That would be extrapolation. And that is actually the exact reason why the GPS lags on exits if they are off-route because it has extrapolated your position based on your route till the next actual GPS location update arrives. I have seen this behaviour with my Garmin device too when I decide not to follow the route.
On Friday, August 3, 2012 11:46:45 AM UTC-4, Nobu Games wrote: > I'd go for interpolation and take the current average speed and the > "structure" of the streets into account. That of course only works when you > have something like a graph / vector representation of the streets and know > how they are connected and what orientation they have. > > It is also pretty common that even Google Navigation is off, especially on > highways with exits. Sometimes the navigation draws the car following the > highway even though you are already leaving on an exit. > > > On Wednesday, August 1, 2012 9:18:33 AM UTC-5, bushido wrote: >> >> Hi all, >> >> I'm writing an application for android for which I need good position >> accuracy, I use a Galaxy Nexus as test device. >> >> My test application subscribes to location updates and draws a car >> symbol in a map, the map is centered to the location of the car & >> rotates according to the bearing of the location (exactly like google >> maps on android does). I noticed that when up to speed, the positions >> don't match with reality, they lag behind considerably. >> When I cross a street at 90km/h for example, it will take a few >> seconds before the car on the map is also crossing that street. It >> isn't an error in the map data, because when I'm standing still, the >> car gets drawn on the correct location. Google maps for android shows >> exactly the same behavior. >> >> The position of the car in Google Navigate on the other hand matches >> reality rather closely. I've noticed that the position updates are a >> lot smoother as well. (10Hz rather than the 1Hz updates which you get >> from GPS) >> >> My question is: how do they do it? What I can think of is: >> - using the phone's sensors (gyro & accelero) together with a kalman >> filter or similar. But I can't see how you could make that work for >> every phone, since not all phones have these sensors. >> - interpolating, but in that case I would expect overshooting when >> there is a sudden stop or a sharp corner >> >> Thanks in advance. >> Bushido >> > -- 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
