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In ArcMap, I add a layer from ArcGIS web server projected in "Bessel 1841 Transverse Mercator".
Then I add new layer as a base map from ArcGIS online web server.

This is the result:

screenshot

Shift is around 500 m, and I wonder what shell I do to make correction so that both layers align?


Reported projection for "Bessel 1841 Transverse Mercator" layer is:

PROJCS["Bessel_1841_Transverse_Mercator",
    GEOGCS["GCS_Bessel_1841",
        DATUM["D_Bessel_1841",
            SPHEROID["Bessel_1841",6377397.155,299.1528128]],
        PRIMEM["Greenwich",0.0],
        UNIT["Degree",0.0174532925199433]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["False_Easting",7500000.0],
    PARAMETER["False_Northing",0.0],
    PARAMETER["Central_Meridian",21.0],
    PARAMETER["Scale_Factor",0.9999],
    PARAMETER["Latitude_Of_Origin",0.0],
    UNIT["Meter",1.0]]

It's closest match is SR-ORG:7698 where it differs in "False_Easting" parameter.

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  • Can you tell us the data's location? Bessel 1841 is an ellipsoid, not a geographic CRS, so you might have to define a custom transformation for it. Also, is the CRS for the AGOL data "Web Mercator" (WKID: 102100 or 3857)?
    – mkennedy
    Apr 11, 2016 at 22:50
  • I added proj code. CRS for AGOL is 3857 (it's a basemap imported from ArcMap menu)
    – vedar
    Apr 11, 2016 at 23:17
  • Can you tried to reverse it ? Like clear out the on the fly projection ? First open ArcMap and bring the layer first and then bring in the Traverse Mercator and see what happens ?
    – PROBERT
    Apr 11, 2016 at 23:53
  • Yes I did try that also. It then asks for transformation, where I select obvious choices, and the shift is just the same. I guess I will try to manually correct this.
    – vedar
    Apr 11, 2016 at 23:57
  • I need to do just the opposite thing - from WGS84 to transform coordinates into MGI 1901 / Balkans 7. I did it but there is a shift about 500 m. Could you please advise how to correct this? Thank you!
    – Lucy
    Jan 24, 2017 at 18:01

1 Answer 1

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The EPSG Geodetic Parameter Registry has two coordinate reference systems that match that well-known text.

The first that I looked at was MGI 1901 / Balkans 7, EPSG:3909. The other one was Macedonia State Coordinate System Zone 7, EPSG:6316, which has the same definition. Using that information, I was able to find that the data is in Skopje, Macedonia. Now I can look at geographic/datum transformations for the area.

EPSG shows a few, but the one with the best accuracy is EPSG:6206 at 2 meters.

In order to get your data layers to line up, you will have to use the Create Custom Geographic Transformation tool. Here's the information for the tool:

Transformation name: Bessel_1841_To_WGS_1984_Macedonia (or a name of your choice)
Source/From GCS: Bessel 1841 (in geographic coordinate systems, spheroid-based, Bessel 1841)
Target/To GCS: WGS 1984 (geographic coordinate systems, world, WGS 1984)
Method: Coordinate Frame
X Axis Translation: 521.748
Y Axis Translation: 229.489
Z Axis Translation: 590.921
X Axis Rotation: -4.029
Y Axis Rotation: -4.488
Z Axis Rotation: 15.521
Scale Difference: -9.78

Once the tool is run, and the transformation created, restart ArcMap. Open the data frame property page and select the Coordinate System tab.

Click the Transformations button.

In the middle is the data frame's/target's coordinate system. In the top box are the unique geographic coordinate systems in the map. Make sure that the other GCS is selected. That is, if the data frame is using 3857 (based on WGS 1984), select Bessel 1841.

Click the bottom pull-down. It should list the transformation that you created. Select it, and OK all dialogs.

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  • Excellent! Thank you very much :) I tried to make custom transformation, but I didn't select the right method (nor data). Your solution works great.
    – vedar
    Apr 12, 2016 at 0:23

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