CN104331899A

CN104331899A - Registration method and device for SAR image

Info

Publication number: CN104331899A
Application number: CN201410682140.1A
Authority: CN
Inventors: 杜康宁; 陆萍萍; 汪艮; 邓云凯; 王宇; 禹卫东; 李宁; 鲁萌萌
Original assignee: Institute of Electronics of CAS
Current assignee: Institute of Electronics of CAS
Priority date: 2014-11-24
Filing date: 2014-11-24
Publication date: 2015-02-04
Anticipated expiration: 2034-11-24
Also published as: CN104331899B

Abstract

The invention discloses a registration method for SAR image, and the method comprises the steps as follows: respectively extracting the character point for the SAR image and the first assistant SAR image; having overall situation bilateral matching operation on the character point of the SAR image and the character point of the first assistant SAR image to obtain the overall ground control point GCP set; overall situation registering from the first assistant SAR image to the main SAR image based on the overall ground control point GCP set to obtain the second assistant SAR image after overall situation registering operation; having partial bilateral matching operation on the character point of the main SAR image and the character point of the second assistant SAR image to obtain the partial GCP set; partially registering from the second assistant SAR image to the main SAR image based on the partial GCP set to obtain the third assistant SAR image. A registration device for SAR image is also disclosed.

Description

A SAR image registration method and device

技术领域technical field

本发明涉及合成孔径雷达(SAR，Synthetic Aperture Radar)技术领域，尤其涉及一种SAR图像配准方法及装置。The invention relates to the technical field of synthetic aperture radar (SAR, Synthetic Aperture Radar), in particular to a SAR image registration method and device.

背景技术Background technique

由于SAR具有全天时、全天候的工作特性，使得其在地球观测技术领域具有很重要的作用。大量的地球观测技术需要分析同一区域不同时间、不同入射角获得的多幅SAR图像，比如干涉SAR(InSAR)、信息融合技术、变化检测技术等。然而这些技术能够实施的前提是两幅或多幅图像能够在几何与辐射上精确的配准。Due to the all-day and all-weather working characteristics of SAR, it plays an important role in the field of earth observation technology. A large number of earth observation technologies need to analyze multiple SAR images obtained at different times and different incident angles in the same area, such as interferometric SAR (InSAR), information fusion technology, change detection technology, etc. However, the premise that these techniques can be implemented is that two or more images can be accurately registered geometrically and radiometrically.

然而，由于机载SAR图像数据分辨率的不断提高，不同飞行轨迹上获得的SAR图像会有十分明显的差异，并且，同一图像内不同区域地形变化使得图像间的畸变构成也十分复杂，通过简单的整体图像变换并不能获得配准的图像。However, due to the continuous improvement of the resolution of airborne SAR image data, the SAR images obtained on different flight trajectories will have very obvious differences, and the terrain changes in different areas in the same image make the distortion composition between images very complicated. The overall image transformation of , and cannot obtain the registered image.

发明内容Contents of the invention

为解决现有存在的问题，本发明实施例期望提供一种SAR图像配准方法和装置。In order to solve the existing problems, the embodiments of the present invention expect to provide a SAR image registration method and device.

本发明实施例的技术方案是这样实现的：The technical scheme of the embodiment of the present invention is realized like this:

本发明实施例提供了一种合成孔径雷达SAR图像配准方法，所述方法包括：An embodiment of the present invention provides a synthetic aperture radar SAR image registration method, the method comprising:

对主SAR图像和第一辅SAR图像分别进行特征点提取；Feature point extraction is performed on the main SAR image and the first auxiliary SAR image respectively;

对主SAR图像的特征点和第一辅SAR图像的特征点进行全局双向匹配，获得全局地面控制点GCP集合；Global two-way matching is performed on the feature points of the main SAR image and the feature points of the first auxiliary SAR image to obtain the global ground control point GCP set;

基于所述获得的全局GCP集合执行第一辅SAR图像到主SAR图像的全局配准，得到全局配准后的第二辅SAR图像；Perform global registration of the first auxiliary SAR image to the main SAR image based on the obtained global GCP set, and obtain a second auxiliary SAR image after global registration;

对主SAR图像的特征点和所述第二辅SAR图像的特征点进行局部双向匹配，获得局部GCP集合；performing local bidirectional matching on the feature points of the main SAR image and the feature points of the second auxiliary SAR image to obtain a local GCP set;

基于所述获得的局部GCP集合执行第二辅SAR图像到主SAR图像的局部配准，得到第三辅SAR图像。Perform local registration of the second auxiliary SAR image to the main SAR image based on the obtained local GCP set to obtain a third auxiliary SAR image.

上述方案中，所述对主SAR图像的特征点和第一辅SAR图像的特征点进行全局双向匹配，包括：In the above scheme, the global two-way matching of the feature points of the main SAR image and the feature points of the first auxiliary SAR image includes:

确定主SAR图像特征点集合和第一辅SAR图像特征点集合的前向匹配点集合F_g；Determine the forward matching point set F _g of the main SAR image feature point set and the first auxiliary SAR image feature point set;

确定主SAR图像特征点集合和第一辅SAR图像特征点集合的后向匹配点集合B_g；Determine the backward matching point set B _g of the main SAR image feature point set and the first auxiliary SAR image feature point set;

对所述集合F_g和集合B_g取交集获得主SAR图像和第一辅SAR图像的双向匹配点集合M_g，所述M_g即为全局GCP集合。Take the intersection of the set F _g and the set B _g to obtain a bidirectional matching point set M _g of the main SAR image and the first auxiliary SAR image, and the M _g is the global GCP set.

上述方案中，所述主SAR图像特征点集合为S_s、第一辅SAR图像特征点集合为S_m；In the above solution, the set of feature points of the main SAR image is S _s , and the set of feature points of the first auxiliary SAR image is S _m ;

所述集合中的任一特征点用下式表示：Any feature point in the set is represented by the following formula:

${P P}_{k k} = = \{\begin{matrix} ((x x)),, y the y \\ V V \end{matrix},,$

其中，(x，y)表示特征点的位置信息；V表示特征点的归一化特征描述向量。Among them, (x, y) represents the position information of the feature point; V represents the normalized feature description vector of the feature point.

上述方案中，所述主SAR图像特征点集合S_m和第一辅SAR图像特征点集合S_s的前向匹配点集合F_g通过以下方式确定：In the above scheme, the forward matching point set _Fg of the main SAR image feature point set S _m and the first auxiliary SAR image feature point set S _s is determined in the following manner:

${F f}_{g g} = = \{\begin{matrix} (({P P}_{s the s},, {P P}_{m m})) | | R R (({P P}_{m m},, {S S}_{s the s})) < < {R R}_{th the th},, \\ {P P}_{s the s} = = \underset{{P P}_{s the s}}{arg arg} \underset{{P P}_{s the s}^{' '} &Element; &Element; {S S}_{s the s}}{min min} ((a a cos cos (({| | | | {P P}_{s the s}^{' '} \cdot \cdot V V - - {P P}_{m m} \cdot &Center Dot; V V | | | |}_{22})))),, &ForAll; &ForAll; {P P}_{m m} &Element; &Element; {S S}_{m m} \end{matrix}\},,$

其中，所述R(P_m,S_s)为主SAR图像特征点P_m和第一辅SAR图像特征点集合S_s的欧式距离的比值；所述R_th为R(P_m,S_s)的预设阈值；P′_s为S_s中任意特征点。Wherein, the R(P _m , S _s ) is the ratio of the Euclidean distance between the main SAR image feature point P _m and the first auxiliary SAR image feature point set S _s ; the R _th is R(P _m ,S _s ) The preset threshold of ; P′ _s is any feature point in S _s .

上述方案中，所述R(P_m,S_s)通过以下方式确定：In the above scheme, the R(P _m , S _s ) is determined by the following method:

$R R (({P P}_{m m},, {S S}_{s the s})) = = \frac{a a cos cos (({| | | | {P P}_{s the s}^{11} \cdot &Center Dot; V- V- {P P}_{m m} \cdot &Center Dot; V V | | | |}_{22}))}{a a cos cos (({| | | | {P P}_{s the s}^{22} \cdot &Center Dot; V- V- {P P}_{m m} \cdot &Center Dot; V V | | | |}_{22}))},,$

其中表示第一辅SAR图像上与P_m相距最近的点；表示第一辅SAR图像上与P_m相距次近的点。in Indicates the point closest to P _m on the first auxiliary SAR image; Indicates the second closest point to P _m on the first auxiliary SAR image.

上述方案中，所述主SAR图像特征点集合S_m和第一辅SAR图像特征点集合S_s的后向匹配点集合F_g通过以下方式确定：In the above scheme, the backward matching point set _Fg of the main SAR image feature point set S _m and the first auxiliary SAR image feature point set S _s is determined in the following manner:

${B B}_{g g} = = \{\begin{matrix} (({P P}_{s the s},, {P P}_{m m})) | | R R (({P P}_{s the s},, {S S}_{m m})) < < {R R}_{th the th},, \\ {P P}_{m m} = = \underset{{P P}_{m m}}{arg arg} \underset{{P P}_{m m}^{' '} &Element; &Element; {S S}_{m m}}{min min} ((a a cos cos (({| | | | {P P}_{m m}^{' '} \cdot &Center Dot; V V - - {P P}_{s the s} \cdot &Center Dot; V V | | | |}_{22})))),, &ForAll; &ForAll; {P P}_{s the s} &Element; &Element; {S S}_{s the s} \end{matrix}\},,$

其中，所述R(P_s,S_m)为第一辅SAR图像特征点P_s和主SAR图像特征点集合S_m的欧式距离的比值；所述R_th为R(P_s,S_m)的预设阈值。Wherein, the R(P _s , S _m ) is the ratio of the Euclidean distance between the feature point P _s of the first auxiliary SAR image and the feature point set S _m of the main SAR image; the R _th is R(P _s , S _m ) preset threshold.

上述方案中，所述R(P_s,S_m)通过以下方式确定：In the above scheme, the R(P _s , S _m ) is determined by the following method:

$R R (({P P}_{s the s},, {S S}_{m m})) = = \frac{a a cos cos (({| | | | {P P}_{m m}^{11} \cdot \cdot V- V- {P P}_{s the s} \cdot \cdot V V | | | |}_{22}))}{a a cos cos (({| | | | {P P}_{m m}^{22} \cdot \cdot V- V- {P P}_{s the s} \cdot \cdot V V | | | |}_{22}))},,$

其中，表示主SAR图像上与P_s相距最近的点；表示主SAR图像上与P_s相距次近的点。in, Indicates the point closest to P _s on the main SAR image; Indicates the second closest point to P _s on the main SAR image.

上述方案中，所述双向匹配点集合M_g通过以下方式确定：In the above scheme, the two-way matching point set _Mg is determined in the following manner:

M_g＝{(P_s,P_m)|(P_s,P_m)∈F_g∩(P_s,P_m)∈B_g}＝{(P_s,P_m)|P_s∈M_s,P_m∈M_m}。M _g ＝{(P _s ,P _m )|(P _s ,P _m )∈F _g ∩(P _s ,P _m )∈B _g }＝{(P _s ,P _m )|P _s ∈M _s , P _m ∈ M _m }.

上述方案中，所述基于获得的全局GCP集合执行第一辅SAR图像到主SAR图像的全局配准，包括：In the above solution, the global registration of the first auxiliary SAR image to the main SAR image is performed based on the obtained global GCP set, including:

根据M_m1和M_s1确定仿射变换的变换矩阵A；其中，M_m1是M_g中属于主SAR图像的全局GCP集合，M_s1是M_g中属于辅SAR图像的全局GCP集合；Determine the transformation matrix A of the affine transformation according to M _m1 and M _s1 ; among them, M _m1 is the global GCP set belonging to the main SAR image in M _g , and M _s1 is the global GCP set belonging to the auxiliary SAR image in M _g ;

根据所述确定的变换矩阵A对辅图像的所有特征点各自作仿射变换，得到全局配准后的辅图像。Affine transformation is performed on all the feature points of the auxiliary image according to the determined transformation matrix A to obtain the auxiliary image after global registration.

上述方案中，所述变换矩阵A通过以下方式确定：In the above scheme, the transformation matrix A is determined in the following manner:

$A A = = \underset{A A}{arg arg min min} \underset{{I I}_{s the s} &Element; &Element; {M m}_{s the s},, {I I}_{m m} &Element; &Element; {M m}_{m m}}{Σ Σ} | | | | {I I}_{m m} - - {AI AI}_{s the s} | | | |;;$

根据所述变换矩阵A对辅图像的所有特征点各自作仿射变换为：According to the transformation matrix A, affine transformation is performed on all the feature points of the auxiliary image as follows:

I_m1＝A·I_s1 I _m1 =A·I _s1

其中， $I_{m 1} = [\begin{matrix} x_{m 1} \\ y_{m 1} \end{matrix}], A = [\begin{matrix} a_{0} & a_{1} & a_{2} \\ b_{0} & b_{1} & b_{2} \end{matrix}], I_{s 1} = [\begin{matrix} x_{s 1} \\ y_{s 1} \\ 1 \end{matrix}];$ in, $I_{m 1} = [\begin{matrix} x_{m 1} \\ {the y}_{m 1} \end{matrix}], A = [\begin{matrix} a_{0} & a_{1} & a_{2} \\ b_{0} & b_{1} & b_{2} \end{matrix}], I_{the s 1} = [\begin{matrix} x_{the s 1} \\ {the y}_{the s 1} \\ 1 \end{matrix}];$

所述I_m1表示M_m1中的GCP，I_s1表示M_s1中的GCP。Said I _m1 represents the GCP in M _m1 , and I _s1 represents the GCP in M _s1 .

上述方案中，所述对主SAR图像的特征点和第二辅SAR图像的特征点进行局部双向匹配，包括：In the above scheme, the local two-way matching of the feature points of the main SAR image and the feature points of the second auxiliary SAR image includes:

对主SAR图像和第二辅SAR图像中的每一个特征点，在半径D_th范围内，执行以下处理：For each feature point in the main SAR image and the second auxiliary SAR image, within the range of radius D _th , perform the following processing:

确定所述主SAR图像特征点和第二辅SAR图像特征点的前向匹配点集合F_l；Determine the forward matching point set F _l of the feature points of the main SAR image and the feature points of the second auxiliary SAR image;

对主SAR图像和第二辅SAR图像中的每一个特征点，在半径D_th范围内，确定该主SAR图像特征点和第二辅SAR图像特征点的后向匹配点集合B_l；For each feature point in the main SAR image and the second auxiliary SAR image, within the radius D _th range, determine the backward matching point set B _l of the main SAR image feature point and the second auxiliary SAR image feature point;

对所述集合F_l和集合B_l取交集获得所述主SAR图像特征点和辅SAR图像特征点的双向匹配点集合M_l。Take the intersection of the set F _l and the set B _l to obtain the two-way matching point set M _l of the feature points of the main SAR image and the feature points of the auxiliary SAR image.

上述方案中，通过以下方式确定所述主SAR图像特征点和第二辅SAR图像特征点的前向匹配点集合F_l：In the above solution, the forward matching point set F _l of the feature points of the main SAR image and the feature points of the second auxiliary SAR image is determined in the following manner:

${F f}_{l l} = = \{\begin{matrix} (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) | | R R (({P P}_{m m},, {\overset{&OverBar; &OverBar;}{S S}}_{s the s})) < < {R R}_{th the th} \cap \cap D D. (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) < < {D D.}_{th the th},, \\ {\overset{&OverBar; &OverBar;}{P P}}_{s the s} = = \underset{{\overset{&OverBar; &OverBar;}{P P}}_{s the s}}{arg arg} \underset{{\overset{&OverBar; &OverBar;}{P P}}_{s the s}^{' '}}{min min} ((a a cos cos (({| | | | {\overset{&OverBar; &OverBar;}{P P}}_{s the s}^{' '} - - {P P}_{m m} | | | |}_{22})))),, &ForAll; &ForAll; {P P}_{m m} &Element; &Element; {S S}_{m m} \end{matrix}\},,$

其中，所述第二辅SAR图像的特征点集合为所述中的特征点为所述为主SAR图像特征点P_m和第二辅SAR图像特征点集合的欧式距离的比值；所述R_th为的预设阈值。Wherein, the set of feature points of the second auxiliary SAR image is said The feature points in are said The main SAR image feature point P _m and the second auxiliary SAR image feature point set The ratio of the Euclidean distance; the R _th is preset threshold.

上述方案中，所述通过下式确定：In the above scheme, the Determined by:

$R R (({P P}_{m m},, {\overset{&OverBar; &OverBar;}{S S}}_{s the s})) = = \frac{a a cos cos (({| | | | {\overset{&OverBar; &OverBar;}{P P}}_{s the s}^{11} \cdotV- \cdotV- {P P}_{m m} \cdot \cdot v v | | | |}_{22}))}{a a cos cos (({| | | | {\overset{&OverBar; &OverBar;}{P P}}_{s the s}^{22} \cdot \cdot V V {- - p p}_{m m} \cdot \cdot v v | | | |}_{22}))},,$

其中，表示第二辅SAR图像上与P_m相距最近的点；表示第二辅SAR图像上与P_m相距次近的点。in, Indicates the point closest to P _m on the second auxiliary SAR image; Indicates the second closest point to P _m on the second auxiliary SAR image.

上述方案中，通过以下方式确定所述主SAR图像特征点和第二辅SAR图像特征点的前向匹配点集合B_l：In the above scheme, the forward matching point set B _l of the feature points of the main SAR image and the feature points of the second auxiliary SAR image is determined in the following manner:

${B B}_{l l} = = \{\begin{matrix} (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) | | R R (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {S S}_{m m})) < < {R R}_{th the th} \cap \cap D D. (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) < < {D D.}_{th the th},, \\ {P P}_{m m} = = \underset{{P P}_{m m}}{arg arg} \underset{{P P}_{m m}^{' '} &Element; &Element; {S S}_{m m}}{min min} ((a a cos cos (({| | | | {P P}_{m m}^{' '} \cdot \cdot V V - - {P P}_{s the s} \cdot \cdot V V | | | |}_{22})))),, &ForAll; &ForAll; {\overset{&OverBar; &OverBar;}{P P}}_{s the s} &Element; &Element; {\overset{&OverBar; &OverBar;}{S S}}_{s the s} \end{matrix}\},,$

其中，所述第二辅SAR图像的特征点集合为所述中的特征点为所述为第二辅SAR图像特征点和主SAR图像特征点集合S_m的欧式距离的比值；所述R_th为的预设阈值。Wherein, the set of feature points of the second auxiliary SAR image is said The feature points in are said is the feature point of the second auxiliary SAR image and the ratio of the Euclidean distance of the main SAR image feature point set S _m ; the R _th is preset threshold.

$R R (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {S S}_{m m})) = = \frac{a a cos cos (({| | | | {P P}_{m m}^{11} \cdot \cdot V V - - {\overset{&OverBar; &OverBar;}{P P}}_{s the s} \cdot &Center Dot; V V | | | |}_{22}))}{a a cos cos (({| | | | {P P}_{m m}^{22} \cdot &Center Dot; V V - - {\overset{&OverBar; &OverBar;}{P P}}_{s the s} \cdot &Center Dot; V V | | | |}_{22}))},,$

其中，表示主SAR图像上与相距最近的点；表示主SAR图像上与相距次近的点。in, Indicates that on the main SAR image with the closest point; Indicates that on the main SAR image with The next closest point.

上述方案中，所述双向匹配点集合M_l通过下式确定：In the above scheme, the set of bidirectional matching points _M1 is determined by the following formula:

${M m}_{l l} = = {{(({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) | | (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) &Element; &Element; {F f}_{l l} \cap \cap (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) &Element; &Element; {B B}_{l l}}} = = {{(({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) | | {\overset{&OverBar; &OverBar;}{P P}}_{s the s} &Element; &Element; {\overset{&OverBar; &OverBar;}{L L}}_{s the s},, {P P}_{m m} &Element; &Element; {L L}_{m m}}} . .$

上述方案中，所述基于获得的局部GCP集合执行第二辅SAR图像到主SAR图像的局部配准，包括：In the above solution, the local registration of the second auxiliary SAR image to the main SAR image is performed based on the obtained local GCP set, including:

根据M_m2和M_s2确定仿射变换的变换矩阵A；其中，M_m2是M_l中属于主SAR图像的全局GCP集合，M_s2是M_l中属于辅SAR图像的全局GCP集合；Determine the transformation matrix A of the affine transformation according to M _m2 and M _s2 ; wherein, M _m2 is the global GCP set belonging to the main SAR image in M _l , and M _s2 is the global GCP set belonging to the auxiliary SAR image in M _l ;

根据所述确定的变换矩阵B对所述第二辅SAR图像特征点半径D_th范围内的所有特征点各自作仿射变换。Perform an affine transformation on all feature points within a radius D _th of feature points in the second auxiliary SAR image according to the determined transformation matrix B.

上述方案中，所述变换矩阵B通过以下方式确定：In the above scheme, the transformation matrix B is determined in the following manner:

$B B = = \underset{B B}{arg arg min min} \underset{{I I}_{s the s 22} &Element; &Element; {M m}_{s the s 22},, {I I}_{m m 22} &Element; &Element; {M m}_{m m 22}}{Σ Σ} | | | | {I I}_{m m 22} - - {BI BI}_{s the s 22} | | | |;;$

根据所述变换矩阵B对辅图像的所有特征点各自作仿射变换为：According to the transformation matrix B, the affine transformation is performed on all the feature points of the auxiliary image as follows:

I_m2＝B·I_s2 I _m2 = B·I _s2

其中， $I_{m 2} = [\begin{matrix} x_{m 2} \\ y_{m 2} \end{matrix}], B = [\begin{matrix} c_{0} & c_{1} & c_{2} \\ d_{0} & d_{1} & d_{2} \end{matrix}], I_{s} = [\begin{matrix} x_{s} \\ y_{s} \\ 1 \end{matrix}];$ in, $I_{m 2} = [\begin{matrix} x_{m 2} \\ {the y}_{m 2} \end{matrix}], B = [\begin{matrix} c_{0} & c_{1} & c_{2} \\ d_{0} & d_{1} & d_{2} \end{matrix}], I_{the s} = [\begin{matrix} x_{the s} \\ {the y}_{the s} \\ 1 \end{matrix}];$

所述I_m2表示M_m2中的GCP，I_s2表示M_s2中的GCP。Said I _m2 represents the GCP in M _m2 , and I _s2 represents the GCP in M _s2 .

本发明实施例提供了一种合成孔径雷达SAR图像配准装置，所述装置包括：特征点提取模块、第一双向匹配模块、第一配准模块、第二双向匹配模块和第二配准模块；其中，An embodiment of the present invention provides a synthetic aperture radar SAR image registration device, which includes: a feature point extraction module, a first two-way matching module, a first registration module, a second two-way matching module and a second registration module ;in,

所述特征点提取模块，用于对主SAR图像和第一辅SAR图像分别进行特征点提取；The feature point extraction module is used to extract feature points from the main SAR image and the first auxiliary SAR image respectively;

所述第一双向匹配模块，用于对主SAR图像的特征点和第一辅SAR图像的特征点进行全局双向匹配，获得全局地面控制点GCP；The first two-way matching module is used to perform global two-way matching on the feature points of the main SAR image and the feature points of the first auxiliary SAR image to obtain the global ground control point GCP;

第一配准模块，用于基于所述获得的全局GCP执行第一辅SAR图像到主SAR图像的全局配准，得到全局配准后的第二辅SAR图像；The first registration module is used to perform the global registration of the first auxiliary SAR image to the main SAR image based on the obtained global GCP, and obtain the second auxiliary SAR image after global registration;

所述第二双向匹配模块，用于对主SAR图像的特征点和所述第二辅SAR图像的特征点进行局部双向匹配，获得局部GCP集合；The second bidirectional matching module is configured to perform local bidirectional matching on the feature points of the main SAR image and the feature points of the second auxiliary SAR image to obtain a local GCP set;

所述第二配准模块，用于基于所述获得的局部GCP集合执行第二辅SAR图像到主SAR图像的局部配准，得到第三辅SAR图像。The second registration module is configured to perform local registration of the second auxiliary SAR image to the main SAR image based on the obtained local GCP set to obtain a third auxiliary SAR image.

本发明实施例所提供的SAR图像配准方法和装置，对主SAR图像和第一辅SAR图像分别进行特征点提取；对主SAR图像的特征点和第一辅SAR图像的特征点进行全局双向匹配，获得全局地面控制点GCP集合；基于所述获得的全局GCP集合执行第一辅SAR图像到主SAR图像的全局配准，得到全局配准后的第二辅SAR图像；对主SAR图像的特征点和所述第二辅SAR图像的特征点进行局部双向匹配，获得局部GCP集合；基于所述获得的局部GCP集合执行第二辅SAR图像到主SAR图像的局部配准，得到第三辅SAR图像；如此，能够在对辅SAR图像进行全局配准之后，进一步进行局部配准，从而使最终得到的SAR图像达到较高的配准精度。The SAR image registration method and device provided by the embodiments of the present invention perform feature point extraction on the main SAR image and the first auxiliary SAR image respectively; perform global bidirectional Match to obtain the global ground control point GCP set; perform the global registration of the first auxiliary SAR image to the main SAR image based on the global GCP set obtained, and obtain the second auxiliary SAR image after the global registration; the main SAR image The feature points and the feature points of the second auxiliary SAR image are locally matched bidirectionally to obtain a local GCP set; based on the obtained local GCP set, the local registration of the second auxiliary SAR image to the main SAR image is performed to obtain a third auxiliary SAR image. SAR image; in this way, local registration can be further performed after the auxiliary SAR image is globally registered, so that the finally obtained SAR image can achieve higher registration accuracy.

附图说明Description of drawings

图1为本发明实施例提供的一种SAR图像配准方法的流程示意图；FIG. 1 is a schematic flow chart of a SAR image registration method provided by an embodiment of the present invention;

图2为本发明实施例提供的一种SAR图像配准装置的结构示意图。FIG. 2 is a schematic structural diagram of a SAR image registration device provided by an embodiment of the present invention.

具体实施方式Detailed ways

本发明实施例中，对主SAR图像和第一辅SAR图像分别进行特征点提取；对主SAR图像的特征点和第一辅SAR图像的特征点进行全局双向匹配，获得全局地面控制点GCP集合；基于所述获得的全局GCP集合执行第一辅SAR图像到主SAR图像的全局配准，得到全局配准后的第二辅SAR图像；对主SAR图像的特征点和所述第二辅SAR图像的特征点进行局部双向匹配，获得局部GCP集合；基于所述获得的局部GCP集合执行第二辅SAR图像到主SAR图像的局部配准，得到第三辅SAR图像。In the embodiment of the present invention, feature point extraction is performed on the main SAR image and the first auxiliary SAR image respectively; global two-way matching is performed on the feature points of the main SAR image and the feature points of the first auxiliary SAR image, and the global ground control point GCP set is obtained ; Based on the obtained global GCP set, perform the global registration of the first auxiliary SAR image to the main SAR image, and obtain the second auxiliary SAR image after global registration; for the feature points of the main SAR image and the second auxiliary SAR Local bidirectional matching is performed on the feature points of the image to obtain a local GCP set; based on the obtained local GCP set, local registration of the second auxiliary SAR image to the main SAR image is performed to obtain a third auxiliary SAR image.

下面通过附图及具体实施例对本发明做进一步的详细说明。The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

本发明实施例实现一种SAR图像配准方法，如图1所示，该方法包括以下几个步骤：The embodiment of the present invention implements a SAR image registration method, as shown in Figure 1, the method includes the following steps:

步骤101：对主SAR图像和第一辅SAR图像分别进行特征点提取；Step 101: Extract feature points from the main SAR image and the first auxiliary SAR image respectively;

具体的，在这一步骤中，输入两幅SAR图像，将其中一幅SAR图像定义为主SAR图像，则另外一幅SAR图像作为第一辅SAR图像；Specifically, in this step, two SAR images are input, one of the SAR images is defined as the main SAR image, and the other SAR image is used as the first auxiliary SAR image;

接下来，采用特征点提取算法对所述两幅SAR图像进行特征点提取；可以采用的特征点提取算法包括：尺度不变特征变换(SIFT)算法、SURF算法(尺度不变特征变换SIFT算法的加速版算法)以及角点检测Harris算法等等；Next, the feature point extraction algorithm is used to extract feature points from the two SAR images; the feature point extraction algorithms that can be used include: Scale Invariant Feature Transform (SIFT) algorithm, SURF algorithm (Scale Invariant Feature Transform SIFT algorithm Accelerated version algorithm) and Harris algorithm for corner detection, etc.;

经过特征点提取之后，针对主SAR图像和第一辅SAR图像将生成两个特征点集合，具体的，设主SAR图像的特征点集合为S_m，第一辅SAR图像的特征点集合为S_s，这里的特征点集合S_m和S_s中的任意特征点P_k均可以表示为以下形式：After feature point extraction, two sets of feature points will be generated for the main SAR image and the first auxiliary SAR image. Specifically, let the feature point set of the main SAR image be S _m , and the feature point set of the first auxiliary SAR image be S _s , here the feature point set S _m and any feature point P _k in S _s can be expressed as the following form:

${P P}_{k k} = = \{\begin{matrix} ((x x)),, y the y \\ V V \end{matrix} - - - - - - ((11))$

其中，V是特征点的归一化描述向量；(x，y)为特征点的位置信息；特征点P_k的位置可以用P_k.(x,y)表示，特征点P_k的描述符可以用P_k.V来表示。Among them, V is the normalized description vector of the feature point; (x, y) is the position information of the feature point; the position of the feature point P _k can be represented by P _k .(x, y), and the descriptor of the feature point P _k It can be represented by P _k .V.

步骤102：对主SAR图像的特征点和第一辅SAR图像的特征点进行全局双向匹配，获得全局GCP集合；Step 102: Perform global two-way matching on the feature points of the main SAR image and the feature points of the first auxiliary SAR image to obtain a global GCP set;

具体的，所述对主SAR图像的特征点和第一辅SAR图像的特征点进行全局双向匹配，包括：Specifically, the global two-way matching of the feature points of the main SAR image and the feature points of the first auxiliary SAR image includes:

确定主SAR图像特征点集合和第一辅SAR图像特征点集合的前向匹配点集合F_g；确定主SAR图像特征点集合和第一辅SAR图像特征点集合的后向匹配点集合B_g；对所述集合F_g和集合B_g取交集获得主SAR图像和第一辅SAR图像的双向匹配点集合M_g，所述M_g即为全局GCP集合。Determine the forward matching point set F _g of the main SAR image feature point set and the first auxiliary SAR image feature point set; determine the backward matching point set B _g of the main SAR image feature point set and the first auxiliary SAR image feature point set; Take the intersection of the set F _g and the set B _g to obtain a bidirectional matching point set M _g of the main SAR image and the first auxiliary SAR image, and the M _g is the global GCP set.

具体的，所述主SAR图像特征点集合S_m和第一辅SAR图像特征点集合S_s的前向匹配点集合F_g通过下式确定：Specifically, the forward matching point set _Fg of the main SAR image feature point set _Sm and the first auxiliary SAR image feature point set _Ss is determined by the following formula:

${F f}_{g g} = = \{\begin{matrix} (({P P}_{s the s},, {P P}_{m m})) | | R R (({P P}_{m m},, {S S}_{s the s})) < < {R R}_{th the th},, \\ {P P}_{s the s} = = \underset{{P P}_{s the s}}{arg arg} \underset{{P P}_{s the s}^{' '} &Element; &Element; {S S}_{s the s}}{min min} ((a a cos cos (({| | | | {P P}_{s the s}^{' '} \cdot &Center Dot; V V - - {P P}_{m m} \cdot &Center Dot; V V | | | |}_{22})))),, &ForAll; &ForAll; {P P}_{m m} &Element; &Element; {S S}_{m m} \end{matrix}\} - - - - - - ((22))$

其中，所述R(P_m,S_s)为主SAR图像特征点P_m和辅SAR图像特征点集合S_s的欧式距离的比值；所述R_th为R(P_m,S_s)的预设阈值；P′_s为S_s中任意特征点。Wherein, the R(P _m , S _s ) is the ratio of the Euclidean distance between the main SAR image feature point P _m and the auxiliary SAR image feature point set S _s ; the R _th is the preset value of R(P _m ,S _s ). Set the threshold; P' _s is any feature point in S _s .

具体的，所述R(P_m,S_s)通过下式确定：Specifically, the R(P _m , S _s ) is determined by the following formula:

$R R (({P P}_{m m},, {S S}_{s the s})) = = \frac{a a cos cos (({| | | | {P P}_{s the s}^{11} \cdot \cdot V- V- {P P}_{m m} \cdot \cdot V V | | | |}_{22}))}{a a cos cos (({| | | | {P P}_{s the s}^{22} \cdot &Center Dot; V- V- {P P}_{m m} \cdot &Center Dot; V V | | | |}_{22}))} - - - - - - ((33))$

其中，表示第一辅SAR图像上与P_m相距最近的点；表示第一辅SAR图像上与P_m相距次近的点。in, Indicates the point closest to P _m on the first auxiliary SAR image; Indicates the second closest point to P _m on the first auxiliary SAR image.

具体的，所述主SAR图像特征点集合S_m和第一辅SAR图像特征点集合S_s的后向匹配点集合F_g通过下式确定：Specifically, the backward matching point set _Fg of the main SAR image feature point set _Sm and the first auxiliary SAR image feature point set _Ss is determined by the following formula:

${B B}_{g g} = = \{\begin{matrix} (({P P}_{s the s},, {P P}_{m m})) | | R R (({P P}_{s the s},, {S S}_{m m})) < < {R R}_{th the th},, \\ {P P}_{m m} = = \underset{{P P}_{m m}}{arg arg} \underset{{P P}_{m m}^{' '} &Element; &Element; {S S}_{m m}}{min min} ((a a cos cos (({| | | | {P P}_{m m}^{' '} \cdot \cdot V V - - {P P}_{s the s} \cdot \cdot V V | | | |}_{22})))),, &ForAll; &ForAll; {P P}_{s the s} &Element; &Element; {S S}_{s the s} \end{matrix}\} - - - - - - ((44))$

其中，所述R(P_s,S_m)通过下式确定：Wherein, the R(P _s , S _m ) is determined by the following formula:

$R R (({P P}_{s the s},, {S S}_{m m})) = = \frac{a a cos cos (({| | | | {P P}_{m m}^{11} \cdot \cdot V- V- {P P}_{s the s} \cdot \cdot V V | | | |}_{22}))}{a a cos cos (({| | | | {P P}_{m m}^{22} \cdot \cdot V- V- {P P}_{s the s} \cdot &Center Dot; V V | | | |}_{22}))} - - - - - - ((55))$

具体的，所述双向匹配点集合M_g通过下式确定：Specifically, the two-way matching point set _Mg is determined by the following formula:

M_g＝{(P_s,P_m)|(P_s,P_m)∈F_g∩(P_s,P_m)∈B_g}＝{(P_s,P_m)|P_s∈M_s,_Pm∈M_m} (6)M _g ＝{(P _s ,P _m )|(P _s ,P _m )∈F _g ∩(P _s ,P _m )∈B _g }＝{(P _s ,P _m )|P _s ∈M _s , _P m∈M _m } (6)

步骤103：基于所述获得的全局GCP集合执行第一辅SAR图像到主SAR图像的全局配准，得到全局配准后的第二辅SAR图像；Step 103: Perform global registration of the first auxiliary SAR image to the main SAR image based on the obtained global GCP set, and obtain a second auxiliary SAR image after global registration;

具体的，所述基于所述获得的全局GCP集合执行第一辅SAR图像到主SAR图像的全局配准，包括：Specifically, the global registration of the first auxiliary SAR image to the main SAR image based on the obtained global GCP set includes:

根据M_m1和M_s1确定仿射变换的变换矩阵A；其中，Mm1是M_g中属于主SAR图像的全局GCP集合，M_s1是M_g中属于辅SAR图像的全局GCP集合；Determine the transformation matrix A of the affine transformation according to M _m1 and M _s1 ; among them, Mm1 is the global GCP set belonging to the main SAR image in M _g , and M _s1 is the global GCP set belonging to the auxiliary SAR image in M _g ;

所述变换矩阵A通过以下方式确定：The transformation matrix A is determined in the following way:

$A A = = \underset{A A}{arg arg min min} \underset{{I I}_{s the s} &Element; &Element; {M m}_{s the s},, {I I}_{m m} &Element; &Element; {M m}_{m m}}{Σ Σ} | | | | {I I}_{m m} - - {AI AI}_{s the s} | | | | - - - - - - ((77))$

I_m1＝A·I_s1 (8)I _m1 = A·I _s1 (8)

其中，所述I_m1表示M_m1中的GCP，I_s1表示M_s1中的GCP。Wherein, said I _m1 represents the GCP in M _m1 , and I _s1 represents the GCP in M _s1 .

进一步的，在执行第一辅SAR图像到主SAR图像的全局配准之前，还可以包括以下步骤：Further, before performing the global registration of the first auxiliary SAR image to the main SAR image, the following steps may also be included:

滤除所述全局GCP集合中的错误GCP点之后；基于剩下的全局GCP执行第一辅SAR图像到主SAR图像的全局配准；After filtering out the wrong GCP points in the global GCP set; performing the global registration of the first auxiliary SAR image to the main SAR image based on the remaining global GCP;

具体的，可以使用随机样本一致(RANCAC，Random Sample Consensus)算法滤除错误匹配点，具体包括以下处理步骤：Specifically, the random sample consensus (RANCAC, Random Sample Consensus) algorithm can be used to filter out the wrong matching points, which specifically includes the following processing steps:

S201：从全局匹配GCP集合M_g中随机抽选一个RANSAC样本，所述RANSAC样本包括3个匹配GCP点对；S201: Randomly select a RANSAC sample from the global matching GCP set _Mg , the RANSAC sample includes 3 matching GCP point pairs;

S202：根据这3个匹配GCP点对计算变换矩阵A，即求解将所述3个GCP点对代入公式(7)计算变换矩阵A；S202: Calculate the transformation matrix A according to the three matching GCP point pairs, that is, calculate the transformation matrix A by substituting the three GCP point pairs into formula (7);

S203：根据样本集M_g，仿射变换矩阵A，计算各个样本点的误差，即||l_m-Al_s||,l_s∈M_s,l_m∈M_m；S203: According to the sample set M _g and the affine transformation matrix A, calculate the error of each sample point, namely ||l _m -Al _s ||, l _s ∈ M _s , l _m ∈ M _m ;

当误差小于设定阈值时，将该样本点归类于“一致点”，统计“一致点”的数量；所述阈值可以根据实际需要进行设置，这里不作限制。When the error is smaller than the set threshold, the sample point is classified as a "consistent point", and the number of "consistent points" is counted; the threshold can be set according to actual needs, and there is no limitation here.

S204：根据当前一集合中元素个数判断当前一致集是否为最优一致集，若是，则更新当前最优一致集；S204: Determine whether the current consistent set is the optimal consistent set according to the number of elements in the current set, and if so, update the current optimal consistent set;

S205：更新当前“一致点”所占的比例p，若p大于允许的最小错误概率则重复S201至S204继续迭代，直到当前错误概率p小于最小错误概率，这样就确定了一个变换模型M_C，该变换模型M_C即为滤除了错误匹配点后剩余的全局GCP集合；S205: Update the proportion p of the current "consistent point", if p is greater than the allowable minimum error probability, repeat S201 to S204 to continue iterating until the current error probability p is less than the minimum error probability, thus determining a transformation model M _C , The transformation model M _C is the remaining global GCP set after filtering out the wrong matching points;

步骤104：对主SAR图像的特征点和与所述第二辅SAR图像的特征点进行局部双向匹配，获得局部GCP集合；Step 104: Perform local bidirectional matching on the feature points of the main SAR image and the feature points of the second auxiliary SAR image to obtain a local GCP set;

具体的，所述对主SAR图像的特征点和与所述第二辅SAR图像的特征点进行局部双向匹配，包括：Specifically, the local two-way matching of the feature points of the main SAR image and the feature points of the second auxiliary SAR image includes:

对所述集合F_l和集合B_l取交集获得所述主SAR图像特征点和第二辅SAR图像特征点的双向匹配点集合M_l。Take the intersection of the set F _l and the set B _l to obtain the two-way matching point set M _l of the feature points of the main SAR image and the feature points of the second auxiliary SAR image.

具体的，可以通过以下方式确定所述主SAR图像特征点和第二辅SAR图像特征点的前向匹配点集合F_l：Specifically, the forward matching point set F _l of the feature points of the main SAR image and the feature points of the second auxiliary SAR image can be determined in the following manner:

对于多时相机载高分辨率SAR图像而言，由于不同的成像几何，不同地物的畸变形式也不同，因而，仅仅使用单一的全局配准并不能够表征真实的畸变，也就不能达到精确的图像配准目的，因此，本发明实施例在全局配置的基础上，需要进一步进行局部配准，从而使配准精度大大提高。For high-resolution SAR images carried by multi-temporal cameras, due to different imaging geometries, the distortion forms of different ground objects are also different. Therefore, only a single global registration cannot represent the real distortion, and it cannot achieve accurate The purpose of image registration, therefore, the embodiment of the present invention needs to further perform local registration on the basis of the global configuration, so that the registration accuracy is greatly improved.

步骤105：基于所述获得的局部GCP集合执行第二辅SAR图像到主SAR图像的局部配准，得到第三辅SAR图像；Step 105: Perform local registration of the second auxiliary SAR image to the main SAR image based on the obtained local GCP set to obtain a third auxiliary SAR image;

具体的，所述基于所述获得的局部GCP集合执行第二辅SAR图像到主SAR图像的局部配准，包括：Specifically, performing local registration of the second auxiliary SAR image to the main SAR image based on the obtained local GCP set includes:

根据所述确定的变换矩阵B对所述第二辅SAR图像特征点半径Dth范围内的所有特征点各自作仿射变换。Perform an affine transformation on all the feature points within the range of the feature point radius Dth of the second auxiliary SAR image according to the determined transformation matrix B.

具体的，所述变换矩阵B通过以下方式确定：Specifically, the transformation matrix B is determined in the following manner:

具体的，根据所述变换矩阵B对辅图像的所有特征点各自作仿射变换为：Specifically, according to the transformation matrix B, an affine transformation is performed on all the feature points of the auxiliary image as follows:

I_m2＝B·I_s2 I _m2 = B·I _s2

通过步骤105，执行完第二辅SAR图像到主SAR图像的局部配准之后，得到第三辅SAR图像即为最终的配准图像。Through step 105, after the local registration of the second auxiliary SAR image to the main SAR image is performed, the third auxiliary SAR image is obtained as the final registration image.

为了实现上述方法，本发明实施例还提供了一种SAR配准装置，如图2所示，所述装置包括：特征点提取模块21、第一双向匹配模块22、第一配准模块23、第二双向匹配模块24和第二配准模块25；其中，In order to implement the above method, an embodiment of the present invention also provides a SAR registration device, as shown in FIG. 2 , the device includes: a feature point extraction module 21, a first bidirectional matching module 22, a first registration module 23, The second two-way matching module 24 and the second registration module 25; wherein,

所述特征点提取模块21，用于对主SAR图像和第一辅SAR图像分别进行特征点提取；The feature point extraction module 21 is used to extract feature points from the main SAR image and the first auxiliary SAR image respectively;

所述第一双向匹配模块22，用于对主SAR图像的特征点和第一辅SAR图像的特征点进行全局双向匹配，获得全局地面控制点GCP；The first two-way matching module 22 is used to perform global two-way matching on the feature points of the main SAR image and the feature points of the first auxiliary SAR image to obtain the global ground control point GCP;

第一配准模块23，用于基于所述获得的全局GCP集合执行第一辅SAR图像到主SAR图像的全局配准，得到全局配准后的第二辅SAR图像；The first registration module 23 is configured to perform global registration of the first auxiliary SAR image to the main SAR image based on the obtained global GCP set, and obtain a second auxiliary SAR image after global registration;

所述第二双向匹配模块24，用于对主SAR图像的特征点和所述第二辅SAR图像的特征点进行局部双向匹配，获得局部GCP集合；The second bidirectional matching module 24 is configured to perform local bidirectional matching on the feature points of the main SAR image and the feature points of the second auxiliary SAR image to obtain a local GCP set;

所述第二配准模块25，用于基于所述获得的局部GCP集合执行第二辅SAR图像到主SAR图像的局部配准，得到第三辅SAR图像。The second registration module 25 is configured to perform local registration of the second auxiliary SAR image to the main SAR image based on the obtained local GCP set to obtain a third auxiliary SAR image.

在具体实施过程中，上述特征点提取模块21、第一双向匹配模块22、第一配准模块23、第二双向匹配模块24和第二配准模块25可以由雷达信号地面接收站中的信号处理器、PC机、服务器或任何可实现图像处理功能的设备内的中央处理器(CPU，Central Processing Unit)、微处理器(MPU，Micro ProcessingUnit)、数字信号处理器(DSP，Digital Signal Processor)或可编程逻辑阵列(FPGA，Field－Programmable Gate Array)来实现；In the specific implementation process, the above-mentioned feature point extraction module 21, the first two-way matching module 22, the first registration module 23, the second two-way matching module 24 and the second registration module 25 can be obtained from the signal in the radar signal ground receiving station Central processing unit (CPU, Central Processing Unit), microprocessor (MPU, Micro Processing Unit), digital signal processor (DSP, Digital Signal Processor) in processor, PC, server or any device that can realize image processing function Or programmable logic array (FPGA, Field-Programmable Gate Array) to achieve;

本领域内的技术人员应明白，本发明的实施例可提供为方法、系统、或计算机程序产品。因此，本发明可采用硬件实施例、软件实施例、或结合软件和硬件方面的实施例的形式。而且，本发明可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器和光学存储器等)上实施的计算机程序产品的形式。Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the present invention can take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) having computer-usable program code embodied therein.

本发明是参照根据本发明实施例的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

以上所述，仅为本发明的较佳实施例而已，并非用于限定本发明的保护范围。The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims

1. a synthetic aperture radar SAR image registration method, is characterized in that, described method comprises:

Feature point extraction is performed on the main SAR image and the first auxiliary SAR image respectively;

Global two-way matching is performed on the feature points of the main SAR image and the feature points of the first auxiliary SAR image to obtain the global ground control point GCP set;

Perform global registration of the first auxiliary SAR image to the main SAR image based on the obtained global GCP set, and obtain a second auxiliary SAR image after global registration;

performing local bidirectional matching on the feature points of the main SAR image and the feature points of the second auxiliary SAR image to obtain a local GCP set;

Perform local registration of the second auxiliary SAR image to the main SAR image based on the obtained local GCP set to obtain a third auxiliary SAR image.

2. The method according to claim 1, wherein said carrying out global two-way matching to the feature points of the main SAR image and the feature points of the first auxiliary SAR image comprises:

Determine the forward matching point set F _g of the main SAR image feature point set and the first auxiliary SAR image feature point set;

Determine the backward matching point set B _g of the main SAR image feature point set and the first auxiliary SAR image feature point set;

Take the intersection of the set F _g and the set B _g to obtain a bidirectional matching point set M _g of the main SAR image and the first auxiliary SAR image, and the M _g is the global GCP set.

3. The method according to claim 2, wherein the set of feature points of the main SAR image is S _s , and the set of feature points of the first auxiliary SAR image is S _m ;

Any feature point in the set is represented by the following formula:

{P P}_{k k} = = \{\begin{matrix} ((x x,, y the y)) \\ V V \end{matrix},,

Among them, (x, y) represents the position information of the feature point; V represents the normalized feature description vector of the feature point.

4. The method according to claim 3, wherein the forward matching point set F _g of the main SAR image feature point set S _m and the first auxiliary SAR image feature point set S _s is determined in the following manner:

{F f}_{g g} = = \{\begin{matrix} (({P P}_{s the s},, {P P}_{m m})) | | R R (({P P}_{m m},, {S S}_{s the s})) < < {R R}_{th the th} \\ {P P}_{s the s} = = \underset{{P P}_{s the s}}{arg arg} \underset{{P P}_{s the s}^{' '} &Element; &Element; {S S}_{s the s}}{min min} ((a a cos cos ((| | {| | {P P}_{s the s}^{' '} . . V V - - {P P}_{m m} . . V V | | | |}_{22})))),, {&ForAll; &ForAll; P P}_{m m} &Element; &Element; {S S}_{m m} \end{matrix}\},,

Wherein, the R(P _m , S _s ) is the ratio of the Euclidean distance between the main SAR image feature point P _m and the first auxiliary SAR image feature point set S _s ; the R _th is R(P _m ,S _s ) The preset threshold of ; P′ _s is any feature point in S _s .

5. The method according to claim 4, characterized in that, the R(P _m , S _s ) is determined in the following manner:

R R (({P P}_{m m},, {S S}_{s the s})) = = \frac{a a cos cos (({| | | | {P P}_{s the s}^{11} . . V V - - {P P}_{m m} . . V V | | | |}_{22}))}{a a cos cos (({| | | | {P P}_{s the s}^{22} . . V V - - {P P}_{m m,,} . . V V | | | |}_{22}))},,

in Indicates the point closest to P _m on the first auxiliary SAR image; Indicates the second closest point to P _m on the first auxiliary SAR image.

6. The method according to claim 3, wherein the backward matching point set _F of the main SAR image feature point set S _m and the first auxiliary SAR image feature point set S _s is determined in the following manner:

{B B}_{g g} = = \{\begin{matrix} (({P P}_{s the s},, {P P}_{m m})) | | R R (({P P}_{s the s},, {S S}_{m m})) < < {R R}_{th the th},, \\ {P P}_{m m} = = \underset{{P P}_{m m}}{arg arg} \underset{{P P}_{m m}^{' '} &Element; &Element; {S S}_{m m}}{min min} ((a a cos cos (({| | | | {P P}_{m m}^{' '} . . V V - - {P P}_{s the s} . . V V | | | |}_{22})))),, {&ForAll; &ForAll; P P}_{s the s} &Element; &Element; {S S}_{s the s} \end{matrix}\},,

Wherein, the R(P _s , S _m ) is the ratio of the Euclidean distance between the feature point P _s of the first auxiliary SAR image and the feature point set S _m of the main SAR image; the R _th is R(P _s , S _m ) preset threshold.

7. The method according to claim 6, wherein the R(P _s , S _m ) is determined by the following method:

R R (({P P}_{s the s},, {S S}_{m m})) = = \frac{a a cos cos (({| | | | {P P}_{m m}^{11} . . V V - - {P P}_{s the s} . . V V | | | |}_{22}))}{a a cos cos (({| | | | {P P}_{m m}^{22} . . V V - - {P P}_{s the s} . . V V | | | |}_{22}))},,

in, Indicates the point closest to P _s on the main SAR image; Indicates the second closest point to P _s on the main SAR image.

8. according to the method described in any one of claim 4 to 7, it is characterized in that, described two-way matching point set M _g is determined by the following manner:

M _g ＝{(P _s ,P _m )|(P _s ,P _m )∈F _g ∩(P _s ,P _m )∈B _g }＝{(P _s ,P _m )|P _s ∈M _s , P _m ∈ M _m }.

9. The method according to claim 8, wherein the global registration of the first auxiliary SAR image to the main SAR image is performed based on the obtained global GCP set, comprising:

Determine the transformation matrix A of the affine transformation according to M _m1 and M _s1 ; among them, M _m1 is the global GCP set belonging to the main SAR image in M _g , and M _s1 is the global GCP set belonging to the auxiliary SAR image in M _g ;

Affine transformation is performed on all the feature points of the auxiliary image according to the determined transformation matrix A to obtain the auxiliary image after global registration.

10. The method according to claim 9, wherein the transformation matrix A is determined in the following manner:

A A = = \underset{A A}{arg arg} min min \underset{{I I}_{s the s} &Element; &Element; {M m}_{s the s},, {I I}_{m m} &Element; &Element; {M m}_{m m}}{Σ Σ} | | | | {I I}_{m m} - - {AI AI}_{s the s} | | | |;;

According to the transformation matrix A, affine transformation is performed on all the feature points of the auxiliary image as follows:

I _m1 =A·I _s1

in,

I_{m 1} = [\begin{matrix} x_{m 1} \\ {the y}_{m 1} \end{matrix}],

A = [\begin{matrix} a_{0} & a_{1} & a_{2} \\ b_{0} & b_{1} & b_{2} \end{matrix}],

I_{the s 1} = [\begin{matrix} x_{the s 1} \\ {the y}_{the s 1} \\ 1 \end{matrix}];

Said I _m1 represents the GCP in M _m1 , and I _s1 represents the GCP in M _s1 .

11. The method according to claim 9 or 10, wherein the local bidirectional matching of the feature points of the main SAR image and the feature points of the second auxiliary SAR image comprises:

For each feature point in the main SAR image and the second auxiliary SAR image, within the range of radius D _th , perform the following processing:

Determine the forward matching point set F _l of the feature points of the main SAR image and the feature points of the second auxiliary SAR image;

For each feature point in the main SAR image and the second auxiliary SAR image, within the radius D _th range, determine the backward matching point set B _l of the main SAR image feature point and the second auxiliary SAR image feature point;

Take the intersection of the set F _l and the set B _l to obtain the two-way matching point set M _l of the feature points of the main SAR image and the feature points of the auxiliary SAR image.

12. The method according to claim 11, wherein the forward matching point set F _l of the main SAR image feature point and the second auxiliary SAR image feature point is determined in the following manner:

{F f}_{l l} = = \{\begin{matrix} (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) | | R R (({P P}_{m m},, {\overset{&OverBar; &OverBar;}{S S}}_{s the s})) < < {R R}_{th the th} \cap \cap D D. (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) < < {D D.}_{th the th},, \\ {\overset{&OverBar; &OverBar;}{P P}}_{s the s} = = \underset{{\overset{&OverBar; &OverBar;}{P P}}_{s the s}}{arg arg} \underset{{\overset{&OverBar; &OverBar;}{P P}}_{s the s}^{' '} &Element; &Element; {\overset{&OverBar; &OverBar;}{S S}}_{s the s}}{min min} ((a a cos cos (({| | | | {\overset{&OverBar; &OverBar;}{P P}}_{s the s}^{' '} - - {P P}_{m m} | | | |}_{22})))),, {&ForAll; &ForAll; P P}_{m m} &Element; &Element; {S S}_{m m} \end{matrix}\},,

Wherein, the set of feature points of the second auxiliary SAR image is said The feature points in are said The main SAR image feature point P _m and the second auxiliary SAR image feature point set The ratio of the Euclidean distance; the R _th is preset threshold.

13. The method of claim 12, wherein the Determined by:

R R (({P P}_{m m},, \overset{&OverBar; &OverBar;}{{S S}_{s the s}})) = = \frac{a a cos cos (({| | | | {\overset{&OverBar; &OverBar;}{P P}}_{s the s}^{11} . . V V - - {P P}_{m m} . . V V | | | |}_{22}))}{a a cos cos (({| | | | {\overset{&OverBar; &OverBar;}{P P}}_{s the s}^{22} . . V V - - {P P}_{m m} . . V V | | | |}_{22}))},,

in, Indicates the point closest to P _m on the second auxiliary SAR image; Indicates the second closest point to P _m on the second auxiliary SAR image.

14. The method according to claim 11, wherein the forward matching point set _B1 of the main SAR image feature point and the second auxiliary SAR image feature point is determined in the following manner:

{B B}_{l l} = = \{\begin{matrix} (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) | | R R (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {S S}_{m m})) < < {R R}_{th the th} \cap \cap D D. (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) < < {D D.}_{th the th},, \\ {P P}_{m m} = = \underset{{P P}_{m m}}{arg arg} \underset{{P P}_{m m}^{' '}}{min min} ((a a cos cos (({| | | | {P P}_{m m}^{' '} . . V V - - {P P}_{s the s} . . V V | | | |}_{22})))),, &ForAll; &ForAll; {\overset{&OverBar; &OverBar;}{P P}}_{s the s} &Element; &Element; {\overset{&OverBar; &OverBar;}{S S}}_{s the s} \end{matrix}\},,

Wherein, the set of feature points of the second auxiliary SAR image is said The feature points in are said is the feature point of the second auxiliary SAR image and the ratio of the Euclidean distance of the main SAR image feature point set S _m ; the R _th is preset threshold.

15. The method of claim 14, wherein the Determined by:

R R (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {S S}_{m m})) = = \frac{a a cos cos (({| | | | {P P}_{m m}^{11} . . V V - - {\overset{&OverBar; &OverBar;}{P P}}_{s the s} V V | | | |}_{22}))}{a a cos cos (({| | | | {P P}_{m m}^{22} . . V V - - {\overset{&OverBar; &OverBar;}{P P}}_{s the s} . . V V | | | |}_{22}))},,

in, Indicates that on the main SAR image with the closest point; Indicates that on the main SAR image with The next closest point.

16. according to the method described in any one of claim 12 to 15, it is characterized in that, described two-way matching point set _M1 is determined by following formula:

{M m}_{l l} = = {{(({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) | | (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) &Element; &Element; {F f}_{l l} \cap \cap (({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) &Element; &Element; {B B}_{l l}}} = = {{(({\overset{&OverBar; &OverBar;}{P P}}_{s the s},, {P P}_{m m})) | | {\overset{&OverBar; &OverBar;}{P P}}_{s the s} &Element; &Element; {\overset{&OverBar; &OverBar;}{L L}}_{s the s},, {P P}_{m m} &Element; &Element; {L L}_{m m}}} . .

17. The method according to claim 16, wherein the local registration of the second auxiliary SAR image to the main SAR image is performed based on the obtained local GCP set, comprising:

Determine the transformation matrix A of the affine transformation according to M _m2 and M _s2 ; wherein, M _m2 is the global GCP set belonging to the main SAR image in M _l , and M _s2 is the global GCP set belonging to the auxiliary SAR image in M _l ;

Perform an affine transformation on all feature points within a radius D _th of feature points in the second auxiliary SAR image according to the determined transformation matrix B.

18. The method according to claim 17, wherein the transformation matrix B is determined in the following manner:

B B = = \underset{B B}{arg arg} min min \underset{{I I}_{s the s 22} &Element; &Element; {M m}_{s the s 22},, {I I}_{m m 22} &Element; &Element; {M m}_{m m 22}}{Σ Σ} | | | | {I I}_{m m 22} - - {BI BI}_{s the s 22} | | | |;;

According to the transformation matrix B, the affine transformation is performed on all the feature points of the auxiliary image as follows:

I _m2 = B·I _s2

in,

I_{m 2} = [\begin{matrix} x_{m 2} \\ {the y}_{m 2} \end{matrix}],

B = [\begin{matrix} c_{0} & c_{1} & c_{2} \\ d_{0} & d_{1} & d_{2} \end{matrix}],

I_{the s} = [\begin{matrix} x_{the s} \\ {the y}_{the s} \\ 1 \end{matrix}];

Said I _m2 represents the GCP in M _m2 , and I _s2 represents the GCP in M _s2 .

19. A synthetic aperture radar SAR image registration device, characterized in that the device comprises: a feature point extraction module, a first two-way matching module, a first registration module, a second two-way matching module and a second registration module ;in,

The feature point extraction module is used to extract feature points from the main SAR image and the first auxiliary SAR image respectively;

The first two-way matching module is used to perform global two-way matching on the feature points of the main SAR image and the feature points of the first auxiliary SAR image to obtain the global ground control point GCP;

The first registration module is used to perform the global registration of the first auxiliary SAR image to the main SAR image based on the obtained global GCP, and obtain the second auxiliary SAR image after global registration;

The second bidirectional matching module is configured to perform local bidirectional matching on the feature points of the main SAR image and the feature points of the second auxiliary SAR image to obtain a local GCP set;

The second registration module is configured to perform local registration of the second auxiliary SAR image to the main SAR image based on the obtained local GCP set to obtain a third auxiliary SAR image.