Trajectory Location Filtering for Path Reconstructability
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Solution Overview
Problem
Modern devices that track their locations via onboard sensors often collect and transmit excessive location data, leading to significant challenges in balancing the amount of data needed for path reconstruction while minimizing resource usage and costs.
Innovation Solution
A method that filters location points in a sampled trajectory by determining the sampling time difference between consecutive points and designating them as unfiltered or filtered based on a threshold value of the free-flow travel time calculated for the fastest alternative path, ensuring path reconstructability with reduced data transmission and storage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If devices track location points at a higher sampling rate, then path reconstruction accuracy is improved, but data transmission and storage requirements increase
Solution Approach 1:
The patent extracts only the essential location points needed for path reconstruction by applying filtering criteria based on geometric relationships and road network constraints. Instead of transmitting all sampled location points, the system identifies and transmits only those points that are critical for accurate path reconstruction, thereby reducing data volume while maintaining reconstruction accuracy.
Solution Approach 2:
The patent applies different quality requirements to different segments of the trajectory based on local road network characteristics. In areas with complex road networks or intersections, more location points are retained to ensure accurate path reconstruction, while in simpler areas, fewer points are sufficient. This localized quality adjustment optimizes the balance between data volume and reconstruction accuracy.
2Loss of information
If all sampled location points are transmitted, then complete path information is available, but resource consumption and costs increase
Solution Approach 1:
The patent performs preliminary filtering and selection of location points before transmission by evaluating geometric relationships and road network constraints. This preliminary action identifies which location points are essential for path reconstruction and which can be omitted, allowing the system to transmit only the necessary data and thereby reduce resource consumption while maintaining path information completeness.
Solution Approach 2:
The patent changes the parameter of location point selection from transmitting all points to transmitting only filtered points that meet specific criteria. By changing this parameter, the system reduces data transmission volume and associated resource consumption while ensuring that the transmitted points are sufficient for accurate path reconstruction.
3Productivity
If location points are filtered to reduce data, then transmission efficiency is improved, but path reconstructability may be compromised
Solution Approach 1:
The patent incorporates feedback mechanisms where the filtering criteria are based on evaluating whether retained location points satisfy geometric relationships and road network constraints. This feedback ensures that only location points that maintain path reconstructability are filtered out, while essential points are retained, thus balancing transmission efficiency with path reconstructability.
Solution Approach 2:
The patent performs preliminary evaluation of location points against geometric and road network criteria before filtering. This preliminary action ensures that the filtering process maintains path reconstructability by identifying and retaining critical points that are necessary for accurate path reconstruction, thereby preventing compromise of reliability.
4Measurement precision
If densely sampled trajectories are used, then location tracking precision is improved, but processing complexity increases
Solution Approach 1:
The patent extracts only the essential location points from densely sampled trajectories by applying filtering criteria based on geometric relationships and road network constraints. This extraction process reduces the number of points that need to be processed while maintaining location tracking precision, thereby reducing processing complexity.
Solution Approach 2:
The patent changes the parameter of location point density by filtering out redundant points while retaining essential ones. This parameter change reduces the data volume requiring processing while maintaining the precision needed for accurate location tracking, thus reducing processing complexity.
Data Source
AI summary
An approach is provided for filtering device location points in a sampled trajectory while maintaining path reconstructability. The approach involves determining a first location point in the sampled trajectory that is an unfiltered location point. The sampled trajectory includes device location points sampled by a device traversing a road network. The approach also involves determining a fastest alternative path from the first location point to a second location point. The approach further involves calculating a sampling time difference between a time at which the first location point was sampled and another time at which the second location point was sampled. The approach further involves designating the second location point as a next unfiltered location point when the sampling time difference is within a threshold value of a free-flow travel time calculated for the fastest alternative path. Otherwise, the second location point is designated as a filtered location point.