Multiband InSAR (Interferometric Synthetic Aperture Radar) phase unwrapping method based on differential filtration
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A phase unwrapping and differential filtering technology, applied in the multi-band InSAR field, can solve the problems of interference phase undersampling, interference fringe aliasing, and inability to perform, and achieve the effects of high precision, improved solvability, and easy phase unwrapping.
Inactive Publication Date: 2010-11-10
THE PLA INFORMATION ENG UNIV
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In fact, for areas with large terrain fluctuations and the use of shorter wavelengths and longer baselines for interference imaging, it is easy to under-sample the interference phase and alias the interference fringes
For such interference fringes, it is difficult or even impossible to perform efficient and high-precision phase unwrapping
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Embodiment 1
[0037] For interferometric data in different bands, the difficulty and precision of interferometric processing are different. When the wavelength is long, the frequency of the interferogram is low, and the interferometric phase unwrapping is easy, but the elevation accuracy obtained is low; conversely, when the wavelength is short, the elevation accuracy can be obtained theoretically, but interference is prone to occur at this time The phase is under-sampled, and its interference quality is low. It is difficult to effectively filter and phase unwrap the interferogram, and it is impossible to perform effective interferometry and elevation information acquisition.
[0038] In order to make full use of the respective advantages of the interference data of different wave bands, the present invention combines the interference data of different wave bands, uses the unwrapping results of the longer wavelength interferograms to guide the phase unwrapping of the shorter wavelength inter...
Embodiment 2
[0076] The difference between this embodiment and Embodiment 1 is that in step ① of this embodiment, the longest wavelength and lowest frequency interferogram Interferogram Inter 1 Perform filtering.
[0077] Specifically, as image 3 As shown, it includes the following steps:
[0078] (a) Mapping interferometric phase values to unit vectors in vector space. Assume Indicates the interferometric phase value containing noise at a certain pixel in the interferogram, which is mapped to a unit vector in the vector space as:
[0079]
[0080] (b) Decompose the interferogram in vector space into sinusoidal components and cosine components
[0081] (c) Carry out mean filtering processing on the sine component sin(φ(x, y)+n(x, y)) and the cosine component cos(φ(x, y)+n(x, y)) respectively;
[0082] (d) by the filtered sine component and cosine components Computing the filtered interferogram, let The calculation formula is:
[0083] φ ...
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Abstract
The invention relates to a Multiband InSAR (Interferometric Synthetic Aperture Radar) phase unwrapping method based on differential filtration. The method comprises the following steps of: from the beginning of interference data with the longest wavelength and on the basis of carrying out effective unwrapping on a long-wavelength and low-frequency interferogram, generating a short-wavelength and high-frequency reference interferogram from an unwrapped low-frequency interferogram according to a proportional relation among wavelengths, and then carrying out differential filtration on the short-wavelength and high-frequency interferogram and the reference interferogram to obtain a differential interferogram, thereby reducing the fringe frequency of the short-wavelength and high-frequency interferogram; carrying out filtration and phase unwrapping on the differential interferogram, and then obtaining an unwrapping result of the short-wavelength and high-frequency interferogram according to the unwrapping results of the reference interferogram and the differential interferogram; and accordingly, continuously carrying out unwrapping till the lowest-wavelength interferogram. The invention effectively solves the phase unwrapping difficulty of aliasing interference fringes at steep areas under the condition of shorter-wavelength and improves the phase unwrapping solvability and the unwrapping accuracy.
Description
technical field [0001] The present invention relates to multi-band InSAR (Multi-band Interferometric Synthetic Aperture Radar, multi-band synthetic aperture radar interferometry) technology, in particular to a multi-band InSAR phase unwrapping method based on differential filtering. Background technique [0002] Using multi-band InSAR technology, InSAR data of different bands (frequency) can be jointly processed to improve the unwrapping accuracy and reliability of aliasing interferometric phases in steep terrain areas, thereby improving the acquisition of DEM (Digital Elevation Model, digital elevation model) accuracy and reliability. [0003] For multi-band InSAR technology, phase unwrapping is still a key link in interferometric processing. Most of the traditional phase unwrapping methods are based on the assumption that the phase difference between adjacent pixels does not exceed half a period π. In fact, for areas with large terrain fluctuations and using shorter wave...
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