gvernar

Datum shift problem with user location

Discussion created by gvernar on May 11, 2010
Latest reply on Feb 22, 2012 by geogurugr
Our map service has

"spatialReference" : {
      "wkid" : 2100
    },

When we show the user location it is dislocated  (~150 m) from the real location.

Something in the conversion from Iphone WGS84 GPS DATA  --> GREEK GRID ( 2100 ) is wrong.


Here is a working projection that we use in our c# classes

PROJCS["GGRS87 / Greek Grid",GEOGCS["GGRS87",DATUM["Greek_Geodetic_Reference_System_1987",SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],TOWGS84[-199.87,74.79,246.62,0,0,0,0],AUTHORITY["EPSG","6121"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4121"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",24],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AUTHORITY["EPSG","2100"]]

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