I've never gotten around to experimenting to see just how good you CAN get -- but there are some reference points that should help considerably.
* Gravity * The magnetic field * Any period of low acceleration noise in the vicinity of about 1 g total acceleration probably indicates it has been set down on a surface (or in the original scenario -- the car has come to a stop). There other possibilities in other situations: * Camera data can indicate relative motion * Acoustical echoic signature and ambient sounds * Wifi transmitter signal strengths * 3G signal strengths. (Hey, I'm outdoors, maybe try GPS again!) * Sonar! A typical android device has more senses than humans. We synthesize an understanding of our location and environment via a process of sensor fusion. There's more opportunity for this sort of thing on Android than Nintendo, as there's more processing power available and more sensors to gather information -- especially when connected to a power source or otherwise on a larger power budget than a cell phone. Look at Dempster-Shafer Theory and Kahlman filters for techniques to handle this sort of process. On Jan 12, 5:10 pm, keyboardr <[email protected]> wrote: > I know Nintendo originally tried to use accelerometers to figure out > where it was pointing, and while that's theoretically possible, in > practice the accuracy just isn't good enough. The acceleration most > of the time is small enough that even the slightest error will throw > the whole calculation way off, and since you're relying on all of your > previous results, errors get compounded over time. That's why > Nintendo switched to an IR camera setup. > > On Jan 12, 7:22 am, cellurl <[email protected]> wrote: > > > > > > > > > couldn't you use the accelerometer? > > Integrate that? Use time. s=Integral(a dt) > > If that doesn't work, look to skyhook wireless! > > -cellurl > > > On Jan 12, 8:20 am, Brill Pappin <[email protected]> wrote: > > > > Well you pretty much need distance traveled over time to find speed, > > > so anything you can do to determine distance travelled should allow > > > you to calculate the speed. > > > > For instance you could use cell tower location, but I wouldn't class > > > it as even remotely accurate. > > > If you want to give an actual real value, your going to need the > > > accuracy of the GPS unit. > > > > - Brill Pappin > > > > On Jan 11, 11:13 pm, darrinps <[email protected]> wrote: > > > > > All the examples I see use GPS, and I have that working just fine but > > > > I've noticed that every time I'm in a car, that unless the phone is > > > > close to a window or the windshield the GPS does not work so... > > > > > I thought that there should be a way using course grained location > > > > between cell towers. Does anyone know if this is possible and if so > > > > might know where I could find some sample code please? > > > > > Thanks! > > > > > Darrin -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
