Swissgrid CH1903 is off by up to 3 meters (does not use data set of local corrections )
|Reported by:||bastiK||Owned by:||team|
|Keywords:||projection swiss unit test ntv2 grid||Cc:||sbrunner, stoecker, simon04, wiktorn, Klumbumbus, sebastic|
Description (last modified by )
To calculate CH1903, 2 steps are required:
(1) WSG84 -> CH1903+ (using a formula)
(2) CH1903+ -> CH1903 (using a grid / triangulation file)
Step (1) if fully implemented. However step (2) is missing. It introduces corrections of up to 3 meters (plus false easting/northing of 2000000/1000000) and accounts for the historical deviations from the modern system.
To fix this, we could:
- Use the "official" triangulation file and FINELTRA algorithm.
- Use the NTv2 grid file provided by swisstopo. This is an approximation, but should be in general good enough for osm use.
Change History (36)
comment:17 Changed 4 weeks ago by
|Keywords:||ntv2 grid added|
|Priority:||minor → normal|
comment:31 Changed 3 weeks ago by
|Summary:||Swissgrild CH1903 is off by up to 3 meters (does not use data set of local corrections ) → Swissgrid CH1903 is off by up to 3 meters (does not use data set of local corrections )|