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Pushpin Accuracy on Bing Maps RRS feed

  • Question

  • Hello,

    i can not find any information on msdn, bing, google about follwing question:

    Up to what degree of accuracy in meters in Virtual Earth (with 6 relevant decimal places ) locations (push-pins) being displayed?
    What is the accuracy? 1m, 5m, 10m ?
    Is there a general statement on the accuracy?

    Thanks in advance for any help about this topic.

    best regards

    P.S.

     

    • Moved by Ricky_Brundritt Friday, March 9, 2012 4:15 PM (From:Bing Maps: Map Control and Web services Development)
    Wednesday, March 9, 2011 11:21 AM

Answers

  • Some comments:

    - Pushpins (and polylines, polygons) are defined using latitude/longitude coordinates, measured using the WGS84 spatial reference system. These coordinates represent an angle, measured at the centre of the earth relative to the prime meridian and the equator. So, the distance covered by 1 degree (or 6 d.p. of a degree, if you prefer) depends where on the earth's surface you are. At the equator, where the distance along the earth's surface covered by one degree of longitude is greatest, 1 degree = approx 111.3km. So the "accuracy" of a pushpin coordinate given to 0.000001 of a degree corresponds to about 10cm.

    - However, just because you're stating the coordinates with that degree of accuracy doesn't mean that they will be displayed with that degree of accuracy relative to, say, the satellite imagery map of the given location. There are inherent approximations in the data collection of any of the background map styles - satellite/road/or ortho-photo, which are captured at different resolutions from a variety of different data sources - which is why it's pretty pointless to state the coordinate location of a pushpin with very high accuracy, because it will exceed the accuracy of the background map anyway. There is no statement of "guarantee" of accuracy for Bing Maps - the accuracy is good enough for most consumer-mapping purposes, but I certainly wouldn't rely on it for a detailed specialist land survey, for example.


    twitter: @alastaira blog: http://alastaira.wordpress.com/
    Wednesday, March 9, 2011 1:05 PM
    Moderator

All replies

  • Some comments:

    - Pushpins (and polylines, polygons) are defined using latitude/longitude coordinates, measured using the WGS84 spatial reference system. These coordinates represent an angle, measured at the centre of the earth relative to the prime meridian and the equator. So, the distance covered by 1 degree (or 6 d.p. of a degree, if you prefer) depends where on the earth's surface you are. At the equator, where the distance along the earth's surface covered by one degree of longitude is greatest, 1 degree = approx 111.3km. So the "accuracy" of a pushpin coordinate given to 0.000001 of a degree corresponds to about 10cm.

    - However, just because you're stating the coordinates with that degree of accuracy doesn't mean that they will be displayed with that degree of accuracy relative to, say, the satellite imagery map of the given location. There are inherent approximations in the data collection of any of the background map styles - satellite/road/or ortho-photo, which are captured at different resolutions from a variety of different data sources - which is why it's pretty pointless to state the coordinate location of a pushpin with very high accuracy, because it will exceed the accuracy of the background map anyway. There is no statement of "guarantee" of accuracy for Bing Maps - the accuracy is good enough for most consumer-mapping purposes, but I certainly wouldn't rely on it for a detailed specialist land survey, for example.


    twitter: @alastaira blog: http://alastaira.wordpress.com/
    Wednesday, March 9, 2011 1:05 PM
    Moderator
  • Hello tanoshimi,

    your reply helped me well to understand that pushpin georelated topic.

     

    thanks alot!

     

     

    Wednesday, March 9, 2011 2:50 PM