Information on the Swiss geoid model CHGeo2004
by Urs Marti, December 2023

The Swiss Geoid and Quasigeoid is the official model to be used in Switzerland and Liechtenstein.
It is a hybrid solution with a strong weight on GNSS-Levelling measurements
compared to astro-geodetic data and a global model (EGM96) was used as a reference.
The solution is relative to ETRS89 (GRS80-Ellipsoid) with a resolution of 30".
The format of the original files is "ESRI ASCII grid" (.agr)

There are several variants of the model, which are shortly described here:
CHGeo04: Geoid model, compatible with Swiss orthometric heights LHN95
CHQua04_RPN: Quasigeoid model compatible with Swiss normal heights LHN95
CHQua04_EF: Quasigeoid model compatible with EVRF2000 (it is just a shifted version of CHQua04_RPN by 10.31 cm)
CHGeo2004_htrans: A height transformation surface compatible to the offical Swiss heights LN02.
