AUSPOS - Understanding the Results

Question 4.1 - How do I read the processing report?

The processing report is provided in Adobe PDF format.

Download Adobe Reader for free here.

Question 4.2 - What parts of the report should I check carefully?

It is recommended that you read the whole report thoroughly to familiarise yourself with the AUSPOS process. The important quality statistics related to your processing job are located in Sections 3-5 of the AUSPOS Report. This includes information such as the Coordinate Precision and Ambiguity Resolution.

Question 4.3 - What are the 'Derived AHD' and 'Derived Above Geoid' heights?

In the GDA section of the AUSPOS report, the user is supplied with a 'Derived AHD' height. This is a height computed using AUSGeoid2020 model. The offset between the ellipsoid and AHD is computed using Geoscience Australia's AUSGeoid2020 product and subtracted from the ellipsoidal height providing the user with a Derived AHD height. The AUSGeoid2020 model of ellipsoid to AHD separation values only extends 33 km offshore. Between 33 km and 50 km offshore, the AUSGeoid2020 ellipsoid to AHD separation values are linearly blended with Gaussian weighting with the DTU15 Mean Sea Surface model. The closer to shore, the higher the weighting of AUSGeoid2020 values. From 50 km outwards, the model is only the DTU15 Mean Sea Surface model For more information, refer to the AUSGeoid09 page.

In the ITRF section of the AUSPOS report, the user is supplied with a 'Derived Above Geoid' height. This is a height relative to the Earth Geopotential Model 2008 (EGM2008). More information on the EGM2008 geoid can be found here.

Question 4.4 - The report provides GDA and ITRF coordinates, but what about WGS84 coordinates?

ITRF and WGS84 are generally considered to be equivalent (to within 0.1 m).

Further information