SAR Coherence Change Detection via Amplitude Extraction
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Solution Overview
Problem
Real-time change detection in SAR imaging applications is hindered by the large size and high acquisition rates of SAR composite images, which require significant data communication bandwidths, leading to increased costs, weight, and energy consumption when transmitting amplitude and phase information from moving platforms to ground control systems.
Innovation Solution
Processing only the amplitude image data of SAR composite images to estimate the phase data, allowing for the generation of restored images and coherency maps without the need for original phase data, enabling change detection without substantial deterioration in results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If amplitude and phase information of SAR composite images are transmitted from moving platforms to ground control systems, then change detection capability is improved, but data communication bandwidth requirements increase leading to increased costs, weight, and energy consumption
Solution Approach 1:
The patent extracts only the amplitude information from SAR composite images for transmission, leaving out the phase information. This extraction principle reduces the data volume by approximately half while still enabling effective change detection through coherency map generation and temporal decorrelation analysis, thus resolving the bandwidth vs. detection capability contradiction
Solution Approach 2:
The patent creates a simplified copy of the SAR data by transmitting only amplitude information rather than the complete complex data. This amplitude-only copy is sufficient for generating coherency maps and detecting changes, reducing transmission requirements while maintaining essential detection functionality
2Measurement precision
If complete SAR composite images with phase data are processed onboard moving platforms, then detection accuracy is improved, but processing complexity and energy consumption increase
Solution Approach 1:
The patent removes the computationally intensive phase data processing from onboard systems, extracting only amplitude information for transmission. This extraction shifts the processing burden to ground-based systems with greater computational resources, reducing onboard energy consumption while maintaining detection accuracy through proper coherency map generation
Solution Approach 2:
The patent uses amplitude information as an intermediary that carries essential change detection capabilities without requiring full complex SAR data processing onboard. This intermediary approach enables effective change detection while reducing the computational and energy demands on moving platforms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables real-time change detection with reduced data transmission requirements, minimizing the need for increased bandwidth and onboard processing capabilities, thus reducing costs and energy consumption while maintaining effective detection of subtle changes.
Implementation Method 1
Processing only the amplitude image data of SAR composite images to estimate the phase data, allowing for the generation of restored images and coherency maps without the need for original phase data
Implementation Method 2
Interferometry utilizes wave signals (e.g., electromagnetic, sound) reflected from objects to collect information thereabout, that can be used to measure small displacements/changes and surface/object irregularities, mainly due to the phase information present in the full interferometric SAR image (SI)
Data Source
Figure 1A
Figure 1B~2A
Figure 2B~2E
AI summary
Techniques for determining coherency between composite images having phase and amplitude components are disclosed. The coherency can be determined based on the amplitude components of the images, by providing first (42) and second amplitude images (43) indicative of amplitude values of pixels of a respective first and second composite images, applying to each of the first and second amplitude images a first directional derivative operator and a second directional derivative operator, thereby generating (44) for each of the amplitude images respective first directional derivative image and second directional derivative image thereof, and generating a first coherency map (47) based at least on the directional derivative images of the first and second amplitude images. The first coherency map is indicative of decorrelation between the first and second composite images.