2

I want to transform vector points from EPSG:4326 to EPSG:4258 and vice versa for survey application. Currently the difference between the two is about 70 cm in xy direction. Using QGIS to transform does not yield correct results (both CRS are basically identical in proj4).

I read about this problem but have not found a workable solution for whole layers. In my layers I have usually up to ten ground control points that need to be transformed.

Is there a solution out there that you could point me to?

3
  • 2
    Update to latest version of QGIS and therefore switch to using proj6. You should be able to choose which transformation you need for the accuracy required.
    – nmtoken
    Jan 31 '20 at 11:52
  • Do you know the transformation that you need? Feb 1 '20 at 7:25
  • I guess it is EPSG:4258 to the current epoque of WGS84... But I am not 100% sure. Basically the CRS that GPS/Glonass delivers in, and EPSG:4258..
    – S.K.
    Feb 1 '20 at 13:45
2

Proj6 seems to consider that EPSG:4258 and EPSG:4326 mean the same and conversion between them does not change anything.

projinfo -o PROJ -s "EPSG:4258" -t "EPSG:4326"
Candidate operations found: 1
-------------------------------------
Operation n 1:

EPSG:1149, ETRS89 to WGS 84 (1), 1.0 m, Europe - ETRS89

projinfo -k operation EPSG:1149
PROJ string:
+proj=noop

WKT2_2018 string:
COORDINATEOPERATION["ETRS89 to WGS 84 (1)",
    VERSION["EPSG-eur"],
    SOURCECRS[
        GEOGCRS["ETRS89",
            DATUM["European Terrestrial Reference System 1989",
                ELLIPSOID["GRS 1980",6378137,298.257222101,
                    LENGTHUNIT["metre",1]]],
            PRIMEM["Greenwich",0,
                ANGLEUNIT["degree",0.0174532925199433]],
            CS[ellipsoidal,2],
                AXIS["geodetic latitude (Lat)",north,
                    ORDER[1],
                    ANGLEUNIT["degree",0.0174532925199433]],
                AXIS["geodetic longitude (Lon)",east,
                    ORDER[2],
                    ANGLEUNIT["degree",0.0174532925199433]],
            ID["EPSG",4258]]],
    TARGETCRS[
        GEOGCRS["WGS 84",
            DATUM["World Geodetic System 1984",
                ELLIPSOID["WGS 84",6378137,298.257223563,
                    LENGTHUNIT["metre",1]]],
            PRIMEM["Greenwich",0,
                ANGLEUNIT["degree",0.0174532925199433]],
            CS[ellipsoidal,2],
                AXIS["geodetic latitude (Lat)",north,
                    ORDER[1],
                    ANGLEUNIT["degree",0.0174532925199433]],
                AXIS["geodetic longitude (Lon)",east,
                    ORDER[2],
                    ANGLEUNIT["degree",0.0174532925199433]],
            ID["EPSG",4326]]],
    METHOD["Geocentric translations (geog2D domain)",
        ID["EPSG",9603]],
    PARAMETER["X-axis translation",0,
        LENGTHUNIT["metre",1],
        ID["EPSG",8605]],
    PARAMETER["Y-axis translation",0,
        LENGTHUNIT["metre",1],
        ID["EPSG",8606]],
    PARAMETER["Z-axis translation",0,
        LENGTHUNIT["metre",1],
        ID["EPSG",8607]],
    OPERATIONACCURACY[1.0],
    USAGE[
        SCOPE["unknown"],
        AREA["Europe - ETRS89"],
        BBOX[32.88,-16.1,84.17,40.18]],
    ID["EPSG",1149]]
5
  • That is what I thought, thank you for checking....
    – S.K.
    Jan 31 '20 at 16:59
  • But with HTDP grid shifts gis.stackexchange.com/questions/345612/… you can get more accurate results if you only know from what epoch your EPSG:4326 data are.
    – user30184
    Jan 31 '20 at 18:03
  • But can I make this work in QGIS?
    – S.K.
    Jan 31 '20 at 18:56
  • I had a quick look at it and I do not see, how I can make this a clickable solution to reproject whole layers without using the command line every time. I checked this pager here (confluence.qps.nl/qinsy/8.0/en/…) for more information on the different epochs but I still don't see how to make this work in QGIS. If I would use the latest realization of WGS84 (EPSG:7662) I still have the problem that this one uses cartesian coordinates while EPSG:4326 is in degrees.....
    – S.K.
    Feb 3 '20 at 9:26
  • You might try EPSG:15843, PZ-90 to WGS84. As far as I know Glonass uses various PZ realizations rather than WGS84 or ITRF. It's from EPSG registry
    – mkennedy
    Feb 5 '20 at 0:49

This site is temporarily in read only mode and not accepting new answers.

Not the answer you're looking for? Browse other questions tagged .