Datums, Coordinate Systems, Coordinate Reference …

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Datums, Coordinate Systems, Coordinate Reference Systems and datum TransformationsDean C. Mikkelsen, , Warmerdam, OSGeo, FWToolsFOSS4G2007 Sept. 2007 Victoria, BC ! " # $ % " # $ " # & ' " # " # ( # ) $ * # + , - . . $ . / ' 0" # 1 2 2 2 2 2 2 2 2 . . . . . . . . ! 3 # ! 3 # ! 3 # ! 3 # ! 3 # ! 3 # ! 3 # ! 3 # Latitude and Longitude areNOT UNIQUE!NOT UNIQUE!'# / . . # 0" # 1 0" # 1 ! 4 4 . 4 . * 4 . 4 - # "35 ! 6% - $ + ' / Geoid (MSL)SphereEllipsoid / SpheroidWGS72/84. 7 # . 7 # . 7 # . 7 # . 7 # . 7 # . 7 # . 7 # * * * * * * * * " # " # " # " # " # " # " # " # Used for a specific region North America, Europe, South America etc. A Coordinate frame is determined and an ellipsoid chosen to minimize the local geoid-ellipsoid separation. Not Earth centered! Hundreds have been defined for countries all over the planetBEST FITTINGELLIPSOID FORTHE REGIONDatum datum = Coordinate FRAME + Reference ELLIPSOIDEllipsoidSemi Major AxisInv.

world : as sorted additional common projections ... • From the perspective of a geographic software design three coordinate systems can potentially be addressed. Each differ either in the order of the coordinate tuple or in the direction of increasing values.

  System, Reference, Coordinates, Projection, Datum, Coordinate systems, Reference coordinate