Re: [Flightgear-devel] Positioning Aircraft: accuracy

2013-06-29 Thread Saikrishna Arcot
If it helps, when building Flightgear, I get compile warnings saying that there's a narrowing conversion from double to float in some YASim methods: |flightgear/src/FDM/YASim/YASim.cxx:261:30: warning: narrowing conversion of ‘((YASim*)this)->YASim::.FGInterface::get_uBody()’ from ‘double’ to ‘floa

Re: [Flightgear-devel] Positioning Aircraft: accuracy

2013-06-25 Thread Adam Dershowitz
: FlightGear developers discussions mailto:flightgear-devel@lists.sourceforge.net>> Subject: Re: [Flightgear-devel] Positioning Aircraft: accuracy It really smells like a double -> float conversion somewhere in the pipeline (more than a geocentric / geodetic conversion or something like t

Re: [Flightgear-devel] Positioning Aircraft: accuracy

2013-06-25 Thread Curtis Olson
It really smells like a double -> float conversion somewhere in the pipeline (more than a geocentric / geodetic conversion or something like that). Curt. On Tue, Jun 25, 2013 at 2:01 PM, D-NXKT wrote: > > How far off is the aircraft placement - how much is the "jump"? Is it > > many hundreds o

Re: [Flightgear-devel] Positioning Aircraft: accuracy

2013-06-25 Thread D-NXKT
> How far off is the aircraft placement - how much is the "jump"? Is it > many hundreds of meters, or on the order a meter or two, or just > centimeters? > > Jon Several meters! Or more precise: first: lat= 47.306263 lon= 11.379070 "jump" to: lat= 47.3062060567 lon= 11.3790703145

Re: [Flightgear-devel] Positioning Aircraft: accuracy

2013-06-24 Thread Jon S. Berndt
> It seems that we have a problem with the FG/JSBSim-interface or it's a > rounding error during JSBSim-initialisation?! > > Summarizing my observations: > - immediately after FG is started the property browser shows the > correct values > - this values hold true as long as the splash-screen appea

Re: [Flightgear-devel] Positioning Aircraft: accuracy

2013-06-24 Thread D-NXKT
> The hang glider is using the UIUC fdm, right? Perhaps that is using a > float (6-7 digits of precision) to represent it's initial > conditions ... or somewhere in the startup pipeline or the flightgear > interface to the uiuc > model, the initial lon/lat is stored as a float? Curt, you poin

Re: [Flightgear-devel] Positioning Aircraft: accuracy

2013-06-23 Thread Curtis Olson
The hang glider is using the UIUC fdm, right? Perhaps that is using a float (6-7 digits of precision) to represent it's initial conditions ... or somewhere in the startup pipeline or the flightgear interface to the uiuc model, the initial lon/lat is stored as a float? On Sun, Jun 23, 2013 at 5:2

Re: [Flightgear-devel] Positioning Aircraft: accuracy

2013-06-23 Thread D-NXKT
Hmm, everything is fine if I use a different plane. Seems to be a hang glider specific problem. Monitoring the latitude and longitude variabel from the very beginning shows, that both variables have at first indeed the correct values. Then the latitude value suddenly jumps from 47.306263 to 47.306

Re: [Flightgear-devel] Positioning Aircraft: accuracy

2013-06-23 Thread D-NXKT
Hi Tom, > How have you checked these values? I've just tried it myself and in > the property browser exactly the same values appear. I started FG with --lon=11.379070 --lat=47.306263 --heading=155 --units-meters --on-ground and found me at --lon=11.3791 -

Re: [Flightgear-devel] Positioning Aircraft: accuracy

2013-06-23 Thread Thomas Geymayer
Hi, Am 2013-06-23 22:27, schrieb D-NXKT: > I noticed that positioning an aircraft at FG startup with --lon= and > lat= has only a limited accuracy. It seems that only the first 7 > digits are read. This leads to an uncertainty of several > meters/feet! For example lon=11.379070 --lat=47.306263 is

[Flightgear-devel] Positioning Aircraft: accuracy

2013-06-23 Thread D-NXKT
Hello, I noticed that positioning an aircraft at FG startup with --lon= and lat= has only a limited accuracy. It seems that only the first 7 digits are read. This leads to an uncertainty of several meters/feet! For example lon=11.379070 --lat=47.306263 is needed to place our hang glider directly i