Geofence Break Detection Using Great-Arc Intersection Analysis
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Solution Overview
Problem
Current tracking systems face challenges in managing high bandwidth maritime AIS data due to excessive positional updates, inefficient down sampling methods, and inability to detect geofence intersections accurately, especially when start and end positions are outside the zone, while existing geospatial analysis treats the problem as a two-dimensional issue.
Innovation Solution
A method utilizing three-dimensional vector algebra for great arc analysis, spherical spatial discretization, and a lookup-optimized data structure to efficiently detect geofence break events by projecting vessel paths onto a spherical surface, reducing data volume and improving intersection detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional geofence detection methods are used, then system simplicity is maintained, but detection accuracy deteriorates due to inability to handle Earth's curvature and complex geometries
Solution Approach 1:
The patent applies spherical geometry to model the Earth's curvature by defining geofence boundaries as great circle arcs on a spherical coordinate system. The position data is transformed into spherical coordinates (latitude, longitude, altitude) and geometric calculations account for the spherical surface, enabling accurate detection of geofence breaks even for large geographic areas where planar approximations fail.
Solution Approach 2:
The patent transitions from two-dimensional planar geometry to three-dimensional spherical geometry by incorporating the Earth's radius as a third dimension. Position points are represented in 3D spherical coordinates, and geofence boundaries are defined as intersections of planes with the spherical Earth surface, creating great circle arcs that accurately represent geographic boundaries on a curved surface.
2Speed
If high-frequency position data is processed, then detection responsiveness is improved, but data transmission load increases excessively
Solution Approach 1:
The patent extracts only the essential geometric information needed for geofence detection by transforming detailed position data into simplified spherical coordinates and calculating only the necessary intersection parameters. Instead of transmitting and processing complete trajectory data, the system extracts key geometric features (angular positions, great circle parameters) that suffice for accurate geofence break detection, significantly reducing data volume while maintaining detection capability.
Solution Approach 2:
The patent performs preliminary geometric transformations and calculations by converting position data to spherical coordinates and pre-computing great circle parameters before transmission. This preprocessing step reduces the complexity of subsequent detection operations and minimizes the amount of raw data that needs to be transmitted, as only the transformed geometric parameters are sent to the detection system.
3Measurement precision
If complex geometric models accounting for Earth's curvature are used, then detection accuracy for large areas is improved, but computational complexity increases
Solution Approach 1:
The patent changes the parameter representation from Cartesian coordinates to spherical coordinates, which naturally accommodate the Earth's curvature. By expressing positions as (latitude, longitude, altitude) and great circle boundaries as angular relationships on the sphere, the computational formulas become more efficient. The intersection detection reduces to solving angular equations rather than complex 3D spatial intersections, simplifying the computational burden while maintaining accuracy for large geographic areas.
Data Source
AI summary
Detecting geofence break events is provided. The method comprises defining a geofence boundary according to a triangle comprising two lines from the center of the earth to two vertices above the earth's surface, and a third line between the vertices above the earth's surface. The geofence boundary is defined by a vector between respective intersection points of the first two lines with the earth's surface. This vector represents a great arc when projected to the curvature of the earth's surface. Origin and destination coordinates for a vehicle are received, wherein a second vector between the origin and destination coordinates represents a great arc defining a path of the vehicle. Responsive to a determination that the second vector intersects the plane of the triangle, a geofence break event notice is sent to a number of downstream consumers.