CN109754004B - Dual G4U target decomposition method for polarized SAR image - Google Patents

Abstract

A method of dual G4U target decomposition of a polarimetric SAR image, the method comprising: for the polarized SAR image to be decomposed, based on a balance equation abandoned by G4U, a dual G4U decomposition is obtained, effective supplement to the original G4U decomposition is obtained, and the polarized SAR image is subjected to target decomposition. The target decomposition method of the invention obtains a brand-new dual G4U decomposition by the balance equation abandoned by G4U, realizes effective supplement of the original G4U decomposition performance, and leads the identification and understanding of radar targets to be more accurate.

Description

Dual G4U target decomposition method for polarized SAR image

Technical Field

The invention relates to the field of polarized SAR image information processing, in particular to the field of polarized SAR target decomposition and model-based target decomposition, and specifically relates to a dual G4U target decomposition method of a polarized SAR image.

Background

Model-based polarization decomposition is directed to polarizing coherence matrix [ T ] of unknown objects]And (4) expanding the standard scattering models to realize the identification and classification of the standard scattering models. It represents a three-component model decomposition and Yamaguchi et al (Y.Yamaguchi, T.Moryama, M.Ishido, and andH.Yamada, "Four-component analysis model for polar SAR, IEEE Transactions on Geosy and Remote analysis, 43, No.8, 1699-16, pp.2005) and a Four-component decomposition model (abbreviated as Y4 decomposition 4O) proposed by Freeman-Durden (A.Freeman and S.L.Durden," A.three-component analysis model for polar SAR image analysis data, "IEEE Transactions on Geosy and Remote analysis, vol.Yamaguchi, T.Moroyama, M.Ishido, and Yamada," Four-component analysis model for polar SAR image analysis, IEEE Transactions on Geosy and Remote analysis, J.43, No.8, 1699-1, Aug.2005). Y4O is the objective coherence matrix [ T ]]The decomposition is carried out into the combination of surface scattering, two-surface scattering, volume scattering and spiral scattering, and the coherent matrix T is realized]Six degrees of freedom interpretation, but three degrees of freedom remain unused, corresponding to T respectively₁₃Component and T₂₃The real part of the component. To realize the pair T₂₃Real part of componentYamaguchi et al (Y. Yamaguchi, a. sato, w. -m. boerner, r. sato, and h. yamada, "Four-component profiling power consumption with rotation of coherence matrix," IEEE Transactions on Geoscience and remove Sensing, vol.49, No.6, pp.2251-2258, jun.2011) developed a Y4R decomposition on the basis of Y4O by introducing a rotating unitary transformation, using a disorientation operation to propagate T with T₂₃Zero setting of real component part realizes coherent matrix T]Interpretation of seven degrees of freedom. On the basis of Y4R, Sato et al (A.Sato, Y.Yamaguchi, G.Singh, and S.E.park, "Four-component characterization power consumption with extended volume characterization model," IEEE geoceicience and remove Sensing Letters, vol.9, No.2, pp.166-170, Mar.2012) further developed S4R decomposition, but like Y4R, T4R decomposition₁₃The component is still not effectively utilized in S4R. To achieve this, Singh et al (G.Singh, Y.Yamaguchi, and S.E.park, "General four-component characterization power consumption transformation of coherence matrix," IEEEtransformations on coherence and removal Sensing, vol.51, No.5, pp.3014-3022, May2013) proposed in 2013 a G4U decomposition by introducing another unitary transformation that achieved the splitting of T.sub.₁₃Partial interpretation of the components, representing the latest level of the four component decomposition.

The core of the model decomposition is to solve a decomposition equilibrium equation set, and conventional Y4O, Y4R, and S4R provide five equations for unknown parameters, but none of these equations involve a coherence matrix [ T]T of₁₃Component, therefore, pair T cannot be realized₁₃The effective use of (1). G4U forms one of five balance equations of Y4O, Y4R and S4R by a mathematical unitary transform: f. of_Sβ+f_Dα+f_Vd＝T′₁₂Is divided into f_Sβ+f_Dα+f_Vd＝T′₁₂+T′₁₃And f_Sβ+f_Dα+f_Vd＝T′₁₂-T′₁₃Two equations, successfully sum T₁₃The components are included at the right end of the equation, so that T₁₃The fractions are used for the first time in a four-component decomposition. However, since the two equations are derived from bisection of the same equation, they are not exactly betweenIndependent, resulting in the final set of equilibrium equations no longer having a unique exact solution. For this reason Singh et al only chose the equation f in G4U_Sβ+f_Dα+f_Vd＝T′₁₂+T′₁₃While abandoning the equation f_Sβ+f_Dα+f_vd＝T′₁₂-T′₁₃. This operation is only to get a set of valid solutions, not due to equation f_Sβ+f_Dα+f_Vd＝T′₁₂-T′₁₃There are drawbacks. This abandonment degrades the otherwise existing recognition of the diversity of the target scattering mechanisms into a fixed G4U decomposition, thereby potentially adversely affecting the accurate identification and understanding of radar targets.

Disclosure of Invention

The invention aims to overcome the technical defects, and a brand-new dual G4U decomposition is obtained based on the balance equation abandoned by G4U, so that the original G4U decomposition is effectively supplemented.

In order to achieve the above object, the present invention provides a dual G4U target decomposition method of a polarized SAR image, the method comprising: for the polarized SAR image to be decomposed, based on a balance equation abandoned by G4U, a dual G4U decomposition is obtained, effective supplement to the original G4U decomposition is obtained, and the polarized SAR image is subjected to target decomposition.

As an improvement of the above method, the method specifically comprises:

step 1) reading a coherent matrix [ T ] of a to-be-decomposed polarized SAR image, and performing de-orientation operation to obtain a de-oriented coherent matrix [ T' ];

step 2) removing orientation coherent matrix [ T 'based on the obtained step 1)']Calculating the helical scattering power P_CAnd branch condition parameter BC₀、BC₁And BC₂Based on BC₁And BC₂Determining the parameters a, b, c and d of the volume scattering model and calculating the volume scattering power P_VAccording to P_VSymbol pair P_C、BC₀、BC₁、BC₂A, b, c, d, etc. are updated to obtain P satisfying non-negative physical criteria_V；

Step 3) obtaining a coherent matrix [ T 'based on the step 1)']And step 2), further calculating decomposition parameters S and D according to the determined parameters a, b, c and D of the volume scattering model, executing a power conservation criterion according to the sign of S + D, and if the parameters are not positive, not calculating the surface scattering power P_SAnd the two-sided scattered power P_DDirect update of the bulk scattering power P_V(ii) a Otherwise, turning to the step 4);

step 4) based on the decomposition parameters S and D obtained in step 3), and if S + D is positive, based on the coherence matrix [ T 'obtained in step 1)']And step 2) further calculating a decomposition parameter C by the determined parameters a, b, C and D of the volume scattering model, and calculating the surface scattering power P by combining the decomposition parameters S and D_SAnd the two-sided scattered power P_DAccording to P_SAnd P_DSymbol pair P_SAnd P_DUpdating again to obtain P satisfying non-negative physical criterion_SAnd P_D。

As an improvement of the above method, in step 1), if the coherence matrix [ T ] of the polar SAR image to be decomposed is:

the desriented coherence matrix [ T' ] is:

wherein [ U ] is₃(θ)]Represent the SU (3) rotation matrix:

the orientation angle θ is estimated as follows:

as a further improvement of the above method, the step 2) further comprises:

step 2-1) calculationHelical scattered power P_C：

P_C＝2|Im{T′₂₃}|

Step 2-2) based on P_CCalculating branch condition parameters BC₀、BC₁And BC₂：

Step 2-3) based on BC₁And BC₂Determining the parameters a, b, c and d of the volume scattering model:

step 2-4) calculating the volume scattering power P_V：

Step 2-5) according to P_VSymbol pair P_C、BC₀、BC₁、BC₂A, b, c, d, etc. update: if P_V<0, then put

P_C＝0

And returning to the step 2-2), otherwise, turning to the step 3).

As a further improvement of the above method, the step 3) further comprises:

step 3-1) calculating decomposition parameters S and D:

step 3-2) executing a power conservation criterion according to the S + D symbol, and if the S + D symbol is less than or equal to 0, setting the power conservation criterion

P_S＝0,P_D＝0

Updating P_V

P_V＝SPAN-P_C

Wherein, SPAN is the total scattering power of the target:

SPAN＝T′₁₁+T′₂₂+T′₃₃。

as a further improvement of the above method, the step 4) further comprises:

step 4-1), if S + D is not less than 0, calculating a decomposition parameter C:

C＝T′₁₂-T′₁₃-P_Vd

step 4-2) calculating surface scattering power P_SAnd the two-sided scattered power P_D：

Step 4-3) according to P_SAnd P_DSymbol pair P_SAnd P_DAnd (3) carrying out non-negative updating:

the invention has the advantages that:

the target decomposition method of the invention obtains a brand-new dual G4U decomposition by the balance equation abandoned by G4U, realizes effective supplement of the original G4U decomposition performance, and leads the identification and understanding of radar targets to be more accurate.

Drawings

FIG. 1 is a general flow diagram of the dual G4U target decomposition method of the polarized SAR image of the present invention;

FIG. 2 is a detailed flow chart of the dual G4U target decomposition method of the polarized SAR image of the present invention;

FIG. 3 is a Pauli diagram of the coherence matrix [ T ] data of the polar SAR image to be decomposed employed in one embodiment of the present invention;

FIG. 4 shows the spiral scattering power P obtained by decomposing the polarized SAR image by the method of the present invention in the embodiment of the present invention_CLogarithmic display (i.e. log)₁₀P_C)；

FIG. 5 shows the volume scattering power P obtained by decomposing the polarized SAR image by the method of the present invention in the embodiment of the present invention_VLogarithm ofChemical display (i.e. log)₁₀P_V)；

FIG. 6 shows the surface scattering power P obtained by decomposing the polarized SAR image by the method of the present invention in the embodiment of the present invention_SLogarithmic display (i.e. log)₁₀P_S)；

FIG. 7 shows the dihedral scattering power P obtained by decomposing the polarized SAR image by the method of the present invention in the embodiment of the present invention_DLogarithmic display (i.e. log)₁₀P_D)；

Fig. 8 is a final result obtained after the polarized SAR image is decomposed by the method of the present invention in the embodiment of the present invention.

Detailed Description

The invention will now be further described with reference to the accompanying drawings.

The research work shows that the equation f_Sβ+f_Dα+f_Vd＝T′₁₂-T′₁₃It also provides a reasonable decomposition which is exactly a dual form with G4U and is therefore referred to as a dual G4U decomposition. The pair G4U can compensate the decomposition defect of G4U and provides a perfect complement to G4U.

That is, equation f_Sβ+f_Dα+f_Vd＝T′₁₂-T′₁₃Not only has no defects, but also can further provide a group of effective solutions which are exactly in a dual form with G4U, so that the solution is called dual G4U decomposition. The dual G4U can make up for the decomposition defect of G4U, and provides a perfect complement to G4U, so that the identification and understanding of radar targets are more accurate.

Referring to fig. 1 and 2, the dual G4U target decomposition method of the polarized SAR image of the present invention comprises the following steps:

step 1), reading in coherent matrix [ T ] data of a to-be-decomposed polarized SAR image, and performing de-orientation operation to obtain [ T' ];

step 2), obtaining a coherent matrix [ T 'based on the step 1)']Calculating the helical scattering power P_CAnd branch condition parameter BC₀、BC₁And BC₂Based on BC₁And BC₂Determining the parameters a, b, c and d of the volume scattering model and calculating the volumeScattered power P_VAccording to P_VSymbol pair P_C、BC₀、BC₁、BC₂A, b, c, d, etc. are updated to obtain P satisfying non-negative physical criteria_V；

Step 3), obtaining a coherent matrix [ T 'based on the step 1)']And step 2), further calculating decomposition parameters S and D according to the determined parameters a, b, c and D of the volume scattering model, executing a power conservation criterion according to the sign of S + D, and if the parameters are not positive, not calculating the surface scattering power P_SAnd the two-sided scattered power P_DDirect update of the bulk scattering power P_V；

Step 4), based on the decomposition parameters S and D obtained in step 3), and if S + D is positive, based on the coherence matrix [ T 'obtained in step 1)']And step 2) further calculating a decomposition parameter C by the determined parameters a, b, C and D of the volume scattering model, and calculating the surface scattering power P by combining the decomposition parameters S and D_SAnd the two-sided scattered power P_DAccording to P_SAnd P_DSymbol pair P_SAnd P_DUpdating again to obtain P satisfying non-negative physical criterion_SAnd P_D。

The steps in the method of the present invention are further described below.

Reading in coherent matrix [ T ] data of a to-be-decomposed polarized SAR image in step 1), and performing de-orientation operation to obtain [ T' ]; in one embodiment, a Pauli diagram of read-in polarized SAR image coherence matrix [ T ] data to be decomposed is shown in FIG. 3, and the image size is 920 x 456, and the region of san Francisco USA is acquired by Canadian C-band Radarsat-2 radar 2008, 4/9. If the read-in target coherence matrix [ T ] is

The desriented target coherence matrix [ T' ] is calculated as follows:

wherein [ U ] is₃(θ)]Indicating SU (3) moment of rotationArraying:

the orientation angle θ is estimated as follows:

based on the coherence matrix [ T' ] obtained in step 1), in step 2), the following is further performed:

step 2-1), calculating the spiral scattering power P_C：

P_C＝2|Im{T′₂₃}|

Step 2-2) based on P_CCalculating branch condition parameters BC₀、BC₁And BC₂：

Step 2-3) based on BC₁And BC₂Determining the parameters a, b, c and d of the volume scattering model:

step 2-4), calculating the scattering power P of the body_V：

Step 2-5) according to P_VSymbol pair P_C、BC₀、BC₁、BC₂A, b, c, d, etc. update: if P_V<0, then put

P_C＝0

Returning to the step 2-2), 2-3) and 2-4) to update the parameter BC₀、BC₁、BC₂A, b, c and d, otherwise, turning to the step 3);

FIG. 4 shows the method in implementationIn the example, on the polarized SAR data, the logarithmic form P obtained by the method of the invention_C(i.e. log)₁₀P_CHere, the logarithm operation is only to reduce the dynamic range, so that the decomposition result is conveniently displayed).

Based on the coherence matrix [ T' ] obtained in step 1) and the volume scattering model parameters a, b, c and d determined in step 2), in step 3), the following is further performed:

step 3-1), calculating decomposition parameters S and D:

step 3-2), executing a power conservation criterion according to the S + D symbol, and if the S + D symbol is less than or equal to 0, setting the power conservation criterion

P_S＝0,P_D＝0

Updating P_V

P_V＝SPAN-P_C

Wherein, SPAN is the total scattering power of the target:

SPAN＝T′₁₁+T′₂₂+T′₃₃

FIG. 5 shows the logarithmic form P obtained by the method of the present invention on the polarized SAR data in the example_VI.e. log₁₀P_V。

Based on the decomposition parameters S and D obtained in step 3), if S + D is positive, based on the coherence matrix [ T' ] obtained in step 1) and the volume scattering model parameters a, b, c and D determined in step 2), in step 4), we further perform the following:

step 4-1), if S + D is more than or equal to 0, calculating a decomposition parameter C:

C＝T′₁₂-T′₁₃-P_vd

step 4-2), calculating surface scattering power P_SAnd the two-sided scattered power P_D：

Step 4-3) according toP_SAnd P_DSymbol pair P_SAnd P_DAnd (3) carrying out non-negative updating:

FIGS. 6 and 7 show the logarithmic form P obtained by the method of the present invention on the polarized SAR data in the examples_SAnd P_DI.e. log₁₀P_SAnd log₁₀P_D. Fig. 8 is a diagram showing the final decomposition result obtained on the polarized SAR data in the embodiment of the method of the present invention.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (1)

1. A method of dual G4U target decomposition of a polarimetric SAR image, the method comprising: for the polarized SAR image to be decomposed, based on a balance equation abandoned by G4U, obtaining a dual G4U decomposition, obtaining effective supplement to the original G4U decomposition, and realizing target decomposition of the polarized SAR image;

the method specifically comprises the following steps:

step 1) reading a coherent matrix [ T ] of a to-be-decomposed polarized SAR image, and performing de-orientation operation to obtain a de-oriented coherent matrix [ T' ];

step 2) removing orientation coherent matrix [ T 'based on the obtained step 1)']Calculating the helical scattering power P_CAnd branch condition parameter BC₀、BC₁And BC₂Based on BC₁And BC₂Determining the parameters a, b, c and d of the volume scattering model and calculating the volume scattering power P_VAccording to P_VSymbol pair P_C、BC₀、BC₁、BC₂A, b, c, d, etc. are updated to obtain a signal that satisfies non-negative physical criteriaP_V；

Step 3) obtaining a coherent matrix [ T 'based on the step 1)']And step 2), further calculating decomposition parameters S and D according to the determined parameters a, b, c and D of the volume scattering model, executing a power conservation criterion according to the sign of S + D, and if the parameters are not positive, not calculating the surface scattering power P_SAnd the two-sided scattered power P_DDirect update of the bulk scattering power P_V(ii) a Otherwise, turning to the step 4);

step 4) based on the decomposition parameters S and D obtained in step 3), and if S + D is positive, based on the coherence matrix [ T 'obtained in step 1)']And step 2) further calculating a decomposition parameter C by the determined parameters a, b, C and D of the volume scattering model, and calculating the surface scattering power P by combining the decomposition parameters S and D_SAnd the two-sided scattered power P_DAccording to P_SAnd P_DSymbol pair P_SAnd P_DUpdating again to obtain P satisfying non-negative physical criterion_SAnd P_D；

The step 1) is specifically as follows:

if the coherent matrix [ T ] of the polarized SAR image to be decomposed is:

the desriented coherence matrix [ T' ] is:

wherein [ U ] is₃(θ)]Represent the SU (3) rotation matrix:

the orientation angle θ is estimated as follows:

the step 2) further comprises the following steps:

step 2-1) calculating the spiral scattering power P_C：

P_C＝2|Im{T′₂₃}|

Step 2-2) based on P_CCalculating branch condition parameters BC₀、BC₁And BC₂：

Step 2-3) based on BC₁And BC₂Determining the parameters a, b, c and d of the volume scattering model:

step 2-4) calculating the volume scattering power P_V：

Step 2-5) according to P_VSymbol pair P_C、BC₀、BC₁、BC₂A, b, c, d, etc. update: if P_V<0, then put

P_C＝0

Returning to the step 2-2), otherwise, turning to the step 3);

the step 3) further comprises the following steps:

step 3-1) calculating decomposition parameters S and D:

step 3-2) executing a power conservation criterion according to the S + D symbol, and if the S + D symbol is less than or equal to 0, setting the power conservation criterion

P_S＝0,P_D＝0

Updating P_V

P_V＝SPAN-P_C

Wherein, SPAN is the total scattering power of the target:

SPAN＝T′₁₁+T′₂₂+T′₃₃

the step 4) further comprises the following steps:

step 4-1), if S + D is not less than 0, calculating a decomposition parameter C:

C＝T′₁₂-T′₁₃-P_Vd

step 4-2) calculating surface scattering power P_SAnd the two-sided scattered power P_D：

Step 4-3) according to P_SAnd P_DSymbol pair P_SAnd P_DAnd (3) carrying out non-negative updating:

Images