On Mon, 3 Aug 2009 11:04:20 -0500, Curtis wrote in message <ef5fc9920908030904o75b75204j9abe3c3350eb3...@mail.gmail.com>:
> I asked earlier about using the FlightGear view system to keep a > camera fixed on a specific point in the world. A real world usage > example perhaps could be a gyro stabilized view on a news > helicopter. ..hum, most of the youtube footage I see shot from news helicopters, involve ground targets at high speeds in e.g. car chases. :o) > Ron Jensen was kind enough to post a view configuration > that did exactly this. I've been looking though the viewer math that > processes this configuration and it I think I am understanding a fair > bit of it, but the code is designed to produce a view transformation > matrix (I believe) is OSG world space. > > What I am trying to accomplish is a bit different. I want to know the > heading and pitch offsets (pan & tilt angles) that will point the > camera at the target ... while the aircraft flies through any > arbitrary position and orientation. > > I know the target lon/lat/elevation. > I know the viewer lon/lat/elevation. > I know the viewer orientation in the local world coordination frame. > > It seems like it makes sense to transform these to ECEF (earth > centered coordinate frame.) > > I should be able to compute my aircraft "up" vector in ECEF > I should be able to compute a "forward" vector in ECEF (or which ever > vector corresponds to my camera's zero/zero pan/tilt orientation.) > > Once the view and target locations are transformed to ECEF, I can > compute a vector from the eye to the target in ECEF. > I can compute an aircraft up vector in ECEF > I can compute a "forward" vector in ECEF. The forward vector should > correspond to a camera pan/tilt orientation of zero/zero relative to > the aircraft. > > Can I use the quaternian fromRotateTo() function to create a > quaternian than represents a rotation from the camera's default > zero/zero direction to the target direction? > > I see two forms of the quaternian fromRotateTo() function, one that > just takes two vectors and one that includes indices to two unit > vectors? Is there any explanation of how that works? The comments > in the code are pretty thin. > > Then assuming I'm on the right track here, from this quaternian, how > do I extract out the actual euler angles. Can I just call > getEulerRad() and will my angles just pop out, or do I need to do > additional work? > > Am I on the right track here? Are there easier/better ways to > accomplish this? > > What I want in the end are two angles (pan & tilt) to move my camera > to stay fixed on an arbitrary point, no matter how the aircraft moves > or is oriented. > > Thanks, > > Curt. -- ..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. ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
