the text/csv files. With PythonXY the files are in: C:\Python27\GDAL\data (contains csv files, and pci_datum.txt seems to contain references to grid shift files but not to EPSG codes) C:\Python27\Lib\site-packages\pyproj\data (contains an epsg file and the grid shift files with few lines containing the +nadgrids=@null parameter) I thought about editing relevant files of my GDAL and PROJ4 installation but I could not understand which one as I based my search on the NAD27/NAD83 datum shift and could not understand how it is working... Any idea about which files to edit to add the nadgrids parameter to the proj string referenced by a given EPSG code (4202 for AGD66 as example)? Thomas -----Original Message----- From: Hermann Peifer [mailto:[email protected]] Sent: May-17-13 7:36 AM To: Thomas Campagne Subject: Re: How to set GDAL/cs2cs/proj to use NTv2 grid shift file when using EPSG codes? What about editing relevant files of your GDAL and PROJ4 installation, as a diry quick hack? On my MacBook, I would look for the csv files at /opt/local/share/gdal/ and the epsg file at /opt/local/share/proj/ /opt/local/share/proj/ is also the directory where I put extra grid shift files like OSTN02_NTv2.gsb and BETA2007.gsb Hermann On 2013-05-16 19:56, Thomas Campagne wrote: > Hi, > > I am using the GDAL API for Python for a script that takes only EPSG > codes for inputs to specify source and target coordinate systems. > > While the cs2cs command seems to handle quite well transformation > between NAD27 (EPSG:4267) and NAD83 (EPSG:4326) coordinates in North > America, I would like to have similar capabilities for AGD66 > (EPSG:4202) to GDA94 (EPSG:4283) and AGD84 (EPSG:4203) to GDA94 > (EPSG:4283) in Australia. > > When using the -v option with cs2cs to look at the proj string being > used i get the following: > > >cs2cs -v +init=epsg:4267 > > ># ---- From Coordinate System ---- > > >#Lat/long (Geodetic alias) > > ># > > ># +init=epsg:4267 +proj=longlat +datum=NAD27 +no_defs > +ellps=clrk66 > > ># +nadgrids=@conus,@alaska,@ntv2_0.gsb,@ntv1_can.dat > > ># ---- To Coordinate System ---- > > >#Lat/long (Geodetic alias) > > ># > > ># +proj=latlong +datum=NAD27 +ellps=clrk66 > > ># +nadgrids=@conus,@alaska,@ntv2_0.gsb,@ntv1_can.dat > > The nadgrids parameters tells cs2cs to use the best fitting datum grid > shift file from conus, alaska, ntv2_0.gsb, and ntv1_can.dat. > > For AGD66 (EPSG:4202) cs2cs returns: > > >cs2cs -v +init=epsg:4202 > > ># ---- From Coordinate System ---- > > >#Lat/long (Geodetic alias) > > ># > > ># +init=epsg:4202 +proj=longlat +ellps=aust_SA > > ># +towgs84=-117.808,-51.536,137.784,0.303,0.446,0.234,-0.29 > +no_defs > > ># ---- To Coordinate System ---- > > >#Lat/long (Geodetic alias) > > ># > > ># +proj=latlong +ellps=aust_SA > > ># +towgs84=-117.808,-51.536,137.784,0.303,0.446,0.234,-0.29 > > There is no nadgrids parameter but a towgs84 instead. A grid shift > file from the ICSM; "A66 National (13.09.01).gsb" contains the shift > between > AGD66 and GDA94. > > How can I make GDAL/cs2cs/proj identify this file when using EPSG codes? > > I tried to reinstall GDAL/cs2cs/proj using the osgeo4w installer with > A66 National (13.09.01).gsb within the directory containing the other > datum shift files prior to the reinstallation but without success. > > I also posted an enhancement ticket on Trac: > > http://trac.osgeo.org/gdal/ticket/5085 > > Cheers > > Thomas > > *Description: cid:[email protected]* > > *Thomas Campagne, M.Sc. Geophysics, Consultant > **A**DVANCED**G**EOPHYSICAL**I**NTERPRETATION**C**ENTRE** > *www.MiraGeoscience.com <http://www.mirageoscience.com/>**tel +1 778 > 329 > 0430 ext 227, 512B - 409 Granville St, Vancouver, BC, V6C 1T2, Canada > > ** > > *+ *Our Q2 eNewsletter 2013 is now out!You may download it here > <http://goo.gl/9GDBi>. > > + August 11-14 We will be hosting a workshop at the ASEG Conference in > Melbourne, Australia. Stop by Booth 49. More details here > <http://www.mirageoscience.com/events/upcoming_events.php>. > > + August 12-15 We will be hosting a workshop at the SGA Biennial > + Meeting > in Uppsala, Sweden. More details here > <http://www.mirageoscience.com/events/upcoming_events.php>. > > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
