Re: [Flightgear-devel] aircraft modeling question
Hi Curt, On Thursday 16 April 2009 20:24:02 Curtis Olson wrote: I was hoping for a reasonably simple solution without needing new external software development, but the idea of leveraging the multiplayer protocol is interesting. I notice that with our existing multiplayer servers, there is at least a many second delay in positioning the MP aircraft. Is that delay imposed by the server side, or is there something built into the protocol that could cause position updates to be delayed before they are drawn? There is not 'hard' time relationship in the multiplayer protocol. This is due to the totally unreliable lags between the participiants. The multiuplayer protocol just tries its best to have something that behaves like the external multiplayer ... So, for that puropse you are trying to do I believe that this loose time coupling of the mp protocol might introduce problems you do not want to have. OTOH, if the mp players happen in a local network, at least my personal experience with the mp stuff tells me that you do not see to much of that time adjustments so this might work well enough. But whatever you try to debug with that visualization, keep in mind that there is a loose coupling of simulations times. Back to my other idea. It shouldn't be hard to figure out an XYZ offset of a 2nd piggyback model. But in terms of orientation, are there animation primitives that would allow me to specify absolute euler angles for the 2nd model, or would those angle also have to be computed relative to the primary model orientation (that's doable I suppose, but my brain has begun to hurt just at the suggestion of having to do it.) :-) As far as I remember, we do not have an absolute euler angle animation in this sense. But you can compute the relative orientation using the quaternion stuff and use the relative orientations euler angles in the animation. Greetings Mathias -- Stay on top of everything new and different, both inside and around Java (TM) technology - register by April 22, and save $200 on the JavaOne (SM) conference, June 2-5, 2009, San Francisco. 300 plus technical and hands-on sessions. Register today. Use priority code J9JMT32. http://p.sf.net/sfu/p ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] aircraft modeling question
Mathias Fröhlich Hi Curt, On Thursday 16 April 2009 20:24:02 Curtis Olson wrote: I was hoping for a reasonably simple solution without needing new external software development, but the idea of leveraging the multiplayer protocol is interesting. I notice that with our existing multiplayer servers, there is at least a many second delay in positioning the MP aircraft. Is that delay imposed by the server side, or is there something built into the protocol that could cause position updates to be delayed before they are drawn? There is not 'hard' time relationship in the multiplayer protocol. This is due to the totally unreliable lags between the participiants. The multiuplayer protocol just tries its best to have something that behaves like the external multiplayer ... So, for that puropse you are trying to do I believe that this loose time coupling of the mp protocol might introduce problems you do not want to have. OTOH, if the mp players happen in a local network, at least my personal experience with the mp stuff tells me that you do not see to much of that time adjustments so this might work well enough. But whatever you try to debug with that visualization, keep in mind that there is a loose coupling of simulations times. Back to my other idea. It shouldn't be hard to figure out an XYZ offset of a 2nd piggyback model. But in terms of orientation, are there animation primitives that would allow me to specify absolute euler angles for the 2nd model, or would those angle also have to be computed relative to the primary model orientation (that's doable I suppose, but my brain has begun to hurt just at the suggestion of having to do it.) :-) As far as I remember, we do not have an absolute euler angle animation in this sense. But you can compute the relative orientation using the quaternion stuff and use the relative orientations euler angles in the animation. You might find some of the necessary quaternion calculations in the AIBallistic, where we slave a ballistic object to the main model at some given offset. Warning though, because they are intended for droptanks and the like, I didn't compute the yaw offset. Similar computations are in AIWingman, but here deliberate errors are introduced. But I think either might make a starting point for what is required. Vivian -- Stay on top of everything new and different, both inside and around Java (TM) technology - register by April 22, and save $200 on the JavaOne (SM) conference, June 2-5, 2009, San Francisco. 300 plus technical and hands-on sessions. Register today. Use priority code J9JMT32. http://p.sf.net/sfu/p ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] aircraft modeling question
On Thursday 16 April 2009, Curtis Olson wrote: On Tue, Apr 14, 2009 at 12:26 PM, Torsten Dreyer tors...@t3r.de wrote: My questions is this ... from a modeling perspective, can that 2nd aircraft be animated with absolute lon/lat/elev and roll/pitch/yaw degrees? Or would we need to compute an X, Y, Z offset in meters for the second aircraft? It would be a pain to figure out the orientation transform relative to the original aircraft ... can the secondary aircraft be animated with absolute angles relative to the world coordinate frame? (For animating the 2nd aircraft, I imagine we'd create some set of custom property names, and I'd drive them externally via some network/file protocol ... maybe creating a custom configuration for the generic protocol.) Don't know if I understand you right, but if you want to create arbitrary aircraft with independent position and attitude values, you might want to use the multiplayer protocol. If you fake the mp-server, you might inject any number of aircraft into your scene. I was hoping for a reasonably simple solution without needing new external software development, but the idea of leveraging the multiplayer protocol is interesting. I notice that with our existing multiplayer servers, there is at least a many second delay in positioning the MP aircraft. Is that delay imposed by the server side, or is there something built into the protocol that could cause position updates to be delayed before they are drawn? Back to my other idea. It shouldn't be hard to figure out an XYZ offset of a 2nd piggyback model. But in terms of orientation, are there animation primitives that would allow me to specify absolute euler angles for the 2nd model, or would those angle also have to be computed relative to the primary model orientation (that's doable I suppose, but my brain has begun to hurt just at the suggestion of having to do it.) :-) Thanks, Curt. I can't recall any animation methods that are not relative to the orientation of the aircraft axis. On the other hand though, things like pitch, roll, altitude, lat, lon etc. are absolutes and available in the property tree, so it should be easy enough to derive an equivalent absolute frame of reference. That is, it should be easy enough to use these property tree nodes in your animations while they're atomic values but if it's decided that they should be represented by compound values, and it makes as much sense to use them for lat, lon alt, or pitch, roll yaw, as using them anywhere else, you'd have to write some code to parse them first. LeeE -- Stay on top of everything new and different, both inside and around Java (TM) technology - register by April 22, and save $200 on the JavaOne (SM) conference, June 2-5, 2009, San Francisco. 300 plus technical and hands-on sessions. Register today. Use priority code J9JMT32. http://p.sf.net/sfu/p ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] aircraft modeling question
On Tue, Apr 14, 2009 at 12:26 PM, Torsten Dreyer tors...@t3r.de wrote: My questions is this ... from a modeling perspective, can that 2nd aircraft be animated with absolute lon/lat/elev and roll/pitch/yaw degrees? Or would we need to compute an X, Y, Z offset in meters for the second aircraft? It would be a pain to figure out the orientation transform relative to the original aircraft ... can the secondary aircraft be animated with absolute angles relative to the world coordinate frame? (For animating the 2nd aircraft, I imagine we'd create some set of custom property names, and I'd drive them externally via some network/file protocol ... maybe creating a custom configuration for the generic protocol.) Don't know if I understand you right, but if you want to create arbitrary aircraft with independent position and attitude values, you might want to use the multiplayer protocol. If you fake the mp-server, you might inject any number of aircraft into your scene. I was hoping for a reasonably simple solution without needing new external software development, but the idea of leveraging the multiplayer protocol is interesting. I notice that with our existing multiplayer servers, there is at least a many second delay in positioning the MP aircraft. Is that delay imposed by the server side, or is there something built into the protocol that could cause position updates to be delayed before they are drawn? Back to my other idea. It shouldn't be hard to figure out an XYZ offset of a 2nd piggyback model. But in terms of orientation, are there animation primitives that would allow me to specify absolute euler angles for the 2nd model, or would those angle also have to be computed relative to the primary model orientation (that's doable I suppose, but my brain has begun to hurt just at the suggestion of having to do it.) :-) Thanks, Curt. -- Curtis Olson: http://baron.flightgear.org/~curt/ -- Stay on top of everything new and different, both inside and around Java (TM) technology - register by April 22, and save $200 on the JavaOne (SM) conference, June 2-5, 2009, San Francisco. 300 plus technical and hands-on sessions. Register today. Use priority code J9JMT32. http://p.sf.net/sfu/p___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] aircraft modeling question
My questions is this ... from a modeling perspective, can that 2nd aircraft be animated with absolute lon/lat/elev and roll/pitch/yaw degrees? Or would we need to compute an X, Y, Z offset in meters for the second aircraft? It would be a pain to figure out the orientation transform relative to the original aircraft ... can the secondary aircraft be animated with absolute angles relative to the world coordinate frame? (For animating the 2nd aircraft, I imagine we'd create some set of custom property names, and I'd drive them externally via some network/file protocol ... maybe creating a custom configuration for the generic protocol.) Don't know if I understand you right, but if you want to create arbitrary aircraft with independent position and attitude values, you might want to use the multiplayer protocol. If you fake the mp-server, you might inject any number of aircraft into your scene. Torsten -- This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] aircraft modeling question
Torsten Dreyer ha scritto: Don't know if I understand you right, but if you want to create arbitrary aircraft with independent position and attitude values, you might want to use the multiplayer protocol. If you fake the mp-server, you might inject any number of aircraft into your scene. Torsten I agree with Torsten, further it could be nice (And I think easy too, working with the liveries png) to make a semi transparent aircraft that could be the Real positioned aircraft or the Algorithmic positioned one. Using a second aircraft and faking the multi player protocol is quite easy, how do you wish to proceed? If this algorithm will output position and rotation values and they can be inserted in the property tree, a program attached with the telnet port could register both the real coordinates/orientation and the algorithmic ones regularly (i.e. every 0.1 sec) into a csv file, with the acquisition time too (Starting from 0). Does a script like this exist yet ? if now I could provide it for you (python, C, php or java), my tip: python data could be pushed into a database too (i.e. mysql or postgres), and we could generated a graph with two data for every parameter (real one and algoritmic one). Further I think (With a little help from a friend of mine) I could create a 3d file (used in blender) that shows in 3d the 2 paths, just like a 3d graph. Cheers Francesco -- This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Brisa Francesco Via Gabelli 16 22077 Olgiate Comasco (CO) http://brisa.homelinux.net france...@brisa.homelinux.net __ / / / / /___ ___ / / __/ / __ / / / __ \/ __ `__ \/ __ \ / /_/ / /___ /_/ / /___/ /_/ / / / / / / /_/ / \/_/\/\/_/ /_/ /_/\/ http://www.gl-como.it My public gpg key: http://minsky.surfnet.nl:11371/pks/lookup?op=getsearch=0xC67DC12DC4361693 -- This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] aircraft modeling question
On Tuesday 14 April 2009, Curtis Olson wrote: I'm involved in a project where we are developing, refining, and tuning a fairly advanced algorithm that fuses inertial data (gyro accelerometer) with gps data to produce a pretty accurate attitude and location estimate. (The algorithm will be released as open-source.) One difficult part of this project is that when we are working with real world sensor data and real world aircraft (or UAV's) we have no truth reference. Our algorithm produces an answer, but we have no idea exactly how close we are to the truth because we don't have any way to record the true location and attitude on a real flight. (And even if we did have a way to record the flight parameters, we would be trying to match more accurate sensors, and better algorithms, but still not the truth.) FlightGear is useful for truth testing because we can fly some flight profile and record the sequence of all the exact locations and attitude angles. We can also record all the perfect sensor readings and later optionally add noise and other real world artifacts. This way we can create a realistic data set of sensor values along with the true location and attitude at every time step for an entire flight profile. We can run the data through our algorithm and work on tuning and refining it to produce optimal results. This is all very nice, but it would be cool to use FlightGear as a visualization tool for the final result. What would be really nice is to animate/replay the true flight of the aircraft and then superimpose the estimated aircraft position and orientation. One way to do this would be to create a version of an aircraft that has a second copy of itself with the ability to offset it's position and orientation from the true model. My questions is this ... from a modeling perspective, can that 2nd aircraft be animated with absolute lon/lat/elev and roll/pitch/yaw degrees? Or would we need to compute an X, Y, Z offset in meters for the second aircraft? It would be a pain to figure out the orientation transform relative to the original aircraft ... can the secondary aircraft be animated with absolute angles relative to the world coordinate frame? (For animating the 2nd aircraft, I imagine we'd create some set of custom property names, and I'd drive them externally via some network/file protocol ... maybe creating a custom configuration for the generic protocol.) Thanks, Curt. I think that if you're trying to do it via animation you can only do it relative to the main aircraft position and attitude because all the aircraft animations are relative to its frame of reference; there's no absolute frame of reference where you could specify an absolute location or attitude. This is the method I used for the old and now defunct SeaHawk-pair, as well as for high-elevation terrain markers and navigation target markers. Working out the relative animations isn't too difficult though; if you've got an absolute lat/lon it's easy enough to find the relative offsets using the Nasal Geo functions. LeeE -- This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] aircraft modeling question
My questions is this ... from a modeling perspective, can that 2nd aircraft be animated with absolute lon/lat/elev and roll/pitch/yaw degrees? Or would we need to compute an X, Y, Z offset in meters for the second aircraft? It would be a pain to figure out the orientation transform relative to the original aircraft ... can the secondary aircraft be animated with absolute angles relative to the world coordinate frame? Hi, you can have a look in tanker.nas, where the tanker move using direcly his lat, lon, alt, and differents inclinaisons with no relative reference, but be sure to not make your model solid, or you may have a lot of crashs. my2 cents jano -- This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] aircraft modeling question
On Tue, 2009-04-14 at 19:58 +0200, francesco wrote: Torsten Dreyer ha scritto: Don't know if I understand you right, but if you want to create arbitrary aircraft with independent position and attitude values, you might want to use the multiplayer protocol. If you fake the mp-server, you might inject any number of aircraft into your scene. Torsten I agree with Torsten, further it could be nice (And I think easy too, working with the liveries png) to make a semi transparent aircraft that could be the Real positioned aircraft or the Algorithmic positioned one. Using a second aircraft and faking the multi player protocol is quite easy, how do you wish to proceed? If this algorithm will output position and rotation values and they can be inserted in the property tree, a program attached with the telnet port could register both the real coordinates/orientation and the algorithmic ones regularly (i.e. every 0.1 sec) into a csv file, with the acquisition time too (Starting from 0). Does a script like this exist yet ? if now I could provide it for you (python, C, php or java), my tip: python data could be pushed into a database too (i.e. mysql or postgres), and we could generated a graph with two data for every parameter (real one and algoritmic one). Further I think (With a little help from a friend of mine) I could create a 3d file (used in blender) that shows in 3d the 2 paths, just like a 3d graph. Cheers Francesco I like Torsten's idea, too. I'm envisioning an app that pushes both models down the mpmplayer udp path. This app can keep both streams synchronized while allowing features like pause, rewind, fast forward, slow motion. These are features the generic protocol lacks. Ron -- This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
