A few years ago, I helped squash a bug that occurred when reading in data with
generic IO (I think that my patch was included in the code). At the time, it
was reading in just a float. So, when using it to read in position, the
doubles for lat/long were being cut (rounded or truncated?) and it meant that
during playback of flight the aircraft would jump around a little bit (on the
order of meters), even when there was actually smooth position data in the
input file. The look was like a bad frame rate, because it would jump from
position to position.
So, I concur that it sounds a lot like just a float is being used for initial
position, when a double is necessary.
-- Adam
From: Curtis Olson <curtol...@flightgear.org<mailto:curtol...@flightgear.org>>
Reply-To: FlightGear developers discussions
<flightgear-devel@lists.sourceforge.net<mailto:flightgear-devel@lists.sourceforge.net>>
Date: Tuesday, June 25, 2013 12:05 PM
To: FlightGear developers discussions
<flightgear-devel@lists.sourceforge.net<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 that).
Curt.
On Tue, Jun 25, 2013 at 2:01 PM, D-NXKT
<d_n...@yahoo.de<mailto:d_n...@yahoo.de>> wrote:
> 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
^
Difference = 6.34 meters (20.80 ft)
Best regards
D-NXKT
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--
Curtis Olson:
http://www.atiak.com<http://www.atiak.com/> - http://aem.umn.edu/~uav/
http://www.flightgear.org<http://www.flightgear.org/> -
http://gallinazo.flightgear.org<http://gallinazo.flightgear.org/>
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