CN105116456A - Combined imaging method of structure and polarized attribute of underground object - Google Patents

Abstract

The invention relates to the geophysical exploration field, and especially relates to a combined imaging method of a structure and a polarized attribute of an underground object. A measuring line is arranged over the object body. A complete polarized common-mid-point antenna assembly moves along a direction of the measuring line. Measuring points are arranged at interval of the same distance on the measuring line. At each measuring point, an object body scattering matrix including three polarized antenna assembly modes is measured and obtained. Decomposition coefficients alpha, beta and gamma which reflect some underground measured point are obtained by Pauli decomposition on the object body scattering matrix. After offset treatment, the offset decomposition coefficients A, B and C are obtained. Imaging is performed on the offset scattering matrix to obtain a profile reflecting the structure of the underground object body. At the same time, images in which the polarized attribute information of the object body is reflected through colors are obtained in the profile of the structure through an RGB imaging method on the offset decomposition coefficients A, B, and C. The offset is used in the electromagnetic wave detection of the underground object body, and is combined with the Pauli decomposition method. The images both reflecting the structure of the underground object body and the polarized attribute of the underground object body are obtained.

Description

A kind of to the structure of buried target and the joint imaging method of polarization properties

Technical field

The present invention relates to field of geophysical exploration, particularly relate to a kind of structure to buried target and polarization properties carries out joint imaging method.

Background technology

In field of geophysical exploration, the method of application electromagnetic wave detection underground medium is more and more extensive, launch electromagnetic pulse signal by transmitting terminal to underground, receiving end receives reflected signal, data is processed to the structure and attribute information that obtain about buried target body.Because underground medium is strong to electromagnetic receptivity, the equipment of single transmitting-receiving form cannot meet the needs of field of geophysical exploration, in the last few years, develop into equipment combination in different ways, not only can obtain co-polarization information and the cross polarization information of underground medium simultaneously, multiple stacking measurement can also be carried out to underground same position, improve signal to noise ratio (S/N ratio), obtain the data containing underground medium information as much as possible, make imaging more clear.But current measurement means only can reflect the structural information of objective body, and joint imaging cannot be carried out to the structure of buried target and polarization properties simultaneously.

Summary of the invention

Technical matters to be solved by this invention is to provide a kind of structure to buried target and polarization properties to carry out joint imaging method, obtains the image not only having reflected buried target body structure but also reflected buried target body polarization attribute.

The present invention realizes like this, a kind of to the structure of buried target and the joint imaging method of polarization properties, a survey line is arranged above objective body, complete polarization common midpoint antenna combination is moved along line direction, a measuring point is arranged every same distance at survey line, the objective body scattering matrix comprising three kinds of poliarizing antenna array modes is obtained in each measuring point measurement, objective body scattering matrix decomposes the decomposition coefficients alpha obtaining lower a certain measured point corresponsively through Pauli, β, γ, carry out migration processing again, obtain the coefficient of dissociation A after offseting, B, C, the sectional view reflecting buried target body structure is obtained to the scattering matrix imaging after skew, simultaneously, by the coefficient of dissociation A through migration processing, B, C, RGB formation method is used to obtain in section of structure, by the image of color reaction objective body polarization properties information.

Further, complete polarization common midpoint antenna combination comprises the vh poliarizing antenna combination that hh poliarizing antenna combination that the horizontal emission with common midpoint and level receive, the vv poliarizing antenna combination of Vertical Launch and vertical reception and Vertical Launch and level receive.

Further, objective body scattering matrix is expressed as:

Wherein, S represents the multiple time domain scattering matrix of Xin Kelai, t _hhin the combination of hh poliarizing antenna, the travel-time of electromagnetic wave between emitting antenna and receiving antenna, t _vvin the combination of vv poliarizing antenna, the travel-time of electromagnetic wave between emitting antenna and receiving antenna, t _vhin the combination of vh poliarizing antenna, the travel-time of electromagnetic wave between emitting antenna and receiving antenna;

D _hhbe in hh complete polarization common midpoint antenna combination, 1/2 of emitting antenna and receiving antenna linearly distance, is called half offset distance, d _vvand d _vhhalf offset distance of vv poliarizing antenna combination and half offset distance of vh poliarizing antenna combination respectively; X, y are the volume coordinate of measurement point; x _out, y _out, z refers to the volume coordinate of scattering point; v _rmsfor scattering point (x _out, y _out, root-mean-square velocity z).

Further,

Scattering matrix relational expression before and after skew is:

Wherein: [S _out(x _out, y _out, z)] and be the multiple scattering matrix of the Xin Kelai after skew

2 × 2 objective body scattering matrix S measuring acquisition are resolved into the linear superposition of three Pauli basis matrixs: [S]=α [S] _a+ β [S] _b+ γ [S] _c

[S] _a, [S] _b, [S] _cbe three Pauli bases:

Coefficient of dissociation in formula

The general power measuring scattering matrix is:

SPAN＝|S _hh| ²+|S _vv| ²+2|S _vh| ²＝|α| ²+|β| ²+|γ| ²

Scattering matrix relation formula before and after then offseting can be write as:

[S _out]＝A[S] _a+B[S] _b+C[S] _c

A, B, C are the α after skew, and beta, gamma, is expressed as:

In formula, r is the distance between measurement point and scattering point, and what θ described is the angle of electromagenetic wave radiation direction and Z axis;

Coefficient of dissociation A, B, C after skew, use RGB formation method, three kinds of Color Channels in RGB imaging are defined as respectively, | B| ²for red channel, | C| ²for green channel, | A| ²for blue channel, Color Channel joins in the sectional view of objective body structure.

The present invention compared with prior art, beneficial effect is: what the present invention utilized is have co-polarization antenna combination and cross polarised antenna combination, and feeding point is at same position, not only can obtain co-polarization information and the cross polarization information of buried target body simultaneously, multiple stacking measurement can also be carried out to underground same position, improve signal to noise ratio (S/N ratio), obtain the data containing underground medium information as much as possible, make imaging more clear.Adopt Pauli decomposition method to obtain the data of different antennae array mode, complete polarization common midpoint antenna combination can obtain the hh needed for Pauli decomposition method simultaneously, and the data of vh and vv tri-kinds of poliarizing antenna combinations, provide desired data body for Pauli decomposes.And skew is incorporated in electromagnetic wave in the detection of underground objective body, first time combines with Pauli decomposition method, in offset equation, first do polarization decomposing, then migration processing is done to coefficient of dissociation, obtain the image not only having reflected buried target body structure but also reflected buried target body polarization attribute.

Accompanying drawing explanation

Fig. 1 is the complete polarization common midpoint antenna combination schematic diagram that the present invention adopts;

In figure, complete polarization common midpoint antenna combination is made up of Vivaldi antenna element, and parallel plane with Electromagnetic Wave Propagation is h mode, and vertical is v mode.

In formula, (a) hh represents in complete polarization common midpoint antenna combination, the antenna combination mode that horizontal emission and level receive, and as 1 expression in Fig. 1 is the combination of hh poliarizing antenna, and the distance of distance center is d _hh;

B () vv represents in complete polarization common midpoint antenna combination, the antenna combination mode of Vertical Launch and vertical reception, and as 2 expressions in Fig. 1 are the combinations of vv poliarizing antenna, and the distance of distance center is d _vv;

C () vh represents in complete polarization common midpoint antenna combination, the antenna combination mode that Vertical Launch and level receive, and as 3 expressions in Fig. 1 are the combinations of vh poliarizing antenna, and the distance of distance center is d _vh;

Fig. 2 is the structure of buried target body of the present invention and the joint imaging figure of polarization properties;

Fig. 3 is the structure imaging figure of buried target body of the present invention.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

See Fig. 1, what adopt is complete polarization common midpoint antenna combination, and be connected with complete polarization common midpoint antenna combination by cable by vector network analyzer, three kinds of poliarizing antenna array modes are hh, vv and vh, because this system is polarimetric radar of singly standing, according to reciprocal theorem S _hv=S _vh, above objective body, arrange a survey line, antenna combination moved along line direction, arranges a measuring point at survey line every same distance, obtain in each measuring point measurement 2 × 2 objective body scattering matrixes comprising three kinds of poliarizing antenna array modes,

Objective body scattering matrix is expressed as:

Wherein, [S (x, y, t)] represents the multiple time domain scattering matrix of Xin Kelai, S _hh(x, y, t _hh) be the multiple time domain scattering matrix of Xin Kelai of hh poliarizing antenna multiple measurement, t _hhin the combination of hh poliarizing antenna, the travel-time of electromagnetic wave between emitting antenna and receiving antenna, S _vv(x, y, t _vv) be the multiple time domain scattering matrix of Xin Kelai of vv poliarizing antenna multiple measurement, t _vvin the combination of vv poliarizing antenna, the travel-time of electromagnetic wave between emitting antenna and receiving antenna, S _vh(x, y, t _vh) be the multiple time domain scattering matrix of Xin Kelai of vh poliarizing antenna multiple measurement, t _vhin the combination of vh poliarizing antenna, the travel-time of electromagnetic wave between emitting antenna and receiving antenna;

D _hhbe in hh complete polarization common midpoint antenna combination, 1/2 of emitting antenna and receiving antenna linearly distance, is called half offset distance, d _vvand d _vhhalf offset distance of vv poliarizing antenna combination and half offset distance of vh poliarizing antenna combination respectively; X, y are the volume coordinate of measurement point; x _out, y _out, z refers to the volume coordinate of scattering point; v _rmsfor scattering point (x _out, y _out, root-mean-square velocity z).

Scattering matrix relational expression before and after skew is:

Wherein: [S _out(x _out, y _out, z)] and be the multiple scattering matrix of the Xin Kelai after skew

2 × 2 objective body scattering matrix S measuring acquisition are resolved into the linear superposition of three Pauli basis matrixs: [S]=α [S] _a+ β [S] _b+ γ [S] _c

[S] _a, [S] _b, [S] _cbe three Pauli bases:

In formula, factor alpha, β and γ are plural numbers, and their value is provided by following formula, is respectively:

The general power that S measures scattering matrix is:

SPAN＝|S _hh| ²+|S _vv| ²+2|S _vh| ²＝|α| ²+|β| ²+|γ| ²

Scattering matrix relation formula before and after then offseting can be write as:

[S _out]＝A[S] _a+B[S] _b+C[S] _c

[S] _a, [S] _b, [S] _cthree Pauli bases are interpreted as respectively and the scattering process Coherent decomposition of target are become three kinds of scattering mechanisms: [S] _ait is the single scattering of flat surfaces; [S] _b[S] _ccorrespondence direction angle is the dihedral angle scattering of the corner reflector of 0 ° and 45 ° respectively.This is that the character of each Pauli matrix of answering according to polarization of electromagnetic wave base transfer pair draws.

A, B, C are the α after skew, and beta, gamma, is expressed as:

Wherein r is electromagnetic wave propagation distance; What θ described is the angle of electromagenetic wave radiation direction and z-axis.α, β and γ are the coefficient of dissociation of a certain measured point, underground, the coefficient of dissociation integration of different for survey line measured point is obtained coefficient of dissociation A, B, C after offseting, uses RGB formation method, defined by the waveform in figure by I: and three kinds of Color Channels in RGB imaging are defined as respectively, | B| ²for red channel, | C| ²for green channel, | A| ²for blue channel.

Then adopt RGB imaging to be very general method, repeat no more here.

By above-mentioned step, the final joint image obtaining reflect structure and polarization properties simultaneously, as shown in illustration 2, and common figure can only reflect the structure of buried target body, as Fig. 3.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (4)

1., to the structure of buried target and a joint imaging method for polarization properties, it is characterized in that:

A survey line is arranged above objective body, complete polarization common midpoint antenna combination is moved along line direction, a measuring point is arranged every same distance at survey line, the objective body scattering matrix comprising three kinds of poliarizing antenna array modes is obtained in each measuring point measurement, objective body scattering matrix decomposes the decomposition coefficients alpha obtaining lower a certain measured point corresponsively through Pauli, β, γ, carry out migration processing again, obtain the coefficient of dissociation A after offseting, B, C, the sectional view reflecting buried target body structure is obtained to the scattering matrix imaging after skew, simultaneously, by the coefficient of dissociation A through migration processing, B, C, RGB formation method is used to obtain in section of structure, by the image of color reaction objective body polarization properties information.

2. according to according to claim 1 to the structure of buried target and the joint imaging method of polarization properties, it is characterized in that: complete polarization common midpoint antenna combination comprises the vh poliarizing antenna combination that hh poliarizing antenna combination that the horizontal emission with identical central point and level receive, the vv poliarizing antenna combination of Vertical Launch and vertical reception and Vertical Launch and level receive.

3. according to described in claim 1 or 2 to the structure of buried target and the joint imaging method of polarization properties, it is characterized in that: objective body scattering matrix is expressed as:

$\[S(x,y,t)\]=\left[\begin{array}{cc}{S}_{hh}(x,y,t_{hh})& S_{vh}(x,y,t_{vh})\\ S_{vh}(x,y,t_{vh})& S_{vv}(x,y,t_{vv})\end{array}\right]$

Wherein, S represents the multiple time domain scattering matrix of Xin Kelai, t _hhin the combination of hh poliarizing antenna, the travel-time of electromagnetic wave between emitting antenna and receiving antenna, t _vvin the combination of vv poliarizing antenna, the travel-time of electromagnetic wave between emitting antenna and receiving antenna, t _vhin the combination of vh poliarizing antenna, the travel-time of electromagnetic wave between emitting antenna and receiving antenna;

$t_{hh}={\[\frac{z^2+(x+d_{hh}-x_{out})+(y-y_{out})}{v_{rms}^2}\]}^{1/2}+{\[\frac{z^2+(x-d_{hh}-x_{out})+(y-y_{out})}{v_{rms}^2}\]}^{1/2}$

$t_{vv}={\[\frac{z^2+(x+d_{vv}-x_{out})+(y-y_{out})}{v_{rms}^2}\]}^{1/2}+{\[\frac{z^2+(x-d_{vv}-x_{out})+(y-y_{out})}{v_{rms}^2}\]}^{1/2}$

$t_{vh}={\[\frac{z^2+(x+d_{vh}-x_{out})+(y-y_{out})}{v_{rms}^2}\]}^{1/2}+{\[\frac{z^2+(x-d_{vh}-x_{out})+(y-y_{out})}{v_{rms}^2}\]}^{1/2}$

D _hhbe in hh complete polarization common midpoint antenna combination, 1/2 of emitting antenna and receiving antenna linearly distance, is called half offset distance, d _vvand d _vhhalf offset distance of vv poliarizing antenna combination and half offset distance of vh poliarizing antenna combination respectively; X, y are the volume coordinate of measurement point; x _out, y _out, z is the volume coordinate of scattering point; v _rmsfor scattering point (x _out, y _out, root-mean-square velocity z).

4. according to according to claim 3 to the structure of buried target and the joint imaging method of polarization properties, it is characterized in that: resolve into the linear superposition of three Pauli basis matrixs by measuring 2 × 2 objective body scattering matrix S obtained: [S]=α [S] _a+ β [S] _b+ γ [S] _c

[S] _a, [S] _b, [S] _cbe three Pauli bases:

${\[S\]}_a=\frac{1}{\sqrt{2}}\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right],{\[S\]}_b=\frac{1}{\sqrt{2}}\left[\begin{array}{cc}1& 0\\ 0& -1\end{array}\right],{\[S\]}_c=\frac{1}{\sqrt{2}}\left[\begin{array}{cc}0& 1\\ 1& 0\end{array}\right];$

Coefficient of dissociation in formula $\mathrm{\α}=\frac{S_{hh}+S_{vv}}{\sqrt{2}},\mathrm{\β}=\frac{S_{hh}-S_{vv}}{\sqrt{2}},\mathrm{\γ}=\sqrt{2}{S}_{vh};$

The general power measuring scattering matrix is:

SPAN=|S _hh| ²+|S _vv| ²+2|S _vh| ²=|α| ²+|β| ²+|γ| ²

Scattering matrix relation before and after skew can be written as:

[S _out]=A[S] _a+B[S] _b+C[S] _c

Wherein: [S _out(x _out, y _out, z)] and be the multiple scattering matrix of the Xin Kelai after skew

$A=\frac{1}{2\mathrm{\π}}\∫\∫\frac{cos\mathrm{\θ}}{v_{rms}r}\frac{\∂}{\∂t}\mathrm{\α}dxdy$

$B=\frac{1}{2\mathrm{\π}}\∫\∫\frac{cos\mathrm{\θ}}{v_{rms}r}\frac{\∂}{\∂t}\mathrm{\β}dxdy$

$C=\frac{1}{2\mathrm{\π}}\∫\∫\frac{cos\mathrm{\θ}}{v_{rms}r}\frac{\∂}{\∂t}\mathrm{\γ}dxdy$

In formula, r is the distance between measurement point and scattering point, and what θ described is the angle of electromagenetic wave radiation direction and Z axis;

Coefficient of dissociation A, B, C after skew, use RGB formation method, three kinds of Color Channels in RGB imaging are defined as respectively, | B| ²for red channel, | C| ²for green channel, | A| ²for blue channel, Color Channel joins in the sectional view of objective body structure.