Summary of the invention
The object of the invention is to propose a kind of QR decomposition method of synthetic aperture radar three-dimensional imaging, be that the height gathering according to synthetic-aperture radar is to the linear equation between observation data and target elevation map picture, based on QR, decompose, to obtain high-resolution three-dimensional imaging result.
For achieving the above object, technical solution of the present invention is:
The QR decomposition method of synthetic aperture radar three-dimensional imaging is to use the height of QR decomposition technique Technologies Against Synthetic Aperture Radar collection to carry out target three-dimensional imaging processing to data of multiple angles;
Synthetic-aperture radar is by target is highly upwards being carried out to observation from various visual angles, obtain target along the sampled data of short transverse, it can realize by airborne radar or spaceborne radar in the flight that repeatedly repeats in differing heights position, also can in flight observation, realize by laying array antenna, also can in ground track radar system, move realization by the two dimensional surface of antenna;
Synthetic-aperture radar along orientation to each observation track keeping parallelism, can generate separately the two dimensional image of observation scene, can be positive side-looking, stravismus, strip-type or the imaging of bunching type observation mode; The orientation of each observation track, is to arrange along vertical height direction, or along continuous straight runs arrangement, or along having the direction of an angle to arrange with horizontal direction.
The QR decomposition method of described synthetic aperture radar three-dimensional imaging, it comprises the steps:
Steps A: the target scene original echo data to each observation collection are carried out two-dimensional imaging, generates the haplopia complex pattern of observing scene range-azimuth plane;
Step B: the two-dimensional image sequence that each observation is generated is carried out registration, the image that minimum observation position place obtains of take is master image;
Step C: the oblique solution of every width image being carried out to phase compensation is processed, and phase modulation factor is by the determining positions of each observation;
Step D: the object height obtaining after being processed by oblique solution, to the computing operator matrix of observed samples data and elevation imaging, obtains the linear equation between observation data and target elevation map picture;
Step e: use QR decomposition method to invert to the linear equation of Vector-Matrix Form, obtain target along the image in different resolution of short transverse;
The target scene two dimensional image that step F: integrating step A generates, obtains range-azimuth-height dimensional resolution image of target.
The QR decomposition method of described synthetic aperture radar three-dimensional imaging, described in it, in step D, the structure formula of the computing operator matrix of elevation imaging is:
Φ is the matrix of N * M, and matrix element is
Wherein, the track number that N is each observation, M be object height to vector length, n=1 ..., N, m=1 ..., M, j is imaginary unit, exp is exponential function, λ is radar wavelength, r ' is target oblique distance value, the reference viewing angle that θ is synthetic-aperture radar,
for the angle of each observation with horizontal direction, l
nbe the n time observation and with reference to the distance between observation position.
The QR decomposition method of described synthetic aperture radar three-dimensional imaging, described in it, in step e, QR decomposition solves linear equation method and obtains target elevation map picture, comprises the steps:
Step e 1: the computing operator matrix to elevation imaging carries out QR decomposition, is decomposed into the product of orthogonal matrix and upper triangular matrix;
Step e 2: invert to decomposing the orthogonal matrix obtaining, its inverse matrix is its associate matrix;
Step e 3: to the linear equation between observed samples data and target elevation map picture, equation both sides are distinguished to the inverse matrix of premultiplication orthogonal matrix by height, obtained the upper triangular matrix equation of inverting target elevation map picture;
Step e 4: solve upper triangular matrix equation, obtain the elevation of target to image.
The beneficial effect of the inventive method is: a kind of method that proposes synthetic aperture radar three-dimensional imaging, according to the observation of synthetic-aperture radar, build height for how much to the linear equation between observation data and target elevation map picture, and use QR decomposition method to solve this linear equation, obtain the elevation image in different resolution of target, thereby realize the high-resolution three-dimensional imaging of target.
Embodiment
The present invention is the QR decomposition method of synthetic aperture radar three-dimensional imaging, how much of the observations of the SAR three-dimensional imaging of method institute foundation as shown in Figure 1, x be carrier aircraft flight orientation to, y is distance direction, z is vertical height direction.Carrier aircraft has been carried out N time parallel observation in short transverse altogether to target scene, the minimum track of definition height and position is reference position, H is its podium level, the visual angle of reference position beam center is θ, its central beam direction is with reference to oblique distance direction r, and the angle of each survey layout direction and horizontal direction is

definition s is orthogonal to carrier aircraft heading x and with reference to the elevation direction of oblique distance direction r, has set up three-dimensional imaging coordinate system x-r-s, and true origin is positioned at reference to position of platform to be located.
The target scene original echo that each observation is obtained through range-azimuth to two-dimensional imaging after, obtain haplopia complex pattern data, now to the impact point in three dimensions, the target focus data that the n time observation station obtains is expressed as
Wherein, λ is radar wavelength, γ (s) be target along elevation to scattering function, the elevation that the size of twice a is observation scene is to scope, r
n(x ', r ', s '), n=1 ..., N is the distance between target and the n time observation, according to Fresnel approximation, it can be expressed as
Wherein, l
nbe the n time observation and with reference to the distance between observation position.Therefore the phase bit position of the resulting target focus data of the n time flight observation can be expressed as
According to the phase place of target focus data, the oblique solution phase factor of linear frequency modulation item is removed in definition
After oblique solution is processed, the focus data phase bit position that the n time observation obtains is
Now, the height obtaining to the signal frequency of observation data is
The target two-dimension focusing signal that the n time observation obtains is
Therefore, to the target in each range-azimuth resolution element, obtained its along elevation to scatter distributions function and height to the linear equation relational expression between synthetic aperture sampled data, be expressed as Vector-Matrix Form and be
g=Φγ
Wherein, the two-dimension focusing data vector that g obtains for each observation, γ be target elevation to scatter distributions function, Φ is the operation matrix between sampled data and elevation map picture, the distance dependent of it and each observation position and target and radar antenna, is expressed as
Wherein, the number that N is each observation, the object height that M is required reconstruction is to vector length, n=1 ..., N, m=1 ..., M, j is imaginary unit, and exp is exponential function, and λ is radar wavelength, and r ' is target oblique distance value, the reference viewing angle that θ is synthetic-aperture radar,
for the angle of each observation with horizontal direction, l
nbe the n time observation and with reference to the distance between observation position.
According to observation data vector sum target elevation, to the linear equation between scattering function, utilize the inversion operation to matrix equation, inverting target elevation to image.
Below in conjunction with accompanying drawing, describe each related detailed problem of QR decomposition method of synthetic aperture radar three-dimensional imaging of the present invention in detail.Be to be noted that described embodiment is only intended to be convenient to the understanding of the present invention, and it is not played to any restriction effect.
The QR decomposition method of synthetic aperture radar three-dimensional imaging of the present invention, its concrete implementation step as shown in Figure 2, mainly contains:
Steps A: the target scene original echo data to each observation collection are carried out two-dimensional imaging, generates the haplopia complex pattern of observing scene range-azimuth plane;
Step B: the two-dimensional image sequence that each observation is generated is carried out registration, the image that minimum observation position place obtains of take is master image;
Step C: the oblique solution of every width image being carried out to phase compensation is processed, and phase modulation factor is by the determining positions of each observation;
Step D: the object height obtaining after being processed by oblique solution, to the computing operator matrix of observed samples data and elevation imaging, obtains the linear equation between observation data and target elevation map picture;
Step e: use QR decomposition method to invert to the linear equation of Vector-Matrix Form, obtain target along the image in different resolution of short transverse;
The target scene two dimensional image that step F: integrating step A generates, obtains range-azimuth-height dimensional resolution image of target.
Structure height in the inventive method is to the linear equation between observation data and target elevation map picture, and the computing operator matrix that calculates elevation imaging is one of core content of the present invention, and concrete implementation step as shown in Figure 3, mainly contains:
Step D1: according to each observation position of synthetic-aperture radar and radar parameter, calculate the computing operator matrix Φ of elevation imaging, computing formula is:
Φ is the matrix of N * M, and matrix element is
Wherein, the number that N is each observation, M be object height to vector length, n=1 ..., N, m=1 ..., M, j is imaginary unit, exp is exponential function, λ is radar wavelength, r ' is target oblique distance value, the reference viewing angle that θ is synthetic-aperture radar,
for the angle of each observation with horizontal direction, l
nbe the n time observation and with reference to the distance between observation position.
Step D2: the object height obtaining after being processed by oblique solution, to observed samples data, obtains the linear equation between observation data and target elevation map picture, is expressed as g=Φ γ; Wherein, g be object height to observed samples data, γ be target elevation to scatter distributions function.
It is one of core content of the present invention that QR decomposition method in the inventive method solves linear equation, and concrete implementation step as shown in Figure 4, mainly contains:
Step e 1: the computing operator matrix to elevation imaging carries out QR decomposition, is decomposed into the product of orthogonal matrix Q and upper triangular matrix R, is expressed as Φ=QR;
Step e 2: invert to decomposing the orthogonal matrix obtaining, its inverse matrix is its associate matrix Q
-1=Q
h;
Step e 3: to the linear equation between observed samples data and target elevation map picture, equation both sides are distinguished to the inverse matrix of premultiplication orthogonal matrix by height, obtained the upper triangular matrix equation of inverting target elevation map picture, be expressed as R γ=Q
hg;
Step e 4: solve upper triangular matrix equation, obtain the elevation of target to image.
The method that the present invention is above-mentioned, has applied on computers MATLAB software and has been verified, and Technologies Against Synthetic Aperture Radar emulated data and ground rail system image data carried out three-dimensional imaging processing, and the validity of method has obtained checking.
The above; it is only the embodiment in the present invention; but protection scope of the present invention is not limited to this; any people who is familiar with this technology is in the disclosed technical scope of the present invention; can understand conversion or the replacement expected; all should be encompassed in of the present invention comprise scope within, therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.