Route Calculation Method and Device with Progressive Elimination of Data Corresponding to the Road Network

A method of determining routes between a point of departure (a) and a point of arrival (β) for a digital road mapping system consisting of a set of segments and nodes each having their importance index, said nodes and segments being put together so as to represent a road network formed of a plurality of meshes of different importance indices, each of the meshes being defined by a set of nodes of identical or greater value than a given value, defining an area, said method comprising the following steps:

• a) via the segments, the nodes surrounding a departure node are scanned so as to determine the cost of each of these nodes;
• b) said scanning is continued until the point of arrival of the route is reached;
• c) during said scanning, the nodes are scanned so as to identify the nodes that can be used to form a mesh with a given starting index Id;
• d) when a mesh with an index Id is identified, the segments whose index is less than this index Id are eliminated;
• e) scanning the nodes continues so as to identify the nodes that can be used to form a new mesh, whose index Is is greater than that of the preceding mesh;
• f) segments whose index is less than this new index Is are eliminated;
• g) steps e and f are repeated until:
• either the scanning enables the point of arrival of the route to be reached;
• or a maximum index Im of elimination is reached.