[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Rugged Users] Time dependent transformation
Hi Issam,
issam.boukerch@yahoo.fr a écrit :
Thank you Luc for your help,
I will explain the problem with more details.
The time-dependant transforms are known (estimated) beforehand , and
are used as refinement of the trajectory to obtein a more accurate
direct location. The use of the ephemeris data only for the direct
location will give a degraded quality of positioning due to the
limited accuracy of the AOCS.The time-dependant correction
transforms are estimated using some Ground Control Points (GCPs)
that are known on the image and accuratly known on the ground. This
is done by estimating the corrections that must be added to the
initial AOCS data to make the direct location of a known pixel
correspond to its accurate ground position.
If I estimate these time-dependent corrections, is there any way to
add theme to the initial trajectory (which is based on ephemeris
that came with the image) directly from Rugged? (which is an
interesting functionality that have to be added to Rugged)
You cannot add them to the initial trajectory, but you can use them
to create a new trajectory and create a new Rugged instance with this
improved trajectory. In some way, this would simply be a two pass
location : first pass with just the few reference points just so you
can do the correction, then a second pass for the other images.
Of course, you can do both in the same process if you want.
if no, then I have to prefilter the position/velocity/quaternions
before giving them the RuggedBuilder. I don't know if it is
possible, but how to do this prefiltering, by adding these
corrections to the initial trajectory and getting the PVs and
quaternions of the corrected trajectory, in Orekit ?
It really depends on how your corrections are computed and what is
the result. If it is simply translations/rotations, you can do it
directly using the Vector3D and Rotation classes from the mathematical
library, without involving Orekit at all.
best regards,
Luc
Regards,