[GRASS-dev] [GRASS GIS] #1452: wx location wizard doesn't ask for datum transform options because proj4 4.7.1's epsg file is broken

[GRASS GIS]

#1452: wx location wizard doesn't ask for datum transform options because proj4
4.7.1's epsg file is broken
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 Reporter:  hamish                   |       Owner:  grass-dev@…              
     Type:  defect                   |      Status:  new                      
 Priority:  critical                 |   Milestone:  6.4.3                    
Component:  Projections/Datums       |     Version:  svn-releasebranch64      
 Keywords:  location wizard, g.proj  |    Platform:  All                      
      Cpu:  All                      |  
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Comment(by mmetz):

 Replying to [comment:27 cmbarton]:
 >
 > All unrecognized datums that I tested are listed in
 ../etc/proj/datums.table

 Datums listed in etc/proj/datums.table but unknown to OGR/proj4 will not
 be recognised if passed to g.proj within a proj4 string. In this case the
 datum option must be added:

 {{{
 GRASS 7.0.svn (nc_spm_08):~ > g.proj -d proj4='+proj=utm +datum=eur50'
 datum=eur50
 WARNING: Datum <unknown> not recognised by GRASS and no parameters found
 Datum set to <eur50>
 GRASS datum code: eur50
 WKT Name: European_Datum_1950
 Datum parameters not present; default for eur50 is:
         towgs84=-87.000,-98.000,-121.000
 }}}

 > Could this be a problem more with g.proj than with proj4?

 g.proj creates an OGR spatial reference system from the proj4 string which
 is then used by libproj to figure out the parameters. If the datum name is
 not recognized by OGR it gets lost and never makes it to libproj, in which
 case the datum name needs to be supplied separately with the datum option.

 HTH,

 Markus M

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Ticket URL: <https://trac.osgeo.org/grass/ticket/1452#comment:28>
GRASS GIS <http://grass.osgeo.org>