Co-ordinate System [South African]

Hello

I have user on OpenCities Map who has enquired about South African co-ordinte system in OpenCIties,

to quote "After assigning any co-ordinate system (and projection) from the Library - while capturing co-ordinates one notices, that X increases in value towards the North and  +Y towards East."

I do recall we had some work around in Bentley Map but I have not touched the software in 11 years, it appears the projected coordinates in OpenCities is not as it should be.

Please let me know if I can provide more information

 

  • South African co-ordinte system in OpenCIties

    Please, which one in detail? Do you find it here: https://epsg.org/home.html ?

    Regards

    Frank

    since 1985: GIS, CAD, Engineering (Civil)  Senior Consultant : [Autodesk Civil 3D , Esri ArcGIS, VertiGIS: in previous days : Bentley MS V4 - V8i, GeoGraphics, Bentley Map V8i, InRoads,  HHK Geograf, IBr DAVID] :  Dev: [C, C++, .NET, Java, SQL, FORTRAN, UML]
    [direct quote by: http://en.wikipedia.org/wiki/Helmut_Schmidt]: "Wer Kritik übel nimmt, hat etwas zu verbergen"
    Wer Grammatik- und/oder Rechtschreibfehler findet, der darf sie behalten :-)

  • Hi Frank

    Thank you for the response, let me try and rope the user into the discussion so we can get more info directly.

    Regards

  • Hi,

    would you note the shortest description of SA co-ordinate system I could compile:

     There are two datums used in South Africa: Hartebeesthoek94 and Cape.

    Hartebeesthoek94 Datum is the official geodetic datum for South Africa.

    • The Capedatum is the older of the two is no longer used, but there is still a vast number of surveyed information on this datum.. This references the Clarke 1880 ellipsoid.
    • Hartebeesthoek94is the datum currently in use in South Africa. Since 1st January 1999 the official coordinate system for South Africa is the Hartebeesthoek94 geodetic datum but referencing the WGS84 ellispoid with the International Terrestrial Reference Frame 1991 coordinates of the Hartebeesthoek Radio Astronomy Observatory Telescope used as the origin of this system.

     A list of coordinate systems for South Africa can be found on http://epsg.io/

     The origin of every 2o wide “zone” is intersection of equator and unequal meridian ( it is called here Lo): Lo13o, Lo15o, Lo17o

    Thus every  beacon in the “zone” has + Y value if it is located to the west of the origin and –Y value if it is located to the east  to the origin and always +X . where X is the distance from the equator along the central meridian of the “zone” – towards south.

    Best Regards

    Bronia 

  • There are two datums used in South Africa: Hartebeesthoek94 and Cape.

    Hartebeesthoek94 Datum is the official geodetic datum for South Africa.

    so... have you searched for this coordinate systems in the Microstation/Map/Opencities coordinate system library?

    I think you will find a lot of  South Africa coordinate systems  with the search criteria "Cape" and/or "Hartebeesthoe".

    IMHO you must only choose the right one for your projection, zone and axis orientation. And do some tests.

    Regards

    Frank

    since 1985: GIS, CAD, Engineering (Civil)  Senior Consultant : [Autodesk Civil 3D , Esri ArcGIS, VertiGIS: in previous days : Bentley MS V4 - V8i, GeoGraphics, Bentley Map V8i, InRoads,  HHK Geograf, IBr DAVID] :  Dev: [C, C++, .NET, Java, SQL, FORTRAN, UML]
    [direct quote by: http://en.wikipedia.org/wiki/Helmut_Schmidt]: "Wer Kritik übel nimmt, hat etwas zu verbergen"
    Wer Grammatik- und/oder Rechtschreibfehler findet, der darf sie behalten :-)

  • A list of coordinate systems for South Africa can be found on http://epsg.io/

    so what are your right EPSG-Codes, in numbers! And you will maybe find this codes in the Microstation/Map/Opencities geo coordinate system library, too .

    Example

    Regards

    Frank

    since 1985: GIS, CAD, Engineering (Civil)  Senior Consultant : [Autodesk Civil 3D , Esri ArcGIS, VertiGIS: in previous days : Bentley MS V4 - V8i, GeoGraphics, Bentley Map V8i, InRoads,  HHK Geograf, IBr DAVID] :  Dev: [C, C++, .NET, Java, SQL, FORTRAN, UML]
    [direct quote by: http://en.wikipedia.org/wiki/Helmut_Schmidt]: "Wer Kritik übel nimmt, hat etwas zu verbergen"
    Wer Grammatik- und/oder Rechtschreibfehler findet, der darf sie behalten :-)