[GRASS-dev] [GRASS GIS] #1988: towgs84 datum transform options not maintained with shapefile export

[GRASS GIS]

#1988: towgs84 datum transform options not maintained with shapefile export
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 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             |  
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 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]]

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Ticket URL: <https://trac.osgeo.org/grass/ticket/1988>
GRASS GIS <http://grass.osgeo.org>