CN1693851A - Aviation linear array CCD image geometric rough correct algorithm - Google Patents

Abstract

A kind of aviation linear array CCD image geometric rough correct algorithm, comprising steps of 1. obtain original aerial linear CCD image and GPS/INS integrated navigation data; 2. extracting air strips image data position corresponding with row and attitude data; 3. obtaining photogrammetric spin matrix according to by the navigation angle (Φ, Θ, Ψ) of GPS/INS system

(Φ, Θ, Ψ)

Spin matrix of the calculating image space coordinate system to object space coordinate system; 4. carrying out geometry according to the collinearity equation of the central projection of multicenter linear CCD sensor image slightly to correct, scattered points coordinate is obtained; 5. gray value resampling, the image after slightly being corrected. The present invention solves the technical problem for the data of GPS/INS combined system measurement being directly used in aviation linear array CCD image geometric rough correct.

Description

A kind of aviation linear array CCD image geometric rough correct algorithm

Technical field

The present invention relates to a kind of how much rough correct algorithms of aviation linear array CCD image, particularly a kind of based on GPS/INS (Global Positioning System, GPS, Inertial Navigation System, inertial navigation system) aviation linear array CCD image geometric rough correct algorithm of integrated navigation technology.

Background technology

Current, line array CCD is widely used in photogrammetric and remote sensing, for example, is used for the ADS40 that LH Systems is arranged, AirMISR, DPA etc. on the conventional airplane, is installed in the TLS on the helicopter, is installed in the SPOT that has on the satellite, IKONOS etc.The line array CCD sensor adopts the pull-broom type scanning imagery usually, and its each imaging delegation is different from each imaging one width of cloth of face battle array or picture formula.For airborne remote sensing, the attitude of aircraft changes more violent, sidewinder generally and between 3 °～25 °, change, the course also can only remain in 5 ° when flying nonstop to, and in this case, serious geometry deformation and distortion can take place the image of line array CCD sensor acquisition, cause image to be difficult to carry out subsequent treatment and use, therefore, all need traditionally to use ground control point to carry out aftertreatment, intractability is bigger.

At present because the development of GPS and INS is with ripe, directly with the GPS/INS combined system be provided as the time the method for elements of exterior orientation begin application.The GPS/INS integrated positioning system is novel posture position measuring system, and GPS is a kind of pure geometry location system, and error is accumulation in time not, and still, its dynamic reliability is poor, and noise is big, influenced often by external factor, and the data output rating is also lower.INS is a kind of pure inertial navigation system, and its error accumulates in time.The GPS/INS combined system can be maximized favourable factors and minimized unfavourable ones: the gps data that absolute precision is high, measure input as the outside, and the frequent INS that revises accumulates in time to control its error in motion process; And high-precision INS positioning result in the short time, can fine signal losing lock and the cycle slip problem that solves in the GPS dynamic environment.Moreover, INS can also strengthen its antijamming capability by the assistant GPS receiver, improves the ability of catching with tracking satellite signal.

It's a pity at present, therefore, particular study is also seldom arranged always based on thick correction of geometry of the aviation linear array CCD image of GPS/INS integrated navigation technology because the development of corresponding GPS/INS technology lags behind.

Summary of the invention

The purpose of this invention is to provide a kind of aviation linear array CCD image geometric rough correct algorithm, solve the technical difficulty that the GPS/INS integrated navigation system is applied to photogrammetric measurement and remote sensing based on GPS/INS integrated navigation technology.

Technical thought of the present invention is as follows:

The measured value of GPS/INS combined system generally all comprise carrier three-dimensional position (X, Y, Z) and three the navigation angle (Ф, Θ, Ψ), three-dimensional position (X, Y Z) generally is coordinate in the WGS84 coordinate system, three rotation angle that carrier coordinate system and local horizontal coordinates are then generally got in the navigation angle.

Carrier coordinate system is defined as: initial point is in carrier center, right hand rectangular coordinate system.

Local horizontal coordinates: initial point is at the measured zone point, and X-axis is pointed to east along the WGS84 ellipsoid, and Y-axis is along WGS84 ellipsoid energized north, right hand rectangular coordinate system.

The pull-broom type imaging is generally adopted in the imaging of line array CCD sensor, and every sweep trace all has a projection centre, and the while, every sweep trace all had the elements of exterior orientation of oneself.

For polycentric line array CCD sensor image, the precondition that realize geometric approximate correction is the elements of exterior orientation that can access every sweep trace.By photogrammetric ultimate principle,, following collinearity equation is arranged for the central projection image:

$\mathrm{XA}=\mathrm{XS}+(\mathrm{ZA}-\mathrm{ZS})\frac{a_{1}x+a_{2}y-a_{3}f}{c_{1}x+c_{2}y-c_{3}f}$

$\mathrm{YA}=\mathrm{YS}+(\mathrm{ZA}-\mathrm{ZS})\frac{b_{1}x+b_{2}y-b_{3}f}{c_{1}x+c_{2}y-c_{3}f}---\left(1\right)$

(XS, YS ZS) are the coordinate of projection centre in the terrestrial photogrammetry coordinate system, (and x, y ,-f) be the image space coordinate of picture point, for line array CCD, x=0, (XA, YA ZA) are the topocentric coordinate of picture point correspondence.

Image space coordinate system is defined as: initial point is in the projection centre of optical system, and X-axis is pointed to heading, and Y-axis is pointed to the left side, on Z is axial, constitutes right hand rectangular coordinate system.The selection of terrestrial photogrammetry coordinate system is relevant with the drawing coordinate system that the user selects.

Image space coordinate system is A to the rotation matrix of terrestrial photogrammetry coordinate system, is defined as follows:

$A=\left[\begin{array}{ccc}{a}_1& a_2& a_3\\ b_1& b_2& b_3\\ c_1& c_2& c_3\end{array}\right]$

Therefore, the key of geometric approximate correction is exactly to obtain rotation matrix A.In photogrammetric, pixel (x _p, y _pTopocentric coordinates (the X of ,-f) and its correspondence _p, Y _p, Z _p) following relation arranged:

${\left[\begin{array}{c}{X}_p\\ Y_p\\ Z_p\end{array}\right]}^m={\left[\begin{array}{c}{X}_c\\ Y_c\\ Z_c\end{array}\right]}^m+\mathrm{kA}{\left[\begin{array}{c}{x}_p\\ y_p\\ -f_p\end{array}\right]}^i---\left(3\right)$

(X _c, Y _c, Z _c) be the optical centre coordinate in the terrestrial photogrammetry coordinate system, k is the scale factor of a dependence.

By the parameter that the GPS/INS combined system provides, can obtain the rotation relationship of carrier coordinate system, and local horizontal coordinate is tied to the rotation of WGS84 coordinate system to local horizontal coordinates.Therefore, can obtain following relation,

${\left[\begin{array}{c}{X}_p\\ Y_p\\ Z_p\end{array}\right]}^m={\left[\begin{array}{c}{X}_c\\ Y_c\\ Z_c\end{array}\right]}^m+k{C}_E^m{C}_g^E{C}_b^g(\mathrm{\Φ},\mathrm{\Θ},\mathrm{\Ψ})C_c^b{C}_i^c{\left[\begin{array}{c}{x}_p\\ y_p\\ -f_p\end{array}\right]}^i---\left(4\right)$

Wherein, C _i ^cIt is the rotation matrix that image space coordinate system transforms to the line array CCD sensor coordinate system;

C _c ^bIt is the rotation matrix that the line array CCD sensor coordinates is tied to carrier coordinate system;

C _b ^gBe the rotation matrix that carrier coordinate system transforms to local horizontal coordinates, (Ф, Θ Ψ) provide at the navigation angle of being write down by the posture position measuring system;

C _g ^EIt is the rotation matrix that local horizontal coordinate is tied to the WGS84 coordinate system;

C _E ^mBe that the WGS84 coordinate is tied to terrestrial photogrammetry coordinate system transformation matrix.

Relatively (3) (4) two formulas have

$A=C_E^m{C}_g^E{C}_b^g(\mathrm{\Φ},\mathrm{\Θ},\mathrm{\Ψ})C_c^b{C}_i^c---\left(5\right)$

Here it is obtains the formula of photogrammetric rotation matrix by the navigation angle of GPS/INS system.

Concrete performing step is as follows:

1) obtains original aviation linear array CCD image and GPS/INS integrated navigation data;

2) extract air strips image data position and the attitude data corresponding with row;

3) utilize formula (5) to calculate the rotation matrix of image space coordinate system to object space coordinate system;

4) carry out the thick correction of geometry by collinearity equation (1), obtain point coordinate at random;

5) gray-scale value resamples, the image after slightly being corrected.

The invention has the advantages that: solved the technical barrier that the data that the GPS/INS combined system is measured are directly used in aviation linear array CCD image geometric rough correct.

Description of drawings

Fig. 1 is the pull-broom type scanning imagery schematic diagram that known line array CCD sensor is adopted.

Fig. 2 is that geometry of the present invention is slightly corrected program flow diagram.

Fig. 3 does not use how much original aviation linear array CCD images of rough correct algorithm of the present invention.

Fig. 4 be Fig. 3 image use correction behind how much rough correct algorithms of the present invention image.

Embodiment

Provide a better embodiment of the present invention below in conjunction with figure Fig. 1～Fig. 4.

The GPS/INS combined system adopts the POS/AV 510 of Canadian Applanix company, and the data definition of its output is as follows:

Data	Unit	Type
			Time	Second	Double precision
Latitude	Radian	Double precision
			Longitude	Radian	Double precision
Highly	Rice	Double precision
			X is to speed	Meter per second	Double precision
Y is to speed	Meter per second	Double precision
			Z is to speed	Meter per second	Double precision
The angle of roll	Radian	Double precision
			The angle of pitch	Radian	Double precision
The platform course angle	Radian	Double precision
			The position angle of vacillating	Radian	Double precision

Illustrate:

1, the POS coordinate system is defined as: X-axis is pointed to the course; Y-axis is pointed to the aircraft right side; Z axially down.The POS data of output are based on user-defined reference frame;

2, the time is GPS week second form;

3, longitude and latitude and highly be the WGS84 coordinate of reference frame initial point;

4, speed definition is in the azimuthal coordinates system of vacillating, and is transformed in the east northeast ground coordinate system (NED) to be:

V _N＝V _Xcosα-V _Ysinα

V _E＝-V _Xsinα-V _Ycosα

V _D＝-V _Z

α is the position angle of vacillating.

5, course angle _WDefinition converts course angle by north at the azimuthal coordinates system of vacillating _TNeed deduct the position angle of vacillating: _T= _W-α

The angle of pitch, the angle of roll, crab angle are the rotation angle of reference frame with respect to east northeast ground coordinate system, implication is as follows: east northeast ground coordinate system is around its Z axle (vertically downward) course angle by north that turns clockwise, again around its Y-axis (referring to east) angle of pitch that turns clockwise, again around its X-axis (referring to north) angle of roll that turns clockwise, the change in coordinate axis direction that obtains just and reference frame identical;

The line array CCD image is provided by Shanghai Inst. of Technical Physics, Chinese Academy of Sciences, CCD pixel size is 12 μ m * 12 μ m, and equivalent focal length is 20mm, is 1.2mrad along heading instantaneous field of view, vertical flight direction instantaneous field of view is 0.6mrad, and the flight flying height is 1000 meters.

How much thick correction procedures are as shown in Figure 2:

S101, obtain original aviation linear array CCD image and POS/AV510 data from Fig. 3;

S102, extraction need the air strips data and the corresponding position and attitude data of processing, and the image data of extraction is seen Fig. 3;

S103, utilize formula (5) $A=C_E^m{C}_g^E{C}_b^g(\mathrm{\Φ},\mathrm{\Θ},\mathrm{\Ψ})C_c^b{C}_i^c$ Calculate the rotation matrix of image space coordinate system to object space coordinate system;

Calculating each used matrix is:

$C_b^g=\left[\begin{array}{ccc}\cos \mathrm{\Θ}\cos \mathrm{\Ψ}& \sin \mathrm{\Φ}\sin \mathrm{\Θ}\cos \mathrm{\Ψ}-\cos \mathrm{\Φ}\sin \mathrm{\Ψ}& \cos \mathrm{\Φ}\sin \mathrm{\Θ}\cos \mathrm{\Ψ}+\sin \mathrm{\Φ}\sin \mathrm{\Ψ}\\ \cos \mathrm{\Θ}\sin \mathrm{\Ψ}& \sin \mathrm{\Φ}\sin \mathrm{\Θ}\sin \mathrm{\Ψ}+\cos \mathrm{\Φ}\cos \mathrm{\Ψ}& \cos \mathrm{\Φ}\sin \mathrm{\Θ}\sin \mathrm{\Ψ}-\sin \mathrm{\Φ}\cos \mathrm{\Ψ}\\ -\sin \mathrm{\Θ}& \sin \mathrm{\Φ}\cos \mathrm{\Θ}& \cos \mathrm{\Φ}\cos \mathrm{\Θ}\end{array}\right]$

$C_g^E=\left[\begin{array}{ccc}-\sin b\cos l& -\sin l& -\cos b\cos l\\ -\sin b\sin l& \cos l& -\cos b\sin l\\ \cos b& 0& -\sin b\end{array}\right]$

$C_i^c=\left[\begin{array}{ccc}1& 0& 0\\ 0& -1& 0\\ 0& 0& -1\end{array}\right]$

$C_c^b\left[\begin{array}{ccc}\cos {\mathrm{\Θ}}_y\cos {\mathrm{\Θ}}_z& \cos {\mathrm{\Θ}}_y\sin {\mathrm{\Θ}}_z& -\sin {\mathrm{\Θ}}_y\\ \sin {\mathrm{\Θ}}_x\sin {\mathrm{\Θ}}_y\cos {\mathrm{\Θ}}_z-\cos {\mathrm{\Θ}}_x\sin {\mathrm{\Θ}}_z& \sin {\mathrm{\Θ}}_x\sin {\mathrm{\Θ}}_y\sin {\mathrm{\Θ}}_z+\cos {\mathrm{\Θ}}_x\cos {\mathrm{\Θ}}_z& \sin {\mathrm{\Θ}}_x\cos {\mathrm{\Θ}}_y\\ \sin {\mathrm{\Θ}}_x\sin {\mathrm{\Θ}}_y\cos {\mathrm{\Θ}}_z+\sin {\mathrm{\Θ}}_x\sin {\mathrm{\Θ}}_z& \cos {\mathrm{\Θ}}_x\sin {\mathrm{\Θ}}_y\sin {\mathrm{\Θ}}_z-\sin {\mathrm{\Θ}}_x\cos {\mathrm{\Θ}}_z& \cos {\mathrm{\Θ}}_x\cos {\mathrm{\Θ}}_y\end{array}\right]$

(Ф, Θ Ψ) are the navigation angle that POS/AV 510 provides, and (l b) is the latitude and longitude coordinates of the carrier that provides of POS/AV 510, (Θ _x, Θ _y, Θ _z) be the imaging sensor established angle.

S104, by collinearity equation (1) $\mathrm{XA}=\mathrm{XS}+(\mathrm{ZA}-\mathrm{ZS})\frac{a_{1}x+a_{2}y-a_{3}f}{c_{1}x+c_{2}y-c_{3}f}$

$\mathrm{YA}=\mathrm{YS}+(\mathrm{ZA}-\mathrm{ZS})\frac{b_{1}x+b_{2}y-b_{3}f}{c_{1}x+c_{2}y-c_{3}f}$

Carry out the thick correction of geometry, obtain point coordinate at random;

S105, gray-scale value resample, and the image after slightly being corrected is seen Fig. 4.

Comparison diagram 3 and 4, visible how much thick back effects of correcting are better, and the visuality of image strengthens greatly.

Claims (1)

1, a kind of aviation linear array CCD image geometric rough correct algorithm based on GPS/INS integrated navigation technology, its step comprises:

1) obtains original aviation linear array CCD image and GPS/INS integrated navigation data;

2) extract air strips image data position and the attitude data corresponding with row;

3) (Φ, Θ Ψ) obtain photogrammetric rotation matrix according to the navigation angle by the GPS/INS system $A=C_E^m{C}_g^E{C}_b^g(\mathrm{\Φ},\mathrm{\Θ},\mathrm{\Ψ})C_c^b{C}_i^c$ Calculate the rotation matrix of image space coordinate system to object space coordinate system;

4) carry out according to the collinearity equation of the central projection of multicenter line array CCD sensor image that geometry is thick to be corrected, obtain point coordinate at random, the collinearity equation formula is:

$\mathrm{XA}=\mathrm{XS}+(\mathrm{ZA}-\mathrm{ZS})\frac{a_{1}x+a_{2}y-a_{3}f}{c_{1}x+c_{2}y-c_{3}f}$

$\mathrm{YA}=\mathrm{YS}+(\mathrm{ZA}-\mathrm{ZS})\frac{b_{1}x+b_{2}y-b_{3}f}{c_{1}x+c_{2}y-c_{3}f}$

Wherein (XS, YS ZS) are the coordinate of projection centre in the terrestrial photogrammetry coordinate system, (and x, y ,-f) be the image space coordinate of picture point, for line array CCD, x=0, (XA, YA ZA) are the topocentric coordinates of picture point correspondence;

5) gray-scale value resamples, the image after slightly being corrected.

Images