Hello,
I’m trying to convert ITRF92 (epoch 93.0) coordinates to ITRF2014 epoch 2023.0.
Having some 8 cms per year movement I expect some 2.4m difference in the
coordinates.
I tried some syntaxes but did not understand clearly how (where) to indicate
the epochs (initial and final) in my tests :
One test applied was :
echo -139.57736536 -8.95162075 2.234 2023.0 | cct +proj=pipeline +step
+proj=cart +ellps=GRS80 +step +proj=helmert +x=-0.0154 +y=-0.0015 +z=0.0708
+rx=0 +ry=0 +rz=-0.00026 +s=-0.00309 +dx=-0.0001 +dy=0.0005 +dz=0.0033 +drx=0
+dry=0 +drz=-2e-05 +ds=-0.00012 +t_epoch=1993 +convention=position_vector +step
+inv +proj=cart +ellps=GRS80
Which gave me
-139.5773658008 -8.9516192265 2.1701 2023.0000
As result. Difference much lower than expected representing some 20 cm
variation from one epoch to the other.
I indicated the final epoch desired in my input and the initial epoch in the
helmert transform.
This is probably false, but I did not encounter this kind of indication in the
documentation.
Where is the misunderstanding?
Thank you for any help,
Alain Orsoni
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