Route Search Acceleration Data Compression for Faster Map Planning
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Solution Overview
Problem
Current route planning methods are inefficient due to the complexity and time-consuming nature of processing extensive map data, which includes millions of navigable segments, leading to slow calculation times and a trade-off between accuracy and speed.
Innovation Solution
A method that reduces the number of navigable segments by creating a core network, compresses search acceleration data using techniques like Huffman encoding, and categorizes navigable segments into hierarchical regions to accelerate route planning, allowing for quicker generation of search acceleration data and more efficient route calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If extensive map data with millions of navigable segments is processed using traditional route planning methods, then route planning accuracy is maintained, but processing time becomes excessively long and computational complexity increases
Solution Approach 1:
The patent divides the extensive map data into multiple hierarchical regions (e.g., coarse regions, fine regions) and processes each region separately. This segmentation allows the route planning algorithm to focus computation on relevant regions only, dramatically reducing processing time while maintaining routing accuracy through the hierarchical structure that preserves global route options.
Solution Approach 2:
The patent performs preliminary processing to generate search acceleration data (such as bit vectors indicating reachable regions) before the actual route planning query. This pre-computed acceleration data is stored and reused for multiple queries, eliminating redundant computations and significantly speeding up subsequent route planning operations without sacrificing accuracy.
2Reliability
If traditional route planning algorithms are used on extensive map data, then comprehensive route options are considered, but the computational complexity and processing requirements become unmanageable
Solution Approach 1:
The patent segments the computational problem by dividing the map into hierarchical regions and using bit vectors to represent reachable regions at each level. This segmentation transforms the complex global routing problem into a series of simpler regional sub-problems, reducing computational complexity while maintaining completeness through the hierarchical aggregation of region reachability information.
Solution Approach 2:
The patent changes the representation parameters by using bit vectors instead of traditional distance matrices, and by introducing hierarchical region levels. These parameter changes reduce the complexity of the routing algorithm from polynomial to near-linear time complexity, making it feasible to process extensive map data while maintaining comprehensive route consideration.
3Speed
If search acceleration data is stored in uncompressed format, then route planning speed is improved, but memory usage and data storage requirements become excessive
Solution Approach 1:
The patent applies Huffman encoding to compress the search acceleration data (bit vectors) by changing the representation parameter from fixed-width binary to variable-length Huffman codes. This compression reduces the storage volume of acceleration data while maintaining the ability to quickly decode and use the data for route planning, thus preserving speed benefits while reducing memory requirements.
4Measurement precision
If the entire map data is processed for each route planning query, then accurate routing is achieved, but the time required for route generation becomes unacceptably long
Solution Approach 1:
The patent performs preliminary computation to generate search acceleration data (region reachability bit vectors) that capture essential routing information for the entire map. This pre-computed data is stored and reused for each query, eliminating the need to reprocess the entire map for every route planning request, thus dramatically improving route generation speed while maintaining routing accuracy through the preserved reachability information.
Solution Approach 2:
The patent segments the map into hierarchical regions and computes reachability information for each region separately. This segmentation allows the system to quickly determine which regions are relevant for a given origin-destination pair and focus computation only on those regions, rather than processing the entire map, thereby improving productivity while maintaining routing accuracy.
Data Source
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Figure 1b~1c
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AI summary
A method of creating map data, including search acceleration data arranged to increase the speed at which a route can be planned across an electronic map, which comprises a plurality of navigable segments, representing segments of a navigable route in the area covered by the map, wherein the method comprises: a) processing the navigable segments in order to generate the search acceleration data for at least some of, and generally each of, the navigable segments of the electronic map indicating whether that navigable segment is part of a minimum cost route; and b) processing the generated search acceleration data in order to compress that data wherein the compression includes computing the correlation of pairs of bits in the search acceleration data and coalescing correlated bits.