shaysil wrote:someone notice the gps position on the map(the black dot) is on the other lane (near the arrow)!!!!!!
The little black dot shows your
exact location according to the acquired coordinates from your GPS chip.
Since the common GPS chips on the market, and especially the built-in ones on PDAs/PNAs, are not so accurate (usually about 10-15 meters precision), iGO (and other navigation softwares) knows how to correct this misplacement, and put the navigation cursor on the nearest road, so you won't see on your map that you are driving on air/houses/off-road etc., when this is not the case.
In fact, the placement algorithem is much more sophisticated than that: in very crowded cities or settlement, where sometimes the distance between parallel streets can be less than 5 meters, iGO is also helped in your last location data, as well as your last direction and velocity when calculating your position on the map, so your location won't be jumped every second like crazy from street to street without actually moving, making navigation invalid.
This feature is called in iGO8: "Keep Position on Road", and can be found under: "Settings -> Navigation" menu.
Try to turn it off, and see for yourself the difference while navigating.