Dual-camera combined sea surface aerial photography method and device

Abstract

The invention mainly solves the problem of how to simplify a shooting method and an image synthesis algorithm between two parallel cameras during sea surface aerial photography. A dual-camera combined sea surface aerial photography method comprises the following steps: obtaining earth coordinates of an aircraft, and converting elevation into altitude; acquiring the altitude of the ground right below the aircraft according to the earth coordinates of the aircraft; the two transversely parallel cameras are installed under the aircraft, and according to the altitude difference h between the cameras and the sea surface under the cameras, the visual angle alpha of each camera and the distance i between the visual angle intersection points of the two cameras, the rotation angle of each camera around the respective visual angle intersection point is adjusted. And adjusting the visual axis of each camera to an included angle beta between the visual axis of each camera and the vertical direction, wherein beta = alpha / 2-arctan (0.5 i / h), so that the ground areas shot by the two cameras are spliced together in the transverse direction. The method has the beneficial effects that a shooting method and an image synthesis algorithm between the two parallel cameras are simple and feasible; no overlapping area exists, and the shooting efficiency is higher.

Description

Technical Field

[0001] The present invention relates to the field of aerial photography technology, and in particular to a dual-camera combined sea surface aerial photography device and method. Background Art

[0002] Aerial photography of the sea surface refers to the photography of the sea surface by a camera device mounted under the aircraft while the aircraft is flying.

[0003] Ocean surface aerial photography technology has become an innovative tool for applications in multiple fields due to its unique aerial perspective and flexible and efficient operating capabilities.

[0004] In terms of natural landscape recording and tourism promotion, aerial photography can accurately capture stunning images such as surging waves and sunsets on the beach, and inject visual appeal into social media dissemination and tourism promotion through the creation of high-resolution images and dynamic videos. This type of content can not only inspire the public's resonance with the beauty of the ocean, but also significantly enhance the brand influence of tourist destinations by showing the ecological characteristics of seaside resorts in a panoramic manner.

[0005] In the field of science and environment, drone aerial photography has broken through the time and space limitations of traditional observation. Equipped with professional equipment such as multispectral sensors and thermal imagers, researchers can obtain key data such as ocean surface temperature and chlorophyll concentration in real time, and simultaneously track environmental events such as the spread of red tides and oil migration. Combined with AI image recognition technology, the aerial photography system can also realize ecological research such as whale migration trajectory analysis, coral bleaching degree assessment, and interannual evolution of mangrove wetlands, providing accurate data support for marine life protection and pollution control. Its rapid response characteristics have greatly improved the monitoring efficiency of sudden environmental disasters.

[0006] In terms of commercial applications, aerial photography of the sea surface demonstrates strong practical value. The real estate industry uses aerial images to present the location advantages and landscape resources of coastal properties in three dimensions, helping customers build immersive spatial cognition; the geographic information field uses aerial photography data to generate high-precision three-dimensional maps to support coastal planning and resource management. By integrating multi-source data and intelligent analysis, this technology has developed into an efficient solution that connects natural exploration, scientific research and commercial innovation, and continues to promote the digital reconstruction of the relationship between people and the sea.

[0007] The problem is that if the aircraft is at a low altitude from the sea surface, the shooting range will be small, and if the aircraft is at a high altitude from the sea surface, the resolution will be reduced. It is difficult for a single camera to achieve both a large range and high resolution at the same time. In the prior art, there are solutions for shooting with multiple cameras in parallel, but the shooting methods and image synthesis algorithms between multiple cameras are complicated, which affects the shooting effect and efficiency. Summary of the invention

[0008] The main problem solved by the present invention is how to simplify the shooting method and image synthesis algorithm between two parallel cameras during sea surface aerial photography.

[0009] A dual-camera combined sea surface aerial photography method comprises the following steps: Get the earth coordinates of the aircraft, where the elevation is converted to altitude; According to the earth coordinates of the aircraft, obtain the altitude of the ground directly below it; Two transversely parallel cameras are installed under the aircraft. According to the earth coordinates of the aircraft and the relative position between the camera and the aircraft camera, the altitude difference h between the camera and the sea surface directly below it is obtained. Each camera can rotate around its own perspective intersection point to adjust the shooting angle. The perspective intersection point is the intersection point of the reverse extension line of the horizontal perspective when each camera is imaging. When each camera shoots downward, its own perspective intersection point is located above the camera objective lens. According to the altitude difference h between the camera and the sea surface directly below it, the perspective α of each camera head, and the distance i between the perspective intersection points of the two cameras, the rotation angle of each camera around its own perspective intersection point is adjusted so that the visual axis of each camera is adjusted to an angle β=α / 2-arctan (0.5i / h) with the vertical direction, so that the ground area photographed by the two cameras is stitched together in the transverse direction.

[0010] The beneficial effect is that as long as the visual axis of each camera is adjusted to the angle with the vertical direction, the ground area photographed by the two cameras is spliced ​​together in the horizontal direction, so that the shooting method and image synthesis algorithm between the two parallel cameras during the aerial photography of the sea surface are simple and easy; because the ground area photographed by the two cameras is directly spliced ​​together in the horizontal direction without overlapping areas, the overall shooting range of the two cameras is larger and the shooting efficiency is higher; when the aircraft is at a large height from the sea surface, because there are two cameras shooting in parallel and can just be spliced ​​into a complete photo or video, a large range and high resolution can be achieved at the same time, and sea surface photos can be taken quickly and with high resolution. The view intersection is the intersection of the reverse extension lines of the view in the horizontal direction when each camera is imaging. No matter how the angle of the camera is adjusted, the position of the view intersection and the relative position of the two view intersections remain unchanged, ensuring that the algorithm is simple and reliable. In addition, the reason why the present invention can ensure the accurate splicing of the images of each camera at a height h is that the sea surface is flat, and the height of the sea surface is basically determined, and the calculation can be strictly in accordance with the plane and geometric relationship, with high accuracy. According to the definition of Baidu Encyclopedia, an aircraft is a device that flies within the atmosphere or in space outside the atmosphere (space). The aircraft described in the present invention mainly refers to those that fly within the atmosphere, such as balloons, airplanes (including drones), etc. The specific aircraft can be selected according to actual conditions.

[0011] Each camera uses a fixed-focus lens, and the intersection point of the viewing angle of each camera is fixed.

[0012] The beneficial effect is that the influence of the camera size is taken into account, and at the same time the rotation center point of each camera is very accurate and strictly complies with the calculation formula, which together ensures the accuracy of the calculation results. A fixed-focus lens is a lens with a certain focal length. Since all cameras use a fixed-focus lens, their viewing angle is fixed. Therefore, the intersection of the reverse extension lines of the viewing angles of each camera is fixed in position, which is more convenient for the installation and accurate calculation of the camera position.

[0013] The angle of view intersection point is located on the optical axis of the lens. Assuming the focal length of the lens is f, the camera angle of view intersection point is located at the point f where the camera image sensor extends toward the lens.

[0014] The beneficial effect is that the angle of view intersection point, i.e., the optical center point of the lens, is accurately located, and the calculation can be performed strictly according to the formula. The specific position of the angle of view intersection point of each camera can be obtained through experiments or according to relevant parameters of the camera.

[0015] The images captured by the two cameras are stretched by [cosβ+sinβ*cot(π / 2-α / 2-β)] times in the horizontal direction.

[0016] The beneficial effect is that since the cameras on both sides shoot obliquely, the width of the image is smaller than the actual width of the ground. In order to match each point on the image with the coordinates on the ground, the images taken by the two cameras are stretched in the horizontal direction.

[0017] The stretching of the images captured by the two cameras is based on the stitching line of the captured images. The image captured by the left camera is stretched to the left, and the image captured by the right camera is stretched to the right.

[0018] The beneficial effect is that it not only ensures the accurate splicing of the images taken by the two cameras, but also ensures that each point on the image matches the coordinates on the ground, and the operation and algorithm are very simple. However, due to the horizontal stretching of the image, its horizontal resolution will decrease, but usually the stretching ratio is not large, and the horizontal resolution decrease is not large, which basically does not affect the overall sea surface aerial photography effect.

[0019] After the aircraft flies a certain distance, the camera below it will take another photo, so that the ground area captured twice can be exactly stitched together in the vertical direction.

[0020] The beneficial effect is that continuous aerial photography images in the flight direction can be formed.

[0021] The camera captures video.

[0022] The beneficial effect is that, similar to the principle of horizontal stitching of pictures, videos can also be stitched horizontally, and large-scale high-resolution videos can also be shot.

[0023] A dual-camera combined sea surface aerial photography device is characterized by comprising an angle adjustment module, a rotating shaft, and two cameras. The two cameras are installed in parallel horizontally under the aircraft. According to the earth coordinates of the aircraft and the relative position between the camera and the aircraft camera, the altitude difference h between the camera and the sea surface directly below it is obtained. Each camera can rotate around its own view intersection point to adjust the shooting angle. The view intersection point is the intersection point of the reverse extension line of the horizontal view when each camera is imaging. When each camera shoots downward, the respective view intersection point is located above the camera objective lens. According to the altitude difference h between the camera and the sea surface directly below it, the view angle α of each camera head, and the distance i between the view intersection points of the two cameras, a rotating shaft is provided at the view intersection point. The angle adjustment module can make the camera rotate around the rotating shaft, so as to adjust the rotation angle of each camera around its own view intersection point. When the visual axis of each camera is adjusted to an angle β=α / 2-arctan (0.5i / h) with the vertical direction, the ground area photographed by the two cameras is spliced ​​together in the horizontal direction.

[0024] The beneficial effect is that as long as the visual axis of each camera is adjusted to the angle with the vertical direction, the ground area photographed by the two cameras is spliced ​​together in the horizontal direction, so that the shooting method and image synthesis algorithm between the two parallel cameras during the aerial photography of the sea surface are simple and easy; because the ground area photographed by the two cameras is directly spliced ​​together in the horizontal direction without overlapping areas, the overall shooting range of the two cameras is larger and the shooting efficiency is higher; when the aircraft is at a large height from the sea surface, because there are two cameras shooting in parallel and can just be spliced ​​into a complete photo or video, a large range and high resolution can be achieved at the same time, and sea surface photos can be taken quickly and with high resolution. The view intersection is the intersection of the reverse extension lines of the view in the horizontal direction when each camera is imaging. No matter how the angle of the camera is adjusted, the position of the view intersection and the relative position of the two view intersections remain unchanged, ensuring that the algorithm is simple and reliable. In addition, the reason why the present invention can ensure the accurate splicing of the images of each camera at a height h is that the sea surface is flat, and the height of the sea surface is basically determined, and the calculation can be strictly in accordance with the plane and geometric relationship, with high accuracy.

[0025] Each camera uses a fixed-focus lens, and the intersection point of the viewing angle of each camera is fixed.

[0026] The beneficial effect is that the influence of the camera size is taken into account, and at the same time the rotation center point of each camera is very accurate and strictly complies with the calculation formula, which together ensures the accuracy of the calculation results. A fixed-focus lens is a lens with a certain focal length. Since all cameras use a fixed-focus lens, their viewing angle is fixed. Therefore, the intersection of the reverse extension lines of the viewing angles of each camera is fixed in position, which is more convenient for the installation and accurate calculation of the camera position. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 . A schematic diagram of the structure of a dual-camera combined sea surface aerial photography device; Figure 2 .Sketch of camera installation structure; Figure 3 . A schematic diagram of the shooting principle of a dual-camera combined sea surface aerial photography device (the center O is the location of the rotation axis of one camera, that is, the intersection of the viewing angles); Figure 4 .Sketch of the camera; Figure 5 .Calculation principle diagram.

[0028] In the figure: 1. Aircraft, 2. Camera, 3. Rotating shaft, 21. Lens, 22. Image sensor. DETAILED DESCRIPTION Example

[0029] As shown in 1-5, a dual-camera combined sea surface aerial photography method includes the following steps: Get the earth coordinates of the aircraft, where the elevation is converted to altitude; According to the earth coordinates of the aircraft, obtain the altitude of the ground directly below it; Two transversely parallel cameras are installed under the aircraft. According to the earth coordinates of the aircraft and the relative position between the camera and the aircraft camera, the altitude difference h between the camera and the sea surface directly below it is obtained. Each camera can rotate around its own perspective intersection point to adjust the shooting angle. The perspective intersection point is the intersection point of the reverse extension line of the horizontal perspective when each camera is imaging. When each camera shoots downward, its own perspective intersection point is located above the camera objective lens. According to the altitude difference h between the camera and the sea surface directly below it, the perspective α of each camera head, and the distance i between the perspective intersection points of the two cameras, the rotation angle of each camera around its own perspective intersection point is adjusted so that the visual axis of each camera is adjusted to an angle β=α / 2-arctan (0.5i / h) with the vertical direction, so that the ground area photographed by the two cameras is stitched together in the transverse direction.

[0030] The specific calculation is as follows Figure 5As shown, OD is the plumb line passing through point O, OE is the angle bisector of ∠AOB, ∠AOD = arctan (0.5i / h), β = ∠AOE-∠AOD = α / 2-arctan (0.5i / h).

[0031] Each camera uses a fixed-focus lens, and the intersection point of the viewing angle of each camera is fixed.

[0032] The angle of view intersection point is located on the optical axis of the lens. Assuming the focal length of the lens is f, the camera angle of view intersection point is located at the point f where the camera image sensor extends toward the lens.

[0033] The images captured by the two cameras are stretched by [cosβ+sinβ*cot(π / 2-α / 2-β)] times in the horizontal direction.

[0034] The specific calculation is as follows Figure 5 As shown, in triangle ABC, ∠ABC=π / 2-α / 2-β, ∠ACB=π / 2+α / 2, ∠CAB=β, AB=AC*cos∠CAB+AC*sinβ*cot∠ABC= AB=AC*[ cosβ+sinβ*cot (π / 2-α / 2-β)].

[0035] The stretching of the images captured by the two cameras is based on the stitching line of the captured images. The image captured by the left camera is stretched to the left, and the image captured by the right camera is stretched to the right.

[0036] After the aircraft flies a certain distance, the camera below it will take another photo, so that the ground area captured twice can be exactly stitched together in the vertical direction.

[0037] The camera captures video. Example

[0038] As shown in 1-5, a dual-camera combined sea surface aerial photography device is characterized in that it includes an angle adjustment module, a rotating shaft, and two cameras. The two cameras are installed in parallel horizontally under the aircraft. According to the earth coordinates of the aircraft and the relative position between the aircraft camera and the camera, the altitude difference h between the camera and the sea surface directly below it is obtained. Each camera can rotate around its own perspective intersection to adjust the shooting angle. The perspective intersection is the intersection of the reverse extension lines of the horizontal perspective when each camera is imaging. When each camera shoots downward, its respective perspective intersection is located above the camera objective lens. According to the altitude difference h between the camera and the sea surface directly below it, the perspective α of each camera head, and the distance i between the perspective intersections of the two cameras, a rotating shaft is provided at the perspective intersection. The angle adjustment module can make the camera rotate around the rotating shaft, thereby adjusting the rotation angle of each camera around its respective perspective intersection. When the visual axis of each camera is adjusted to an angle β=α / 2-arctan (0.5i / h) with the vertical direction, the ground area photographed by the two cameras is spliced ​​together in the horizontal direction.

[0039] The specific algorithm is as follows Figure 5 As shown, OD is the plumb line passing through point O, OE is the angle bisector of ∠AOB, ∠AOD = arctan (0.5i / h), β = ∠AOE-∠AOD = α / 2-arctan (0.5i / h).

[0040] Each camera uses a fixed-focus lens, and the intersection point of the viewing angle of each camera is fixed.

Claims

1. A dual-camera combined sea surface aerial photography method, comprising the following steps: Get the earth coordinates of the aircraft, where the elevation is converted to altitude; According to the earth coordinates of the aircraft, obtain the altitude of the ground directly below it; Two transversely parallel cameras are installed under the aircraft. According to the earth coordinates of the aircraft and the relative position between the camera and the aircraft camera, the altitude difference h between the camera and the sea surface directly below it is obtained. Each camera can rotate around its own perspective intersection point to adjust the shooting angle. The perspective intersection point is the intersection point of the reverse extension line of the horizontal perspective when each camera is imaging. When each camera shoots downward, its own perspective intersection point is located above the camera objective lens. According to the altitude difference h between the camera and the sea surface directly below it, the perspective α of each camera head, and the distance i between the perspective intersection points of the two cameras, the rotation angle of each camera around its own perspective intersection point is adjusted so that the visual axis of each camera is adjusted to an angle β=α / 2-arctan (0.5i / h) with the vertical direction, so that the ground area photographed by the two cameras is stitched together in the transverse direction.

2. The dual-camera combined sea surface aerial photography method according to claim 1, characterized in that: Each camera uses a fixed-focus lens, and the intersection point of the viewing angle of each camera is fixed.

3. The dual-camera combined sea surface aerial photography method according to claim 2, characterized in that: The angle of view intersection point is located on the optical axis of the lens. Assuming the focal length of the lens is f, the camera angle of view intersection point is located at the point f where the camera image sensor extends toward the lens.

4. The dual-camera combined sea surface aerial photography method according to claim 1, characterized in that: The images captured by the two cameras are stretched by [cosβ+sinβ*cot(π / 2-α / 2-β)] times in the horizontal direction.

5. The dual-camera combined sea surface aerial photography method according to claim 4, characterized in that: The stretching of the images captured by the two cameras is based on the stitching line of the captured images. The image captured by the left camera is stretched to the left, and the image captured by the right camera is stretched to the right.

6. The dual-camera combined sea surface aerial photography method according to claim 1, characterized in that: After the aircraft flies a certain distance, the camera below it will take another photo, so that the ground area captured twice can be exactly stitched together in the vertical direction.

7. The dual-camera combined sea surface aerial photography method according to claim 1, characterized in that: The camera captures video.

8. A dual-camera combined sea surface aerial photography device, characterized by: The invention comprises an angle adjustment module, a rotating shaft, and two cameras. The two cameras are installed in parallel horizontally under the aircraft. According to the earth coordinates of the aircraft and the relative position between the camera and the aircraft camera, the altitude difference h between the camera and the sea surface directly below the camera is obtained. Each camera can rotate around its own view intersection point to adjust the shooting angle. The view intersection point is the intersection point of the reverse extension line of the horizontal view when each camera is imaging. When each camera shoots downward, the respective view intersection point is located above the camera objective lens. According to the altitude difference h between the camera and the sea surface directly below the camera, the view angle α of each camera head, and the distance i between the view intersection points of the two cameras, a rotating shaft is arranged at the view intersection point. The angle adjustment module can make the camera rotate around the rotating shaft, so as to adjust the rotation angle of each camera around its own view intersection point. When the visual axis of each camera is adjusted to an angle β=α / 2-arctan (0.5i / h) with the vertical direction, the ground area photographed by the two cameras is spliced ​​together in the horizontal direction.

9. The dual-camera combined sea surface aerial photography device according to claim 8, characterized in that: Each camera uses a fixed-focus lens, and the intersection point of the viewing angle of each camera is fixed.

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