Transforming coordinates between two different epochs in the same reference frame (ex: [email protected] to ex: [email protected])

[QuanticDisaster]

Hello,

I am a bit new to proj, And i have been currently struggling to find for multiple days to find how and if it is possible to do some things, so this ticket may also be a hint to ask for clearer documentation.

I am trying to perform a transformation from the same CRS in different epochs, such as from ITRF2014 @ 2000.0 to ITRF2014 @ 2020.0

As an example I can take a station from https://itrf.ign.fr/en/homepage in France that have around 1cm / year of motion in X,Y and Z coordinates

Looking at the documentation, the only option I found was to manually look for the nearest station to my coordinates, get their velocity and use an helmert transformation with only the velocity and epoch.

echo X Y Z 2000 | cct +proj=helmert +dx=-0.01 +dy=-0.2 +dz=-0.03 +t_epoch=2020 +convention=position_vector

So is this currently implemented in proj and if its the case, how can I perform the same operation without the hassle of looking for the velocity of each neighboring station by myself ?

Thanks