Re: [Orekit Users] How should I model satellite sensor event detection of a single ground point?

[Luc Maisonobe <Luc.Maisonobe@c-s.fr>]

Le 22/06/2017 à 02:16, Glenn Ehrlich a écrit :
> All,
> 

Hi Glenn

>  
> 
> What would be the best event detector to use to model when a satellite
> 
> sensor with a FieldOfView has visibility of a single point on the Earth.
> 
>  
> 
> My modeling situation is I want to model when a ground site is in view
> 
> of the sensor. I tried using a FieldOfViewDetector with the target
> 
> being a TopocentricFrame built from the coordinates of the ground site
> 
> but that does not find any events.

This may be due to the fact TopocentricFrame seen as a
PVCoordinatesProvider only represent the point itself, not the ground
on which it sits. This means that the spacecraft doesn't see when the
points disappears because it goes below horizon. So if the spacecraft
always points to where the point should be, it will consider it always
ses it.

You could combine the FieldOfViewDetector with an
ElevationDetector using the AND operator from BooleanDetector. Then,
the horizon crossing will trigger events, as well as the attitude
changes.

hope this helps,
Luc

> 
>  
> 
> I am able to get a GeographicZoneDetector to work with a
> 
> GeographicZone built from a triangle enclosing the ground site, but
> 
> I'm wondering if there is some combination of objects where I can just
> 
> specify the coordinates of the ground site itself.
> 
>  
> 
> Thank you.
> 
>  
> 
> Glenn Ehrlich
> 
> KinetX Aerospace
> 
>  
>