Patent ID: 8165804

Claim:
A navigation apparatus having a hard disk drive as map data storage, wherein the apparatus calculates a route toward a destination and provides a route guidance based on the calculated route according to map data retrieved from the hard disk drive, wherein the apparatus includes a position detector for detecting a current vehicle position, and wherein the apparatus stops an operation of the hard disk drive upon determining that the current vehicle position is in a high-altitude area that is higher than a predetermined altitude based on a detection result of the position detector, the apparatus comprising: an area data storage storing high-altitude area determination data that defines, in a coordinate plane, the high-altitude area and a non-high-altitude area for both of map coordinates in the map data and position coordinates of the current vehicle position based on the detection result of the position detector for a determination whether the current vehicle position is in the high-altitude area; a list storage storing a branch list data; a list generation unit reading a list display data from the map data in the hard disk drive and storing the list display data as the branch list data in the list storage, wherein the list generation unit compares the route toward the destination with the high-altitude area determination data in the area data storage, and wherein the list generation unit retrieves, from the map data, the list display data listing guidance information for a portion of the route that is at least in the high-altitude area in terms of branches and inter-branch sections in the route arranged according to a travel sequence of the route if the comparison of the route with the high-altitude area determination data shows that the route is at least partially included in the high-altitude area; a high-alt area determination unit determining whether or not the current vehicle position is in the high-altitude area based on a comparison of the position coordinates with the high-altitude area determination data; and a display control unit displaying a branch list that is based on the branch list data stored in the list storage in place of providing the route guidance based on the map data retrieved from the hard disk drive while, in a course of route guidance toward the destination along the calculated route, the current vehicle position is determined to be in the high-altitude area by the high-alt area determination unit.