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Confused by coordinate systems?

  • 1.  Confused by coordinate systems?

    Pitney Bowes
    Posted 13 days ago
    Edited by Susan Bardet 10 days ago

    What is the difference between latitude/longitude and Easting/Northing?

    Latitude/longitude, Easting/Northing, X/Y are ways we uniquely identify a position on Earth and are also called coordinates. There are 2 coordinate systems namely geographic and projected.

    A geographic coordinate system uses a spherical surface and a position is identified by its latitude and longitude. Latitude and Longitude are angular units of measure and are denoted in degrees minutes and seconds or decimal degrees. The Longitude values range between -180 to +180°. Latitude values range between +90° to - 90°.

    When we create a map we project a sphere (Earth) onto a flat surface and we use projected coordinate systems to do this. The latitude and longitude are converted to X and Y coordinates. During this transformation the surface of the earth is distorted. There is no perfect map projection and one chooses a projection based on what distortion is acceptable for their purposes. Projections is a complex topic which I do not intend to touch upon in this article. After transformation Latitude is denoted by Y (northing) and Longitude by X (Easting). The most common units of measure in projected coordinate systems are meters and feet. For example UTM is a common projection, a location is identified with easting and northing and the units are in meters.

    Summarizing the above, the units for Latitude and longitude is degrees, minutes and seconds and the units for Easting and Northing is linear the most common being meters and feet. You can find several free convertors online to do the conversions for you or you can attempt it yourself in excel. Below are a 2 websites where you can convert

    https://www.bgs.ac.uk/data/webservices/convertForm.cfm

    https://gridreferencefinder.com/

     I have drawn a map below to illustrate the above explanation. The black grid lines are Latitude and Longitude and in red are the Eastings and Northings.

    The position of Pitney Bowes office in Henley is

    Latitude 51.553299 Longitude -0.92593001

    X(Easting) 474565 Y (Northing) 184370

    Grid reference: SU 74565 84370

    If you have a large number of coordinates to convert then this is best done within a GIS software. How this is achieved would be the topic of another article.

     



    ------------------------------
    Susan Bardet
    Software Support Engineer
    susan.bardet@pb.com

    Pitney Bowes
    Henley-on-Thames
    RG9 6AB Oxfordshire
    pitneybowes.com
    ------------------------------


  • 2.  RE: Confused by coordinate systems?

    Pitney Bowes
    Posted 12 days ago
    Hi Susan,

    Thank you for explanation. In Confirm, we have assets which are associated with geometry information. I was often confused between the terms.

    Regards
    Ritushree

    ------------------------------
    Ritu Mishra
    Knowledge Community Shared Account
    Shelton CT
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  • 3.  RE: Confused by coordinate systems?

    Pitney Bowes
    Posted 11 days ago
    Hello Ritu,

    I am glad that you found it useful.

    Best regards
    Susan ​

    ------------------------------
    Susan Bardet
    Software Support Engineer
    susan.bardet@pb.com

    Pitney Bowes
    Henley-on-Thames
    RG9 6AB Oxfordshire
    pitneybowes.com
    ------------------------------



  • 4.  RE: Confused by coordinate systems?

    Posted 11 days ago

    Thanks, Susan.

    Even though I have worked in the GIS & LI space for more than two decades, I have always struggled to remember the difference between Longitude and Latitude, eg. which refers to the X axis and which refers to the Y axis.

    I think this quote of yours just gave me a clue to how to remember:

    "The Longitude values range between -180 to +180°. Latitude values range between +90° to - 90°."

    The Longitude, the X axis, has a "longer" range. I'll try to use this next time.



    ------------------------------
    Peter Horsbøll Møller
    Pitney Bowes
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  • 5.  RE: Confused by coordinate systems?

    Pitney Bowes
    Posted 11 days ago
    ​Hello Peter,

    I am glad that this article helped.

    Best regards
    Susan

    ------------------------------
    Susan Bardet
    Software Support Engineer
    susan.bardet@pb.com

    Pitney Bowes
    Henley-on-Thames
    RG9 6AB Oxfordshire
    pitneybowes.com
    ------------------------------