Sea surface aerial photography device and method

Abstract

The invention mainly solves the problem of how to enable images shot by a plurality of cameras to be accurately spliced during sea surface aerial photography. A sea surface aerial photography device is characterized in that the aerial photography device is loaded under an aircraft, the aerial photography device comprises a guide rail and three cameras, the guide rail is fixed under the aircraft, the guide rail is in a circular arc shape, and the three cameras are arranged 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 radius r of the circular arc. The positions of the cameras on the guide rails are adjusted, so that ground areas shot by the cameras are spliced together in the transverse direction, and at the moment, the visual axes of the cameras on the two sides are adjusted to form included angles beta = 2 * arctan [h * tan alpha / (h + r)] with the vertical direction. The device has the beneficial effects that the guide rail is arc-shaped, and the reverse extension lines of the visual axes of the three cameras intersect at the center of the arc, so that the three cameras have enough adjusting angles when shooting the lower part, and the implementation simplicity and the calculation accuracy are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of aerial photography, and in particular to a device and method for aerial photography of sea surface. 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 accurately combine images taken by multiple cameras during aerial photography of the sea surface.

[0009] A sea surface aerial photography device, characterized in that the aerial photography device is loaded under an aircraft, the aerial photography device comprises a guide rail and three cameras, the guide rail is fixed under the aircraft, the guide rail is in an arc shape, the center of the arc is at the top, the three cameras are mounted on the guide rail, the reverse extension lines of the three camera visual axes intersect at the center of the arc, wherein one camera has a constant position and is always located directly under the aircraft, referred to as the directly below camera, and the other two cameras are located on both sides of the directly below camera and can adjust their positions on the guide rail, referred to as the two side cameras, and the positions of the cameras on the guide rail are adjusted according to the altitude difference h between the directly below camera and the sea surface directly below it, the viewing angle α of each camera, and the radius r of the arc, so that the ground areas photographed by each camera are pieced together in the horizontal direction. At this time, the visual axes of the cameras on both sides are adjusted to an angle β=2*arctan[h*tanα / (h+r)] with the vertical direction.

[0010] The beneficial effect is that the guide rail is in an arc shape, and the reverse extension lines of the three camera visual axes intersect at the center of the arc, so that the three cameras have enough adjustment angles when shooting below, and can achieve accurate splicing shooting in a large range of heights, and ensure the simplicity of implementation and the accuracy of calculation; when the aircraft is at a large height from the sea surface, because there are three cameras shooting in parallel, and they can just be spliced ​​into a complete photo or video, it can achieve a large range and high resolution at the same time, and can quickly and high-resolution photos of the sea surface; the shooting method and image synthesis algorithm between multiple cameras are simple, and the shooting effect and efficiency are greatly improved; because the ground area shot by the three cameras is directly spliced ​​together in the horizontal direction without overlapping areas, the overall shooting range of the three cameras is larger and the shooting efficiency is higher; in addition, the reason why the present invention can ensure the accurate splicing of each camera image under the condition of 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. Since the camera size is usually only about ten centimeters, it is usually negligible compared with the ground width, so it can be regarded as a point during calculation. Of course, based on the concept and principle of the present invention, the number of cameras is variable and all belong to the protection scope of the present invention. According to the definition of Baidu Encyclopedia, an aircraft is a device that flies in the atmosphere or in the space outside the atmosphere (space). The aircraft described in the present invention mainly refers to those that fly in the atmosphere, such as balloons, airplanes (including drones), etc. The specific aircraft can be selected according to the actual situation.

[0011] The intersection points of the reverse extension lines of the viewing angles of each camera are located on the arc line of the circular arc, and the intersection points are located on the optical axes of the lenses of each camera. Each camera adopts a fixed-focus lens, and the intersection points are fixed in position.

[0012] The beneficial effect is that the influence of the camera size is taken into account, and at the same time the radius of the arc is very accurate and strictly complies with the calculation formula, which together ensures the accuracy of the calculation result. 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] Assuming the focal length of the camera lens is f, the intersection point is located at the point f extending from the camera image sensor toward the lens.

[0014] The beneficial effect is that the intersection point, which is also the optical center point of the lens, is accurately located, and the calculation can be performed strictly according to the formula. The intersection point of the reverse extension line of each camera angle of view (hereinafter referred to as the intersection point) can be obtained through experiments or according to relevant parameters of the camera.

[0015] When the camera positions are adjusted, the reverse extension lines of the visual axes of the three cameras always intersect at the center of the arc.

[0016] The beneficial effects are that the geometric relationship is strictly guaranteed, the calculation is accurate, and the measurement accuracy is high.

[0017] A method for aerial photography of sea surface comprises the following steps: Assume that the width of the ground captured by the camera directly below is k, where k is known and k=2(h*tanα+d / 2); According to the ground width k, the altitude difference between the camera directly below and the sea surface directly below it is obtained as h=0.5k / tanα, and the flight altitude of the aircraft is determined; Adjust and fix the visual axes of the cameras on both sides to an angle β with the vertical direction, so that β=2*arctan[h*tanα / (h+r)]; The ground areas captured by each camera are stitched together in the horizontal direction.

[0018] The beneficial effect is that the visual axes of the cameras on both sides can be adjusted and fixed to an angle β with the vertical direction before aerial photography, and no adjustment is required during aerial photography, which is simple to operate and easy to implement; the guide rail is in an arc shape, and the reverse extension lines of the visual axes of the three cameras intersect at the center of the arc, so that the three cameras have sufficient adjustment angles when shooting below, and accurate stitching shooting can be achieved within a wide range of heights, and the simplicity of implementation and the accuracy of calculation are guaranteed; when the aircraft is at a large altitude from the sea surface, because there are three cameras shooting in parallel, and they can just be stitched into a complete photo or video, it can be simultaneously Achieve wide range and high resolution, and can take photos of the sea surface quickly and with high resolution; because the ground areas photographed by the three cameras are directly stitched together in the horizontal direction without overlapping areas, the overall shooting range of the three cameras is larger and the shooting efficiency is higher; the shooting method and image synthesis algorithm between multiple cameras are simple, and the shooting effect and efficiency are greatly improved; in addition, the reason why the present invention can ensure the accurate stitching of the images of each camera at a height of 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. The k is known, which means that the ground width photographed by the camera directly below can be determined in advance according to the requirements of the sea surface aerial photography project.

[0019] The images taken by the cameras on both sides are stretched in the horizontal direction by [cosβ+sinβ*cot∠(π / 2-β-α / 2)] times.

[0020] 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 cameras on both sides are stretched in the horizontal direction.

[0021] The stretching of the images taken by the cameras on both sides is based on the stitching line of the images taken by the camera directly below, the image taken by the left camera is stretched to the left, and the image taken by the right camera is stretched to the right.

[0022] The beneficial effect is that it not only ensures the accurate splicing of the images taken by the three cameras, but also ensures that the coordinates of each point on the image match those on the ground, and the operation and algorithm are very simple. It is just that the lateral resolution of the images on both sides will decrease due to lateral stretching, but usually the stretching ratio is not large, and the lateral resolution decrease is not large, which basically does not affect the overall sea surface aerial photography effect.

[0023] 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.

[0024] The beneficial effect is that continuous aerial photography images in the flight direction can be formed.

[0025] The camera captures video.

[0026] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 . A schematic diagram of the structure of a sea surface aerial photography device; Figure 2 . A schematic diagram of the shooting principle of a sea surface aerial photography device (the center O is the center of the arc-shaped guide rail); Figure 3 . A partial enlarged diagram of the arc center (point J is the intersection of the reverse extension lines of the camera angles); Figure 4 .Sketch of camera installation location; Figure 5 .Calculation principle diagram.

[0028] In the figure: 1. Aircraft, 2. Sea surface aerial photography device, 21. Guide rail, 22. Camera, 221. Lens, 222. Image sensor. DETAILED DESCRIPTION Example

[0029] As shown in 1-5, a sea surface aerial photography device is characterized in that the aerial photography device is loaded under an aircraft, the aerial photography device includes a guide rail and three cameras, the guide rail is fixed under the aircraft, the guide rail is arc-shaped, the center of the arc is at the top, the three cameras are mounted on the guide rail, and the reverse extension lines of the visual axes of the three cameras intersect at the center of the arc, wherein one camera has a constant position and is always located directly below the aircraft, referred to as the directly below camera, and the other two cameras are located on both sides of the directly below camera and can adjust their positions on the guide rail, referred to as the two side cameras, and the positions of the cameras on the guide rail are adjusted according to the altitude difference h between the directly below camera and the sea surface directly below it, the viewing angle α of each camera, and the radius r of the arc, so that the ground areas photographed by each camera are stitched together in the horizontal direction. At this time, the visual axes of the cameras on both sides are adjusted to an angle β=2*arctan[h*tanα / (h+r)] with the vertical direction.

[0030] The calculation principle is as follows Figure 5As shown, the width of the ground captured by the camera directly below is k=2h*tanα, and the visual axes of the cameras on both sides are adjusted to an angle β=2*arctan[(0.5*k / (h+r)] = 2*arctan[h*tanα / (h+r)] with the vertical direction.

[0031] like Figure 4 As shown, the intersection of the reverse extension lines of the viewing angles of each camera is located on the arc line of the arc, and the intersection is located on the optical axis of each camera lens. Each camera uses a fixed-focus lens, and the intersection is fixed in position. Assuming the focal length of the camera lens is f, the intersection is located at the point where the camera image sensor extends toward the lens.

[0032] When the camera positions are adjusted, the reverse extension lines of the visual axes of the three cameras always intersect at the center of the arc. Example

[0033] like Figure 1-5 As shown, a method for aerial photography of sea surface comprises the following steps: Assume that the width of the ground captured by the camera directly below is k, where k is known and k=2h*tanα; According to the ground width k, the altitude difference between the camera directly below and the sea surface directly below it is obtained h=(k / tanα, to determine the flight altitude of the aircraft; Adjust and fix the visual axes of the cameras on both sides to an angle β with the vertical direction, so that β=2*arctan[h*tanα / (h+r)]; The ground areas captured by each camera are stitched together in the horizontal direction.

[0034] The calculation principle is as follows Figure 5 As shown, the width of the ground captured by the camera directly below is k=2h*tanα, and the altitude difference between the camera directly below and the sea surface directly below it is h=0.5k / tanα, so the visual axes of the cameras on both sides are adjusted to an angle β=2*arctan[(0.5*k / (h+r)] =2*arctan[h*tanα / (h+r)] with the vertical direction.

[0035] The images taken by the cameras on both sides are stretched in the horizontal direction by [cosβ+sinβ*cot∠(π / 2-β-α / 2)] times.

[0036] The calculation principle is as follows Figure 5As shown, in triangle ABC, ∠CAB=β, ∠ABC=π / 2-β-α / 2, therefore, AB=AC*cos∠CAB+AC*sin∠CAB*cot∠ABC=AC*[cosβ+sinβ*cot∠(π / 2-β-α / 2)], therefore, the images taken by the cameras on both sides are stretched [cosβ+sinβ*cot∠(π / 2-β-α / 2)] times in the horizontal direction.

[0037] The stretching of the images taken by the cameras on both sides is based on the stitching line of the images taken by the camera directly below, the image taken by the left camera is stretched to the left, and the image taken by the right camera is stretched to the right.

[0038] 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.

[0039] The camera captures video.

Claims

1. A sea surface aerial photography device, characterized in that: The aerial photography device is loaded under the aircraft, and includes a guide rail and three cameras. The guide rail is fixed under the aircraft, and is in an arc shape with the center of the arc at the top. The three cameras are mounted on the guide rail, and the reverse extension lines of the visual axes of the three cameras intersect at the center of the arc. Among them, one camera remains in a constant position and is always located directly below the aircraft, referred to as the directly below camera. The other two cameras are located on both sides of the directly below camera and can be adjusted on the guide rail, referred to as the two side cameras. The positions of the cameras on the guide rail are adjusted according to the altitude difference h between the directly below camera and the sea surface directly below it, the viewing angle α of each camera, and the radius r of the arc, so that the ground areas photographed by each camera are stitched together in the horizontal direction. At this time, the visual axes of the cameras on both sides are adjusted to an angle β=2*arctan[h*tanα / (h+r)] with the vertical direction.

2. A sea surface aerial photography device according to claim 1, characterized in that: The intersection points of the reverse extension lines of the viewing angles of each camera are located on the arc line of the circular arc, and the intersection points are located on the optical axes of the lenses of each camera. Each camera adopts a fixed-focus lens, and the intersection points are fixed in position.

3. The sea surface aerial photography device according to claim 2 is characterized in that: The focal length of the camera lens is f, and the intersection point is located at the point f where the camera image sensor extends toward the lens.

4. The sea surface aerial photography device according to claim 1, characterized in that: When the camera positions are adjusted, the reverse extension lines of the visual axes of the three cameras always intersect at the center of the arc.

5. The aerial photography method of the sea surface aerial photography device according to claim 1, characterized in that: The steps include: Assume that the width of the ground captured by the camera directly below is k, where k is known and k=2(h*tanα+d / 2); According to the ground width k, the altitude difference between the camera directly below and the sea surface directly below it is obtained as h=0.5k / tanα, and the flight altitude of the aircraft is determined; Adjust and fix the visual axes of the cameras on both sides to an angle β with the vertical direction, so that β=2*arctan[h*tanα / (h+r)]; The ground areas captured by each camera are stitched together in the horizontal direction.

6. The aerial photography method of the sea surface aerial photography device according to claim 5, characterized in that: The images taken by the cameras on both sides are stretched in the horizontal direction by [cosβ+sinβ*cot∠(π / 2-β-α / 2)] times.

7. The aerial photography method of the sea surface aerial photography device according to claim 6, characterized in that: The stretching of the images taken by the cameras on both sides is based on the stitching line of the images taken by the camera directly below, the image taken by the left camera is stretched to the left, and the image taken by the right camera is stretched to the right.

8. The aerial photography method of the sea surface aerial photography device according to claim 5, 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.

9. The aerial photography method of the sea surface aerial photography device according to claim 5, characterized in that: The camera captures video.

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