| 摘要 |
<p>PURPOSE:To make a search by using an intersection network so that a guide course includes a U-turn course. CONSTITUTION:An optimum course search part 15g finds a 1st optimum course connecting an upper-layer start point and an end point, which are the closest to a starting point and a destination and present on a freeway or national road in an upper layer, and the starting point and upper-layer start point and a 2nd optimum course connecting the upper-layer end point and the destination by Dijksta method by using an intersection network list regarding a small-scale lower-layer map in a course search memory 15h, and then finds a 3rd optimum course connecting the upper-layer start point and upper-layer end point by the Dijksta method by using an intersection network list regarding an large-scale upper-layer map; when the upper-layer start point or upper-layer end point is not a dummy intersection based upon the upper-layer road data, an upper- layer intersection network list regarding the dummy intersection is previously added and the 1st course, 3rd course, and 2nd course are connected in order to obtain the optimum course connecting the starting point and destination.</p> |
