Description:
RAF20 is a hybrid quasi-geoid model for France, covering the area 42° < lat < 51.5°, -5.5° < lon < 8.5° with a grid spacing of 1.5' in latitude and 2' in longitude. It is an update of the previous RAF18b model. In particular it is an adaptation of the QGF16 gravimetric model to GNSS/levelling points, adding new acquisitions to those used for the computation of the RAF18b model. The RAF20 model provides the height of the IGN69 reference surface above the GRS80 ellipsoid (RGF93v2b datum). It has been assessed by using about 6800 independent GNSS/levelling points, showing differences with a standard deviation of 1 cm. RAF18b and RAF20 models mainly differ in the South-Eastern quarter of the country due to the inclusion of new GNSS/levelling points, as well as in Sète due to the removal of an outlier in the GNSS/levelling data.
Reference:
F. L'Ecu (2021). Description technique de la surface de conversion altimétrique RAF20. Service de Geodesie et de Métrologie, IGN
R. Fages (2021). Le RGF93v2b: une nouvelle réalisation du RGF93. Revue XYZ, 167, pp. 26-29
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