Navigation Device Hierarchical Map Data Segmentation
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Solution Overview
Problem
Existing navigation devices often set detour routes due to incomplete route searches, leading to longer calculation times and inefficient route guidance, as they do not adequately account for potential shortcuts among narrow roads.
Innovation Solution
The navigation device identifies partial routes with significant deviations from the straight-line distance and performs a re-search using lower-level map data only on those sections, replacing the detour portions to provide a more accurate and efficient guide route.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If route search is performed using higher-level map data in intermediate regions to reduce calculation time, then calculation time is reduced, but route accuracy deteriorates because narrow roads and potential shortcuts are eliminated from search objects
Solution Approach 1:
The route search process is segmented into different regions: surrounding areas of current location and destination use level 0 map data for detailed search, while intermediate regions use level 1 or higher map data for rough calculation. This segmentation allows the system to balance between search detail and calculation time by applying appropriate map data levels to appropriate regions.
Solution Approach 2:
Different levels of map data are applied to different regions of the route. Level 0 (detailed) map data is used locally around the current location and destination where accuracy is critical, while higher levels (coarser) are used in intermediate regions where speed is more important. This local differentiation resolves the contradiction by matching data granularity to regional needs.
2Measurement precision
If route search is performed using level 0 map data covering all roads throughout the entire route, then route accuracy is improved, but calculation time increases significantly
Solution Approach 1:
Instead of performing exhaustive level 0 search throughout the entire route (excessive action), the system performs level 0 search only in necessary surrounding areas of current location and destination (partial action). This partial application of detailed search maintains accuracy where it matters most while avoiding the time cost of searching every segment at full detail level.
3Loss of time
If the route search uses hierarchical map data levels, then calculation time is reduced by performing rough calculations in intermediate regions, but detour routes may be set as guide routes because narrow roads are eliminated from search objects in intermediate areas
Solution Approach 1:
The system performs route search using hierarchical map data levels and then checks the result. If the calculated route distance is not appropriate (indicating a detour), the system feeds back to perform re-search using level 0 map data specifically in the surrounding area of the current location. This feedback mechanism ensures reliability by correcting detour routes while maintaining the time efficiency of hierarchical search.
Data Source
AI summary
A navigation device and a guide route search method prevents searching for a detour route, and shortens the time required for setting an eventual guide route. A first partial route is extracted from a first guide route found in accordance with map data divided into three hierarchical levels, based on information about a road network. The first guide route is the route from the current location to a destination. A second partial route is obtained by performing a route search between the nodes at opposite ends of the first partial route, based on the map data containing the lowest level. A second guide route is obtained by replacing the first partial route in the first guide route with the second partial route, and is set as the eventual guide route.