On-Orbit IR Georeferencing with Real-Time Feature Matching
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Solution Overview
Problem
Existing satellite-based georeferencing techniques for infrared (IR) images suffer from significant uncertainties in determining the actually covered geographical area, especially for smaller satellites like CubeSats, leading to inaccurate results in real-time applications such as fire detection and burnt area detection, and are limited by transmission delays and computational constraints.
Innovation Solution
A method for satellite-based georeferencing that uses on-board image features matching, leveraging pre-stored images with known coordinates, to determine accurate geographical areas covered by IR images, employing trigonometry, ray tracing, and machine/deep learning algorithms, enabling real-time and accurate georeferencing without data transfer to ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ADCS-based pointing direction estimation is used, then the system is simple and cost-effective, but the measurement precision of the covered geographical area deteriorates with ≈2.5km on-ground error
Solution Approach 1:
The patent replaces the mechanical ADCS-based pointing estimation with an optical/image-based feature matching system. Instead of relying on mechanical attitude sensors, the system uses IR image features matched against pre-stored reference images to determine actual pointing direction and covered area, achieving ≈10x improvement in accuracy while maintaining computational efficiency on small satellites.
Solution Approach 2:
The patent introduces pre-stored reference images with known coordinates as an intermediary between the satellite's imaging system and the georeferencing process. These reference images serve as a mediator that enables accurate determination of covered geographical areas by providing a comparison basis for feature matching, eliminating the need for expensive high-precision ADCS systems.
2Power
If on-ground georeferencing is performed after data downlink, then computational resources are sufficient, but transmission delays occur and real-time processing is not achieved
Solution Approach 1:
The patent performs georeferencing processing on-board the satellite before data downlink to ground. By executing the feature matching and coordinate determination algorithms directly on the satellite using its own computational resources, the system eliminates transmission delays and achieves real-time georeferencing, while the preliminary preparation of reference images enables this capability even on resource-constrained small satellites.
3Ease of manufacture
If conventional visible light georeferencing techniques are used, then the method is well-established, but applicability to IR images and nighttime operation deteriorates
Solution Approach 1:
The patent changes the spectral parameter from visible light to infrared (IR) wavelength range. By adapting the feature matching approach to work with IR image characteristics and using pre-stored IR reference images, the system maintains the simplicity of feature matching while achieving versatility across different spectral bands, enabling operation during nighttime and in conditions where visible light is unavailable.
Data Source
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AI summary
This application relates to a method of satellite-based georeferencing for IR images of Earth surface captured by a satellite-mounted IR imaging device pointing towards Earth. The method comprises capturing an IR image of Earth surface using the IR imaging device; determining an estimated pointing direction of the IR imaging device at the time of capturing the IR image, based on an on-board attitude determination system of the satellite; determining an estimated area of Earth surface that is covered by the captured IR image, based on the estimated pointing direction; obtaining a set of image features in one or more pre-stored images of areas of Earth surface that at least partially overlap with the estimated area of Earth surface, wherein the pre-stored images are associated with known position coordinates; performing matching of the set of image features against the captured IR image to identify matching features; and determining an actual area of Earth surface that is covered by the captured IR image or an actual pointing direction of the IR imaging device at the time of capturing the IR image based on the identified matching features. The application further relates to corresponding apparatus, satellites, programs, and computer-readable storage media.