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 ˘ˇ ... • A reference system using latitude and longitude to define the location of points on the surface of a sphere or spheroid decimal degrees (DD) -92.5 ... – Little sharing of geodetic information.

  System, World, Reference, Coordinates, Datum, Coordinate systems, Geodetic, Reference coordinate