Image Sensor Misalignment Correction Using AIS Ship Coordinates
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Solution Overview
Problem
Existing methods for correcting image sensor misalignment on satellites are limited by the need for ground-based reference targets, which are costly and difficult to install and maintain, especially for optical and radar satellites.
Innovation Solution
Utilize an automatic identification system (AIS) to transmit ship positions for correcting image sensor misalignment by calculating a mounting misalignment value using synchronized image-based and AIS-based ship coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ground-based reference targets are used for correcting image sensor misalignment, then misalignment correction can be achieved, but installation and maintenance costs increase and accessibility is limited
Solution Approach 1:
The patent uses ships as intermediary objects that naturally exist in the imaging area and carry AIS transponders. These ships serve as mediators between the satellite image sensor and the correction system, providing reference points without requiring ground-based infrastructure. The AIS signals act as an intermediary data source that complements visual ship detection, enabling accurate coordinate extraction and misalignment calculation.
Solution Approach 2:
The patent leverages the self-service capability of ships by utilizing their own AIS transponders to provide positioning information. Ships automatically transmit their identity and location data through AIS, eliminating the need for external reference target installation. This self-service mechanism allows the system to use existing maritime traffic as free reference targets, reducing dependency on costly ground-based infrastructure.
2Measurement precision
If more reference targets are installed to improve statistical precision, then correction accuracy improves, but installation area and cost increase
Solution Approach 1:
The patent applies universality by using ships that serve multiple functions: they are both maritime vessels performing their primary function and simultaneous reference targets for satellite image correction. This multi-functionality allows the same objects to provide correction data across different satellite passes and imaging conditions, eliminating the need for dedicated reference target installations and expanding the effective reference target pool without additional area requirements.
Solution Approach 2:
The patent transitions from two-dimensional ground-based reference targets to three-dimensional maritime reference targets that move dynamically across the imaging area. By utilizing the vertical dimension and maritime space, the system accesses a much larger pool of potential reference targets without increasing ground installation area. Ships can be detected and used as reference points throughout the satellite's imaging coverage area.
3Measurement precision
If ground reference targets are used, then misalignment correction is possible, but the system complexity and difficulty of operation increase
Solution Approach 1:
The patent replaces the mechanical system of ground-based reference target installation and maintenance with an electronic/information-based system using AIS signals. Instead of physically deploying and maintaining reference targets, the system uses electronic communication to acquire ship position data from AIS transponders, automatically matching these with detected ships in satellite images to calculate misalignment parameters.
Data Source
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Figure 3A~3B
AI summary
Disclosed are a method and a device for correcting image sensor misalignment. A method for correcting image sensor misalignment according to an example embodiment of the present disclosure may include: acquiring a ship image from an image sensor; acquiring ship identification information from an automatic identification system (AIS); and correcting a misalignment value of the image sensor using first coordinates of a ship, which is calculated from the ship image, and second coordinates of the ship, which is calculated from the ship identification information.