CN105116409A - Transmission line elevation extraction method based on circular synthetic aperture radar two-dimensional images - Google Patents

Abstract

The present invention relates to a transmission line elevation extraction method based on circular synthetic aperture radar two-dimensional images. The method comprises a step 1 of constructing an everywhere equal altitude ideal transmission line height model relating to the relation among an ideal transmission line height, the azimuth and the downwards angle of visibility of a single channel circular synthetic aperture radar and an imaging plane height; a step 2 of selecting one imaging plane higher or lower than an actual transmission line height, and carrying out the circular synthetic aperture radar two-dimensional imaging on the everywhere equal altitude actual transmission lines of which the height change is less than 10% of an actual transmission line average height; a step 3 of extracting the elevation initial values of the actual transmission lines from the circular synthetic aperture radar two-dimensional images according to the everywhere equal altitude ideal transmission line height model; a step 4 of obtaining a series of focused two-dimensional images of the actual transmission lines at different positions, and carrying out the curve fitting by taking the heights at the focused positions as samples to obtain the elevation of the whole transmission line.

Description

Based on the power transmission line elevation extraction method of circle mark synthetic-aperture radar two dimensional image

Technical field

The present invention relates to radar signal processing field, particularly relating to a kind of power transmission line elevation extraction method based on circle mark synthetic-aperture radar two dimensional image, for obtaining actual power transmission line elevation, and then obtaining the power transmission line two dimensional image focused on.

Background technology

Circle mark synthetic-aperture radar is the synthetic aperture imaging pattern that a kind of radar surrounding target carries out 360 degree of circular flights, not only has the two-dimentional ground range resolution of sub-wavelength level in theory, and has certain three-dimensional imaging ability.The unique advantage of circle mark synthetic-aperture radar makes it have great importance in the application such as high resolving power and three-dimensional imaging.

Under circle mark synthetic-aperture radar pattern, two dimensional image contains the three-dimensional information of target.When imaging level and point target height inconsistent time, point target will be defocused to annulus, and annular radii and radar downwards angle of visibility, object height are relevant.On this basis, the people such as Palm has derived the pixel-shift amount of target two dimensional image under two different orientations, radar bearing angle, relation between downwards angle of visibility and object height.The pixel-shift amount of the two dimensional image of Urban Architecture thing under different orientations is obtained by image registration mode, and further combined with radar bearing angle and downwards angle of visibility, be extracted the elevation (StephanPalm of buildings, HeleneM.Oriot, HubertM.Cantallouble, " RadargrammetricDEMExtractionOverUrbanAreaUsingCircularSA RImagery ", IEEETransactiononGeoscienceandRemoteSensing, 2012,50 (11): 4720-4725).But this kind of elevation extraction method is not suitable for linear target, reason is the registration being difficult to realize linear target two dimensional image.

Power transmission line has very important significance to people's life and socio-economic development.Due to the limited directional scattering properties of actual power transmission line, under conventional strip pattern, if flight path is unreasonable, then power transmission line likely cannot be detected; And under circle mark synthetic-aperture radar pattern, actual power transmission line can not only be detected, and can realize two-dimensional imaging.Further, if circle mark synthetic-aperture radar two dimensional image can be utilized to obtain the elevation of actual power transmission line, then will contribute to obtaining the power transmission line two dimensional image focused on, so obtain actual power transmission line distribution and towards etc. information.

Summary of the invention

The object of the invention is to provide a kind of power transmission line elevation extraction method based on circle mark synthetic-aperture radar two dimensional image, utilizes the elevation of actual power transmission line to carry out two-dimensional imaging, can obtain the actual power transmission line two dimensional image focused on.

For achieving the above object, the invention provides a kind of power transmission line elevation extraction method based on circle mark synthetic-aperture radar two dimensional image, the step of the method comprises:

Step S1: build position angle, downwards angle of visibility that contour desirable power transmission line height and single channel justify mark synthetic-aperture radar everywhere, and the desirable power transmission line height model of relation between imaging plane height;

Step S2: choose an imaging plane higher or lower than actual power transmission line height, to the actual power transmission line that non-contour but height change is everywhere less than actual power transmission line average height 10%, carries out justifying mark synthetic-aperture radar two-dimensional imaging;

Step S3: according to desirable power transmission line height model contour everywhere, extracts the elevation initial value of actual power transmission line from circle mark synthetic-aperture radar two dimensional image;

Step S4: obtain the two dimensional image that a series of actual power transmission line focuses at diverse location place, carry out curve fitting as sample using the height of the position focused on, obtain the elevation of the actual power transmission line of whole piece.

The invention has the beneficial effects as follows:

The position angle of contour desirable power transmission line height and single channel circle mark synthetic-aperture radar, downwards angle of visibility is built everywhere in the present invention, and the desirable power transmission line height model of relation between imaging plane height, under solving round mark synthetic-aperture radar pattern, linear target is difficult to the problem being realized elevation extraction by method for registering images;

The present invention, according to desirable power transmission line height model, extracts the elevation initial value of actual power transmission line, under solving round mark synthetic-aperture radar pattern, is difficult to the elevation problem obtaining actual power transmission line from single width two dimensional image from circle mark synthetic-aperture radar two dimensional image;

The two dimensional image that a series of actual power transmission line focuses at diverse location place is obtained in the present invention, carry out curve fitting using the elevation of the position focused on as sample, obtain the elevation of the actual power transmission line of whole piece, solve and be difficult to obtain the actual power transmission line elevation problem with ground elevation change;

In addition, utilize actual power transmission line elevation, the actual power transmission line two dimensional image of focusing can be obtained, so obtain actual power transmission line distribution and towards etc. information.

Accompanying drawing explanation

Fig. 1 is the process flow diagram based on the power transmission line elevation extraction method of circle mark synthetic-aperture radar two dimensional image in the present invention;

Fig. 2 is the two-dimensional imaging schematic diagram of a single point target on different focussing plane;

Fig. 3 is the two-dimensional imaging schematic diagram of contour desirable power transmission line everywhere under circle mark synthetic-aperture radar pattern;

Fig. 4 is the process flow diagram that the present invention extracts actual power transmission line elevation initial value;

Fig. 5 is the process flow diagram that the present invention obtains the actual power transmission line elevation of whole piece.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly understand, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in further detail.

Refer to the process flow diagram that Fig. 1 shows the power transmission line elevation extraction method that the present invention is based on round mark synthetic-aperture radar two dimensional image.The method specific implementation step is as follows:

Step S1: build position angle, downwards angle of visibility that contour desirable power transmission line height and single channel justify mark synthetic-aperture radar everywhere, and the desirable power transmission line height model of relation between imaging plane height.

Refer to Fig. 2 and the two-dimensional imaging schematic diagram of a single point target on different focussing plane is shown, under single channel circle mark synthetic-aperture radar pattern, two-dimensional imaging is carried out to the ideal point target P with a height, if select imaging plane height and object height inconsistent time, then there will be point target and be defocused to annulus phenomenon.If radar carries out circular flight centered by O ', the position angle of radar is φ, and downwards angle of visibility is θ, and measured target regional center is O, then the three-dimensional position P (x, y, z) of point target P is being highly z with it _planplane on pass between pixel coordinate position after two-dimensional imaging (x ', y ') be

$\left\{\begin{array}{c}{x}^{\′}\≈x+(z-z_{plan})tan\mathrm{\θ}cos\mathrm{\φ}\\ y^{\′}\≈y+(z-z_{plan})tan\mathrm{\θ}\sin \mathrm{\φ}\end{array}\right.---\left(1\right)$

Contour desirable power transmission line can be regarded as and be made up of the point target of numerous equal altitudes everywhere.In order to make the scattering properties of desirable power transmission line closer to truth, the high computational step of desirable power transmission line illustrates as follows:

Refer to the two-dimensional imaging schematic diagram that Fig. 3 illustrates contour desirable power transmission line everywhere under single channel circle mark synthetic-aperture radar pattern, under HH polarization mode, when select imaging plane height and desirable power transmission line height inconsistent time, each point on desirable power transmission line is not be defocused to annulus, but only approximately perpendicular on circle mark synthetic-aperture radar heading, namely two differ the position angle of 180 degree, and desirable power transmission line just has scattering properties, establishes imaging plane to be chosen as z according to described scattering properties _plan, height and the desirable power transmission line height z of imaging plane are unequal, and now, desirable power transmission line imaging results contour everywhere shows as two parallel straight lines.

If be φ in central party parallactic angle ₁first sub-aperture under, imaging results is Article 1 straight line a; Be φ in central party parallactic angle ₂second sub-aperture under, imaging results is Article 2 straight line b; On desirable power transmission line, the pixel coordinate of arbitrfary point (x, y, z) under first sub-aperture is (x ₁, y ₁), the pixel coordinate under second sub-aperture is (x ₂, y ₂), then the pass that can be obtained between the coordinate of desirable power transmission line under two sub-aperture and its pixel coordinate in two dimensional image by formula (1) is:

$\left\{\begin{array}{c}{x}_1\≈x+(z-z_{plan}){\mathrm{tan\θcos\φ}}_1\\ y_1\≈y+(z-z_{plan}){\mathrm{tan\θsin\φ}}_1\end{array}\right.---\left(2\right)$

With

$\left\{\begin{array}{c}{x}_2\≈x+(z-z_{plan}){\mathrm{tan\θcos\φ}}_2\\ y_2\≈y+(z-z_{plan}){\mathrm{tan\θsin\φ}}_2\end{array}\right.---\left(3\right)$

The slope supposing two straight lines is k, by (x ₁, y ₁) make vertical line to Article 2 straight line b, intersection point is (x ₀, y ₀), then (x ₀, y ₀) be the intersection point of Article 2 straight line b and vertical line, namely

$\left\{\begin{array}{c}y-y_2=k(x-x_2)\\ y-y_1=-\frac{1}{k}(x-x_1)\end{array}\right.---\left(4\right)$

Intersection point (the x of Article 2 straight line b and vertical line is obtained according to formula (2), (3), (4) ₀, y ₀) be expressed as follows:

$\left\{\begin{array}{c}{x}_0=\frac{1}{1+k^2}{x}_1+\frac{k^2}{1+k^2}{x}_2+\frac{k}{1+k^2}{y}_1-\frac{k}{1+k^2}{y}_2\\ y_0=\frac{k}{1+k^2}\left(x_1-x_2\right)+\frac{k^2}{1+k^2}{y}_1+\frac{1}{1+k^2}{y}_2\end{array}\right.---\left(5\right)$

In conjunction with formula (2), (3) and (5), Article 1 straight line a and the Article 2 straight line b that can obtain imaging results are parallel to each other, and the distance d between described two parallel lines is,

$\begin{array}{c}d=\sqrt{{(x_1-x_0)}^2+{(y_1-y_0)}^2}\\ =\frac{\left|z-z_{plan}\right|}{\sqrt{1+k^2}}|({\mathrm{sin\φ}}_2-{\mathrm{sin\φ}}_1)-k({\mathrm{cos\φ}}_2-{\mathrm{cos\φ}}_1)|tan\mathrm{\θ}\end{array}---\left(6\right)$

Can obtain desirable power transmission line object height z further by formula (6) is

$z=\±\frac{d\sqrt{1+k^2}}{|({\mathrm{sin\φ}}_2-{\mathrm{sin\φ}}_1)-k({\mathrm{cos\φ}}_2-{\mathrm{cos\φ}}_1)|tan\mathrm{\θ}}+z_{plan}---\left(7\right)$

If imaging plane height is higher than desirable power transmission line height z, then on the right of formula (7) equal sign, Section 1 gets negative sign, if the height z of described imaging plane _planlower than desirable power transmission line height z, then first get positive sign on the right of above formula equal sign.

Due under single channel circle mark synthetic-aperture radar pattern, non-contour but height change is little actual power transmission line two dimensional image can be approximately two straight lines defocused everywhere, therefore, the high computational formula of contour desirable power transmission line everywhere can be adopted, obtain the non-contour but initial value of the actual power transmission line elevation that height change is little everywhere.

Step S2: the actual power transmission line of actual power transmission line average height 10% is less than to non-contour but height change everywhere, chooses an imaging plane higher or lower than actual power transmission line height, carry out justifying mark synthetic-aperture radar two-dimensional imaging.

Step S3: according to desirable power transmission line height model contour everywhere, extracts the elevation initial value of actual power transmission line from circle mark synthetic-aperture radar two dimensional image.

Refer to Fig. 4 and illustrate that the idiographic flow extracting the elevation initial value of actual power transmission line from circle mark synthetic-aperture radar two dimensional image is divided into following four steps:

Step S31: under circle mark synthetic-aperture radar pattern, non-contour and that height change is little actual power transmission line two dimensional image is approximately two straight lines defocused everywhere, selects actual power transmission line from described two dimensional image;

Step S32: utilize Hough transform to detect the slope of two dimensional image cathetus, two differences picked out corresponding to same actual power transmission line defocus straight line;

Step S33: calculate the distance between two straight lines according to any point coordinate on straight slope and straight line;

Step S34: according to desirable power transmission line height model, calculates the initial value of actual power transmission line elevation.

Step S4: obtain the two dimensional image that a series of actual power transmission line focuses at diverse location place, carry out curve fitting as sample using the height of the position focused on, obtain the elevation of the actual power transmission line of whole piece.

Refer to Fig. 5 and illustrate that the idiographic flow of the elevation obtaining the actual power transmission line of whole piece is divided into following four steps:

Step S41: the elemental height value adopting actual power transmission line two-dimensional imaging result and actual power transmission line, determines variation range and the interval of imaging plane;

Step S42: change over picture level, obtain the two-dimensional image sequence that actual power transmission line focuses at diverse location place;

Step S43: pick out the pixel focused in every width image, and record imaging plane height corresponding to the pixel that focused on, namely actual power transmission line is at the height of this position;

Step S44: carry out curve fitting as sample using the height that the pixel focused on is corresponding, obtains the elevation of the actual power transmission line of whole piece.

The above; be only the embodiment in the present invention, but protection scope of the present invention is not limited thereto, any people being familiar with this technology is in the technical scope disclosed by the present invention; the conversion or replacement expected can be understood, all should be encompassed in of the present invention comprising within scope.

Claims (9)

1., based on a power transmission line elevation extraction method for circle mark synthetic-aperture radar two dimensional image, it is characterized in that, the step of the method comprises:

Step S1: build position angle, downwards angle of visibility that contour desirable power transmission line height and single channel justify mark synthetic-aperture radar everywhere, and the desirable power transmission line height model of relation between imaging plane height;

Step S2: choose an imaging plane higher or lower than actual power transmission line height, to the actual power transmission line that non-contour but height change is everywhere less than actual power transmission line average height 10%, carries out justifying mark synthetic-aperture radar two-dimensional imaging;

Step S3: according to desirable power transmission line height model contour everywhere, extracts the elevation initial value of actual power transmission line from circle mark synthetic-aperture radar two dimensional image;

Step S4: obtain the two dimensional image that a series of actual power transmission line focuses at diverse location place, carry out curve fitting as sample using the height of the position focused on, obtain the elevation of the actual power transmission line of whole piece.

2. according to claim 1 based on the power transmission line elevation extraction method of circle mark synthetic-aperture radar two dimensional image, it is characterized in that, adopt single channel circle mark synthetic-aperture radar two dimensional image to extract actual power transmission line elevation.

3., according to claim 1 based on the power transmission line elevation extraction method of circle mark synthetic-aperture radar two dimensional image, it is characterized in that, described desirable power transmission line height z model is as follows:

$z=\±\frac{d\sqrt{1+k^2}}{|({\mathrm{sin\φ}}_2-{\mathrm{sin\φ}}_1)-k({\mathrm{cos\φ}}_2-{\mathrm{cos\φ}}_1)|tan\mathrm{\θ}}+z_{plan}$

Wherein: d is the distance between Article 1 straight line and Article 2 straight line that in two-dimensional imaging result, slope is identical, k is the Article 1 straight line of imaging results or the slope of Article 2 straight line, φ ₁for the central party parallactic angle of first sub-aperture of circle mark synthetic-aperture radar, φ ₂for the central party parallactic angle of second sub-aperture of circle mark synthetic-aperture radar, θ is the downwards angle of visibility of circle mark synthetic-aperture radar, z _planfor the height of imaging plane.

4. according to claim 3 based on the power transmission line elevation extraction method of circle mark synthetic-aperture radar two dimensional image, it is characterized in that, if the height of described imaging plane is higher than desirable power transmission line height, then on the right of above formula equal sign, Section 1 gets negative sign, if the height of described imaging plane is lower than desirable power transmission line height, then on the right of above formula equal sign, Section 1 gets positive sign.

5. according to claim 3 based on the power transmission line elevation extraction method of circle mark synthetic-aperture radar two dimensional image, it is characterized in that, Article 1 straight line and the Article 2 straight line of described imaging results are parallel to each other, and the distance d between described two parallel lines is expressed as follows:

$\begin{array}{c}d=\sqrt{{(x_1-x_0)}^2+{(y_1-y_0)}^2}\\ =\frac{\left|z-z_{plan}\right|}{\sqrt{1+k^2}}|({\mathrm{sin\φ}}_2-{\mathrm{sin\φ}}_1)-k({\mathrm{cos\φ}}_2-{\mathrm{cos\φ}}_1)|\tan \mathrm{\θ}\end{array}$

Wherein: (x ₁, y ₁) be arbitrfary point (x, y, the z) pixel coordinate under first sub-aperture on desirable power transmission line, (x ₀, y ₀) for intersection point is the intersection point of Article 2 straight line and vertical line, described vertical line is the pixel coordinate (x under first sub-aperture ₀, y ₁) to Article 2 straight line do vertical line.

6., according to claim 5 based on the power transmission line elevation extraction method of circle mark synthetic-aperture radar two dimensional image, it is characterized in that, the intersection point (x of described Article 2 straight line and vertical line ₀, y ₀) be expressed as follows:

$\left\{\begin{array}{c}{x}_0=\frac{1}{1+k^2}{x}_1+\frac{k^2}{1+k^2}{x}_2+\frac{k}{1+k^2}{y}_1-\frac{k}{1+k^2}{y}_2\\ y_0=\frac{k}{1+k^2}(x_1-x_2)+\frac{k^2}{1+k^2}{y}_1+\frac{1}{1+k^2}{y}_2\end{array}\right.$

Wherein, (x ₂, y ₂) be the pixel coordinate of arbitrfary point on power transmission line under second sub-aperture.

7., according to claim 5 based on the power transmission line elevation extraction method of circle mark synthetic-aperture radar two dimensional image, it is characterized in that, the pixel coordinate (x under described first sub-aperture ₁, y ₁) and second sub-aperture under pixel coordinate (x ₂, y ₂) be calculated as follows:

Under HH polarization mode, when select imaging plane height and desirable power transmission line height inconsistent time, each point on desirable power transmission line is not be defocused to annulus, but only approximately perpendicular on circle mark synthetic-aperture radar heading, namely two differ the position angle of 180 degree, and desirable power transmission line just has scattering properties; Imaging plane is established to be chosen as z according to described scattering properties _plan, height and the desirable power transmission line height z of imaging plane are unequal, then contour everywhere desirable power transmission line imaging results shows as two parallel straight lines;

If be φ in central party parallactic angle ₁first sub-aperture under, imaging results is Article 1 straight line, is φ in central party parallactic angle ₂second sub-aperture under, imaging results is Article 2 straight line, and on desirable power transmission line, arbitrfary point (x, y, z) pixel coordinate under first sub-aperture is (x ₁, y ₁), the pixel coordinate under second sub-aperture is (x ₂, y ₂), then the pass under two sub-aperture between power transmission line pixel coordinate and actual coordinate is:

$\left\{\begin{array}{c}{x}_1\≈x+(z-z_{plan})tan\mathrm{\θ}cos{\mathrm{\φ}}_1\\ y_1\≈y+(z-z_{plan}){\mathrm{tan\θsin\φ}}_1\end{array}\right.$

With

$\left\{\begin{array}{c}{x}_2\≈x+(z-z_{plan}){\mathrm{tan\θcos\φ}}_2\\ y_2\≈y+(z-z_{plan}){\mathrm{tan\θsin\φ}}_2\end{array}\right..$

8. the power transmission line elevation extraction method of round mark synthetic-aperture radar two dimensional image according to claim 1, is characterized in that, it is as follows that the described elevation initial value extracting actual power transmission line from circle mark synthetic-aperture radar two dimensional image comprises step:

Step S31: under circle mark synthetic-aperture radar pattern, non-contour and that height change is little actual power transmission line two dimensional image is approximately two straight lines defocused everywhere, selects actual power transmission line from described two dimensional image;

Step S32: utilize Hough transform to detect the slope of two dimensional image cathetus, two differences picked out corresponding to same actual power transmission line defocus straight line;

Step S33: calculate the distance between two straight lines according to any point coordinate on straight slope and straight line;

Step S34: according to desirable power transmission line height model, calculates the initial value of actual power transmission line elevation.

9. the power transmission line elevation extraction method of round mark synthetic-aperture radar two dimensional image according to claim 1, is characterized in that, the step obtaining the elevation of the actual power transmission line of whole piece is as follows:

Step S41: the elemental height value adopting actual power transmission line two-dimensional imaging result and actual power transmission line, determines variation range and the interval of imaging plane;

Step S42: change over picture level, obtain the two-dimensional image sequence that actual power transmission line focuses at diverse location place;

Step S43: pick out the pixel focused in every width image, and record imaging plane height corresponding to the pixel that focused on, namely actual power transmission line is at the height of this position;

Step S44: carry out curve fitting as sample using the height that the pixel focused on is corresponding, obtains the elevation of the actual power transmission line of whole piece.