MAP-MATCHING
Map-matching compares a current location detected by the method in the "Location Detection Principle" with a road map data from DVD-ROM stored in DVD-ROM drive.
Note. The road map data is based on data stored in the DVD-ROM.
The vehicle position may not be corrected under the following circumstances and after driving for a certain time when GPS information is difficult to receive. In this case, the current-location mark on the display must be corrected manually.
Scheme 88
Scheme 89
- In map-matching, alternative routes to reach the destination will be shown and prioritized, after the road on which the vehicle is currently driven has been judged and the current-location mark has been repositioned. If there is an error in distance and/or direction, alternative routes will be shown in different order of priority, and the incorrect road can be avoided. If two roads are running in parallel, they are of the same priority. Therefore, the current-location mark may appear on either of them alternately, depending on maneuvering of the steering wheel and configuration of the road. see scheme 56: Identifying Actual Vehicle Raised Route
- Map-matching does not function correctly when a road on which the vehicle is driving is new and not recorded in the DVD-ROM, or when road pattern stored in the map data and the actual road pattern are different due to repair. When driving on a road not present in the map, the map-matching function may find another road and position the current-location mark on it. Then, when the correct road is detected, the current-location mark may change to it.
- Effective range for comparing the vehicle position and travel direction calculated by the distance and direction with the road data read from the DVD-ROM is limited. Therefore, when there is an excessive gap between current vehicle position and the position on the map, correction by map-matching is not possible. see scheme 57: Identifying Actual Vehicle Traced Route