CN110297243B - Phase error compensation method and device in synthetic aperture radar tomography three-dimensional imaging - Google Patents

Phase error compensation method and device in synthetic aperture radar tomography three-dimensional imaging Download PDF

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CN110297243B
CN110297243B CN201910665019.0A CN201910665019A CN110297243B CN 110297243 B CN110297243 B CN 110297243B CN 201910665019 A CN201910665019 A CN 201910665019A CN 110297243 B CN110297243 B CN 110297243B
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CN110297243A (en
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刘慧�
庞蕾
黎芳
张学东
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Beijing University of Civil Engineering and Architecture
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
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    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/9021—SAR image post-processing techniques
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    • G—PHYSICS
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    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section

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Abstract

The embodiment of the invention provides a phase error compensation method and a phase error compensation device in synthetic aperture radar tomography three-dimensional imaging. The method comprises the following steps: for each auxiliary image, acquiring a phase compensation factor according to a baseline parameter corresponding to the auxiliary image; performing phase error compensation on the auxiliary image according to the phase compensation factor; the auxiliary image is a single-vision complex image of the ground object target acquired by the auxiliary image satellite. According to the method and the device for compensating the phase error in the synthetic aperture radar tomography three-dimensional imaging, provided by the embodiment of the invention, the phase compensation factor is obtained according to the baseline parameter corresponding to the auxiliary image, and the phase error compensation is carried out on the auxiliary image according to the phase compensation factor, so that the phase error compensation can be carried out more accurately, quickly and conveniently, the compensation effect can be improved, and the synthetic aperture radar tomography three-dimensional imaging result with better effect can be obtained.

Description

Phase error compensation method and device in synthetic aperture radar tomography three-dimensional imaging
Technical Field
The invention relates to the technical field of electronic signal processing, in particular to a phase error compensation method and device in synthetic aperture radar tomography three-dimensional imaging.
Background
Synthetic Aperture Radar (SAR) is an active earth observation technology, and compared with a traditional optical sensor, the SAR can realize all-time and all-weather earth real-time observation and has certain earth surface penetration capability. The development of the SAR technology brings about rapid expansion of data volume and calculated amount, and the real-time imaging processing of large-scale SAR echo data becomes more important along with the enhancement of the real-time imaging requirement.
The satellite-borne synthetic aperture radar tomography (SAR tomography or SAR tomography, SAR Tomoghaghy, TomogAR) technology is one of multi-dimensional SAR imaging, is a ground three-dimensional information inversion technology developed on the basis of interferometric SAR (InSAR), and can invert four-dimensional information through differential tomography.
Compressive sensing is a mainstream method for tomographic SAR imaging. In the tomography SAR imaging process based on compressed sensing, the randomness of phase errors seriously influences the precision of tomography SAR three-dimensional imaging. Before tomography SAR imaging, phase compensation is required to be carried out, and then third-dimensional tomography can be carried out, otherwise, the correctness of the three-dimensional point cloud is difficult to verify. The existing phase error compensation method cannot perform phase error compensation specially for SAR tomography, and usually performs phase error compensation by referring to a multi-temporal differential interference technology (such as a permanent scatterer interferometry technology, a small baseline set technology, an enhanced spatial differential technology, and the like) used in interferometric SAR imaging. However, the multi-temporal differential interference techniques have the disadvantages of complicated steps, high computation overhead, low efficiency, and good compensation effect only for some situations, but do not have universality. Therefore, the phase error compensation method in the existing synthetic aperture radar tomography three-dimensional imaging is difficult to obtain correct three-dimensional point cloud, is difficult to perform effective compensation, and has the defect of poor compensation effect.
Disclosure of Invention
The embodiment of the invention provides a phase error compensation method and a phase error compensation device in synthetic aperture radar tomography three-dimensional imaging, which are used for overcoming or at least partially overcoming the defect of poor compensation effect in the prior art.
In a first aspect, an embodiment of the present invention provides a method for compensating a phase error in synthetic aperture radar tomography, including:
for each auxiliary image, acquiring a phase compensation factor according to a baseline parameter corresponding to the auxiliary image;
performing phase error compensation on the auxiliary image according to the phase compensation factor;
the auxiliary image is a single-vision complex image of a ground object target acquired by an auxiliary image satellite.
Preferably, the step of obtaining the phase compensation factor according to the baseline parameter corresponding to each auxiliary image comprises:
for each auxiliary image, acquiring a dip angle between a base line corresponding to the auxiliary image and a horizontal plane, a length of the base line corresponding to the auxiliary image, a viewing angle of a reference satellite for observing the ground, a radar wavelength and a coordinate of a ground object target in a distance direction;
and acquiring a comprehensive compensation factor according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the coordinates of the distance direction of the ground object target.
Preferably, the step of obtaining the phase compensation factor according to the baseline parameter corresponding to each auxiliary image comprises:
for each auxiliary image, acquiring the inclination angle between a base line corresponding to the auxiliary image and a horizontal plane, the length of the base line corresponding to the auxiliary image, the view angle of the reference satellite for observing the ground and the radar wavelength, and acquiring a first compensation factor according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the view angle of the reference satellite for observing the ground and the radar wavelength; acquiring the distance direction coordinate of a ground object target, and acquiring a second compensation factor according to the inclination angle of the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of a reference satellite for observing the ground, the radar wavelength and the distance direction coordinate of the ground object target;
or, for each auxiliary image, acquiring a tilt angle between a base line corresponding to the auxiliary image and a horizontal plane, a length of the base line corresponding to the auxiliary image, a viewing angle of a reference satellite for observing the ground, a radar wavelength and a coordinate of a ground object target in a distance direction; and acquiring the second compensation factor according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the coordinates of the ground object target in the distance direction.
Preferably, the integrated compensation factor is
Figure BDA0002139813020000031
Wherein j represents an imaginary unit; biRepresenting auxiliary shadowLike the corresponding baseline; theta represents the view angle of the reference satellite for observing the ground; alpha is alphaiRepresenting the inclination angle of the base line corresponding to the auxiliary image and the horizontal plane; r represents the coordinates of the distance direction of the ground object target; λ represents a radar wavelength; i represents the number of the auxiliary image satellite, i is more than or equal to 1 and less than or equal to N-1, and N-1 represents the total number of the auxiliary image satellites.
Preferably, the first compensation factor is
Figure BDA0002139813020000032
The second compensation factor is
Figure BDA0002139813020000033
Wherein j represents an imaginary unit; biA base line corresponding to the auxiliary image is represented; theta represents the view angle of the reference satellite for observing the ground; alpha is alphaiRepresenting the inclination angle of the base line corresponding to the auxiliary image and the horizontal plane; r represents the coordinates of the distance direction of the ground object target; λ represents a radar wavelength; i represents the number of the auxiliary image satellite, i is more than or equal to 1 and less than or equal to N-1, and N-1 represents the total number of the auxiliary image satellites.
Preferably, before the phase error compensation of the auxiliary image according to the phase compensation factor, the method further includes:
pre-compensating the auxiliary image according to the reference image;
the reference image is a single-vision complex image of the ground object target acquired by a reference satellite.
Preferably, the pre-compensating the auxiliary image according to the reference image comprises:
obtaining a precompensation factor from the reference image
Figure BDA0002139813020000041
Pre-compensating the auxiliary image according to the pre-compensation factor;
wherein j represents an imaginary unit; r represents the coordinates of the distance direction of the ground object target; λ represents the radar wavelength.
In a second aspect, an embodiment of the present invention provides an apparatus for compensating phase error in synthetic aperture radar tomography, including:
the factor acquisition module is used for acquiring a phase compensation factor according to the baseline parameter corresponding to each auxiliary image;
the phase compensation module is used for carrying out phase error compensation on the auxiliary image according to the phase compensation factor;
the auxiliary image is a single-vision complex image of a ground object target acquired by an auxiliary image satellite.
In a third aspect, an embodiment of the present invention provides an electronic device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor, and when executing the program, the method for compensating phase error in synthetic aperture radar tomography three-dimensional imaging provided in any one of the various possible implementations of the first aspect is implemented.
In a fourth aspect, an embodiment of the present invention provides a non-transitory computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements the steps of the method for phase error compensation in synthetic aperture radar tomographic three-dimensional imaging as provided in any one of the various possible implementations of the first aspect.
According to the method and the device for compensating the phase error in the synthetic aperture radar tomography three-dimensional imaging, provided by the embodiment of the invention, the phase compensation factor is obtained according to the baseline parameter corresponding to the auxiliary image, and the phase error compensation is carried out on the auxiliary image according to the phase compensation factor, so that the phase error compensation can be carried out more accurately, quickly and conveniently, the compensation effect can be improved, and the synthetic aperture radar tomography three-dimensional imaging result with better effect can be obtained.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
Fig. 1 is a schematic flowchart of a phase error compensation method in three-dimensional tomography of synthetic aperture radar according to an embodiment of the present invention;
fig. 2 is a schematic geometric model diagram of a TomoSAR system according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a phase error compensation device in three-dimensional tomography of synthetic aperture radar according to an embodiment of the present invention;
fig. 4 is a schematic physical structure diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to overcome the above problems in the prior art, embodiments of the present invention provide a method and an apparatus for compensating a phase error in a synthetic aperture radar tomography, which do not need to extract an interference phase according to an interference complex image, perform phase error compensation according to the interference phase, and only need to perform accurate, fast, and convenient phase error compensation according to a baseline parameter corresponding to each auxiliary image.
Fig. 1 is a schematic flow chart of a phase error compensation method in synthetic aperture radar tomography according to an embodiment of the present invention. As shown in fig. 1, the method includes: step S101, for each auxiliary image, a phase compensation factor is obtained according to a baseline parameter corresponding to the auxiliary image.
The auxiliary image is a single-vision complex image of the ground object target acquired by the auxiliary image satellite.
Fig. 2 is a schematic geometric model diagram of a TomoSAR system according to an embodiment of the present invention. It should be noted that the phase error compensation method in the synthetic aperture radar tomography three-dimensional imaging provided by the embodiment of the present invention can be used in the TomoSAR system shown in fig. 2.
TomosAR is a SAR three-dimensional imaging system, as shown in FIG. 2, in which s0And si(i-1, 2, …, N-1) is N satellites (N is a positive integer) distributed along the baseline direction b, where s is0As reference satellite, si(i-1, 2, …, N-1) is a secondary imaging satellite. When performing TomosAR imaging, passing through s0And si(i-1, 2, …, N-1) respectively acquiring monoscopic complex images of ground object targets, si(i-1, 2, …, N-1) acquired monoscopic complex images are respectively compared with s0And carrying out registration on the acquired single-vision complex images to obtain N-1 interference complex images. si(i-1, 2, …, N-1) the acquired monoscopic complex image is called an auxiliary image, s0The acquired single-view complex image is called a reference image. Each auxiliary image corresponds to one auxiliary image satellite and one interference complex image.
B is the total baseline length of the TomosAR system, which is equal to the secondary imaging satellite si(i-1, 2, …, N-1) difference between maximum and minimum values of b-coordinate along the baseline direction. Theta is a reference satellite s0Observing the visual angle of the ground; alpha is alphaiRepresents the base line biInclination to the horizontal, base line biFor the ith auxiliary image satellite si(i-1, 2, …, N-1) and a reference satellite s0A base line formed therebetween, the length being bi(ii) a s represents a vertical coordinate of the slope distance, and the vertical direction of the slope distance is parallel to the direction of the base line; r is a coordinate of a distance direction and represents a reference satellite s0Distance to a certain distance-azimuth cell; r iskRepresenting the kth scattering point σ in the vertical direction of the slantkTo reference satellite s0The distance of (d); r isikRepresenting the kth scattering point σ in the vertical direction of the slantkTo the ith secondary image satellite si(i-1, 2, …, N-1).
The coordinates of the range direction of the ground object target are the distances between the range-azimuth unit and the reference satellite, on which the scattering point falls.
The mathematical model of the single-view complex image of the satellite-borne SAR two-dimensional image is
Figure BDA0002139813020000061
Wherein s (x, r) represents a two-dimensional single-view complex image; x represents the coordinate of the azimuth direction; r represents a coordinate of a distance direction; σ (x, r) represents the backscatter coefficient of the range-azimuth cell (x, r); raAnd RrResolution representing the azimuth direction and the distance direction, respectively; λ represents the radar wavelength.
All scattering points of the target ground object in the vertical direction of the slant range can fall in the same distance-azimuth unit, the mathematical model of the single-vision complex image of the two-dimensional image is popularized to three dimensions, and then the ith auxiliary image satellite siThe three-dimensional mathematical model of the SAR image of (i ═ 1,2, …, N-1) can be expressed as
Figure BDA0002139813020000071
Wherein s isi(x, r, s) represents an auxiliary image acquired by the ith auxiliary image satellite;
Figure BDA0002139813020000072
represents a convolution; j represents an imaginary unit; sigmak(x, r, s) represents the backscattering coefficient of the kth scattering point falling within the same range-azimuth unit; r isik(r, s) being rikDenotes the kth scattering point σ in the vertical direction of the slope distancekTo the ith secondary image satellite si(i-1, 2, …, N-1).
In order to simplify the model, the convolution part is omitted, and the three-dimensional mathematical model of the SAR image can be abbreviated as
Figure BDA0002139813020000073
According to the actual geometrical relationship shown in FIG. 2, there are
Figure BDA0002139813020000074
Due to s and biIs much smaller than r, so that in two-dimensional imaging, the above formula is (s ═ 0, bi0) is used, one-order taylor expansion is used. However, when three-dimensional imaging is performed, the above formula (s ═ 0, b) is requiredi0) is performed, the above formula is expressed as a function of the vertical slope and the length of the base line as arguments, having
Figure BDA0002139813020000075
Further, each partial derivative can be obtained as follows
Figure BDA0002139813020000081
Figure BDA0002139813020000082
Figure BDA0002139813020000083
Figure BDA0002139813020000084
Figure BDA0002139813020000085
Figure BDA0002139813020000086
Substituting each partial derivative into a mathematical equivalent model approximation formula of the distance
Figure BDA0002139813020000087
Further finishing with
Figure BDA0002139813020000088
According to the distance mathematical equivalent model approximation formula, the three-dimensional mathematical model of the SAR can be further simplified into
Figure BDA0002139813020000089
Order to
Figure BDA00021398130200000810
Then there is
Figure BDA00021398130200000811
In imaging in the third dimension, the portion associated with the third-dimensional spatial variable s may be further written as
Figure BDA00021398130200000812
Further finishing and simplifying to obtain
Figure BDA00021398130200000813
Wherein the content of the first and second substances,
Figure BDA00021398130200000814
the tomography SAR three-dimensional imaging of various methods is based on a theoretical model shown as the following formula:
Figure BDA0002139813020000091
wherein, gi(x, r, s) represents an SAR three-dimensional image corresponding to the ith auxiliary image satellite; sigmak(x, r, s) represents the backscattering coefficient of the kth scattering point falling within the same range-azimuth unit; f. ofiFor spectral components, a base line b is indicatedi(i.e., the ith baseline) is formed.
It follows that in the vertical direction of the distance, the base lines b are differentiThe corresponding SAR image can be regarded as a ground object in the vertical direction of the distance
Figure BDA0002139813020000092
At frequency fiThe result of the discrete fourier transform.
But at a different base line b from the vertical siThe corresponding SAR image also has spatial offset
Figure BDA0002139813020000093
When various algorithms are used for the compressed sensing imaging of the third dimension, the phase difference caused by the spatial offset must be eliminated.
Thus, the phase error includes at least the flat phase
Figure BDA0002139813020000094
And spatial offset
Figure BDA0002139813020000095
Error caused by
Figure BDA0002139813020000096
Due to the fact that
Figure BDA0002139813020000097
Thus, it is possible to provide
Figure BDA0002139813020000098
Generally, the phase error can be removed by the method of removing the flat ground effect, but the flat ground phase estimation with very high precision needs to be performed through the spectrum of the interference phase, and the phase difference caused by the spatial offset can be removed only by requiring the quite accurate spectrum estimation of the interference phase. Meanwhile, each auxiliary image and each reference image need to be subjected to interference processing, the process is complicated, the consumed time is long, the operation is not easy, the efficiency is low, and the method is difficult to realize. In addition, in general, the SAR tomographic three-dimensional imaging method does not detect a phase deviation due to a spatial offset, and further does not perform phase error compensation for the phase deviation due to the spatial offset, so that the compensation effect is poor.
Therefore, the embodiment of the invention directly adopts the method for phase compensation based on the baseline parameters, and can realize accurate, rapid and convenient phase error compensation for each auxiliary image according to the baseline parameters corresponding to the auxiliary image.
Auxiliary image is composed of auxiliary image satellite si(i-1, 2, …, N-1) then the baseline parameter corresponding to the auxiliary image includes baseline biAngle of inclination alpha to the horizontaliBase line biLength of, reference satellite s0And observing a visual angle theta of the ground, a radar wavelength lambda and a coordinate r of a ground object target distance direction.
For the auxiliary image collected by the ith auxiliary image satellite, the flat ground phase thereof
Figure BDA0002139813020000101
And spatial offset
Figure BDA0002139813020000102
BringError of (2)
Figure BDA0002139813020000103
The phase compensation factor for compensating the phase error of the auxiliary image can be obtained based on the baseline parameter.
Step S102, phase error compensation is performed on the auxiliary image according to the phase compensation factor.
Specifically, after the phase compensation factor is obtained, the phase compensation factor may be multiplied by the subsidiary image, so that the flat ground phase may be removed
Figure BDA0002139813020000104
And spatial offset
Figure BDA0002139813020000105
Error caused by
Figure BDA0002139813020000106
Figure BDA0002139813020000107
Becomes a phase error due to the spatial offset.
It should be noted that only by effectively eliminating the phase error caused by the spatial offset, the effective phase error compensation can be performed, and the corresponding compressed sensing result can be obtained.
According to the embodiment of the invention, the phase compensation factor is obtained according to the baseline parameter corresponding to the auxiliary image, and the phase error compensation is carried out on the auxiliary image according to the phase compensation factor, so that the phase error compensation can be carried out more accurately, quickly and conveniently, the compensation effect can be improved, and the synthetic aperture radar tomography three-dimensional imaging result with better effect can be obtained.
Based on the content of the above embodiments, for each auxiliary image, the specific step of obtaining the phase compensation factor according to the baseline parameter corresponding to the auxiliary image includes: and for each auxiliary image, acquiring the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the coordinates of the distance direction of the ground object target.
Specifically, the phase error can be directly compensated once according to the baseline parameters.
The baseline parameters corresponding to the auxiliary image can be obtained according to the auxiliary image and the reference image, and comprise the inclination angle between the baseline corresponding to the auxiliary image and the horizontal plane, the length of the baseline corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the coordinates of the ground object target in the distance direction.
And acquiring a comprehensive compensation factor according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the coordinates of the distance direction of the ground object target.
Specifically, the comprehensive compensation factor can be obtained according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength, and the coordinates of the distance direction of the ground object target.
And the comprehensive compensation factor is used for simultaneously compensating phase errors caused by the phase and the space offset of the flat ground.
Correspondingly, the phase error compensation of the auxiliary image according to the phase compensation factor specifically includes: and multiplying the comprehensive compensation factor by the auxiliary image to finish the phase error compensation brought by the flat ground phase and the space offset.
According to the embodiment of the invention, the phase error caused by the phase and the space offset of the flat ground is directly compensated at one time according to the baseline parameters, the compensation process is extremely simple, the compensation efficiency can be greatly improved, and the expenditure of hardware resources such as computers can be greatly saved.
Based on the content of the above embodiments, for each auxiliary image, the specific step of obtaining the phase compensation factor according to the baseline parameter corresponding to the auxiliary image includes: for each auxiliary image, acquiring the inclination angle between a base line corresponding to the auxiliary image and a horizontal plane, the length of the base line corresponding to the auxiliary image, the visual angle of the reference satellite for observing the ground and the radar wavelength, and acquiring a first compensation factor according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the visual angle of the reference satellite for observing the ground and the radar wavelength; and acquiring the distance direction coordinate of the ground object target, and acquiring a second compensation factor according to the inclination angle of the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the distance direction coordinate of the ground object target.
Specifically, the first compensation factor and the second compensation factor may be obtained according to the baseline parameter corresponding to the auxiliary image.
The first compensation factor is used for compensating the flat ground phase.
And the second compensation factor is used for compensating the phase error caused by the spatial offset.
Correspondingly, the phase error compensation of the auxiliary image according to the phase compensation factor specifically includes: the first compensation factor is multiplied by the auxiliary image, the phase compensation on the flat ground is finished, and then the multiplication result is multiplied by the second compensation factor, so that the phase error caused by the space offset is finished.
For each auxiliary image, the specific step of obtaining the phase compensation factor according to the baseline parameter corresponding to the auxiliary image comprises: for each auxiliary image, acquiring the inclination angle between a base line corresponding to the auxiliary image and a horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of a reference satellite for observing the ground, the radar wavelength and the coordinates of the distance direction of a ground object target; and acquiring a second compensation factor according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the coordinates of the ground object target in the distance direction.
For each auxiliary image, the second compensation factor can be obtained only according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the coordinate of the ground object target in the distance direction.
Correspondingly, the phase error compensation of the auxiliary image according to the phase compensation factor specifically includes: compensating the flat ground phase according to a method for removing the flat ground effect with general precision; and compensating the phase error of the result of removing the flat ground effect according to the second compensation factor.
According to the embodiment of the invention, the flat ground phase is removed firstly, the compensation of the phase error caused by the spatial offset is carried out according to the baseline parameters, the flat ground frequency spectrum does not need to be interpolated and estimated in the time domain, the compensation process is simple, the compensation efficiency can be improved, and the expenditure of hardware resources of a computer and the like can be saved.
Based on the above embodiments, the overall compensation factor is
Figure BDA0002139813020000121
Wherein j represents an imaginary unit; biA base line corresponding to the auxiliary image is represented; theta represents the view angle of the reference satellite for observing the ground; alpha is alphaiRepresenting the inclination angle of the base line corresponding to the auxiliary image and the horizontal plane; r represents the coordinates of the distance direction of the ground object target; λ represents a radar wavelength; i represents the number of the auxiliary image satellite, i is more than or equal to 1 and less than or equal to N-1, and N-1 represents the total number of the auxiliary image satellites.
Based on the content of the above embodiments, the first compensation factor is
Figure BDA0002139813020000131
The second compensation factor is
Figure BDA0002139813020000132
Wherein j represents an imaginary unit; biA base line corresponding to the auxiliary image is represented; theta represents the view angle of the reference satellite for observing the ground; alpha is alphaiRepresenting the inclination angle of the base line corresponding to the auxiliary image and the horizontal plane; r represents the coordinates of the distance direction of the ground object target; λ represents a radar wavelength; i represents the number of the auxiliary image satellite, i is more than or equal to 1 and less than or equal to N-1, and N-1 represents the total number of the auxiliary image satellites.
Based on the content of the foregoing embodiments, before performing phase error compensation on an auxiliary image according to a phase compensation factor, the method further includes: and pre-compensating the auxiliary image according to the reference image.
The reference image is a single-vision complex image of a ground object target acquired by a reference satellite.
It should be noted that the phase error further includes
Figure BDA0002139813020000133
The common phase compensation method based on the reference image can be adopted to eliminate the phase factor
Figure BDA0002139813020000134
According to the embodiment of the invention, the auxiliary image is pre-compensated according to the reference image, so that the phase error can be accurately removed.
Based on the content of the above embodiments, the specific steps of pre-compensating the auxiliary image according to the reference image include: obtaining a precompensation factor from a reference image
Figure BDA0002139813020000135
And pre-compensating the auxiliary image according to the pre-compensation factor.
Wherein j represents an imaginary unit; r represents the coordinates of the distance direction of the ground object target; λ represents the radar wavelength.
Specifically, according to the reference image, the coordinates of the ground object target in the distance direction and the radar wavelength can be obtained, so that the pre-compensation factor can be obtained
Figure BDA0002139813020000136
Will pre-compensate the factor
Figure BDA0002139813020000137
Multiplication with auxiliary image to eliminate phase error
Figure BDA0002139813020000138
And after the pre-compensation processing is carried out, phase error compensation is carried out on the auxiliary image after the pre-compensation processing according to the phase compensation factor.
Fig. 3 is a schematic structural diagram of a phase error compensation apparatus in synthetic aperture radar tomography according to an embodiment of the present invention. Based on the content of the above embodiments, as shown in fig. 3, the apparatus includes a factor obtaining module 301 and a phase compensation module 302, wherein:
a factor obtaining module 301, configured to, for each auxiliary image, obtain a phase compensation factor according to a baseline parameter corresponding to the auxiliary image;
a phase compensation module 302, configured to perform phase error compensation on the auxiliary image according to the phase compensation factor;
the auxiliary image is a single-vision complex image of the ground object target acquired by the auxiliary image satellite.
Specifically, the factor obtaining module 301 may obtain the phase compensation factor according to the baseline parameter corresponding to each auxiliary image.
The phase compensation module 302 performs phase error compensation on the auxiliary image according to the phase compensation factor to eliminate the flat phase
Figure BDA0002139813020000141
And spatial offset
Figure BDA0002139813020000142
Error caused by
Figure BDA0002139813020000143
The phase error compensation device in synthetic aperture radar tomography three-dimensional imaging provided in the embodiments of the present invention is configured to execute the phase error compensation method in synthetic aperture radar tomography three-dimensional imaging provided in each embodiment of the present invention, and specific methods and processes for implementing corresponding functions by each module included in the phase error compensation device in synthetic aperture radar tomography three-dimensional imaging are described in detail in the embodiments of the phase error compensation method in synthetic aperture radar tomography three-dimensional imaging, and are not described herein again.
The phase error compensation device in the synthetic aperture radar tomography is used for the phase error compensation method in the synthetic aperture radar tomography in the foregoing embodiments. Therefore, the description and definition of the phase error compensation method in the synthetic aperture radar tomography in the foregoing embodiments can be used for understanding the implementation modules in the embodiments of the present invention.
According to the embodiment of the invention, the phase compensation factor is obtained according to the baseline parameter corresponding to the auxiliary image, and the phase error compensation is carried out on the auxiliary image according to the phase compensation factor, so that the phase error compensation can be carried out more accurately, quickly and conveniently, the compensation effect can be improved, and the synthetic aperture radar tomography three-dimensional imaging result with better effect can be obtained.
Fig. 4 is a block diagram of an electronic device according to an embodiment of the present invention. Based on the content of the above embodiment, as shown in fig. 4, the electronic device may include: a processor (processor)401, a memory (memory)402, and a bus 403; wherein, the processor 401 and the memory 402 complete the communication with each other through the bus 403; the processor 401 is configured to invoke computer program instructions stored in the memory 402 and executable on the processor 401 to perform the method for compensating phase error in synthetic aperture radar tomography three-dimensional imaging provided by the above-mentioned embodiments of the method, for example, comprising: for each auxiliary image, acquiring a phase compensation factor according to a baseline parameter corresponding to the auxiliary image; performing phase error compensation on the auxiliary image according to the phase compensation factor; the auxiliary image is a single-vision complex image of the ground object target acquired by the auxiliary image satellite.
Another embodiment of the present invention discloses a computer program product, the computer program product comprises a computer program stored on a non-transitory computer readable storage medium, the computer program comprises program instructions, when the program instructions are executed by a computer, the computer can execute the method for compensating phase error in synthetic aperture radar tomography three-dimensional imaging provided by the above-mentioned method embodiments, for example, the method comprises: for each auxiliary image, acquiring a phase compensation factor according to a baseline parameter corresponding to the auxiliary image; performing phase error compensation on the auxiliary image according to the phase compensation factor; the auxiliary image is a single-vision complex image of the ground object target acquired by the auxiliary image satellite.
Furthermore, the logic instructions in the memory 402 may be implemented in software functional units and stored in a computer readable storage medium when sold or used as a stand-alone product. Based on such understanding, the technical solutions of the embodiments of the present invention may be essentially implemented or make a contribution to the prior art, or may be implemented in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the methods of the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
Another embodiment of the present invention provides a non-transitory computer-readable storage medium storing computer instructions, which cause a computer to execute a method for compensating phase error in three-dimensional imaging of synthetic aperture radar tomography provided by the above method embodiments, for example, the method includes: for each auxiliary image, acquiring a phase compensation factor according to a baseline parameter corresponding to the auxiliary image; performing phase error compensation on the auxiliary image according to the phase compensation factor; the auxiliary image is a single-vision complex image of the ground object target acquired by the auxiliary image satellite.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. It is understood that the above-described technical solutions may be embodied in the form of a software product, which may be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method of the above-described embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (6)

1. A method for compensating phase error in three-dimensional imaging of synthetic aperture radar tomography is characterized by comprising the following steps:
for each auxiliary image, acquiring a phase compensation factor according to a baseline parameter corresponding to the auxiliary image;
performing phase error compensation on the auxiliary image according to the phase compensation factor;
the auxiliary image is a single-vision complex image of a ground object target acquired by an auxiliary image satellite;
the specific step of obtaining the phase compensation factor according to the baseline parameter corresponding to each auxiliary image comprises:
for each auxiliary image, acquiring a dip angle between a base line corresponding to the auxiliary image and a horizontal plane, a length of the base line corresponding to the auxiliary image, a viewing angle of a reference satellite for observing the ground, a radar wavelength and a coordinate of a ground object target in a distance direction;
acquiring a comprehensive compensation factor according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the coordinates of the distance direction of the ground object target;
the comprehensive compensation factor is
Figure FDA0002919287300000011
Wherein j represents an imaginary unit; biA base line corresponding to the auxiliary image is represented; theta represents the view angle of the reference satellite for observing the ground; alpha is alphaiRepresenting the inclination angle of the base line corresponding to the auxiliary image and the horizontal plane; r represents the coordinates of the distance direction of the ground object target; λ represents a radar wavelength; i represents the number of the auxiliary image satellite, i is more than or equal to 1 and less than or equal to N-1, and N-1 represents the total number of the auxiliary image satellites;
or, the specific step of obtaining the phase compensation factor according to the baseline parameter corresponding to each auxiliary image includes:
for each auxiliary image, acquiring the inclination angle between a base line corresponding to the auxiliary image and a horizontal plane, the length of the base line corresponding to the auxiliary image, the view angle of the reference satellite for observing the ground and the radar wavelength, and acquiring a first compensation factor according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the view angle of the reference satellite for observing the ground and the radar wavelength; acquiring the distance direction coordinate of a ground object target, and acquiring a second compensation factor according to the inclination angle of the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of a reference satellite for observing the ground, the radar wavelength and the distance direction coordinate of the ground object target;
or, for each auxiliary image, acquiring a tilt angle between a base line corresponding to the auxiliary image and a horizontal plane, a length of the base line corresponding to the auxiliary image, a viewing angle of a reference satellite for observing the ground, a radar wavelength and a coordinate of a ground object target in a distance direction; acquiring a second compensation factor according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the coordinates of the ground object target in the distance direction;
the first compensation factor is
Figure FDA0002919287300000021
The second compensation factor is
Figure FDA0002919287300000022
Wherein j represents an imaginary unit; biA base line corresponding to the auxiliary image is represented; theta represents the view angle of the reference satellite for observing the ground; alpha is alphaiRepresenting the inclination angle of the base line corresponding to the auxiliary image and the horizontal plane; r represents the coordinates of the distance direction of the ground object target; λ represents a radar wavelength; i represents the number of the auxiliary image satellite, i is more than or equal to 1 and less than or equal to N-1, and N-1 represents the total number of the auxiliary image satellites.
2. The method of claim 1, wherein the phase error compensation of the auxiliary image according to the phase compensation factor further comprises:
pre-compensating the auxiliary image according to the reference image;
the reference image is a single-vision complex image of the ground object target acquired by a reference satellite.
3. The method for compensating phase error in three-dimensional tomography according to claim 2, wherein the pre-compensating the auxiliary image according to the reference image comprises:
obtaining a precompensation factor from the reference image
Figure FDA0002919287300000023
Pre-compensating the auxiliary image according to the pre-compensation factor;
wherein j represents an imaginary unit; r represents the coordinates of the distance direction of the ground object target; λ represents the radar wavelength.
4. A phase error compensation device in three-dimensional imaging of synthetic aperture radar chromatography is characterized by comprising:
the factor acquisition module is used for acquiring a phase compensation factor according to the baseline parameter corresponding to each auxiliary image;
the phase compensation module is used for carrying out phase error compensation on the auxiliary image according to the phase compensation factor;
the auxiliary image is a single-vision complex image of a ground object target acquired by an auxiliary image satellite;
the specific step of obtaining the phase compensation factor according to the baseline parameter corresponding to each auxiliary image comprises:
for each auxiliary image, acquiring a dip angle between a base line corresponding to the auxiliary image and a horizontal plane, a length of the base line corresponding to the auxiliary image, a viewing angle of a reference satellite for observing the ground, a radar wavelength and a coordinate of a ground object target in a distance direction;
acquiring a comprehensive compensation factor according to the inclination angle between the base line corresponding to the auxiliary image and the horizontal plane, the length of the base line corresponding to the auxiliary image, the viewing angle of the reference satellite for observing the ground, the radar wavelength and the coordinates of the distance direction of the ground object target;
the comprehensive compensation factor is
Figure FDA0002919287300000031
Wherein j represents an imaginary unit; biA base line corresponding to the auxiliary image is represented; theta represents the view angle of the reference satellite for observing the ground; alpha is alphaiRepresenting the inclination angle of the base line corresponding to the auxiliary image and the horizontal plane; r represents the coordinates of the distance direction of the ground object target; λ represents a radar wavelength; i represents the number of the auxiliary image satellite, i is more than or equal to 1 and less than or equal to N-1, and N-1 represents the total number of the auxiliary image satellites.
5. An electronic device comprising a memory, a processor and a computer program stored on the memory and being executable on the processor, characterized in that the processor, when executing the program, performs the steps of the method for phase error compensation in synthetic aperture radar tomography three-dimensional imaging as claimed in any of the claims 1 to 3.
6. A non-transitory computer readable storage medium having stored thereon a computer program, which when executed by a processor performs the steps of the method for phase error compensation in synthetic aperture radar tomography three-dimensional imaging as claimed in any one of the claims 1 to 3.
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