1. A nine-camera oblique photography system is characterized by comprising three camera groups which are arranged side by side, wherein each camera group consists of three cameras with coplanar long axes; the included angles between two adjacent cameras in each camera group are equal, and the included angles between two adjacent camera groups are equal; the short axes of the cameras in the middle of each camera group are parallel to each other.

2. The oblique photography system of claim 1, wherein when the ground projection of the image captured by the central camera is rectangular, the ground projection of the image captured by the front, rear, left, right, and four cameras is trapezoidal, and the ground projection of the image captured by the upper left, upper right, lower left, and lower right, four cameras is trapezoidal or trapezoidal.

3. The oblique photography system of a nine-camera system according to claim 1, wherein each camera is configured with a-plane and a B-plane, the a-planes of the three cameras in each camera group are parallel to each other, and the B-planes of the cameras in the middle of the camera groups are parallel to each other; the surface A is a through lens central line and is parallel to a plane of a long axis of the camera base; the surface B is a plane passing through the central line of the lens and parallel to the short axis of the camera base.

4. The oblique photography system of claim 3, wherein the angle between two adjacent cameras in each camera group is the angle between the B-planes of two adjacent cameras.

5. The oblique photography system of claim 3, wherein the angle between two adjacent camera sets is the angle between the A faces of the cameras in the two adjacent camera sets.

6. The oblique photographing system of claim 1, wherein the focal length of the lens of the right middle camera is less than or equal to the focal length of the lens of the other cameras.

7. The oblique photography system of nine cameras of claim 6, characterized by satisfying:

f1/cosα≤f3≤2f1；f1/cosβ≤f2≤2f1；f1/cosα≤f4≤2.5f1；

wherein alpha is an included angle between two adjacent cameras in each camera group, beta is an included angle between two adjacent camera groups, and f1 is a lens focal length of the camera in the middle; f2 is the focal length of the lenses of the two marginal cameras in the middle camera group; f3 is the focal length of the lens of the camera in the middle of the two camera groups at the edge; f4 is the focal length of the lens of the remaining cameras.

8. The oblique photography system of nine cameras according to claim 1, wherein the nine cameras are arranged in a 3 x 3 manner; nine cameras are fixedly connected through a rigid structure.

9. The oblique photography system of claim 1, wherein each camera comprises an image sensor and a fixed focus lens.

10. The method for using a nine-camera oblique photography system according to any one of claims 1 to 9, wherein the system is mounted on an aircraft such that the camera in the middle is facing vertically downwards when the aircraft fuselage is horizontal; during the shooting process, all the cameras simultaneously take one shot at a fixed flight time and/or a fixed flight distance.

Background

The traditional oblique photography camera for unmanned aerial vehicle aerial photography is 5-lens photography, and is specifically composed of a middle camera and four oblique cameras in front, back, left and right, for example, a light and small oblique photography measurement system and method disclosed by CN106052648B, namely, the oblique photography camera with the 5-camera layout is simple in structure, few in data acquisition surface, and poor in modeling effect on the current complex modeling scenes, such as urban high-rise areas, dense building areas, glass buildings and other areas.

A 9-lens photographing apparatus also appears in the prior art: for example, CN108327922A discloses a nine-view angle aerial tilt camera platform, which uses 3-camera swing to form a 9-view angle tilt camera, but the time for completing one-cycle exposure of this camera is long, and it is not suitable for being mounted on an aircraft with a high speed, and is not beneficial to integrating a high-precision inertial navigation system; in addition, the focal lengths of the inclined camera lens and the vertical camera lens are the same, so that the difference of the resolution of the shot scene is large. Also, for example, CN107257427A discloses a nine-lens unmanned aerial vehicle panoramic camera and an image processing method thereof, which is a 9-lens panoramic camera, and is a camera for acquiring 360 ° view angle of the same coordinate point, and the working principle of the camera is completely different from the working principle of an oblique photography camera and the arrangement mode of the cameras, and therefore, the camera cannot be used in aerial photography of an aircraft at all.

Disclosure of Invention

The invention aims to provide a nine-camera oblique photography system and a use method thereof, so as to solve the problems that in the prior art, an oblique photography camera is difficult to meet complex modeling requirements, and the modeling effect of a complex modeling scene is poor, and achieve the purpose of establishing a complex model with better appearance effect and higher precision through the oblique photography system.

The invention is realized by the following technical scheme:

a nine-camera oblique photography system comprises three camera groups arranged side by side, wherein each camera group consists of three cameras with coplanar long axes; the included angles between two adjacent cameras in each camera group are equal, and the included angles between two adjacent camera groups are equal; the short axes of the cameras in the middle of each camera group are parallel to each other.

Aiming at the problems that the oblique photography camera in the prior art is difficult to meet the complex modeling requirement and the modeling effect on a complex modeling scene is poor, the invention provides the oblique photography system with the nine cameras. The long axis of the camera is the long axis of the camera base, and for the existing cameras for oblique photography, the structure is square, so that the long axis can be accurately determined by a person skilled in the art. The included angles between two adjacent cameras in the same camera group are equal, and the included angles are also equal relative to different camera groups. Moreover, the included angles between two adjacent camera sets are also equal for the three camera sets. The short axes of the cameras in the middle of each camera group are parallel to each other, i.e. one camera in each camera group is located between the other two cameras, and three cameras in the middle of the three camera groups have their short axes parallel to each other. In principle, the more angles of shooting the same vertical plane are, the smaller the angle difference is, and the higher the success rate of the space-three matching is. The five-lens oblique photography camera used in the prior art can often appear the condition that the three air can not pass through many times in the collected data, and the nine-camera system adopting the arrangement mode has more angles and smaller angle intervals than the five lenses, the success rate of the three air matching can be higher, the data processing time can be effectively reduced, and the internal work burden is lightened. In addition, by adopting the nine-camera system in the arrangement mode, the building vertical face with a higher angle can be acquired, so that the side texture of the model is smoother; more ground feature image data information can be collected, and the established model has better appearance effect and higher precision; the single shooting is carried out, the overlapping area of shooting areas of all cameras is small, and the effective area is large; through the cooperation of adjusting each camera inclination and camera lens focal length, can also guarantee the uniformity of each camera aerial photograph resolution ratio, effectively improve the model quality.

Further, when the ground projection of the image taken by the camera in the middle is rectangular, the ground projections of the images taken by the four cameras in the front, back, left and right are trapezoidal, and the ground projections of the images taken by the four cameras in the upper left, upper right, lower left and lower right are trapezoidal or trapezoid. For three camera units, three cameras in each camera unit are inevitably located at the center, and the rest cameras can be divided into eight directions of front, back, left, right, left upper, right upper, left lower and right lower according to spatial positions.

Furthermore, each camera is provided with an A surface and a B surface, the A surfaces of the three cameras in each camera group are parallel to each other, and the B surfaces of the cameras in the middle of each camera group are parallel to each other; the surface A is a through lens central line and is parallel to a plane of a long axis of the camera base; the surface B is a plane passing through the central line of the lens and parallel to the short axis of the camera base. In the scheme, a surface which penetrates through the central line of the lens and is parallel to the long edge of the camera base is set as an A surface, and a surface which penetrates through the central line of the lens and is parallel to the long edge of the camera base is set as a B surface. The plane a and the plane B are non-physical planes, and are assumed virtual planes only for convenience of text description.

The included angle between two adjacent cameras in each camera group is the included angle between the B surfaces of the two adjacent cameras.

The included angle between two adjacent camera sets is the included angle between the A surfaces of the cameras in the two adjacent camera sets.

Furthermore, the focal length of the lens of the camera in the middle is less than or equal to the focal lengths of the lenses of the other cameras.

Preferably, f1/cos alpha is not less than f3 not more than 2f 1; f1/cos beta is not less than f2 and not more than 2f 1; f1/cos alpha is not less than f4 and not more than 2.5f 1; wherein alpha is an included angle between two adjacent cameras in each camera group, beta is an included angle between two adjacent camera groups, and f1 is a lens focal length of the camera in the middle; f2 is the focal length of the lenses of the two marginal cameras in the middle camera group; f3 is the focal length of the lens of the camera in the middle of the two camera groups at the edge; f4 is the focal length of the lens of the remaining cameras. The inclination angle and the camera lens focal length of each camera of this scheme are satisfied, through the cooperation of adjusting each camera inclination angle and camera lens focal length, compare in the current five camera lens oblique photography cameras and can effectively guarantee the uniformity of each camera aerial photograph resolution ratio, effectively improve the model quality.

Furthermore, nine cameras are arranged in a 3 × 3 mode; nine cameras are fixedly connected through a rigid structure. Of course, the specific connection manner between the nine cameras is not the subject of the claims, and any rigid connection manner in the prior art can be applied to the present application for connecting the nine cameras. .

Further, each camera includes an image sensor and a fixed focus lens.

A method for using a nine-camera oblique photography system is arranged on an aircraft, so that when the fuselage of the aircraft is horizontal, a camera in the middle is vertically downward; during the shooting process, all the cameras simultaneously take one shot at a fixed flight time and/or a fixed flight distance. That is, during shooting, all cameras are started at set time intervals or distance intervals and shooting is performed once. The data shot by each camera are calculated in an overlapping rate calculation mode, the distance between exposure points and the route distance can be effectively increased, the method can be suitable for an aircraft with higher flying speed, the total shot data volume under the same survey area can be reduced, and the aviation flight efficiency is improved.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the five-lens oblique photography camera used in the prior art can often appear the condition that the three air can not pass through many times in the collected data, and the nine-camera system adopting the arrangement mode has more angles and smaller angle intervals than the five lenses, the success rate of the three air matching can be higher, the data processing time can be effectively reduced, and the internal work burden is lightened.

2. The oblique photographing system with the nine cameras and the use method thereof can acquire a building facade with a higher angle, so that the side texture of a model is smoother.

3. The oblique photographing system with the nine cameras and the using method thereof can acquire more ground feature image data information, and the established model has better appearance effect and higher precision.

4. According to the oblique photographing system of the nine cameras and the using method thereof, for single photographing, the overlapping area of photographing areas of the cameras is small, and the effective area is large; through the cooperation of adjusting each camera inclination and camera lens focal length, can also guarantee the uniformity of each camera aerial photograph resolution ratio, effectively improve the model quality.

5. The oblique photographing system with the nine cameras and the using method thereof can effectively increase the distance between exposure points and the distance between flight paths, can be suitable for an aircraft with higher flying speed, can reduce the total shooting data volume under the same measuring area, and improve the flight efficiency.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a schematic structural diagram of an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a camera set according to an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating the position relationship of the middle camera in the three camera groups according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a single camera in an embodiment of the invention;

fig. 5 is a schematic view of the projection of each camera on the horizontal plane when the camera is horizontally placed on the ground according to the embodiment of the present invention.

Reference numbers and corresponding part names in the drawings:

1-camera one, 2-camera two, 3-camera three, 4-camera four, 5-camera five, 6-camera six, 7-camera seven, 8-camera eight, 9-camera nine.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

Example 1:

a nine-camera oblique photography system comprises three camera groups arranged side by side, wherein each camera group consists of three cameras with coplanar long axes; the included angles between two adjacent cameras in each camera group are equal, and the included angles between two adjacent camera groups are equal; the short axes of the cameras in the middle of each camera group are parallel to each other. As shown in fig. 1, the present embodiment includes nine cameras each including an image sensor and a fixed-focus lens. The nine cameras are distributed in a 3 x 3 mode; nine cameras are fixedly connected through a rigid structure.

The three camera groups of this embodiment are distributed laterally in fig. 1, and the three cameras in each camera group are distributed longitudinally, that is, the leftmost camera group is composed of a first camera 1, a fourth camera 4, and a seventh camera 7, the middle camera group is composed of a second camera 2, a fifth camera 5, and a eighth camera 8, and the rightmost camera group is composed of a third camera 3, a sixth camera 6, and a ninth camera 9.

The a-and B-faces of each camera are shown in fig. 4.

The included angles between the B surfaces of the camera I1 and the camera IV 4, the camera IV 7 and the camera IV 4, the camera II 2 and the camera V5, the camera VIII 8 and the camera V5, the camera III 3 and the camera 6, and the camera IX 9 and the camera VI 6 are all alpha;

the A surfaces of the first camera 1, the fourth camera 4 and the seventh camera 7 are coplanar, the A surfaces of the second camera 2, the fifth camera 5 and the eighth camera 8 are coplanar, and the A surfaces of the third camera 3, the fourth camera 6 and the ninth camera 9 are coplanar, namely the A surfaces of all the cameras in any camera group are coplanar. For any two adjacent camera groups, the included angle between the A faces is beta as shown in FIG. 3. In addition, the B-planes of camera four 4, camera five 5, and camera six 6 are also coplanar.

This embodiment is connected by rigid structure by 9 cameras, and the integrated high accuracy of being convenient for is used to lead the system, when adopting the overlap ratio calculation mode, can increase distance and the route interval between the exposure point, can be applicable to on the faster aircraft of flying speed, and can reduce the total data volume of shooing under the same survey area, improves the aviation efficiency.

The embodiment is used by being installed on an aircraft, so that when the fuselage of the aircraft is horizontal, the camera in the middle is vertically downward; during the shooting process, all the cameras simultaneously take one shot at a fixed flight time and/or a fixed flight distance.

Example 2:

in the oblique photographing system with nine cameras according to embodiment 1, when the ground projection of the image taken by the center camera is rectangular, the ground projections of the images taken by the front, rear, left and right cameras are trapezoidal, and the ground projections of the images taken by the left upper, right upper, left lower and right lower cameras are trapezoidal or trapezoidal.

The included angle between two adjacent cameras in each camera group is the included angle between the B surfaces of the two adjacent cameras. The included angle between two adjacent camera sets is the included angle between the A surfaces of the cameras in the two adjacent camera sets.

The embodiment satisfies f1/cos alpha ≦ f3 ≦ 2f 1; f1/cos beta is not less than f2 and not more than 2f 1; f1/cos alpha is not less than f4 and not more than 2.5f 1;

as shown in fig. 2, α is an included angle between two adjacent cameras in each camera group; as shown in fig. 3, β is an included angle between two adjacent camera sets, and f1 is a focal length of the lens of camera five 5; f2 is the focal length of the lens of camera two 2 and camera eight 8; f3 is the focal length of the lenses of camera four 4 and camera six 6; f4 is the focal length of the lenses of camera one 1, camera three 3, camera seven 7 and camera nine 9.

By adopting the nine-camera system in the arrangement mode, the building vertical face with a higher angle can be collected, so that the side texture of the model is smoother; the single shooting is carried out, the overlapping area of shooting areas of all cameras is small, and the effective area is large; by adjusting the inclination angle of each camera and the matching of the focal length of the lens, the consistency of the resolution of each camera is ensured, and the quality of the model is effectively improved. The five-lens oblique photography camera used at present can often appear the condition that many times of blank three can not pass through in the data of collection, and the nine-camera system that adopts this embodiment arrangement has more angles than five-lens, and littleer angle interval, blank three match success rate can be higher, can effectively reduce data processing time, alleviate interior work burden.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.