2

I have a shape POSGAR 1994, I tested several reprojections and I cannot delete a displacement of about 100 meters with google earth. These are the shape data:

PROJCS["POSGAR_1994_Argentina_Zone_5",
GEOGCS["GCS_POSGAR_1994",
DATUM["D_POSGAR_1994",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["False_Easting",5500000.0],
PARAMETER["False_Northing",0.0],
PARAMETER["Central_Meridian",-60.0],
PARAMETER["Scale_Factor",1.0],
PARAMETER["Latitude_Of_Origin",-90.0],
UNIT["Meter",1.0]]
2

First, you should not trust Google Earth alone. Using QGIS, you might try the OpenLayers plugin with Openstreetmap data to see if that has the same offset.

You might try to set the projection to EPSG:22195 Campo Inchauspe / Argentina 5 which has a datum offset to the current POSGAR transformation. Don't use reprojection, because the data will stay on the same spot on the Earth after reprojection. If the result is getting worse, some more work is to be done.


UPDATE

I have tried several datasets offered by the source you have linked, and they show arbitrary offsets to Google, bing and Openstreetmap, even within the same shapefile. And some align well...

As an alernative, I looked up the Shapefiles and WMS services from http://www.ign.gob.ar/sig, and they all seem to be well-placed. They even offer an openstreetmap WMS service.

You coud try the affine transformation plugin to get the data in place, but since the offset is arbitrary, it will be a lot of work.

  • +1 for suggesting Campo Inchauspe. Any POSGAR realization should be within a meter or two of WGS84, not 100 meters (if GE is relatively accurate). – mkennedy Jan 26 '15 at 17:25
  • AndreJ, I have the same problem with Openstreetmap. And the result becoming worse with EPSG:22195, any suggestion? – AngeG Jan 29 '15 at 13:02
  • Can you give sample point coordinates of POIs or crossings that can be found in OSM? Or upload part of the file to dropbox or similar? – AndreJ Jan 29 '15 at 14:12
  • you can download it, ec.gba.gov.ar/estadistica/censo2010/cartografia.html, in "partidos" Pilar. Thanks again!! – AngeG Jan 30 '15 at 13:45
  • that unfortunate case of an official site. I really appreciate your help. I´ll try the plugin – AngeG Jan 30 '15 at 17:23

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