Difference between NGF-IGN 1969 and NGF-IGN69 heights

[a.billault (Antoine Billault)]

Hello
would you please indicate what is the difference between

NGF-IGN 1969 (is this one depreciate ???)

and

NGF-IGN 1969 height (that one should use RAF18 grid)

thanks

antoine

[kseniia.suzdaltseva]

Hi Antoine,

I’ll check it with the team and get back to you with more information.

[kseniia.suzdaltseva]

Hi Antoine,

Thanks for your patience!

Proj is accumulating CRS and vertical datums from different registries. In this case, there are 2 IGN69 vertical datums from the EPSG and IGNF registries.

EPSG IGN69 has a grid file that can be used for height conversions, while IGNF IGN69 represents only a vertical datum without a grid. We would suggest using EPSG:5720 since it has a grid file and can provide straight conversions between ellipsoidal and orthometric heights.