Achangingapproachtogeodeticnetworksandstandards.pptVIP

Version 3 A changing approach togeodetic networks and standards Overview Historical Based on method of observation Current Based on accuracy achieved Future NZ Geodetic Datum 1949 Limitations of NZGD1949 “New” technology EDM, GPS, etc Public access to global datasets Earth Deformation Earthquakes Edgecumbe 1987 (M6.3) Limitations of NZGD1949 “New” technology EDM, GPS, etc Public access to global datasets Earth Deformation 1855 Wellington earthquake – magnitude 8.2 18m horizontal 2.5m vertical Continuous deformation 5m / century between east and west of NZ Motion relative to geo-centre of Earth New Zealand Geodetic Datum 2000 GPS-based Geocentric Accommodates Earth deformation Monitored by continuous GNSS observations NZGD2000 Zero Order Network NZGD2000 2nd – 4th Order Networks NZGD2000 5th Order Network Current network still not ideal Different and conflicting uses Different and conflicting characteristics Density Accuracy Accessibility Mark construction Site stability Purposes not clear What exactly do we need? Proposed Future Geodetic Networks Networks defined by purpose (not by process) Accuracy of networks related to their purpose not how they are obtained Different mark characteristics for each network Marks can be in multiple networks National Reference Frame Connection to the global frame One station for each tectonic plate Continuous GNSS observations Absolute gravity connection Datum Monitoring Network Maintain accuracy of geodetic datum Monitor earth deformation Re-establish cadastre following major deformation events Density related to deformation rate Stability of marks important Cadastral Control Network Geodetic marks to support cadastral surveys Enable connection to the geodetic datum Enable orientation to the geodetic datum Provided where cadastral surveys are being done Intervisibility important Geospatial Network Alignment of geospatial datasets Datum connection in areas of little cadastral activity Wilderness areas National Parks Offshore Isl