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I got two shapefile of the same coordinate reference system (CGRS93_LTM), one in QGIS and the other in ArcMap. However they got different prj. files QGIS file:

PROJCS["Transverse_Mercator",
 GEOGCS["GCS_WGS_1984",
  DATUM["D_unknown",
  SPHEROID["WGS84",6378137,298.257223563]],
 PRIMEM["Greenwich",0],
 UNIT["Degree",0.017453292519943295]],
PROJECTION["Transverse_Mercator"],
 PARAMETER["latitude_of_origin",0],
 PARAMETER["central_meridian",33],
 PARAMETER["scale_factor",0.99995],
 PARAMETER["false_easting",200000],
 PARAMETER["false_northing",-3500000],
 UNIT["Meter",1]]

ArcMap file:

PROJCS["CGRS_1993_LTM",
 GEOGCS["GCS_CGRS_1993",
  DATUM["D_Cyprus_Geodetic_Reference_System_1993",
  SPHEROID["WGS_1984",6378137.0,298.257223563]],
 PRIMEM["Greenwich",0.0],
 UNIT["Degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
 PARAMETER["False_Easting",200000.0],
 PARAMETER["False_Northing",-3500000.0],
 PARAMETER["Central_Meridian",33.0],
 PARAMETER["Scale_Factor",0.99995],
 PARAMETER["Latitude_Of_Origin",0.0],
 UNIT["Meter",1.0]]

How can i define Datum, ProjCS and GeogCS in QGIS in order to be the same?

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1

Both definitions have identical values. Just the names are different, and there is little you can do about it.

You can run gdalsrsinfo on both files, and they return:

PROJ.4 : '+proj=tmerc +lat_0=0 +lon_0=33 +k=0.99995 +x_0=200000 +y_0=-3500000 +ellps=WGS84 +units=m +no_defs '

This is the format that QGIS uses for the projection definition, without any names.

ESRI software behaves different, they look only at the WKT definition in the .prj file. If Arcmap can not handle the .prj file from QGIS exactly, just exchange the file with one build from Arcmap itself.

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  • If i am correct proj.4 files support defining a datum (+datum=type). For instanace WGS84 defines as (+proj=longlat +datum=WGS84 +no_defs) Which types of datum are included in these definition? – Marios Simou Jul 6 '16 at 6:50
  • CGRS93 is bound to ITRF91 epoch 1993.1, with the same ellipsoid as WGS84. So no extra +towgs84 parameters are necessary, as long as you do not need to keep track of terrestrial plate movements. hence proj -ld does not list CGRS (as it does for GGRS87). – AndreJ Jul 6 '16 at 11:29
  • So for the moment there is no way that allow me changing WKT,proj.4 files for CGRS93 as there specifications, except if i convert it to ITRF91 ? – Marios Simou Jul 7 '16 at 6:57
  • You can not change the names in the WKT with QGIS, only the parameter values; but these are identical with WGS84. If you need it, you can modify the .prj file with any text editor to change the names. – AndreJ Jul 7 '16 at 10:57

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