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STDistance

  • November 12, 2012 at 1:40 pm

    #270766

    Hi All,

    I am trying to get the distance between 2 points:

    DECLARE @g geometry;

    DECLARE @h geometry;

    SET @g = geometry::STGeomFromText('POINT(-118.262449 34.149837)',4326);

    SET @h = geometry::STGeomFromText('POINT(-118.291040 34.255522)',4326);

    SELECT @h.STDistance(@g)

    Result:0.109848...meter(SRID 4326 uses 'Meter' as a unit of mesurment),which is not correct.I picked these from area where i live and should be around 8-9miles(8.5*1600=13600).Any ideas why?

  • November 12, 2012 at 2:37 pm

    #1558330

    Hi

    The issue here is that you are using Geometry for your points rather than Geography. Geometry treats the uses a flat projection and essentially ignores the SRID information, whereas Geography use a spherical projection. So when you used the Geometry the distance is reported in the units defining the points (degrees) rather than meters defined in you projection.

    Try

    DECLARE @g geography;

    DECLARE @h geography;

    SET @g = geography::STGeomFromText('POINT(-118.262449 34.149837)',4326);

    SET @h = geography::STGeomFromText('POINT(-118.291040 34.255522)',4326);

    SELECT @h.STDistance(@g)

    This should give you a distance of 12015 metres

  • November 12, 2012 at 3:24 pm

    #1558337

    Got it.

    Thank you Micky

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