For a real flight playback, if attitude accuracy is not so important, only
GPS position data (one shot every second) is enought for a smooth FG
playback (if no acrobatics have been perform...).

I think this playback function could be a nice for the debriefing of Flight
Intructors who let their students for their first solo country flight. Spy
on board...


----- Original Message -----
From: "Roberto Manca" <[EMAIL PROTECTED]>
To: "FlightGear developers discussions" <[EMAIL PROTECTED]>
Sent: Tuesday, August 24, 2004 3:11 PM
Subject: Re: [Flightgear-devel] Re: Bypass FG Physics and Draw


> While the idea is correct in principle, what you said
> it is not so straightforward.
>
> I've realised a flight recorder and a flight player
> for Flightgear for my thesis so I played around with
> few ideas. Basically I developed a virtual cockpit in
> a distributed environment that uses Flightgear to have
> some 'meaningful' flight data. I had to test different
> configurations so I needed to use always the same data
> that is to fly always the same flight.
>
> My experience is that it's very difficult to
> synchronise Flightgear with an
> initial-position-and-flight-command approach since the
> only cross-platform means of communication available
> is the socket. You always end up with a time shifting
> of the packets that produces a space shifting of the
> flight. Therefore sometimes you try to manouevre into
> a mountain while you did't in the original flight.
> Now what i've done is to record, through a socket, all
> the flight at an accettable frame rate onto a file by
> using the native-fdm data structure. (this is the
> recorder). Then I wrote a player that reads the file
> and sends the data over to Flightgear (previously set
> up with the external-fdm option). It works quite well
> apart from some adjustment in the speed of replay you
> need to experiment with.
>
> Roberto
>
>  --- Harald JOHNSEN <[EMAIL PROTECTED]> ha scritto:
> > [EMAIL PROTECTED] wrote:
> >
> > > Does this mean that we would have the ability to
> > save and load flight
> > > data so as to reproduce, say, a taxi, take off,
> > pattern and landing at
> > > KSFO or another airport automatically (i.e., as a
> > demo or as a
> > > training exercise).  Perhaps a short flight around
> > the SF area also
> > > showing off the new scenery?
> > >
> > > Could we ship such flights around scenic areas
> > (Mount Ranier, Crater
> > > Lake, the Grand Canyon) for new users in the base
> > package or as
> > > downloadables off of flightgear.org?
> > >
> > > How big would such files be? How much data needs
> > to be kept, how much
> > > can be calculated on the fly?  Do weather
> > conditions need to be saved
> > > also?
> > >
> > > Would flights around scenic areas be done better
> > as flight plans with
> > > waypoints or tied into this new playback method
> > somehow?
> > >
> > > Can this playback tool be used as a training
> > method for new simulator
> > > pilots?
> > >
> > > If we are not saving a real recorded flight,
> > perhaps we can use a
> > > similar method to extract either entire flights or
> > the last XX number
> > > of seconds of a flight to save to disk for later
> > replay?
> > >
> > > MS FlightSimulator has an extensive tutorial that
> > involves pre-saved
> > > flights which the users can break into at certain
> > points in the
> > > flights. How difficult would it be to add
> > something similar to FG and
> > > where would one begin (if no one is already
> > working on something like
> > > this).
> > >
> > > Thanks!
> > >
> > > Ima
> > >
> > >
> > > _______________________________________________
> > > Flightgear-devel mailing list
> > > [EMAIL PROTECTED]
> > >
> >
> http://mail.flightgear.org/mailman/listinfo/flightgear-devel
> > > 2f585eeea02e2c79d7b1d8c4963bae2d
> > >
> > I think that the ability to "play" a flight recorded
> > by an external
> > source is different from the ability to save/load a
> > flight from FG.
> > In other words, I don't think we should save any
> > state variable - ie
> > parts of totality of the property tree.
> > We have an initial state when FG is launched with a
> > specific set of
> > parameters. Now how do you fly ? You use your
> > joystick, mouse,
> > keyboard et al to interact with the simulator. So a
> > recorded fligth
> > could be defined as a list of user interactions
> > paired with a time stamp,
> > and to be more accurate a very limited set of
> > properties could be added
> > lets say every 10 or 20 seconds (position, heading,
> > etc).
> > The advantage would be :
> >     - short record file size
> >     - accurate property tree because the simultor
> > would run exactly with
> > the same imputs
> >     - easy to implement because it is not tied to
> > the internals of the
> > simulator (like fdm).
> >
> > Harald.
> >
> >
> > _______________________________________________
> > Flightgear-devel mailing list
> > [EMAIL PROTECTED]
> >
> http://mail.flightgear.org/mailman/listinfo/flightgear-devel
> > 2f585eeea02e2c79d7b1d8c4963bae2d
> >
>
>
>
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