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I have a series of raster maps of geophysics for an archaeological site in Turkey. These are ostensibly in UTM zone 35, WGS84 projection, but the surveyors set their grid with a total station using a slightly different coordinate for our local datum than the one we use, 1.726 m to the W and 0.735 m to the S. So when I bring them into QGIS 3.18 with the data for the site as a whole, they end up shifted a couple meters to the SW. What is the easiest way to bring them all into alignment with the rest of the system?

I naively tried creating a custom projection with a small offset (like post Shift a CRS by an observed offset) by adding 1.726 to the false easting and 0.735 to the false northing of the project CRS 32635, so:

PROJCRS["GeoIm 2018",
    BASEGEOGCRS["WGS 84",
        DATUM["World Geodetic System 1984",
            ELLIPSOID["WGS 84",6378137,298.257223563,
                LENGTHUNIT["metre",1]]],
        PRIMEM["Greenwich",0,
            ANGLEUNIT["degree",0.0174532925199433]],
        ID["EPSG",4326]],
    CONVERSION["unnamed",
        METHOD["Transverse Mercator",
            ID["EPSG",9807]],
        PARAMETER["Latitude of natural origin",0,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8801]],
        PARAMETER["Longitude of natural origin",27,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8802]],
        PARAMETER["Scale factor at natural origin",0.9996,
            SCALEUNIT["unity",1],
            ID["EPSG",8805]],
        PARAMETER["False easting",50001.726,
            LENGTHUNIT["metre",1],
            ID["EPSG",8806]],
        PARAMETER["False northing",0.735,
            LENGTHUNIT["metre",1],
            ID["EPSG",8807]]],
    CS[Cartesian,2],
        AXIS["easting",east,
            ORDER[1],
            LENGTHUNIT["metre",1,
                ID["EPSG",9001]]],
        AXIS["northing",north,
            ORDER[2],
            LENGTHUNIT["metre",1,
    ID["EPSG",9001]]]]

This however shifts a test raster by about 450000 m to the east. I'm obviously flailing here; can someone point me in the right direction? Since I will be getting more data from these folks in the future, it seems better to somehow recognize their system than manually move every raster by a given amount.

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Your false easting is only 50,001 m instead of the required 500,001.

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  • Thank you! But one more problem, this shifts the raster to the SW while I need to shift to the NE. Making the false easting 499999 rather than 500001 works but a negative value for the false northing gives an error. How can I give a negative false northing?
    – ndcahill
    Mar 2 at 16:54

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