[GIS] Converting/transforming coordinates from ETRS89 to WGS84 UTM 36N in QGIS

coordinate systemqgisturkey

I am a student and just getting to know QGIS. At the moment I have to combine data which had been measured in ETRS89 with data in WGS84 UTM 36N. I created several vector layers for the data in ETRS89. Then I tried to transform the data into WGS84 by using "on the fly transformation" but it seemed to me that there was no change visible. The coordinates for one of our fixpoints are in WGS84 279000.000/4207000.000/1616.875 but QGIS shows me the coordinates 542000.00/4206000.00 (the height I can't even see).

How can I transform the coordinates?

I don't mean a change in projection I want to have a proper translation/conversion of the coordinates.

The more western points are the correct ones in the OpenStreetMap. I think we still not have solved the problem. May be I should explain it a little bit better… I have got some data of Turkish students. They contain measurement points which had been acquired with a total station. We also measured with a total station in the same area but we measured in WGS84 UTM 36N relying on fixpoints which had been set witch GPS.

If you now look at the data, there has to be a difference because the coordinates of our Turkish colleagues begin with 542…/420… and ours 279../420… and also the height is divergent. But I'm not quite sure whether the information of the Turkish student was correct that it is ETRS89.

I really don't know how I can bring this data together.

Best Answer

In QGIS, the geographic coordinate systems ETRS89 and WGS84 are assumed to be the same. The difference is about half a meter (only reflecting the tectonic movements), and to make sure it stays little , WGS84 has been adjusted from time to time with so-called time-frames.

There are transformation parametres from ETRS89 to WGS84 time frame xyz, but you have to know the time frame your WGS84 data is actually recorded.

See this ticket for some further reading:

http://trac.osgeo.org/proj/ticket/11

ftp://itrf.ensg.ign.fr/pub/itrf/WGS84.TXT

http://etrs89.ensg.ign.fr/

Adding your coordinates on a Openstreetmap background, I get this picture:

enter image description here

I'm not sure which point is correct for you, but ETRS89 UTM 36N and WGS84 UTM 36N layer align perfectly.

EDIT

The coordinates 542.../420... look like ED50 TM30 EPSG: 2320, which is not the same as ETRS89 TM30.

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