Making Location Count Copyright 2010 Open Geospatial Consortium AIXM GML Profile CRS Considerations 75th OGC Technical Committee Sydney, Australia David Burggraf November 29, 2010 Sponsored by Hosted at The University of Sydney OGC AIXM CRS Considerations Progress of draft doc: Guidelines for the use of GML in AIXM 5.1 2January 27, 2016 OGC AIXM CRS Considerations A CRS relates a coordinate system to the earth by a datum 3January 27, 2016 Powering the Geo-Web U M (earth model) coordinate chart V Coordinate System f coordinate mapping A geodetic datum consists of an ellipsoid model and a prime meridian. The intersection of the equator and prime meridian is the origin. OGC A geodetic CRS (e.g. EPSG 4326) relates a (lat,lon) ellipsoidal coordinate system to the earth 4January 27, 2016 Powering the Geo-Web M (earth model) Domain of validity f coordinate mapping A line of constant longitude corresponds to a meridian A line of constant latitude corresponds to a parallel Ellipsoidal Coordinate System Special Cases of Rhumb lines AIXM CRS Considerations OGC Two fixed end points, several possible curve interpolations as realized on the corresponding earth model (e.g. ellipsoid, sphere, geoid) 5January 27, 2016 Powering the Geo-Web Geodetic CRS interpolation (e.g. EPSG::4326) Geocentric CRS interpolation (e.g. EPSG::4978 ) Geodesic (e.g. great circle) interpolation (e.g. gml:Geodesic) AIXM CRS Considerations OGC January 27, 2016 Maximum difference between the Geodesic and Parallel depends on: Latitude Length of geodesic (i.e. Longitude spread) Estimating diff b/w geodesic and parallel Maximum Distance OGC 7January 27, 2016 Powering the Geo-Web Estimating diff b/w geodesic and parallel OGC 8January 27, 2016 Powering the Geo-Web Estimating diff b/w geodesic and parallel OGC 9January 27, 2016 Powering the Geo-Web Estimating diff b/w geodesic and parallel OGC 10January 27, 2016 Powering the Geo-Web Estimating diff b/w geodesic and parallel OGC 11January 27, 2016 Powering the Geo-Web Estimating diff b/w geodesic and parallel