WO2010025682A1

WO2010025682A1 - Combined wide-angle aerial digital camera system with functions of self-calibration and self-stabilization

Info

Publication number: WO2010025682A1
Application number: PCT/CN2009/073751
Authority: WO
Inventors: 林宗坚; 陈天恩; 孙杰; 苏国中; 张珂殊; 崔红霞; 刘召芹; 李永荣; 尹金宽; 彭晓东; 张峰; 李国胜; 桂德竹; 邓冰; 吴作飞; 李艺; 洪志刚; 孟文利
Original assignee: 中国测绘科学研究院
Priority date: 2008-09-08
Filing date: 2009-09-04
Publication date: 2010-03-11
Also published as: CN101354250B; CN101354250A

Abstract

A combined wide-angle aerial digital camera system with functions of self-calibration and self-stabilization includes four cameras (A, B, C, D) arranged in pairs on a stable platform. The main optical axes of one pair of cameras (A, B) provided on the y-axis symmetrically about the origin of coordinate are equivalently and oppositely inclined with an angle ω relative to the z-axis in the y-z plane, respectively. The main optical axes of the other pair of the cameras (C, D) provided on the x-axis symmetrically about the origin of coordinate are equivalently and oppositely inclined with an angle φ relative to the z-axis in the x-z plane, respectively.

Description

Combined wide-angle aerial digital camera system with self-checking self-stabilization function

The present invention relates to a digital camera system, and more particularly to a combined wide-angle aerial digital camera system having a self-checking self-stabilizing function. Background of the invention

At present, digital cameras are optically converted and digitally encoded, so that they can be quickly imaged without chemical processing, and directly enter computer image processing, so they are widely used in the field of life.

In the field of aerial photography, due to the difficulty of wide-angle lens manufacturing, especially the difficulty of making low-small distortion lens wide-angle lens required by aerial photography, it is common to use a plurality of constant-angle cameras to form a wide-angle camera to construct a combination of air. The digital camera realizes a wide angle of a large area digital camera.

As shown in FIG. 1 , the principle of the large area array digital camera in the prior art is to use four cameras that are close to each other, and respectively tilt a fixed angle to the outside to make the images A, B, C taken by the four cameras. D can be stitched into an equivalent center image that is close to four times the area of a single camera. In Figure lb, if the cameras A, C and B, D are rotated relative to the y-axis or the cameras A, B and C, D are rotated around the x-axis, the geometry of the constellation is not found. School conditions, so it is impossible to self-check the school.

Due to the lack of self-checking function of the large-area digital camera described above, it is not allowed to be completely distorted. In order to obtain a wide field of view image and maintain the distortion difference not exceeding the tolerance, the prior art adopts a very strong mechanical structure. The coupling member couples the plurality of cameras into a rigid unit such that the relative position and direction angle between the plurality of cameras are strictly constant (no deformation in micron-order accuracy). Therefore, the overall size and weight of the camera are large, generally in the order of tens of kilograms to hundreds of kilograms. The stable platform that is matched with the cumbersome camera is also cumbersome, so the total weight of the system exceeds 100 kg.

The above prior art has at least the following disadvantages:

Self-checking is impossible, heavy weight, and low system accuracy. Summary of the invention

SUMMARY OF THE INVENTION It is an object of the present invention to provide a combined wide-angle aerial digital camera system with self-checking and self-stabilizing functions that can realize self-checking, light weight, and high system precision.

The object of the invention is achieved by the following technical solutions:

The combined wide-angle aerial digital camera system with self-checking and self-stabilizing function includes four cameras fixed on a stable platform, and the four cameras are arranged in an overlapping constellation manner, and the overlapping conforming manner includes:

a mutually perpendicular x, y, z-axis spatial coordinate system, wherein a direction of the z-axis coincides with a longitudinal axis of the stable platform; wherein, among the four cameras, the first camera and the second camera are symmetrically set to the coordinate origin at y On the axis, and the main optical axes of the two are relatively inclined in the y and z-axis planes and are at an angle ω with the z-axis _{; the} third camera and the fourth camera are symmetrically placed on the X-axis with respect to the origin, and both The main optical axis is equally inclined in the planes of the χ and ζ axes and is at an angle φ to the ζ axis. It can be seen from the technical solution provided by the present invention that the combined wide-angle aerial digital camera system with self-checking self-stabilization function according to the present invention has four cameras arranged in pairs in an overlapping constellation manner. The relative tilt of each pair of cameras is equivalent to self-calibration, which can reduce the weight of mechanical components, improve system accuracy, and reduce the load on the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic view showing a photograph of a combined wide-angle aerial digital camera in the prior art;

2 is a schematic view showing a photograph of a combined wide-angle aerial digital camera of the present invention;

3 is a schematic diagram showing the spatial relationship between a first camera and a second camera in the present invention;

4 is a schematic diagram showing the spatial relationship between a third camera and a fourth camera in the present invention;

5 is a schematic view showing a mounting structure of a camera and a camera and a stable platform according to the present invention;

6 is a schematic diagram of selecting an image overlap area and a parallax detection point for self-calibration in a specific embodiment of the present invention; FIG. 7 is a step diagram of realizing stability of a stable platform in a specific embodiment of the present invention;

Figure 8 is a schematic diagram of soft correction of φ, ω angles of a stable platform in a specific embodiment of the present invention;

Figure 9 is a schematic diagram of soft correction of the kappa angle of a stable platform in a specific embodiment of the present invention. Mode for carrying out the invention

The preferred embodiment of the combined wide-angle aerial digital camera of the present invention is as shown in FIG. 2-5, including four cameras A, B, C, and D fixed on the stable platform, and four cameras are pressed. Arranged in an overlapping constellation manner, the self-checking condition is formed by the overlapping constellation, and the superimposed constellation method specifically includes: a mutually perpendicular x, y, z-axis spatial coordinate system, wherein the direction of the z-axis coincides with the longitudinal axis of the stable platform, Four cameras

A, B, C, and D are arranged on the plane of the x, y axis or in a plane parallel to the x, y axis.

Among the four cameras, the first camera A and the second camera B are symmetrically disposed on the y-axis with respect to the origin, and the main optical axes of the first camera A and the second camera B are equally inclined in the y and z-axis planes and are inclined with respect to _Z. The angle between the axes is ω, that is, the first camera Α and the second camera B are only rotated relative to each other about the _x- axis; the third camera C and the fourth camera D are symmetrically set at the origin on the X-axis, and the third camera C and The main optical axis of the fourth camera D is equally tilted in the x and z axis planes and is at an angle φ with the z axis, that is, the third camera Α and the fourth camera Β are rotated in equal amounts about the y axis.

As shown in Fig. 3, the short side of the field of view of the first camera A and the second camera B is parallel to the y-axis direction, and the half of the field of view of the short side of the image is θ, which satisfies the formula ω < θ. The difference between the angle ω and the angle 可以 can be 1° to 3°. Thus, the images captured by the first camera Α and the second camera 有 have a slight overlap band (equivalent to) a field of view overlap of 1° to 3°.

As shown in FIG. 4, the short side of the field of view of the third camera C and the fourth camera D is parallel to the X-axis direction, and the half of the field of view of the short side of the image is Θ, which satisfies the formula θ<φ. That is, the angle φ between the main optical axis of the third camera C and the fourth camera D and the _x- axis may be slightly larger than half of the angle of view of the short-side direction, so that the images taken by the two cameras may not overlap. However, they have sufficient overlap with the images taken by the first camera Α and the second camera B for self-checking purposes. As shown in Figure 5, the stable platform in the present invention? a rotating shaft is arranged in the direction and the y direction, respectively, and a mechanical resistance is arranged at the rotating shaft The device is also provided with x, y, and z-axis rotation angle sensors 1 for detecting three rotational degrees of freedom around the x, y, and z axes. The sensor 1 includes an accelerometer, an axial gyroscope, and a magnetic device. One or more sensors such as a compass. A photo exposure controller and the like are also provided on the stable platform T. The stable platform is also connected with an attitude angle correction software unit for soft correction of the stable platform T and the like.

When the invention is applied to an aircraft, the direction of the X-axis can be along the heading of the aircraft. The above-mentioned combined wide-angle aerial digital camera system with self-checking and self-stabilizing function can realize self-calibration and self-stabilization functions, and the specific methods include:

Self-checking of changes in the relative position of four cameras:

Detecting, and correcting, the amount of change Δφ, Δω, Δκ of the attitude angle of each of the four cameras around the four, x, and z axes, respectively, specifically including selecting multiple overlapping regions of the four camera images. The points used for self-checking, the equation for each point is as follows:

Δ^. = ^{f +Χί} + - ^{f +} / ^JL ^ _j -y _j ^K _j

JJJJ (3)

Where i and j represent the two camera numbers corresponding to the overlapping image in which the selected point is located; ", W respectively represents the image plane coordinates of the selected point in the direct image of the two cameras; The selected point is from the parallax between the images projected by the two cameras; the vertical distance from the center of the lens of the camera to the image; the relative control condition equation of the unified coordinate system of the four cameras:

Δ^+Δ +Δ +Δ =0 ,

Αω _Α + Αω _Β + Αω _ε + Αω _Β = 0

A/ _A +A! _B +A! _c +A! _D = j ₍₅₎

Where A, B, C, and D are the numbers of the four cameras, respectively;

Combine the above formulas (3), (4), and (5) to obtain the change amount Δφ of the attitude angle of each camera around the y, x, and z axes.

Δω, Δκ, and then the relative positions of the four cameras are corrected based on the amount of change.

Self-stabilization of the stable platform, including:

Through the two mechanical shafts along the X-axis and the y-axis and their mechanical damping devices, the main optical axes of the four cameras mounted on the stable platform are kept in the vertical direction by gravity;

Through the attitude angle measuring device, the angle value of the attitude angle of the camera on the y, χ, and z axes respectively is measured and corrected, and the attitude angle measuring device includes three accelerometers, three axial gyroscopes, and one magnetic field. Compass

The posture angle of the stable platform is corrected by the attitude angle correction software by the attitude angle correction software unit.

The attitude angle correction software can include:

According to the value of the attitude angle of the stable platform according to the exposure instant, the image edge redundancy of the combined wide-angle aerial digital camera is utilized, Correct the attitude angle of the stable platform. In the present invention, in order to achieve the purpose of self-checking, the orientation elements that need to be self-checked and not required to self-check can be separated first, and the image combination mechanism capable of self-checking can be designed for the elements that need self-checking, and Determine the range of overlapping images that can be self-calibrated, and then design a combined camera-coupled mechanical component according to the calibratable geometric mechanism principle. Lightweight camera attachments can be used to reduce the weight of the combined camera. However, the internal geometric distortion of the combined image caused by the deformation of the lightweight member due to the force and temperature changes can automatically detect (detect) the magnitude of the geometric distortion and correct it by the self-checking method.

In the present invention, the stable platform of the combined camera can be stabilized from the tilting sway of 20-30° to the vertical main optical axis by the mechanical stabilization device; the residual deflection amount and heading of the stable platform can be detected by the electronic sensor The amount of angular skew is then compensated by the correction software unit using the edge margin of the combined wide-angle field of view to obtain an equivalent image as the state of the real stable platform, realizing a stable platform for the compact combination camera, replacing the prior art A bulky and stable platform commonly used in the industry.

The invention is applicable to various aircrafts, and is particularly suitable for unmanned aerial vehicles, small aircrafts and the like having a large change in attitude angle (generally 20-30°). Specific embodiment:

The combination of digital camera installation, as shown in Figure 2, four cameras 4, B, C, D are tilted in pairs, each camera only tilts in the ω or φ direction.

As shown in FIG. 3, the first camera Α and the second camera Β are only inclined by an equal amount of ω angle. The two cameras Α and Β are fixedly placed on the frame 有 with a symmetrical inclined plane. The main optical axes of the two cameras are respectively offset from the _x- axis and the ω angle and the -ω angle around the _Χ axis. The Θ angle in the figure is half of the field of view in the short-side direction of the camera, which can make 0)<6, and the difference can be selected. Between 1° and 3°, so that the images of the camera Α and Β have an overlap of 2 Δ as shown in Fig. 3.

In Fig. 3 is an enlarged display of the main distance of the camera. The image of the camera Α and Β on the equivalent image surface is in the direction scale: 2/ 2/ ' tg(0 + ω), whose scale exceeds the single camera scale 2/ TwO twice.

As shown in FIG. 4, the third camera C and the fourth camera D are only inclined by an equal amount of φ angle. The camera (, D is also placed on the frame 有 with a symmetrical tilt plane (perpendicular to the direction of Figure 3), causing the main optical axes of the two cameras to deviate from the y-axis by the plumb line + φ angle and _φ angle, respectively. It is half of the field of view in the short-side direction of the camera. Unlike Figure 3, the camera (the image of D on the equivalent image surface not only has no overlap but a crack of 2Δ width: Δ= ft _g (cp-e Therefore, the actual imaging width of the third camera C on the equivalent plane is only m = f' tg (cp + e) - f' tg (cp - e), and the fourth camera is also the same.

The choice of φ angle can be based on the following two principles: Make + close to half the field angle of the camera; make (m + Δ) close to 1. 5

The structure of the frame, as shown in Fig. 5, the stable platform Τ contains two axial rotations of x and y, and is mechanically damped so that the central axes of the four cameras in the lower part are close to vertical. At the same time, at the platform position on the top of the camera, sensors ^ω , ^Κ (the angles of rotation around the y, χ, and z axes, respectively) are provided with three attitude angle degrees of freedom for acquiring the three attitude angle values of the camera exposure moment. There is also a camera exposure controller 2 and the like. The following describes in detail the principle of the stability of the calibration platform of the camera in the present invention:

Single camera calibration and combined camera calibration:

First, to check a single camera, a three-dimensional calibration field can be arranged according to the conventional photogrammetry method. For the field photography, the digital point measurement method is used to accurately measure each marker point, and then the distortion difference equation is used to solve the distortion parameter. In use, the distortion of each cell's coordinates is corrected according to the distortion parameter.

Then, the combined camera is initially calibrated, the purpose of which is to determine the relative orientation of each single camera in the combined system. The initial inspection of the combined camera is based on the single calibration of each camera. The single camera is mounted on the combined mechanical frame, and then the inspection field is photographed, and the spatial orientation of the camera is used to solve the external orientation element values of each camera.

The outer orientation elements obtained from the resection of the space are based on the ground coordinate system of the calibration field. There are two ways to solve the relative position of a single camera in a combined system:

One is to take the image coordinate system of the first camera as the system coordinate system, and replace the outer orientation elements obtained by the space resection into the system coordinate system;

The other is to take the average position of the four camera photography centers as the system center point, take the average attitude angle of the four cameras to zero posture, and convert the outer orientation elements obtained by the space back to the system coordinate system. In the present invention, the composition of the combined wide-angle image field and the realization of the self-checking function are:

The end result of the combined wide-angle camera is a central projection image obtained from a wide-angle image as shown in Figure 2 on the equivalent surface. According to the ideal structure shown in Figure 2, if there is no error in machining, the mechanical components are not deformed, and the camera is fine A, B, C, D

X X

Y y

The geometric relationship between the conformation on the equivalent surface — / and the actual image of a single camera - f is as follows:

( 1 )

When there is a certain machining error and deformation, the attitude of each camera is different from the ideal state shown in Figure 2. The φ, ω, κ angle of each camera must be measured by combined camera calibration, and space is used in the calibration field. The resection will determine the 12 attitude angles, and the accuracy should be within 0.5 pixels, then the formula (1) should be changed to:

(2) where i represents eight, B, C, D, and ( s _y s _vs ') represents the camera's center position. ^α ι . ~ is a direction cosine matrix composed of φ, ω, κ. The mechanical design should ensure that the lens centers of the four cameras are as close as possible, ideally they are combined into one point. In fact, the smaller the camera, the closer they are. In theory, it can be proved that when the distance between the cameras is as small as the ground distance over which the aircraft flies during the camera exposure time, and the ground fluctuation is less than one third of the altitude, the resulting four-camera image mosaic error will be zero. Within 3 pixels. When the mechanical components of the four cameras are deformed due to temperature changes and platform motion, the resulting changes are generally small (in the sub-millimeter range), but the resulting changes in φ, ω, κ are not negligible. . Therefore, in the present invention, the relative orientation between adjacent cameras is performed using the overlap degree of the equivalent camera projections of the four camera images shown in FIG. 2, and the increments Δφ, Δω, Δκ of the attitude angles of the respective cameras are obtained.

Specifically, as shown in FIG. 5, 12 points for self-calibration are selected in the overlap region, and the equation for each point is as follows:

ΔΧ,

=

In the above formula, i and j respectively represent two camera numbers (for example, A and C) corresponding to adjacent overlapping images. And "the image plane coordinates of the same feature point in the two camera images in the direct image.") indicates the parallax between the images of the same feature point from the two camera projections, ^^ is the camera lens center to the The vertical distance of the image. The above expression actually expresses the weight distribution of the disparity residual according to the relationship of ^ φ ^^. Therefore, the coordinates ( ^Χ ) in each camera can be used on the right side of the formula.

In addition to the above 24 parallax equations listed in 12 points in the overlap region, considering the relative control conditions of the unified coordinate system of the combined camera system, the following conditional equation can be obtained:

Combining equations (3), (4) and equations (5), we get 27 equations, the number of unknowns is 12, and the number of unnecessary observations is 15. According to the conditional indirect adjustment method, the self-calibration of the combined camera system can be realized. In actual aerial photogrammetry, the above-mentioned self-calibration is performed for each data acquired by each exposure, so that deformation due to temperature and platform motion can be checked. The composition of the self-stabilizing platform and the realization of the combined self-stabilizing function:

As shown in FIG. 7, the stable platform in the specific embodiment of the present invention is composed of the following three parts, and the self-stability of the stable platform is realized step by step:

Mechanical shafts X and Y and their mechanical damping devices:

The main optical axis of the combined camera system mounted on the stable platform τ can maintain the vertical direction by gravity. The force of the damper should be adjusted to a swing angle of less than 10° when the aircraft motion causes a sway.

Attitude angle measuring device - includes three accelerometers, three axial gyroscopes and a magnetic compass to measure the camera's exposure to stabilize the platform! The ^ ω, κ angle value of ^ requires the measurement accuracy to be within 3 ⁸ .

Attitude angle correction software:

According to the measurement value of the camera system attitude angle according to the exposure instant, the combined image angle of the wide-angle camera image is fully utilized, and the combined camera image field is corrected so that the equivalent image formed reaches the level of the attitude angle within 3 ^β . Including soft correction for φ, ω, κ angles: as shown in Figure 8, for soft correction of ω angle, since the image angle of the combined wide-angle camera is wide enough (up to 130 °), there is a certain margin The amount can be used to buffer the stability of the mechanically stable platform. For example, from 10 ° on both sides of a 130 ° wide image field for stable platform fill, there is a 110 clear wide image field for equivalent image use. The corrective processing of the software only needs to add the measured values of the attitude angles φ, ω to the initial inspection and orientation element values of the combined system.

As shown in Fig. 9, for the soft correction of the k-angle, the edge redundancy of the combined wide-angle field of view is still utilized, and the largest circle is centered on the equivalent image main point in the image field range where the maximum possible image is taken. The inscribed square is made in the circle, and its azimuth is determined by the measured value of κ. This solves the problem that the aircraft has a large yaw angle caused by the inclination of the flight platform when the aircraft is flying against the lateral wind, so that the equivalent images are arranged neatly according to the route, which facilitates subsequent mapping operations.

The combined wide-angle camera designed and manufactured according to the present invention and the image obtained by the self-checking process are spliced into an equivalent wide-angle image, and the error of each camera is within 0.3 pixels. In the invention, the self-checking function of the external orientation of the camera is used to realize the light and miniaturization of the mechanical joint structure, and the self-checking school which allows the mechanical deformation to be reserved for the instantaneous conformation of the photographing is compensated and corrected; the special combined imaging structure of the self-checking can be realized, It is the image set by each single camera that is sufficient and suitable for solving the slight change of the relative posture; using the least squares matching method, the camera of each corner is solved by the observation of the parallax margin of the designed feature point and the adjustment Small change in attitude; Self-control correction for each image captured, resulting in an equivalent wide-angle aerial image of good quality.

The stable platform of the invention divides the functions of the conventional stable platform into three parts: mechanical stability, electronic measurement and software correction; realizes the initial stabilization of X and Υ under the gravity environment by the damping mechanism; Gyro and magnetic compass measure the residual attitude deviation of gravity-stabilized mechanical stability; compensate the gravity damping stability by wide image field margin of combined wide-angle camera The residual attitude deviates, and the software is used to achieve self-stability; the self-stabilizing platform has no power drive and open/closed control circuit. The problem of deformation of the mechanical component is reduced in size.

The invention realizes the light and miniaturization of the combined wide-angle camera through the above technical solution; realizes the light and miniaturization of the camera stable platform; the total weight of the camera system and the stable platform is reduced by nearly one order of magnitude (from one hundred kilograms to 15 It can be used as a payload for unmanned aerial vehicles (UAVs, unmanned helicopters, unmanned airships); it can be scaled up. The invention can be applied to the low-altitude aerial survey system of the unmanned aerial vehicle, and the aerial resolution, the definition and the aerial survey accuracy are greatly improved because the aerial photography can be realized at low altitude (low to 100 meters from the ground). It can achieve 1:500 topographic map accuracy, can work under cloudy clouds, and can be a flexible and mobile aeronautical measuring device owned by users.

Light and small aircraft have a series of advantages such as low altitude, low speed, flexibility, maneuverability, flight along complex routes, and no airport take-off and landing, but they all have load limit requirements, it is difficult to carry heavy and stable platforms, and the flight stability of aircraft is relatively large. The aircraft is also much worse. The invention can produce a light and small combined wide-angle low-altitude digital camera and a light and small low-altitude remote sensing platform, which can be applied to unmanned aircraft, unmanned helicopters, unmanned airships, light and small manned aircrafts, light and small manned helicopters and the like. The above is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope disclosed by the present invention. Alternatives are intended to be covered by the scope of the present invention.

Claims

Rights request

A combined wide-angle aerial digital camera system having a self-checking self-stabilizing function, comprising four cameras fixed on a stable platform, wherein the four cameras are arranged in an overlapping constellation manner, the overlapping The conformational approach includes:

a mutually perpendicular x, y, z-axis spatial coordinate system, wherein a direction of the _Z- axis coincides with a longitudinal axis of the stable platform; among the four cameras, the first camera and the second camera are symmetrically set to the coordinate origin at y On the axis, and the main optical axes of the two are relatively inclined in the y and z-axis planes and are at an angle ω with the z-axis; the third camera and the fourth camera are symmetrically placed on the X-axis with respect to the origin, and both The main optical axis is equally inclined in the planes of the χ and _Ζ axes and is at an angle φ to the _Ζ axis.

2. The combined wide-angle aerial digital camera system with self-checking self-stabilization function according to claim 1, wherein the short-side direction of the field of view of the first camera and the second camera is parallel to y In the axial direction, half of the angle of view of the short-side direction is θ, which satisfies the formula ω<θ, and the difference between the angle ω and the angle 为 is 1° to 3°.

3. The combined wide-angle aerial digital camera system with self-checking self-stabilization function according to claim 1, wherein the short-side direction of the field of view of the third camera and the fourth camera is parallel to X In the axial direction, half of the angle of view of the short-side direction is assumed to be a corner, and the formula θ < φ is satisfied.

4. The combined wide-angle aerial digital camera system with self-checking self-stabilization function according to claim 1, wherein the stable platform is respectively provided with a rotating shaft in the X direction and the y direction, and at the rotating shaft Mechanical damping device is provided.

5. The combined wide-angle aerial digital camera system with self-checking self-stabilization function according to claim 4, wherein the stable platform is provided with x, y, and z-axis rotation angle electronic sensors, respectively.

The electronic sensor includes an accelerometer, an axial gyroscope, and a magnetic compass.

6. The combined wide-angle aerial digital camera system with self-checking self-stabilization function according to claim 5, wherein the stable platform is connected with an attitude angle correcting unit.

A combined wide-angle aerial digital camera system with self-checking self-stabilizing function according to any one of claims 1 to 6, characterized in that the system comprises the following functions:

The self-checking function of the change of the relative positions of the four cameras in the system specifically includes: detecting the amount of change Δφ, Δω of the attitude angle of each of the four cameras around the 7, x, and z axes, respectively. Δκ, and correcting it, specifically, selecting a plurality of points for self-calibration in the overlapping area of the four camera images, and the equation of each point is as follows:

^ij = ^{f +} ' Δ^. + ^ - Αω _: + y ^ - ^{f +} f ^J Δ^. - ^Δω. - j _y A/r _;

J J J J ( 3)

=

Where i and j represent the two camera numbers corresponding to the overlapping images in which the selected points are located; ''WW ^ respectively represent the image plane coordinates of the selected points in the direct images of the two cameras; Representing that the selected point is from the parallax between the images projected by the two cameras; that is, the vertical distance from the center of the lens of the camera to the image;

Relative control condition equations for the unified coordinate system of the four cameras: ( ₅ )

Where A, B, C, and D are the numbers of the four cameras, respectively;

The above equations (3), (4), and (5) are jointly solved to obtain the amount of change Δφ, Δω, Δκ of the attitude angle of each camera around the y, x, and z axes.

8. The combined wide-angle aerial digital camera system with self-checking self-stabilization function according to claim 7, wherein the system further comprises the following functions:

The self-stabilizing function of the stable platform in the system includes:

Machinery and mechanical damping means along the shaft axis and the y-axis, respectively _Χ by two, so that four main optical axis of the camera mounted on the stable platform holding the vertical direction by gravity;

And determining, by the attitude angle measuring device, an angle value of the stable platform around the y, χ, and z axes respectively at an exposure moment, wherein the attitude angle measuring device includes three accelerometers and three axial directions Gyro and a magnetic compass;

The attitude angle of the stable platform is corrected by the attitude angle correction software by the attitude angle correction software unit.

9. The combined wide-angle aerial digital camera system with self-checking self-stabilization function according to claim 8, wherein the attitude angle correction unit comprises the following functions:

The attitude angle of the stable platform is corrected by the image edge redundancy of the combined wide-angle aerial digital camera according to the value of the attitude angle of the stable platform at the exposure instant.