Multi-Resolution Routing for Off-Road Navigation
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Solution Overview
Problem
Existing solutions are unable to quickly generate high-quality, long off-road routes on resource-constrained platforms such as mobile phones and personal navigation devices, as they face challenges with memory usage and computational speed when using algorithms like A* for pathfinding.
Innovation Solution
A computer-implemented method using multi-resolution maps, which includes a map generator, route generator, heuristic generator, and search envelope factor generator to efficiently produce on- and off-road travel routes. The route generator refines routes at higher zoom levels by penalizing deviations from previous routes, reducing computation time and memory usage, and incorporates a search envelope factor to limit node exploration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If A* algorithm is used to generate off-road routes, then route quality is improved, but computation time and memory usage increase
Solution Approach 1:
The patent divides the route generation process into multiple resolution levels (coarse and fine). First, a coarse route is generated using a sub-sampled graph, then the route is divided into segments, and fine routes are generated for each segment using high-resolution data. This segmentation allows the system to maintain route quality while reducing overall computation time by avoiding exhaustive search on the entire high-resolution graph.
Solution Approach 2:
The patent introduces a resolution dimension to the routing problem by creating multi-resolution versions of the graph. Instead of working with a single high-resolution graph that requires extensive computation, the system operates on multiple levels of abstraction (coarse and fine resolutions), allowing efficient exploration at lower resolution and detailed refinement at higher resolution only where needed.
2Manufacturing precision
If A* algorithm is used to generate off-road routes, then route quality is improved, but memory consumption increases
Solution Approach 1:
The patent segments the routing problem into coarse and fine resolution stages. The coarse route generation uses a sub-sampled graph that requires minimal memory, and the fine route generation is limited to specific segments along the coarse route rather than the entire search space. This segmentation dramatically reduces peak memory consumption while maintaining route quality.
Solution Approach 2:
The patent performs preliminary route generation at coarse resolution before refining at fine resolution. By first establishing a coarse route using minimal memory, the system can then focus detailed refinement only on specific segments along this pre-established path, rather than maintaining all possible paths in memory simultaneously.
3Productivity
If sub-sampled graph is used to reduce memory consumption, then computation speed is improved, but route quality deteriorates due to tie points in undesirable terrain
Solution Approach 1:
The patent segments the route into coarse and fine components. The coarse route provides overall direction using sub-sampled data, while fine routes are generated separately for each segment using high-resolution data. This segmentation eliminates the tie point problem because fine routes are generated continuously along segment boundaries rather than at discrete coarse graph nodes, ensuring routes follow desirable terrain throughout.
4Quantity of substance
If coarse route is divided into segments for fine route generation, then memory usage is reduced, but computation time increases due to stitching multiple routes
Solution Approach 1:
The patent performs preliminary coarse route generation that establishes the overall path structure. This preliminary action provides a guiding framework that constrains subsequent fine route generation to relevant segments, reducing the total computation time compared to generating fine routes independently without the benefit of the coarse route guidance.
Data Source
AI summary
A system, method and computer program product for efficiently generating on- and off-road travel routes using multi-resolution maps including a map generator (108), map database (106), route generator (100), heuristic generator (102), and search envelope factor generator (104). The map generator (108) converts input raster and vector map data into output multi-resolution raster map data suitable for routing and stores it in the map database (106). The route generator (100) uses the map database (106) to produce a route at a coarse zoom level and then regenerate the route at progressively higher zoom levels. The heuristic generator (102) penalizes high resolution routes that deviate too far from one or more low resolution routes. The search envelope factor generator (104) computes this penalty based on the distance from a given search graph node to the low resolution routes.