CN104835115A - Imaging method for aerial camera, and system thereof - Google Patents

Abstract

The invention discloses an imaging method for an aerial camera, and a system thereof. The imaging method comprises the steps of performing distortion correction on the image which is photographed by the aerial camera for obtaining a sequence image after correction; determining splicing sequence on a corrected sequence image according to the photographing sequence or the photographing time of the image, utilizing a homography matrix between adjacent images for obtaining a synthetic image; detecting the pixel coordinate of a stationary object and/or moving object from an image which is photographed by the aerial camera, and performing distortion correction for obtaining a plurality of target pixel coordinates; performing data fusion on each target pixel coordinate, positioning data which are output from a GPS positioning system, and aircraft attitude data which are output of a flight attitude measuring system, thereby obtaining the geographical coordinate of each target; and superposing the geographical coordinate of each target with the synthetic image for obtaining an electronic map which is geographically positioned by multiple targets.

Description

For image imaging method and the system of aerial camera

Technical field

The present invention relates to machine vision and image processing field, especially, relate to a kind of image imaging method and system of area array CCD aerial camera.

Background technology

Resolution and field angle are the key technical index of aerial camera, owing to there is the relation of restriction mutually between visual field and resolution, by the restriction of material technology level, monolithic matrix CCD is difficult to the requirement simultaneously meeting aerial reconnaissance task high resolving power and Large visual angle, for meeting aerial reconnaissance task Large visual angle, high resolving power, the requirement of high real-time, aerial camera many employings monolithic matrix CCD scanning imagery mode, by ccd sensor and special physical construction, not in the same time, with different angles photographic imagery over the ground, then by image mosaic technology will obtain the wide visual field with the aerial image sequent synthesis one width equivalence of certain overlapping region, high-definition picture.

Due to the design of aviation optical imaging system itself, processing, the reasons such as dress unison ring control can make image produce certain distortion, original image is directly spliced, may occur that overlapping region pixel misplaces the problem causing some target not spliced completely, distort simultaneously and also have a strong impact on target location accuracy, when the high-altitude of about 500m, the positioning error produced because of lens distortion is 0 ~ 15m, near the edge of image, distort more serious, the positioning error caused is larger, the quality improving target location accuracy and guarantee stitching image must be corrected to pattern distortion.

Because area array CCD aerial camera image has the features such as film size is little, quantity is many, resolution is high, pitch angle is large, rotation angle is large, dimensional variation is large, overlap is irregular, background is complicated, there is length consuming time in existing aerial camera image sequence alignment joining method, automatization level is low, the problems such as splicing cumulative errors is large, and general aerial image splicing system does not relate to target localization problem, the stitching image obtained does not have target geographic coordinate information, thus limits its range of application.

And existing general aerial camera adopts One-Point Location method, point to target by attitude measurement/laser ranging location model to picture centre crosshair to position, multiple target enforcement location is then needed frequently to change the sensing of camera optical axis and carries out multiple bearing, elapsed time is long, be difficult to implement to locate in real time or quasi real time to multiple target simultaneously, modern battlefield situation cannot be adapted to changeable in real time, the situation that destination number is many; Existing multi-target orientation method is mainly based on multiple sensor platform, as CN201310384965.0 discloses a kind of method improving polyphaser resultant image photogrammetric accuracy, it adopts optics intersection measurement localization method to realize Multi-target position, and hardware device is complicated, and real-time is poor.

Summary of the invention

The invention provides a kind of image imaging method for aerial camera and system, the hardware device that existing aerial camera causes based on the multi-target orientation method of multisensor platform be complicated to solve, the technical matters of real-time and poor reliability.

The technical solution used in the present invention is as follows:

According to an aspect of the present invention, provide a kind of image imaging method for aerial camera, aerial camera adopts monolithic matrix CCD scanning imagery, and image imaging method comprises:

Distortion correction is carried out to the image of aerial camera shooting, obtains the sequence image after correcting;

To correct after sequence image according to image shooting order or shooting time determine splice order, obtain composograph in conjunction with the homography matrix between adjacent image;

From the image of aerial camera shooting, detect pixel coordinate that is static and/or moving target, line distortion of going forward side by side corrects and obtains multiple object pixel coordinate;

The aspect data that the locator data each object pixel coordinate and GPS positioning system exported, aviation attitude measurement system export carry out data fusion, obtain the geographic coordinate of each target;

The geographic coordinate of each target is superposed with composograph, obtains the electronic chart of multiple goal geo-location.

Further, the geographic coordinate employing obtaining each target, based on the multiple goal autonomic positioning method of pixel sight line vector, comprising:

According to the image-forming principle of monolithic matrix CCD, construct the sight line vector of each target in conjunction with each object pixel coordinate;

The pixel angle of sight of itself and picture centre major heading is calculated according to the sight line vector of each target;

The distance between major heading and aircraft is obtained according to the range finder using laser measurement of camera internal, obtain position angle and the angular altitude of the relative aircraft platform of camera optical axis according to the angular encoder measurement of camera internal, calculate angle and the distance relation of each target and aircraft platform in conjunction with the pixel angle of sight between each target and major heading;

In conjunction with the aircraft position data of GPS positioning system output, the aspect data of aviation attitude measurement system output, calculated the geographic coordinate of multiple target in single image by homogeneous coordinate transformation method.

Further, to correct after sequence image according to image shooting order or shooting time determine splice order, the step obtaining composograph in conjunction with the homography matrix between adjacent image comprises:

Adopt FAST Corner Detection Algorithm to the sequence image extract minutiae after correction, adopt BRISK operator as unique point descriptor, the similarity utilizing Hamming distance to calculate unique point between adjacent image is mated, and obtains the homography matrix between adjacent image;

According to image shooting order or shooting time determine splice order, according to splicing order and adjacent image between homography matrix carry out splicing the composograph obtaining a fabric width visual field.

Further, from the image of aerial camera shooting, detect that pixel coordinate that is static and/or moving target adopts image segmentation, frame difference method or optical flow method; Wherein,

Image is divided into target area and background area according to gray threshold or marginal information by image segmentation, calculates the pixel coordinate of centre coordinate as target of target area;

Frame difference method can detect the moving target of pixel characteristic change fast by the pixel value difference of consecutive frame image;

Similar motion vector, by the sports ground of the changing features estimated image of sequential frame image respective pixel, is merged into moving target by optical flow method.

According to a further aspect in the invention, provide a kind of image imaging system for aerial camera, aerial camera adopts monolithic matrix CCD scanning imagery, and image imaging system comprises:

Image distortion correction unit, carries out distortion correction for the image taken aerial camera, obtains the sequence image after correcting;

Image mosaic unit, for correct after sequence image according to image shooting order or shooting time determine splice order, obtain composograph in conjunction with the homography matrix between adjacent image;

Object detection unit, detects pixel coordinate that is static and/or moving target in the image taken from aerial camera, and line distortion of going forward side by side corrects and obtains multiple object pixel coordinate;

Target localization unit, carries out data fusion for the aspect data locator data of each object pixel coordinate and the output of GPS positioning system, aviation attitude measurement system exported, obtains the geographic coordinate of each target;

Image generation unit, for being superposed with composograph by the geographic coordinate of each target, obtains the electronic chart of multiple goal geo-location.

Further, target localization unit comprises:

Sight line vector builds module, for the image-forming principle according to monolithic matrix CCD, constructs the sight line vector of each target in conjunction with each object pixel coordinate;

Pixel angle of sight computing module, for calculating the pixel angle of sight of itself and picture centre major heading according to the sight line vector of each target;

Orientation computing module, for obtaining the distance between major heading and aircraft according to the range finder using laser measurement of camera internal, obtain position angle and the angular altitude of the relative aircraft platform of camera optical axis according to the angular encoder measurement of camera internal, calculate angle and the distance relation of each target and aircraft platform in conjunction with the pixel angle of sight between each target and major heading;

Geographic coordinate computing module, for export in conjunction with GPS positioning system aircraft position data, aviation attitude measurement system export aspect data, calculated the geographic coordinate of multiple target in single image by homogeneous coordinate transformation method.

Further, image mosaic unit comprises:

Image registration module, for adopting FAST Corner Detection Algorithm to the sequence image extract minutiae after correction, adopt BRISK operator as unique point descriptor, the similarity utilizing Hamming distance to calculate unique point between adjacent image is mated, and obtains the homography matrix between adjacent image;

Image co-registration module, for according to image shooting order or shooting time determine splice order, according to splicing order and adjacent image between homography matrix carry out splicing the composograph obtaining a fabric width visual field.

The present invention has following beneficial effect:

The present invention is used for image imaging method and the system of aerial camera, on the one hand, the image taken by aerial camera carries out distortion correction, obtain the sequence image after correcting, and to correct after sequence image shooting order or shooting time determine splice order, obtain composograph in conjunction with the homography matrix between adjacent image, on the other hand, by detecting the multiple targets in each image, line distortion of going forward side by side corrects and obtains multiple object pixel coordinate, by the locator data that each object pixel coordinate and GPS positioning system export, the aspect data that aviation attitude measurement system exports carry out data fusion, obtain the geographic coordinate of each target, it adopts pipeline system to be corrected by camera distortion, image mosaic and Multi-target position combine, for user provides a width to have multiple goal geographic coordinate information, higher geometric accuracy and the high resolving power electronic chart compared with wide viewing angle, no matter all there is significant application value in military domain or at civil area, and adopt pipeline system to decrease data processing time, improve counting yield, one side array ccd sensor can be utilized to carry out geo-location to multiple target simultaneously, improve reconnaissance efficiency and real-time, thus it is changeable in real time to adapt to modern battlefield situation, the situation that destination number is many.

Except object described above, feature and advantage, the present invention also has other object, feature and advantage.Below with reference to figure, the present invention is further detailed explanation.

Accompanying drawing explanation

The accompanying drawing forming a application's part is used to provide a further understanding of the present invention, and schematic description and description of the present invention, for explaining the present invention, does not form inappropriate limitation of the present invention.In the accompanying drawings:

Fig. 1 is the schematic flow sheet of the preferred embodiment of the present invention for the image imaging method of aerial camera;

Fig. 2 is the structural representation of the preferred embodiment of the present invention for the image imaging system of aerial camera;

Fig. 3 is one side array ccd sensor Multi-target position schematic diagram;

Fig. 4 is certain aerial camera sweeping imaging joint sequence chart;

Fig. 5 is FAST Corner Detection Algorithm schematic diagram;

Fig. 6 is BRISK sampling pattern schematic diagram.

Description of reference numerals:

100: image distortion correction unit;

200: image mosaic unit;

210: image registration module;

220: image co-registration module;

300: object detection unit;

400: target localization unit;

500: image generation unit;

G: camera projection centre;

F _c: camera coordinates system;

F _b: carrier aircraft coordinate system;

F _v: carrier aircraft geographic coordinate system;

U, v: two coordinate axis of image pixel coordinates system, the row of u axle marking image, the row of v axle marking image;

X, y: two coordinate axis of image physical coordinates system, x-axis is parallel with u axle, and y-axis is parallel with v axle;

J: put K picture point on the image plane under machine;

F: major heading P picture point on the image plane;

T: secondary target Q ideal image point on the image plane;

T ＇: secondary target Q actual image point on the image plane;

K: point under machine;

P: major heading;

Q: secondary target;

H: the relative height on camera and ground;

λ ₁: the distance between camera and major heading;

λ ₂: the distance between camera and secondary target.

Embodiment

Below in conjunction with accompanying drawing, embodiments of the invention are described in detail, but the multitude of different ways that the present invention can be defined by the claims and cover is implemented.

With reference to Fig. 1, the preferred embodiments of the present invention provide a kind of image imaging method for aerial camera, and aerial camera adopts monolithic matrix CCD scanning imagery, and the present embodiment image imaging method comprises:

Step S101, carries out distortion correction to the image of aerial camera shooting, obtains the sequence image after correcting;

In the present embodiment, obtained the aberration rate of camera lens by optical device measurement, according to this aberration rate, the image non-linear distortion that camera lens produces is corrected, obtain the aerial sequential images after correcting.Obtained the aberration rate of camera lens in ground survey by optical device, aberration rate is defined as follows:

$D=\frac{\mathrm{\η}-\mathrm{\ζ}}{\mathrm{\ζ}}\×100\%---\left(1\right)$

In formula, D is lens distortion rate, and η is actual imaging height, and ζ is ideal image height.

According to the aberration rate of optical lens, ideal image position ζ can be released as follows:

$\mathrm{\ζ}=\frac{\mathrm{\η}}{1+D}---\left(2\right)$

Step S102, to correct after sequence image according to image shooting order or shooting time determine splice order, obtain composograph in conjunction with the homography matrix between adjacent image;

In the present embodiment, step S102 specifically comprises:

Adopt FAST Corner Detection Algorithm to the sequence image extract minutiae after correction, adopt BRISK operator as unique point descriptor, the similarity utilizing Hamming distance to calculate unique point between adjacent image is mated, and obtains the homography matrix between adjacent image;

According to image shooting order or shooting time determine splice order, according to splicing order and adjacent image between homography matrix carry out splicing the composograph obtaining a fabric width visual field.

Wherein, adopt FAST Corner Detection Algorithm to sequence image zooming-out unique point after correction, feature point detection in such algorithm is mainly based on FAST criterion: as shown in Figure 5, for a certain pixel p, if its discrete 16 of surrounding on circle have at least the brightness value of n continuous image vegetarian refreshments to be greater than the brightness value I of p in selecting _padd a threshold value t, or be less than the brightness value I of p _pdeduct a threshold value t, then judge that p is as angle point, wherein 9≤n≤12.

Adopt BRISK operator as unique point descriptor, BRISK operator is after carrying out Gaussian smoothing filter to original image, by obeying the N of concentric circles sampling pattern to pixel brightness value near comparative feature point position, obtain string of binary characters as unique point descriptor, as shown in Figure 6 (N=60).BRISK operator has unchangeability to translation, rotation, dimensional variation, has stronger robustness to noise, visual angle change.

Utilize Hamming distance to calculate the similarity of unique point between adjacent image to mate, obtain the homography matrix between adjacent image, wherein the calculating of Hamming distance can add a digit counter by XOR (XOR) by turn and realizes.

The present embodiment carries out feature point detection owing to adopting FAST algorithm, detection speed is much larger than existing Harris, DOG feature point detection algorithm, and high duplication is kept to translation, rotation, convergent-divergent change, adopt BRISK operator as unique point descriptor, Euclidean distance is replaced to assess the similarity of unique point by Hamming distance, computing velocity is about than the SURF of classics, fast two orders of magnitude of SIFT algorithm, keep, to the robustness of noise, yardstick, rotation change, being applicable to the aerial image Processing tasks that requirement of real-time is high simultaneously.

In the present embodiment, according to image shooting order or shooting time determine splice order, for certain aerial camera sweeping imaging mode, its image mosaic order is as shown in Figure 4.

Step S103, detects pixel coordinate that is static and/or moving target from the image of aerial camera shooting, and line distortion of going forward side by side corrects and obtains multiple object pixel coordinate;

In the present embodiment, from the image of aerial camera shooting, detect that pixel coordinate that is static and/or moving target adopts image segmentation, frame difference method or optical flow method; Wherein,

Image is divided into target area and background area according to gray threshold or marginal information by image segmentation, calculates the pixel coordinate of centre coordinate as target of target area;

Frame difference method can detect the moving target of pixel characteristic change fast by the pixel value difference of consecutive frame image; It realizes simple, can requirement of real time;

Similar motion vector, by the sports ground of the changing features estimated image of sequential frame image respective pixel, is merged into moving target by optical flow method.

Step S104, the aspect data that the locator data each object pixel coordinate and GPS positioning system exported, aviation attitude measurement system (IMU) export carry out data fusion, obtain the geographic coordinate of each target;

In the present embodiment, adopt a kind of multiple goal autonomic positioning method based on pixel sight line vector, the method is mainly for the aerial camera in middle-size and small-size UAV flight, one side array ccd sensor is adopted to implement low-to-medium altitude reconnaissance flight, flying height lower (being generally less than 3000m), field angle is 30 ~ 40 °, single image ground coverage is 1 ~ 2km, in most cases do not have too large fluctuating, can think near flat, in single image, each target is identical with the relative height between aircraft, Multi-target position model is set up according to the image-forming principle of one side array ccd sensor, pixel sight line vector method is adopted to calculate distance between each target and photoelectric platform and angular relationship, the terrestrial coordinate of each target in single image is obtained by homogeneous coordinate transformation, realize single image in real time multiobject or quasi real time locate, comprise the following steps:

Step a, according to the image-forming principle of one side array ccd sensor, each object pixel coordinate that combining target detection module provides constructs the sight line vector of each target, here the target being positioned at viewing field of camera center is called major heading, the target being positioned at other position, visual field is called time target, and this object localization method can realize the geo-location of optional position target in viewing field of camera, if major heading P, secondary target Q, the sight line vector putting K under machine is respectively as shown in Figure 3.

The coordinate system situation that the present embodiment relates to is described as follows:

Camera coordinates system (F _c): initial point is camera projection centre G, x _caxle, y _caxle is respectively with image pixel coordinates system u axle (row of marking image, unit is pixel), v axle (row of marking image) is parallel and direction is consistent; The initial point of image physical coordinates system is positioned at intersection point and the principle point location of camera optical axis and the plane of delineation, x-axis, y-axis respectively with u axle, v axle is parallel and direction is consistent, this coordinate system is in units of m or mm.

Carrier aircraft coordinate system (F _b): initial point is boat appearance measuring system barycenter, and general boat appearance measuring system is installed on the level reference of camera platform, and boat appearance measuring system barycenter and camera projection centre, apart from very little, can be similar to and think that both overlap, x _baxle is 0 ° of direction of boat appearance measuring system, y _baxle is 90 ° of directions of boat appearance measuring system, z _baxle is determined by right-hand screw rule, distance lambda between the camera that the position angle Θ that camera internal angular encoder exports and angular altitude Ψ and range finder using laser export and field of view center target ₁it is this coordinate system relative.

Carrier aircraft geographic coordinate system (F _v): initial point is positioned at boat appearance measuring system barycenter, is NED (North East Down) coordinate system, the carrier aircraft course angle β that boat appearance measuring system exports, and angle of pitch ε and roll angle γ are this coordinate systems relative.

WGS-84 the earth's core rectangular coordinate system in space (F _e): initial point is earth centroid, z _eaxle points to agreement earth polar (CTP) direction of BIH1984.0 definition, x _eaxle points to the zero degree meridian ellipse of BIH1984.0 and the intersection point in CTP equator, y _eaxle and z _e, x _eaxle forms right-handed coordinate system.

WGS-84 earth coordinates (F _g): true origin is pointed to identical with rectangular coordinate system in space with three axles, adopts geodetic longitude (L), geodetic latitude (M) and geodetic height (H) to describe locus, the carrier aircraft position (L that GPS exports ₀, M ₀, H ₀) be coordinate system relative to the earth.

Step b, calculates the pixel angle of sight of itself and picture centre major heading, if α is according to the sight line vector of each target with between the pixel angle of sight, for with between the pixel angle of sight, can obtain;

$\cos \mathrm{\α}=\frac{\stackrel{\→}{s}\·\stackrel{\→}{j}}{\left|\right|\stackrel{\→}{s}\left|\right|\left|\right|\stackrel{\→}{j}\left|\right|},$

Sight line vector in formula coordinate in camera coordinates system is $\stackrel{\→}{s}={F_c}^T{\left[\begin{array}{ccc}0& 0& f\end{array}\right]}^T,\stackrel{\→}{t}={F_c}^T{\left[\begin{array}{ccc}u-u_0& v-v_0& f\end{array}\right]}^T,$ Wherein f is camera focus, and unit is pixel, (u ₀, v ₀) for putting the pixel coordinate of F, the picture point F that after distortion correction, major heading P is corresponding on image is positioned at picture centre; (u, v) is the pixel coordinate of a T.

Sight line vector along the z of carrier aircraft geographic coordinate system _vunder axis, its coordinate in carrier aircraft geographic coordinate system is

$\stackrel{\→}{j}=F_v^T{j}_v=F_v^T{\left[\begin{array}{ccc}0& 0& j_{v_z}\end{array}\right]}^T.---\left(4\right)$

Solve coordinate under shooting coordinate system is as follows

${\stackrel{\→}{j}}_c=R_{\mathrm{cv}}{j}_v=R_{\mathrm{cb}}{R}_{\mathrm{bv}}{j}_v=\left[\begin{array}{ccc}{c}_{\mathrm{\Θ}}{c}_{\mathrm{\ψ}}& c_{\mathrm{\ψ}}{s}_{\mathrm{\Θ}}& -s_{\mathrm{\ψ}}\\ -s_{\mathrm{\Θ}}& c_{\mathrm{\Θ}}& 0\\ c_{\mathrm{\Θ}}{s}_{\mathrm{\ψ}}& s_{\mathrm{\Θ}}{s}_{\mathrm{\ψ}}& c_{\mathrm{\ψ}}\end{array}\right]\left[\begin{array}{ccc}{c}_{\mathrm{\ϵ}}{c}_{\mathrm{\β}}& c_{\mathrm{\ϵ}}{s}_{\mathrm{\β}}& -s_{\mathrm{\ϵ}}\\ c_{\mathrm{\β}}{s}_{\mathrm{\γ}}{s}_{\mathrm{\ϵ}}-c_{\mathrm{\γ}}{s}_{\mathrm{\β}}& c_{\mathrm{\γ}}{c}_{\mathrm{\β}}+s_{\mathrm{\γ}}{s}_{\mathrm{\ϵ}}{s}_{\mathrm{\β}}& c_{\mathrm{\ϵ}}{s}_{\mathrm{\γ}}\\ s_{\mathrm{\γ}}{s}_{\mathrm{\β}}+c_{\mathrm{\γ}}{c}_{\mathrm{\β}}{s}_{\mathrm{\ϵ}}& c_{\mathrm{\γ}}{s}_{\mathrm{\ϵ}}{s}_{\mathrm{\β}}-c_{\mathrm{\β}}{s}_{\mathrm{\γ}}& c_{\mathrm{\γ}}{c}_{\mathrm{\ϵ}}\end{array}\right]j_v,---\left(5\right)$

C=cos (*), s=sin (*) in formula.

R in formula _bvrepresent the rotation matrix being tied to carrier aircraft coordinate system from carrier aircraft geographic coordinate, R _cbrepresent the rotation matrix being tied to camera coordinates system from carrier aircraft coordinate, R _cvrepresent the rotation matrix being tied to camera coordinates system from carrier aircraft geographic coordinate.

If σ is carrier aircraft geographic coordinate system z _vaxle and camera coordinates system z _cangle between axle, obtains according to the geometric relationship in Fig. 3

$f=j_{v_z}\cos \mathrm{\σ},---\left(6\right)$

$\cos \frac{1}{2}\mathrm{\σ}=\±\frac{1}{2}{(1+\mathrm{tr}{R}_{\mathrm{cv}})}^{\frac{1}{2}},---\left(7\right)$

Simultaneous formula (6), (7)

$j_{v_z}=\frac{f}{\cos \mathrm{\σ}}=\frac{f}{2{\left(\cos \frac{1}{2}\mathrm{\σ}\right)}^2-1}=\frac{2f}{\mathrm{tr}{R}_{\mathrm{cv}}-1}.---\left(8\right)$

Will value substitute in formula (4) and (5), obtain coordinate in camera coordinates system then will substitution formula calculates cos α in (3),

Step c, the range finder using laser measurement according to camera internal obtains distance lambda between major heading and camera ₁, obtain position angle Θ and the angular altitude Ψ of the relative aircraft platform of camera optical axis according to the angular encoder measurement of camera internal, calculate angle and the distance relation of each target and aircraft platform in conjunction with the pixel angle of sight between each target and major heading;

After corrective lens distortion, the picture point of secondary target Q on image moves to ideal position T by distorted position T ＇, projection centre G, and secondary target Q and picture point T 3 corresponding on image thereof point-blank, meet pin-hole imaging model, be calculated as follows the relative height of each target and photoelectric platform:

h＝λ ₁cosα，

In formula, h is relative height, λ ₁for the distance between camera and major heading P, λ ₂for the distance between camera and secondary target Q,

According to known major heading distance value λ ₁, convolution (9) calculates relative height h and time target range value λ ₂.According to secondary target range value λ ₂and the sight line vector in camera coordinates system can calculate time coordinate of target in camera coordinates system is

${\left[\begin{array}{ccc}{x}_c& y_c& z_c\end{array}\right]}^T={\mathrm{\λ}}_2\frac{\stackrel{\→}{t}}{\left|\right|\stackrel{\→}{t}\left|\right|}.---\left(10\right)$

Steps d, in conjunction with aircraft position data (the longitude L that GPS positioning system exports ₀, latitude M ₀with geodetic height H ₀), the aspect data (course angle β, angle of pitch ε and roll angle γ) that export of aviation attitude measurement system (IMU), calculated the terrestrial coordinate of each target in single image by homogeneous coordinate transformation method.

By x _c, y _c, z _cvalue substitute into formula (11) and calculate the coordinate of target in the rectangular coordinate system in space of the earth's core and be

$\begin{array}{c}\begin{array}{}\end{array}\left[\begin{array}{c}{x}_e\\ y_e\\ z_e\\ 1\end{array}\right]=\left[\begin{array}{cccc}-c_{L_0}{s}_{M_0}& -s_{L_0}& -c_{L_0}{c}_{M_0}& (N+H_0)c_{M_0}{c}_{L_0}\\ -s_{L_0}{s}_{M_0}& c_{L_0}& -c_{M_0}{s}_{L_0}& (N+H_0)c_{M_0}{s}_{L_0}\\ c_{M_0}& 0& -s_{M_0}& [N(1-e^2)+H_0]s_{M_0}\\ 0& 0& 0& 1\end{array}\right]\·\\ \left[\begin{array}{cccc}{c}_{\mathrm{\ϵ}}{c}_{\mathrm{\β}}& -c_r{s}_{\mathrm{\β}}+s_{\mathrm{\γ}}{s}_{\mathrm{\ϵ}}{c}_{\mathrm{\β}}& s_{\mathrm{\γ}}{s}_{\mathrm{\β}}+c_{\mathrm{\γ}}{s}_{\mathrm{\ϵ}}{c}_{\mathrm{\β}}& 0\\ c_{\mathrm{\ϵ}}{s}_{\mathrm{\β}}& c_{\mathrm{\γ}}{c}_{\mathrm{\β}}+s_{\mathrm{\γ}}{s}_{\mathrm{\ϵ}}{s}_{\mathrm{\β}}& -s_{\mathrm{\γ}}{c}_{\mathrm{\β}}+c_{\mathrm{\γ}}{s}_{\mathrm{\ϵ}}{s}_{\mathrm{\β}}& 0\\ -s_{\mathrm{\ϵ}}& s_{\mathrm{\γ}}{c}_{\mathrm{\ϵ}}& c_{\mathrm{\γ}}{c}_{\mathrm{\ϵ}}& 0\\ 0& 0& 0& 1\end{array}\right]\left[\begin{array}{cccc}{c}_{\mathrm{\Θ}}{s}_{\mathrm{\Ψ}}& -s_{\mathrm{\Θ}}& c_{\mathrm{\Θ}}{c}_{\mathrm{\Ψ}}& 0\\ s_{\mathrm{\Ψ}}{s}_{\mathrm{\Θ}}& c_{\mathrm{\Θ}}& s_{\mathrm{\Θ}}{c}_{\mathrm{\Ψ}}& 0\\ -c_{\mathrm{\Ψ}}& 0& s_{\mathrm{\Ψ}}& 0\\ 0& 0& 0& 1\end{array}\right]\left[\begin{array}{c}{x}_c\\ y_c\\ z_c\\ 1\end{array}\right]\end{array}---\left(11\right)$

Then according to conversion formula (12) ~ (15) of the earth's core rectangular coordinate system in space to earth coordinates, the terrestrial coordinate obtaining target is as follows

$U=\arctan \frac{a{z}_e}{b\sqrt{x_e^2+y_e^2}},---\left(12\right)$

$M=\arctan \frac{z_e+b{e}^{\′2}{\sin }^{3}U}{\sqrt{x_e^2+y_e^2}-a{e}^2{\cos }^{3}U},---\left(14\right)$

$H=\frac{\sqrt{x_e^2+y_e^2}}{\cos M}-N---\left(15\right)$

In formula (12) ~ (15): L, M, H are respectively the geodetic longitude of target, geodetic latitude and geodetic height, semimajor axis of ellipsoid a=6378137.0m, semiminor axis of ellipsoid b=6356752.0m, ellipsoid first excentricity ellipsoid second excentricity $e^{\′}=\sqrt{a^2-b^2}/b,$ Ellipsoid radius of curvature in prime vertical $N=a/\sqrt{1-e^2{\sin }^{2}M}.$

Step S105, superposes the geographic coordinate of each target with composograph, obtains the electronic chart of multiple goal geo-location.

According to a further aspect in the invention, provide a kind of image imaging system for aerial camera, the present embodiment image imaging system is based on said method embodiment, and with reference to Fig. 2, the present embodiment image imaging system comprises:

Image distortion correction unit 100, carries out distortion correction for the image taken aerial camera, obtains the sequence image after correcting;

Image mosaic unit 200, for correct after sequence image according to image shooting order or shooting time determine splice order, obtain composograph in conjunction with the homography matrix between adjacent image;

Object detection unit 300, detects pixel coordinate that is static and/or moving target in the image taken from aerial camera, and line distortion of going forward side by side corrects and obtains multiple object pixel coordinate;

Target localization unit 400, carries out data fusion for the aspect data locator data of each object pixel coordinate and the output of GPS positioning system, aviation attitude measurement system exported, obtains the geographic coordinate of each target;

Image generation unit 500, for being superposed with composograph by the geographic coordinate of each target, obtains the electronic chart of multiple goal geo-location.

In the present embodiment, target localization unit 400 comprises:

Sight line vector builds module, for the image-forming principle according to monolithic matrix CCD, constructs the sight line vector of each target in conjunction with each object pixel coordinate;

Pixel angle of sight computing module, for calculating the pixel angle of sight of itself and picture centre major heading according to the sight line vector of each target;

Orientation computing module, for obtaining the distance between major heading and aircraft according to the range finder using laser measurement of camera internal, obtain position angle and the angular altitude of the relative aircraft platform of camera optical axis according to the angular encoder measurement of camera internal, calculate angle and the distance relation of each target and aircraft platform in conjunction with the pixel angle of sight between each target and major heading;

Geographic coordinate computing module, for export in conjunction with GPS positioning system aircraft position data, aviation attitude measurement system export aspect data, calculated the geographic coordinate of multiple target in single image by homogeneous coordinate transformation method.

In the present embodiment, image mosaic unit 200 comprises:

Image registration module 210, for adopting FAST Corner Detection Algorithm to the sequence image extract minutiae after correction, adopt BRISK operator as unique point descriptor, the similarity utilizing Hamming distance to calculate unique point between adjacent image is mated, and obtains the homography matrix between adjacent image;

Image co-registration module 220, for according to image shooting order or shooting time determine splice order, according to splicing order and adjacent image between homography matrix carry out splicing the composograph obtaining a fabric width visual field.

In the present embodiment, the design basis ground motion method of each unit or module specifically see embodiment of the method, can not repeat them here.

It should be noted that, can perform in the computer system of such as one group of computer executable instructions in the step shown in the process flow diagram of accompanying drawing, and, although show logical order in flow charts, but in some cases, can be different from the step shown or described by order execution herein.

Obviously, those skilled in the art should be understood that, above-mentioned of the present invention each module or each step can realize with general calculation element, they can concentrate on single calculation element, or be distributed on network that multiple calculation element forms, alternatively, they can realize with the executable program code of calculation element, thus, they can be stored and be performed by calculation element in the storage device, or they are made into each integrated circuit modules respectively, or the multiple module in them or step are made into single integrated circuit module to realize.Like this, the present invention is not restricted to any specific hardware and software combination.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (7)

1., for an image imaging method for aerial camera, described aerial camera adopts monolithic matrix CCD scanning imagery, and it is characterized in that, described image imaging method comprises:

Distortion correction is carried out to the image that described aerial camera is taken, obtains the sequence image after correcting;

To correct after sequence image according to image shooting order or shooting time determine splice order, obtain composograph in conjunction with the homography matrix between adjacent image;

From the image that described aerial camera is taken, detect pixel coordinate that is static and/or moving target, line distortion of going forward side by side corrects and obtains multiple object pixel coordinate;

The aspect data that the locator data each object pixel coordinate and GPS positioning system exported, aviation attitude measurement system export carry out data fusion, obtain the geographic coordinate of each target;

The geographic coordinate of each target is superposed with described composograph, obtains the electronic chart of multiple goal geo-location.

2. the image imaging method for aerial camera according to claim 1, is characterized in that, described in obtain each target geographic coordinate adopt based on the multiple goal autonomic positioning method of pixel sight line vector, comprising:

According to the image-forming principle of described monolithic matrix CCD, construct the sight line vector of each target in conjunction with described each object pixel coordinate;

The pixel angle of sight of itself and picture centre major heading is calculated according to the sight line vector of each target;

The distance between major heading and aircraft is obtained according to the range finder using laser measurement of camera internal, obtain position angle and the angular altitude of the relative aircraft platform of camera optical axis according to the angular encoder measurement of camera internal, calculate angle and the distance relation of each target and aircraft platform in conjunction with the pixel angle of sight between each target and major heading;

In conjunction with the aircraft position data of GPS positioning system output, the aspect data of aviation attitude measurement system output, calculated the geographic coordinate of multiple target in single image by homogeneous coordinate transformation method.

3. the image imaging method for aerial camera according to claim 1, is characterized in that,

To correct after sequence image according to image shooting order or shooting time determine splice order, the step obtaining composograph in conjunction with the homography matrix between adjacent image comprises:

Adopt FAST Corner Detection Algorithm to the sequence image extract minutiae after correction, adopt BRISK operator as unique point descriptor, the similarity utilizing Hamming distance to calculate unique point between adjacent image is mated, and obtains the homography matrix between adjacent image;

According to image shooting order or shooting time determine splice order, carry out splicing the composograph obtaining a fabric width visual field according to the homography matrix between described splicing order and adjacent image.

4. the image imaging method for aerial camera according to claim 1, is characterized in that,

Describedly from the image that described aerial camera is taken, detect that the pixel coordinate of static and/or moving target adopts image segmentation, frame difference method or optical flow method; Wherein,

Image is divided into target area and background area according to gray threshold or marginal information by described image segmentation, calculates the pixel coordinate of centre coordinate as target of described target area;

Described frame difference method can detect the moving target of pixel characteristic change fast by the pixel value difference of consecutive frame image;

Similar motion vector, by the sports ground of the changing features estimated image of sequential frame image respective pixel, is merged into moving target by described optical flow method.

5., for an image imaging system for aerial camera, described aerial camera adopts monolithic matrix CCD scanning imagery, and it is characterized in that, described image imaging system comprises:

Image distortion correction unit, carries out distortion correction for the image taken described aerial camera, obtains the sequence image after correcting;

Image mosaic unit, for correct after sequence image according to image shooting order or shooting time determine splice order, obtain composograph in conjunction with the homography matrix between adjacent image;

Object detection unit, detects pixel coordinate that is static and/or moving target in the image taken from described aerial camera, and line distortion of going forward side by side corrects and obtains multiple object pixel coordinate;

Target localization unit, carries out data fusion for the aspect data locator data of each object pixel coordinate and the output of GPS positioning system, aviation attitude measurement system exported, obtains the geographic coordinate of each target;

Image generation unit, for being superposed with described composograph by the geographic coordinate of each target, obtains the electronic chart of multiple goal geo-location.

6. the image imaging system for aerial camera according to claim 5, is characterized in that,

Described target localization unit comprises:

Sight line vector builds module, for the image-forming principle according to described monolithic matrix CCD, constructs the sight line vector of each target in conjunction with described each object pixel coordinate;

Pixel angle of sight computing module, for calculating the pixel angle of sight of itself and picture centre major heading according to the sight line vector of each target;

Orientation computing module, for obtaining the distance between major heading and aircraft according to the range finder using laser measurement of camera internal, obtain position angle and the angular altitude of the relative aircraft platform of camera optical axis according to the angular encoder measurement of camera internal, calculate angle and the distance relation of each target and aircraft platform in conjunction with the pixel angle of sight between each target and major heading;

Geographic coordinate computing module, for export in conjunction with GPS positioning system aircraft position data, aviation attitude measurement system export aspect data, calculated the geographic coordinate of multiple target in single image by homogeneous coordinate transformation method.

7. the image imaging system for aerial camera according to claim 5, is characterized in that,

Described image mosaic unit comprises:

Image registration module, for adopting FAST Corner Detection Algorithm to the sequence image extract minutiae after correction, adopt BRISK operator as unique point descriptor, the similarity utilizing Hamming distance to calculate unique point between adjacent image is mated, and obtains the homography matrix between adjacent image;

Image co-registration module, for according to image shooting order or shooting time determine splice order, carry out splicing the composograph obtaining a fabric width visual field according to the homography matrix between described splicing order and adjacent image.