#1988: towgs84 datum transform options not maintained with shapefile export
-------------------------------+--------------------------------------------
Reporter: voncasec | Owner: grass-dev@…
Type: defect | Status: new
Priority: normal | Milestone: 6.4.3
Component: Default | Version: unspecified
Keywords: g.proj, v.out.ogr | Platform: Linux
Cpu: x86-64 |
-------------------------------+--------------------------------------------
Perhaps this issue is related to the GDAL ticket 4345
(http://trac.osgeo.org/gdal/ticket/4345).
Including it here in case GRASS handles the data differently.
In general, if I am using a projection defined with towgs84 datum
transform parameters and I want to export the layer to a shapefile, the
+towgs84 datum transform parameters are not included.
Often times, I will just manually modify the .prj file after the fact to
include the TOWGS84 flag to ensure that there is no shift when viewing the
locations in a GIS that allow for on the fly reprojections.
Example of g.proj -e
GRASS 6.4.3svn (Bayaguana_NAD27_Caribbean):/usr/local/grass-6.4.3svn/etc >
g.proj -e
PROJCS["UTM_Zone_19_Northern_Hemisphere",
GEOGCS["GCS_clark66",
DATUM["D_North_American_1927",
SPHEROID["Clarke_1866",6378206.4,294.9786982]],
PRIMEM["Greenwich",0],
UNIT["Degree",0.017453292519943295]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",-69],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["Meter",1]]
Desired output of g.proj -e + .prj file from v.out.ogr
GRASS 6.4.3svn (Bayaguana_NAD27_Caribbean):/usr/local/grass-6.4.3svn/etc >
g.proj -e
PROJCS["UTM_Zone_19_Northern_Hemisphere",
GEOGCS["GCS_clark66",
DATUM["D_North_American_1927",
SPHEROID["Clarke_1866",6378206.4,294.9786982],
TOWGS84[-3.0,142.0,183.0,0,0,0,0]],
PRIMEM["Greenwich",0],
UNIT["Degree",0.017453292519943295]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",-69],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["Meter",1]]
--
Ticket URL: <https://trac.osgeo.org/grass/ticket/1988>
GRASS GIS <http://grass.osgeo.org>