1. ® 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

2. OGC ® AIXM CRS Considerations Progress of draft doc: Guidelines for the use of GML in AIXM 5.1 2January 27, 2016

3. 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.

4. 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

5. 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

6. 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

7. OGC ® 7January 27, 2016 Powering the Geo-Web Estimating diff b/w geodesic and parallel

8. OGC ® 8January 27, 2016 Powering the Geo-Web Estimating diff b/w geodesic and parallel

9. OGC ® 9January 27, 2016 Powering the Geo-Web Estimating diff b/w geodesic and parallel

10. OGC ® 10January 27, 2016 Powering the Geo-Web Estimating diff b/w geodesic and parallel

11. OGC ® 11January 27, 2016 Powering the Geo-Web Estimating diff b/w geodesic and parallel