Re: [Flightgear-devel] Terrain height below aircraft
On Tue, 7 Jun 2005 11:19:02 -0700, Drew wrote in message <[EMAIL PROTECTED]>: > Is there a reliable way to determine the terrain height below the > aircraft that is independent of the view being used? I've tried the > property "/environment/ground-elevation-m", but when I use tower view, > it returns the elevation at the view origin. > > I'm trying to develop an RC-type application, so knowing the height > from the controller's position is worthless. How can I get the > terrain height below the aircraft? It would be helpful if I could > determine the height of any arbitrary lat/lon position, as well, if > that's possible. ..think "gun elevation", as in "aim at it." I view your terrain height angle a detour, you fly either above _or_ in front of terrain, and orient your plane relative to yourself and vice versa, looking at it. -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Terrain height below aircraft
Drew wrote: > I'm not using a YASim model...it's a net-fdm interface...I'm only > using FlightGear as a scenery generator. Anyway, I just looked at > the YASim code, and it uses "environment/ground-elev-m" to derive > the height above terrain, which means it will also fail using tower > view. Er, no. It uses the lowest landing gear AGL distance, which these days comes from the new groundcache code. I assure you it's not using the view location for AGL altitude, as evidenced by the fact that the aircraft doesn't fall through the terrain when you switch views. :) As far as the net-fdm issue goes: you may be stuck. The FDM is the piece of code responsible for deciding on terrain interaction under the FlightGear architecture (it has to be, if you think about it -- otherwise no one is in charge of gear force). How does your external FDM make its own decisions about ground interaction? If you can't get the answer there, you may have to write some C++ code to query the ground cache on your own. Andy ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Terrain height below aircraft
My mistake...I was using "/environment/ground-elevation-m", but what I wanted was "/position/ground-elev-m", which works as advertised, and that's what YASim uses, as well. Thanks again, Drew On 6/7/05, Drew <[EMAIL PROTECTED]> wrote: > I'm not using a YASim model...it's a net-fdm interface...I'm only > using FlightGear as a scenery generator. Anyway, I just looked at the > YASim code, and it uses "environment/ground-elev-m" to derive the > height above terrain, which means it will also fail using tower view. > > On 6/7/05, Andy Ross <[EMAIL PROTECTED]> wrote: > > Drew wrote: > > > Perhaps the FDM needs to set this, in which case, how would the FDM > > > model know what the terrain height is? > > > > Yes, the FDM needs to set this, and it knows it because it needs it to > > compute the gear forces. I know support is there in YASim; if you are > > using a YASim model and this isn't working, it's a bug. > > > > Andy > > > > > > ___ > > Flightgear-devel mailing list > > Flightgear-devel@flightgear.org > > http://mail.flightgear.org/mailman/listinfo/flightgear-devel > > 2f585eeea02e2c79d7b1d8c4963bae2d > > > ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Terrain height below aircraft
I'm not using a YASim model...it's a net-fdm interface...I'm only using FlightGear as a scenery generator. Anyway, I just looked at the YASim code, and it uses "environment/ground-elev-m" to derive the height above terrain, which means it will also fail using tower view. On 6/7/05, Andy Ross <[EMAIL PROTECTED]> wrote: > Drew wrote: > > Perhaps the FDM needs to set this, in which case, how would the FDM > > model know what the terrain height is? > > Yes, the FDM needs to set this, and it knows it because it needs it to > compute the gear forces. I know support is there in YASim; if you are > using a YASim model and this isn't working, it's a bug. > > Andy > > > ___ > Flightgear-devel mailing list > Flightgear-devel@flightgear.org > http://mail.flightgear.org/mailman/listinfo/flightgear-devel > 2f585eeea02e2c79d7b1d8c4963bae2d > ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Terrain height below aircraft
Drew wrote: > Perhaps the FDM needs to set this, in which case, how would the FDM > model know what the terrain height is? Yes, the FDM needs to set this, and it knows it because it needs it to compute the gear forces. I know support is there in YASim; if you are using a YASim model and this isn't working, it's a bug. Andy ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Terrain height below aircraft
Thanks for the suggestion...I just tried it, but the "/position/altitude-agl-ft" property doesn't seem to be working. It's always zero. Perhaps the FDM needs to set this, in which case, how would the FDM model know what the terrain height is? On 6/7/05, Andy Ross <[EMAIL PROTECTED]> wrote: > Drew wrote: > > Is there a reliable way to determine the terrain height below the > > aircraft that is independent of the view being used? > > Subtract the AGL altitude from the MSL altitude? I'm pretty sure both > of these are available in the property tree. > > Andy > > ___ > Flightgear-devel mailing list > Flightgear-devel@flightgear.org > http://mail.flightgear.org/mailman/listinfo/flightgear-devel > 2f585eeea02e2c79d7b1d8c4963bae2d > ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Terrain height below aircraft
Drew wrote: > Is there a reliable way to determine the terrain height below the > aircraft that is independent of the view being used? Subtract the AGL altitude from the MSL altitude? I'm pretty sure both of these are available in the property tree. Andy ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
