1

Could you, please, explain me the difference between two types of coordinates:

[-11539.488377739675,6710096.017961704]

and

51.4977973,-0.2691569

These coordinates represent London location, but they are different! Why?

  • 2
    Are from different CRS... search questions about geographic and proyected coordinates, there are a lot of them – aldo_tapia Oct 29 '17 at 15:53
  • 1
    The top is a projected coordinate system (likely in m), whereas the bottom is a geographic coordinate system in degrees. – Aaron Oct 29 '17 at 16:01
2

The second pair of coordinates is the latitude and longitude, respectively, of a point in London (represented as Y,X here - note that in many cases they would be represented as longitude, latitude as (X,Y)). Lat/Long is a geographic system represented in degrees - as in, degrees of referenced Earth spheroid, for an angle from the centerpoint.

The first pair of coordinates is the same point (presumably), represented in a projected coordinate system. As opposed to geographic systems (lat/long), projected systems create a flat two-dimensional projection of the Earth's surface (as the name suggests). XY coordinates are then assigned based on position along each respective axis, based on distance (in projection system units) from a set origin point.

You have to look and see what projection the dataset or map service is using for that non-geographic coordinate pair.

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