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,