0

I need to process some MapInfo data in QGIS 3.4, but I am unfamiliar with MapInfo. The data seems wrong when compared to a Google Satellite base map. I do not know the projection of the MapInfo layer, and this is the GDAL-Vector information output:

INFO: Open of 'C:/.../LAYER.MIF'
      using driver 'MapInfo File' successful.

Layer name: LAYER
Geometry: Unknown (any)
Feature Count: 9
Extent: (12.291721, 41.737178) - (12.641386, 42.011683)
Layer SRS WKT:
GEOGCRS["unnamed",
    DATUM["Arc 1950",
        ELLIPSOID["Clarke 1880 (modified for Arc 1950)",6378249.145326,293.4663076,
            LENGTHUNIT["metre",1,
                ID["EPSG",9001]]]],
    PRIMEM["Greenwich",0,
        ANGLEUNIT["degree",0.0174532925199433,
            ID["EPSG",9122]]],
    CS[ellipsoidal,2],
        AXIS["latitude",north,
            ORDER[1],
            ANGLEUNIT["degree",0.0174532925199433,
                ID["EPSG",9122]]],
        AXIS["longitude",east,
            ORDER[2],
            ANGLEUNIT["degree",0.0174532925199433,
                ID["EPSG",9122]]]]
Data axis to CRS axis mapping: 2,1
Name: String (50.0)

I have tried reprojecting the layer to the two projections mentioned (EPSG:9001 and EPSG:9122), but the data remains wrong. In an associated .WOR file, I found this command:

Set Map
  CoordSys Earth Projection 1, 5
  Center (12.35610885,41.95712217)
  Zoom 60.26835134 Units "mi"
  Preserve Zoom Display Zoom
  XY Units "m" Distance Units "mi" Area Units "sq mi"

I do not know whether this is relevant, and couldn't find the exact meaning of Earth Projection 1, 5 on MapInfo documentation. Is there a way to know this layer's projection?

9
  • According to read.pudn.com/downloads138/sourcecode/others/592839/… CoordSys Earth Projection 1, 5 is Latlong, Datum Arc1950
    – Hans Erren
    Oct 7 '20 at 15:47
  • 1
    EPSG says that Arc 1950 is used in "Africa - Botswana, Malawi, Zambia, Zimbabwe" but the data extent doesn't seem to match that.
    – mkennedy
    Oct 7 '20 at 16:55
  • The valid datum for Ethiopia is Adindan, this also uses the Clarke1880 ellipsoid, just as Arc1950
    – Hans Erren
    Oct 7 '20 at 20:01
  • @HansErren thank you for the pdf link, that's very useful.
    – bakerysbs
    Oct 8 '20 at 15:32
  • As the mif file is ascii, the line 'CoordSys Earth Projection 1, 5' can be edited to'CoordSys Earth Projection 1, 1' to match the Adindan datum in Ethiopia with EPSG code 4201.
    – Hans Erren
    Oct 8 '20 at 15:48
0

In the MapInfo projection database, 1, 5 is called "Longitude / Latitude (Arc 1950)" and has the EPSG ID 4209.

2
  • Thank you. Unluckily this is bad news, because this projection doesn't make sense considering the data extent, and reprojecting does not make the data look any better. This is the answer I was looking for anyway.
    – bakerysbs
    Oct 9 '20 at 8:49
  • Can you post the first twenty lines of the file Layer.mif, and do you have an idea where the data should be located, then I might be able to help you out.
    – Hans Erren
    Oct 9 '20 at 14:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.