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Author Topic: Exporting TPs with RMS error in xyz  (Read 6585 times)

mauroB

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Re: Exporting TPs with RMS error in xyz
« Reply #15 on: November 02, 2022, 11:40:32 PM »
Dear Paulo,
I'm involved in adjusting a script by adding the BA-derived tie points precisions.
In the previous discussion and posted code snippet you introduced the tranformation matrix T, which basically allows to transform the model (or "internal") coordinates into a local cartesian coordinates system. I was wondering why did you use this reference system for precisions computation insted of the geocentric (or the world reference) one? Am I missing some detail?
Many thanks.
Mauro
« Last Edit: November 02, 2022, 11:43:31 PM by mauroB »

Paulo

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Re: Exporting TPs with RMS error in xyz
« Reply #16 on: November 03, 2022, 05:39:46 PM »
Hola Mauro,

the idea in calculating TPs variance in LRS or local East North Up system reference is that its axii are representative RMS TP east, North up, while using RMS in geocentric is not meaningful and using PCS (ie. UTM or other) is not possible as conversion from geocentric to PCS cannot be represented by a 4x4 transformation matrix which needed in the propagation of variance-covariance matrix from internal CS...
« Last Edit: November 03, 2022, 07:05:44 PM by Paulo »
Best Regards,
Paul Pelletier,
Surveyor