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dr-ni / helmert3d

The 3D Helmert transformation is a frequently used method in geodesy to produce transformations between different Cartesian coordinate systems
http://helmparms3d.sourceforge.net/
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Ellipsoid? #7

Closed zvezdochiot closed 2 years ago

zvezdochiot commented 2 years ago

Hi @dr-ni .

At the moment there is only one ellipsoid: 

GRS80 6378137.0 6356752.3141

A list of commonly used ellipsoids known to me: 

BESSEL 6377397.155 6356078.962822
GRS80 6378137.0 6356752.3141
GSK2011 6378136.5 6356751.758
KRASOVSKIY 6378245.0 6356863.018773
PZ90 6378136.0 6356752.3142
WGS84 6378137.0 6356752.314245

Add those that you see fit (and wherever you see fit) to this repo.

PS: Should we change the form of a b to the more common a 1/f, where b = a * (1 - f)? See:

dr-ni commented 2 years ago

yes, common formats make sense

do you know LGS21?

zvezdochiot commented 2 years ago

@dr-ni say:

do you know LGS21?

Unknow.

zvezdochiot commented 2 years ago

See https://proj.org/usage/ellipsoids.html . Defined by (a rf f b). See https://proj.org/usage/projections.html . Defined by (a b). I'll leave it as it is for now.

https://github.com/dr-ni/helmert3d/commit/975d1b13ad629ec18ba0e385c1aff45195e5a9c6