Re: [Orekit Users] geoid undulation

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

Hi Odi,

Le 22/02/2015 16:30, Odenstein Manfred a écrit :
> Hi, sorry, I'm not the math expert, but I'm using orekit for the
> magnetic field calculations, as I now need also some gravity
> calculations, especially undulation, I've found the implementation of
> a model reader for EGM96, EGM2008, etc but found no method which
> takes lat/lon and date to retrieve the information. I'm just oversee
> something or is nothing there ?

You did not oversee anything. There are no undulation computation yet in
Orekit. We will probably add one in the future, as it is important for
example for some Digital Elevation Models that are referenced to geoid
and not to ellipsoid.

The model readers you found are dedicated to look at the gravity field
from a dynamical point of view, not from the undulation perspective.
This means they are used to compute at any point in space the gravity
vector. Undulation are more seen as an iso-surface on the combination of
this gravity field plus some other parts like inertial forces due
to Earth rotation. So they share some data, but we did not implement yet
the second perspective.

Of course, contributions are welcome so if you decided to come up with
the missing parts, we will look at how to include it in Orekit.

> 
> any help would be appreciated thank you and best regards odi
> 

best regards,
Luc