Persistent Scatterer Identification via Pixel Pair Phase Analysis
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Solution Overview
Problem
Existing methods for identifying Persistent Scatterers in SAR images are sensitive to processing errors and require pre-calibration, which can lead to incomplete measurements, especially in areas with isolated or weak scatterers, and rely on models for atmospheric artifacts and deformation history.
Innovation Solution
A method that identifies Persistent Scatterers by analyzing pairs of nearby pixels in generalized differential interferograms, computing phase-related differential values, and determining temporal-coherence-related values to identify pixels imaging persistent scatterers, without the need for pre-calibration or atmospheric artifact models, using a software program product to implement the Persistent Scatterer Pairs (PSP) method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pre-calibration and model-based methods are used for Persistent Scatterer identification, then measurement accuracy is improved in dense areas, but reliability deteriorates in areas with isolated or weak scatterers due to processing errors and incomplete measurements
Solution Approach 1:
The patent uses pairs of nearby pixels as an intermediary approach. Instead of directly identifying persistent scatterers from individual pixels (which fails in sparse areas), it analyzes phase differences between pairs of nearby pixels. This intermediary method allows the system to detect persistent scatterers indirectly through their relative phase stability, thereby improving reliability in areas with isolated or weak scatterers while maintaining measurement accuracy
Solution Approach 2:
The patent implements an iterative feedback mechanism where persistent scatterer candidates are identified, their phase time series are analyzed, and results are used to refine the identification process. The method computes temporal coherence based on phase differences and uses this feedback to continuously improve the identification of persistent scatterers, resolving the contradiction between accuracy in dense areas and reliability in sparse areas through progressive refinement
2Measurement precision
If pre-calibration is performed to remove orbital and atmospheric phase contributions, then systematic errors are reduced, but device complexity and processing time increase
Solution Approach 1:
The patent extracts and removes only the essential phase contributions (orbital and atmospheric) that affect persistent scatterer identification, rather than performing complete pre-calibration of all SAR image parameters. By selectively extracting and removing only the critical phase errors, the method reduces systematic errors while avoiding the excessive complexity of full pre-calibration processes
Solution Approach 2:
The patent performs preliminary removal of orbital and atmospheric phase contributions before the main persistent scatterer identification process. This preliminary action prepares the data by eliminating major sources of systematic error in advance, making the subsequent identification process simpler and more efficient, thus resolving the contradiction between error reduction and processing complexity
3Quantity of substance
If model-based interpolations are used for atmospheric artifact removal, then measurement completeness is improved, but manufacturing precision deteriorates due to model errors and assumptions
Solution Approach 1:
The patent uses phase differences between pairs of nearby pixels as an intermediary measure to detect persistent scatterers without relying on atmospheric models. By focusing on relative phase stability rather than absolute phase values, the method avoids model-based interpolations entirely, thereby maintaining measurement precision while still achieving complete coverage through the pair-wise analysis approach
Data Source
Figure 1
AI summary
Disclosed herein is a method for identifying persistent scatterers in digital Synthetic Aperture Radar (SAR) images of an area of Earth' s surface each taken at a respective time. The method comprises processing the digital Synthetic Aperture Radar (SAR) images to produce digital generalized differential interf erograms. The method is characterized by further comprising analyzing properties of pairs of pixels in the digital generalized differential interf erograms to identify individual pixels imaging persistent scatterers.