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Re: [Orekit Developers] Status of the Android application -- 2



Alexis ROBERT <alexis.robert@gmail.com> a écrit :

On Fri, Aug 12, 2011 at 4:21 PM, pascal parraud <pascal.parraud@c-s.fr> wrote:
 - start date/end date are confusing to me. What this app does is to
propagate one input orbit from an initial date(practically the input
orbitdate)to some final date, where we want to retrieve the computed orbit
parameters. As we consider an impulse maneuver, with no duration, start date
and end date don't mean maneuver duration, the end date is really the final
date for the propagation, but start date stands here for the maneuver time.
In fact it would be much more suitable to be able to chose the kind of event
which triggers the maneuver (among a predefined TBD list of meaningful ones
such as apside, date...). Luc, what do you think of this ?

Yes exactly, that's what did the little J2SE app I made for testing.

About entering the different kind of events, I'm currently thinking on
how to do the "event detection" part of the program which should input
all kind of event types (if I understood correctly).

Events are meant here as Orekit events. This means classes that implement the EventDetector interface (in org.orekit.propagation.events package). There are several such events classes already defined, each with its own settings.


 - by the way, the TLE format contains the orbit date (line 1 fields 7 & 8),
so we must provide a way to optionnaly input or not some date(this holds
also for the orbit conversion). In the first case, the propagate method must
be called, as it is already done in your code.

Ah ok I didn't know, thanks :)

 - the final orbit is shown in cartesian form ... and I guesssometimesit
won't be the good one, so it will be fine to ask as an input for the choice
of the output orbit format.

Currently all the output part is temporary and would be better
(without just using toString() methods everywhere). About conversion,
I was more thinking of a button which would send it to the orbit
conversion part, but your choice seems to be better.

* about the code :
 - in the ManeuverComputeActivity, even for the TLE you can get :
orbit_frame = propagator.getFrame (line 167) as the TLE propagator is a full
Propagator.

I did that before, and it resulted in a NullPointerException so I forced TEME.

Thank you for this good job (and sorry for these little spec changes...)

No problem for the spec changes, it's normal :)

Here are a few random comments from me, as I just succeeded in installing the application (I had to completely reinstall my tablet with a new ROM, this time with Android 3.0.1).

When we leave go back to an input form after a computation, it is reset back to default values (i.e. all zeros for frame conversions). So if I want to do several conversions from the same parameters and change only the target frame, I have to retype everything again. Could the last entered values be remembered somehow ?

Is the layout of the UI final with the compute button at the top right ?

About Pascal request about units, I am on the fence. On the one hand, Orekit needs SI unit and only SI units. However, entering angles in an end-user application in radians is awkward. Would it be possible to let the user specify the units he wants (SI by default, with m, m/s, m^3/s^2, rad) but allowing to use for example degrees for angles and converting to SI units underneath ?

best regards,
Luc


Have a nice WE

Thanks, you too !

Alexis





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