Le 12/08/2024 à 18:44, Laura, Jason R via PROJ a écrit :
List,
I have a set of body-centered body-fixed coordinates that were
computed with an ellipsoid of +a=3396190 +b=3376200. I am attempting
to reproject these into a spherical datum (+R=3396190) using the
pipeline syntax. For example,
+proj=pipeline +units=m
+step +proj=cart +a=3396190 +b=3376200
+step +proj=cart +R=3396190
Which is failing with a unit warning. I suspect I am missing something
basic.
You need to add +inv in the last step to go from ECEF to lon-lat
coordinate space
I have looked at the geodesic -> Helmert -> geodesic transformation
tutorial, but I am clearly misunderstanding something
(https://proj.org/en/9.3/tutorials/EUREF2019/exercises/pipelines.html#geodetic-helmert-geodetic)
Looking at these docs, I tried:
+proj=pipeline
+step +proj=cart +a=3396190 +b=3376200
+step +proj=helmert +z=19990 +convention=position_vector
+step +inv +proj=cart +R=3396190
But I get an invalid latitude error (which I believe means I am
misspecifying the input system).
Works for me. The input coordinate order is longitude, latitude, Z.
Any suggestions appreciated,
Jay
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