The way we used to visualize a quaternion when working with them at Lockheed was as an eigen vector (just a vector pointing in some 3d direction that extends from the origin to the unit sphere surrounding the origin), and a rotation around the eigen vector.
Quaternions are easier to multiply and easier to add than matrices, and they reduce the number of multiply and divide operations required on the CPU. On Thu, Jan 16, 2003 at 12:06:09AM -0500, Norman Vine wrote: > Mike Bonar writes: > > > > I have it. It looks like a better dead reckoning algorithm for prediction and > > extrapolation, but the math is way over my head. > > I notice they mention using quaternions in the abstract but it is probably easiest > to grasp a Matrix formulation first > http://ocw.mit.edu/13/13.49/f00/lecture-notes/all-Z-H-3.html > > Using a quat is a bit more 'elegant' but is pretty much the same thing > here is a *classic* explaining the relationship that is esp relevant to FlightGear > http://www.movesinstitute.org/~zyda/pubs/Presence.1.4.pdf > > AFAIK Most all prediction and extrapolation is done with a kalman these days > lots of *good* stuff here and also at the MIT site linked above > http://www.cs.unc.edu/~welch/kalman/ > > Norman > > > > (It's $19 from the site with out a web account). > > > > Mike > > > > On Wednesday 15 January 2003 10:39, Alex Perry wrote: > > > I'll go have a look ... > > > > > > > Message: 3 > > > > Date: Tue, 14 Jan 2003 20:14:15 -0600 > > > > From: Mike Bonar <[EMAIL PROTECTED]> > > > > Subject: Re: [Flightgear-devel] IPC communication for FlightGear > > > > To: [EMAIL PROTECTED] > > > > Reply-To: [EMAIL PROTECTED] > > > > > > > > Anyone have an IEEE membership? > > > > > > > > http://www.computer.org/proceedings/ds-rt/1053/10530045abs.htm > > > > > > _______________________________________________ > > > Flightgear-devel mailing list > > > [EMAIL PROTECTED] > > > http://mail.flightgear.org/mailman/listinfo/flightgear-devel > > > > > > > -- > > Linux 2.4.19, P4 1.5, 512MB, Geoforce 3 > > Trim for 60, carb heat on, fuel on, electricals on, throttle open one quarter, > > turn to start... > > > > _______________________________________________ > > Flightgear-devel mailing list > > [EMAIL PROTECTED] > > http://mail.flightgear.org/mailman/listinfo/flightgear-devel > > > > _______________________________________________ > Flightgear-devel mailing list > [EMAIL PROTECTED] > http://mail.flightgear.org/mailman/listinfo/flightgear-devel -- // .--=, .....::://::::::::::::::::::::::::::::.. (o O & [EMAIL PROTECTED] :::::::://:::://://://:/:://::||_// / V K :::::://:::://:/:|//'/' // _,|' r , 'qk :'''/____ // / // |_// // || .'~. .~`, kls \_/-=\_/ _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
