Unmanned aerial vehicle large-width oblique photography system and operation method suitable for plateau environment

Abstract

This invention relates to the field of UAV aerial photogrammetry technology, and proposes a wide-angle oblique photogrammetry system and operation method suitable for high-altitude environments. By integrating a fixed-wing UAV, an ultra-wide-angle oblique photogrammetry aerial camera, a ground control station, and a data processor, an integrated aerial photography system specifically designed for high-altitude environments is formed. Multiple cameras are arranged in two groups along the flight direction, front and rear, with multi-angle oblique configurations, enabling an ultra-wide-angle image acquisition range and significantly improving the efficiency of single-shot acquisition coverage. The ground control station integrates flight path planning and mission monitoring functions, allowing for pre-planning of optimal flight paths for the target survey area and real-time adjustments during flight to cope with complex weather conditions such as strong winds and sandstorms at high altitudes. The data processor directly performs 3D modeling on the acquired oblique images and outputs 3D mapping results, achieving a seamless workflow from image acquisition to 3D model generation.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) aerial photogrammetry technology, and in particular to a UAV wide-swath oblique photography system and operation method suitable for high-altitude environments. Background Technology

[0002] As one of the core technologies in the field of aerial photogrammetry, UAV oblique photogrammetry technology has been widely used in various fields such as topographic mapping, urban planning, disaster monitoring, resource exploration in plateau areas, and ecological protection. Its core principle is to use a UAV equipped with a multi-lens oblique camera to collect ground images from different angles, thereby generating a high-precision three-dimensional model to meet the actual needs of large-area mapping.

[0003] However, the high-altitude environment poses severe technical challenges to UAV aerial photography systems. Taking the Sanjiangyuan National Park on the Qinghai-Tibet Plateau as an example, the area's altitude is 4000-4800 meters, with an air pressure of only 60-65 kPa. The air density and oxygen content are less than half that of the plains, leading to a severe reduction in the power of conventional UAV engines and a significant decrease in service ceiling and endurance. Simultaneously, the region experiences frequent strong winds exceeding level 7, intense solar radiation, frequent sandstorms in spring, and fog and mist in the river valleys during summer. The terrain encompasses complex landforms including plateau hills, river valley wetlands, and high-altitude permafrost.

[0004] Existing oblique photogrammetry techniques mostly focus on conventional environments such as plains and cities, lacking systematic design for harsh conditions such as low air pressure, strong winds, dust storms, and strong radiation at high altitudes, and also lacking corresponding specialized aerial photography methods. Therefore, there is an urgent need for an oblique photogrammetry system and method that can adapt to the complex environment of high altitudes, has wide-swath acquisition capabilities, and is equipped with standardized operating procedures. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a wide-swath oblique photography system and operation method for unmanned aerial vehicles (UAVs) suitable for high-altitude environments, so as to solve the above-mentioned technical problem.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A UAV wide-angle oblique photography system suitable for plateau environments includes a fixed-wing UAV, an ultra-wide-angle oblique photography aerial camera, a ground control station, and a data processor; the fixed-wing UAV is used to carry the ultra-wide-angle oblique photography aerial camera; the ultra-wide-angle oblique photography aerial camera is used to acquire oblique images of a target survey area, and the ultra-wide-angle oblique photography aerial camera includes multiple cameras, which are divided into two groups along the flight direction of the fixed-wing UAV and are configured at multiple angles to form an ultra-wide-angle image acquisition range; the ground control station is used to plan and generate the flight path of the fixed-wing UAV in the target survey area, and to monitor and adjust the flight mission of the fixed-wing UAV and the image acquisition mission of the ultra-wide-angle oblique photography aerial camera; the data processor is used to perform three-dimensional modeling on the oblique images acquired by the ultra-wide-angle oblique photography aerial camera to generate three-dimensional mapping results for the target survey area.

[0007] Based on the above technical solution, the present invention can be further improved as follows.

[0008] Furthermore, the multiple cameras consist of six cameras, each a full-frame CMOS camera; the six cameras are divided into a front group and a rear group along the flight direction of the fixed-wing UAV, with three cameras in each group; the middle camera in the front group is tilted forward by 30° relative to the vertical downward direction, and the two side cameras in the front group are tilted forward by 30° and then tilted to the left and right by 29° respectively, so that the image overlap between the side cameras and the middle camera is greater than or equal to 20%; the three cameras in the rear group are symmetrically arranged in the opposite direction to the three cameras in the front group.

[0009] Furthermore, the fixed-wing UAV adopts a full carbon fiber composite fuselage and is equipped with a sand and dust protection structure. The power system of the fixed-wing UAV includes a high-altitude adapted electronic fuel injection engine.

[0010] Furthermore, each camera lens is equipped with a UV protection coating.

[0011] Furthermore, the data processor is equipped with data processing software, which is used to identify and remove cloud shadows, blemishes, overexposed areas or hazy areas in the acquired oblique images to obtain preprocessed images; and to perform three-dimensional modeling based on the preprocessed images to generate three-dimensional point clouds, and to perform point cloud filtering processing on the areas in the three-dimensional point clouds that correspond to plateau permafrost or wetland landforms.

[0012] To address the aforementioned technical problems, this invention also provides a method for UAV wide-swath oblique photography operations suitable for high-altitude environments. This method employs the aforementioned UAV wide-swath oblique photography system suitable for high-altitude environments, comprising: transporting the fixed-wing UAV and the ultra-wide-angle oblique photography aerial camera to a high-altitude operation base for high-altitude-specific test flights and debugging; using the ground control station to plan and generate the flight path of the fixed-wing UAV within the target survey area; controlling the fixed-wing UAV to execute flight missions according to the flight path and controlling the ultra-wide-angle oblique photography aerial camera to execute image acquisition missions; during the flight of the fixed-wing UAV, using the ground control station to monitor and adjust the flight mission of the fixed-wing UAV and the image acquisition mission of the ultra-wide-angle oblique photography aerial camera; importing the oblique images acquired by the ultra-wide-angle oblique photography aerial camera into the data processor for 3D modeling, and outputting 3D mapping results for the target survey area.

[0013] Furthermore, the step of using the ground control station to plan and generate the flight path of the fixed-wing UAV within the target survey area includes: dividing the target survey area into multiple sub-areas, and setting at least one emergency return point for each sub-area to obtain zoning information; for each sub-area, generating a flight path adapted to the terrain type of the sub-area in the ground control station based on the zoning information; and obtaining the flight path of the fixed-wing UAV within the target survey area based on the flight paths of each sub-area.

[0014] Furthermore, for each sub-region, based on the zoning information, a flight path adapted to the terrain type of the sub-region is generated in the ground control station, including: when the terrain type of the sub-region is a river valley, a forward flight path is generated based on the zoning information, wherein the forward flight path is a flight path whose direction follows the direction of the river valley; when the terrain type of the sub-region is a hilly terrain, a contour line flight path is generated based on the zoning information, wherein the contour line flight path is a flight path laid out along the contour line direction of the hilly terrain.

[0015] Furthermore, before importing the oblique images acquired by the ultra-wide-angle oblique photography aerial camera into the data processor for 3D modeling, the method further includes: performing a quality check on the oblique images acquired by the ultra-wide-angle oblique photography aerial camera, the quality check including at least checking for the existence of mapping loopholes; when mapping loopholes exist and the mapping loopholes are located in plateau and hilly areas, a first supplementary photography route is formulated based on a first supplementary photography rule, and the fixed-wing UAV is controlled to perform supplementary photography flights according to the first supplementary photography route, the first supplementary photography rule being that the supplementary photography range exceeds the area where the mapping loophole is located by three baselines; when mapping loopholes exist and the mapping loopholes are located in river valley wetland areas, a second supplementary photography route is formulated based on a second supplementary photography rule, and the fixed-wing UAV is controlled to perform supplementary photography flights according to the second supplementary photography route, the second supplementary photography rule being that the supplementary photography range exceeds the area where the mapping loophole is located by two baselines.

[0016] Furthermore, the quality check also includes: checking the image clarity, checking whether the forward overlap reaches a first preset threshold, and checking whether the lateral overlap reaches a second preset threshold.

[0017] The beneficial effects of this invention are as follows: By integrating a fixed-wing UAV, an ultra-wide-angle oblique photography aerial camera, a ground control station, and a data processor, an integrated aerial photography system specifically designed for high-altitude environments is formed. Multiple cameras are arranged in two groups, front and rear, along the flight direction and tilted at multiple angles, enabling an ultra-wide-angle image acquisition range and significantly improving the efficiency of single-shot acquisition coverage. The ground control station integrates flight path planning and mission monitoring functions, allowing for pre-planning of the optimal flight path for the target survey area and real-time adjustments during flight to cope with complex weather conditions such as strong winds and sandstorms at high altitudes. The data processor directly performs 3D modeling on the acquired oblique images and outputs 3D mapping results, achieving a seamless workflow from image acquisition to 3D model generation. This system comprehensively solves the technical challenges of small swath width and low operational efficiency in high-altitude environments, exhibiting significant advantages in high integration, high efficiency, and high reliability. Attached Figure Description

[0018] Figure 1 This is a comparison diagram of images acquired by the monocular camera and the hexanocular camera of the present invention; Figure 2 This is a schematic diagram of the flight path within the sub-region of the present invention; Figure 3 This is a schematic diagram of image overlap control according to the present invention; Figure 4 This is a flowchart of the UAV wide-swath oblique photography method applicable to plateau environments according to the present invention. Detailed Implementation

[0019] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0020] As mentioned earlier, existing oblique photogrammetry technologies mostly focus on conventional environments such as plains and cities, lacking specific designs for plateau environments like the Three-River-Source Region. While existing technologies have made improvements in individual aspects such as oblique photogrammetry accuracy and UAV flight performance, none have formed an integrated UAV wide-swath oblique photogrammetry system adapted to plateau environments, and there is a lack of corresponding specialized operational methods. Therefore, they cannot meet the actual needs of large-area, high-precision aerial photography in plateau regions, and specifically suffer from the following prominent shortcomings: 1. Existing UAV platforms are mostly designed for conventional plains environments, and their power systems have not been optimized for high-altitude conditions. They struggle to adapt to the low-pressure, strong-wind environments above 4000 meters in the Sanjiangyuan region, resulting in difficulties with takeoff and poor flight stability. This makes it impossible to guarantee image clarity and data acquisition continuity during oblique photography. 2. Traditional oblique photography cameras typically use 3-5 lenses, resulting in a narrow swath width (typically less than 300 meters per swath). For mapping large areas of the Sanjiangyuan region, frequent route planning and multiple flights are required, increasing operational costs and time, and increasing the risk of damage from repeated flights. 3. Existing camera composite resolution is low, making it difficult to achieve high-precision acquisition with a ground resolution better than 8 cm in the large-scale aerial photography scenario of the Three-River-Source region, and failing to meet the needs of 1:500 topographic mapping and refined 3D modeling; 4. There is a lack of specialized aerial photography operation methods for the special meteorological and topographical environment of the Three-River-Source region. There are technical gaps in aerial photography zoning, route planning, flight time selection, image quality control and supplementary photography mechanisms, which cannot adapt to the complex terrain and variable weather conditions of the Three-River-Source region, and are prone to unqualified aerial photography data and low operation efficiency.

[0021] Example 1 Based on this, this embodiment provides a UAV wide-angle oblique photography system suitable for plateau environments, including a fixed-wing UAV, an ultra-wide-angle oblique photography aerial camera, a ground control station, and a data processor. The fixed-wing UAV carries the ultra-wide-angle oblique photography aerial camera. The ultra-wide-angle oblique photography aerial camera is used to acquire oblique images of the target survey area. The ultra-wide-angle oblique photography aerial camera includes multiple cameras, which are divided into two groups along the flight direction of the fixed-wing UAV and are configured at multiple angles to form an ultra-wide-angle image acquisition range. The ground control station is used to plan and generate the flight path of the fixed-wing UAV in the target survey area, and to monitor and adjust the flight mission of the fixed-wing UAV and the image acquisition mission of the ultra-wide-angle oblique photography aerial camera. The data processor is used to perform 3D modeling on the oblique images acquired by the ultra-wide-angle oblique photography aerial camera to generate 3D mapping results for the target survey area.

[0022] Optionally, in the embodiments, the fixed-wing UAV adopts a full carbon fiber composite fuselage and is equipped with a sand and dust protection structure. The power system of the fixed-wing UAV includes a high-altitude-adaptive electronic fuel injection engine.

[0023] Specifically, the DM150 fixed-wing UAV is used as the flight platform. The UAV's fuselage is made of a single piece of all-carbon fiber composite material, balancing lightweight and structural strength, and is equipped with sand and dust protection structures (for example, key components such as flight control, electronic speed controller, and battery compartment are fully sealed, and all interfaces are fitted with sealing rings to prevent sand and dust intrusion), which can effectively adapt to high-altitude, low-pressure, strong wind, and sand and dust environments.

[0024] In this embodiment, the specific parameters are: wingspan 400cm, fuselage length 226cm, height 57cm, standard takeoff weight 25kg, maximum mission payload not less than 9kg, and capable of stably carrying an ultra-wide-angle oblique photography aerial camera and supporting GPS / POS positioning equipment and communication equipment.

[0025] In terms of power system, the UAV is equipped with a high-altitude-adaptive electronic fuel injection engine, which can maintain stable power output under low air pressure conditions, ensuring normal takeoff at an altitude of 4,500 meters. Its service ceiling reaches 6,500 meters, and its wind resistance capability was tested at 4,400 meters in the Lancang River source area of ​​the Three-River-Source Region, reaching level 7.5. It can stably adapt to high-altitude operational scenarios above 4,000 meters, with an endurance of no less than 3 hours, effectively overcoming the problem of decreased flight stability caused by strong winds at high altitudes, and ensuring the continuity and clarity of image acquisition.

[0026] Through the use of a full carbon fiber fuselage, sand and dust protection modifications, and aerodynamic optimization specifically for the Sanjiangyuan region, the problems of existing drones being unable to adapt to the high-altitude environment of the Sanjiangyuan region, insufficient power, and poor endurance have been effectively solved. It can stably adapt to complex environments such as the Sanjiangyuan region on the Qinghai-Tibet Plateau and overcome the environmental impacts of strong winds, sandstorms, and strong radiation in the Sanjiangyuan region.

[0027] Optionally, in this embodiment, the multiple cameras are six cameras, each of which is a full-frame CMOS camera; the six cameras are divided into a front group and a rear group along the flight direction of the fixed-wing UAV, with three cameras in each group; wherein, the middle camera of the front group is tilted forward by 30° relative to the vertical downward direction, and the two side cameras of the front group are tilted forward by 30° and then tilted to the left and right by 29° respectively, so that the image overlap between the side cameras and the middle camera is greater than or equal to 20%; the three cameras in the rear group are symmetrically reversed to the three cameras in the front group.

[0028] In this embodiment, the KG661 ultra-wide-angle tilting aerial camera is used, which adopts a 6-camera integrated design to replace the traditional 3-5 lens configuration, in order to solve the technical problems of small swath width and insufficient composite resolution.

[0029] The aerial camera is configured in two symmetrical groups, each with three full-frame CMOS cameras. Specifically, the middle camera in the front group is tilted forward 30° relative to the vertical direction, the left camera is tilted forward 30° and then to the left 29°, and the right camera is tilted forward 30° and then to the right 29°. The three cameras in the rear group are configured symmetrically in reverse to the front group; the middle camera is tilted backward 30° relative to the vertical direction, and the two side cameras are tilted backward 30° and then to the left and right respectively, each tilting 29°. This angle configuration ensures that the image overlap between the left / right cameras and the middle camera is no less than 20%, providing sufficient overlap area for subsequent image stitching and 3D modeling, and avoiding stitching defects.

[0030] Each camera uses a 61-megapixel full-frame CMOS sensor with a resolution of 9600×6400, and the total combined resolution of the six cameras is no less than 307.2 million pixels. The combined CMOS sensor size is 88.8mm×47.6mm. Oblique photogrammetry, by mounting multiple sensors on the same flight platform, simultaneously acquires images from vertical and multiple oblique angles, enabling the acquisition of higher resolution, a wider field of view, and more detailed ground information data than traditional methods. Figure 1 As shown.

[0031] At an altitude of 1000 meters, a single image capture covers a length of 1860 meters and a width of 475 meters, far exceeding the conventional 300-meter swath width of traditional 3-5 lens oblique photography systems. The six-lens oblique photography camera, due to its significantly increased downward-looking swath width and the horizontally increased swath width of the left and right oblique cameras, allows for improved flight path spacing compared to traditional five-camera systems. This reduces the number of flight paths in the same area, greatly shortening operation time and improving data acquisition efficiency.

[0032] like Figure 3 As shown, in terms of image quality, the actual measured ground resolution of the Sanjiangyuan region is 7.8 cm, which is better than 8 cm. The forward overlap is 79% and the lateral overlap is 66%, which can meet the requirements of 1:500 high-precision topographic mapping and the refined 3D modeling required for ecological monitoring of the Sanjiangyuan region. This significantly reduces the number of flight routes and flights, and reduces data redundancy.

[0033] The DM150 fixed-wing UAV platform, which has a 3-hour flight time under a 9kg payload, is equipped with a KG661 6-camera aerial camera. Compared with the traditional 5-lens solution, the flight time in the 50km×50km survey area of ​​the Three Rivers Source Region is reduced from 95 hours to 32 hours, the operation efficiency is increased by 66.3%, and the amount of data is reduced by 2 / 3. This significantly reduces the time and manpower costs of field operations on the Three Rivers Source Plateau, making it more practical.

[0034] Optionally, in this embodiment, each camera lens is equipped with a UV protection coating.

[0035] High-altitude areas experience strong solar radiation and significantly higher ultraviolet (UV) intensity compared to plains areas. Ordinary lenses exposed to strong UV radiation suffer from decreased image quality and coating aging. UV-protective coatings effectively filter harmful UV rays, protecting optical components, ensuring image clarity and color reproduction, and extending lens lifespan.

[0036] The ground control station integrates a flight path planning module. Using specialized software (such as GIS software) deployed within this module, the survey area is divided into multiple independent sub-areas based on topographic relief, meteorological conditions, and airspace management requirements. This division follows four principles: terrain consistency, flight efficiency, meteorological adaptability, and airspace management. Clear operational boundaries are defined for each sub-area, and each sub-area has at least two emergency return points located at either end to respond to sudden weather changes such as strong winds, sandstorms, or fog, ensuring flight safety.

[0037] like Figure 2 As shown, the flight path layout is based on dedicated ground station software, which can automatically generate the optimal flight path according to the survey area. For river valley terrain, a forward flight path is generated (the flight path direction is basically consistent with the valley direction), and for hilly terrain, a contour flight path is generated (the flight path is laid out along the contour lines of the hilly terrain). Flight parameters are set as follows: cruising speed 80-120 km / h, climb and descent speed 5 m / s, turning bank angle not exceeding 15°, and lateral coverage exceeding the sub-area boundary by no less than 50% of the image frame width to avoid mapping omissions. After the flight path is generated, manual verification is supported to ensure that there are no overlapping or omitted areas.

[0038] The ground control station also integrates a real-time monitoring module, an emergency control module, and a POS system calibration module. The real-time monitoring module provides real-time feedback on the UAV's flight attitude, altitude, cruising speed, aerial photography parameters, and GPS signal reception status. The emergency control module can initiate an emergency return-to-home procedure when the UAV experiences flight anomalies or encounters sudden strong winds (exceeding force 7), controlling the UAV to return to the nearest emergency return-to-home point, ensuring equipment and data security. The POS system calibration module can perform real-time calibration of the positioning system, avoiding positioning deviations caused by the complex terrain of the plateau. The ground control station can operate normally in extreme environments ranging from -20℃ to 50℃ at altitudes of 5000 meters, fully adapting to the needs of plateau field operations.

[0039] Optionally, in an embodiment, the data processor is equipped with data processing software, which is used to identify and remove cloud shadows, blemishes, overexposed areas or hazy areas in the acquired oblique images to obtain preprocessed images; and to perform three-dimensional modeling based on the preprocessed images to generate three-dimensional point clouds, and to perform point cloud filtering processing on the areas in the three-dimensional point clouds that correspond to plateau permafrost or wetland landforms.

[0040] Specifically, the three-dimensional mapping results include at least one of the following: three-dimensional model, digital surface model, digital elevation model, orthophoto, and topographic map.

[0041] The data processor utilizes a 50-node high-performance server configuration, possessing efficient image stitching and 3D modeling capabilities. It can rapidly process massive amounts of image data collected from large-area aerial photography in the Sanjiangyuan region. Built-in data processing software automatically removes interference factors such as cloud shadows, blemishes, overexposed areas with strong radiation, and blurred areas due to river valley fog, ensuring seamless image stitching, improving data processing efficiency, and adapting to the data processing needs of operations in the Sanjiangyuan region. For the alpine permafrost and river valley wetland landforms of the Sanjiangyuan region, a topographic freeze-thaw zone point cloud filtering function has been added, with a filtering threshold set to 0.3m to improve model accuracy.

[0042] The data processing software possesses efficient image preprocessing, 3D modeling, and data verification capabilities, enabling rapid processing of massive amounts of image data collected from large-area aerial photography of the plateau. The software has the following functions: First, it automatically identifies and removes cloud shadows, blemishes, overexposed areas, or blurred areas due to haze from the acquired oblique images, obtaining preprocessed images. Second, it performs 3D modeling based on the preprocessed images to generate 3D point clouds. Finally, it performs point cloud filtering on areas in the 3D point cloud corresponding to plateau permafrost or wetland landforms, with a filtering threshold set to 0.3m. Simultaneously, it can verify the accuracy of the 3D model and surveying data to ensure that the output meets operational requirements.

[0043] The presence of interfering factors such as cloud shadows, blemishes, overexposed areas, or blurred areas due to haze can affect the accuracy of 3D reconstruction. Data processing software significantly improves the accuracy and efficiency of subsequent 3D modeling by automatically identifying and removing these interfering areas.

[0044] Example 2 like Figure 4 As shown, this embodiment provides a method for UAV wide-swath oblique photography suitable for high-altitude environments, employing a UAV wide-swath oblique photography system suitable for high-altitude environments as described in Embodiment 1, including: S101. After transporting the fixed-wing UAV and ultra-wide-angle oblique photography aerial camera to the plateau operation base, conduct plateau-specific test flights and debugging.

[0045] S102. Use the ground control station to plan and generate the flight path of the fixed-wing UAV in the target survey area.

[0046] S103. Control the fixed-wing UAV to perform flight missions according to the flight path, and control the ultra-wide-angle oblique photography aerial camera to perform image acquisition missions.

[0047] S104. During the flight of the fixed-wing UAV, the ground control station is used to monitor and adjust the flight mission of the fixed-wing UAV and the image acquisition mission of the ultra-wide-angle oblique photography aerial camera.

[0048] S105. Import the oblique images acquired by the ultra-wide-angle oblique photography aerial camera into the data processor for 3D modeling, and output the 3D mapping results for the target survey area.

[0049] Specifically, after transporting fixed-wing UAVs and ultra-wide-angle oblique photography aerial cameras to the high-altitude operation base (altitude ≥ 4000m), a comprehensive inspection of all equipment is carried out. The focus is on inspecting the oil circuit, electrical circuit, and sand and dust prevention modification components of the UAV power system; the lens cleanliness, UV protection coating, and imaging system of the oblique photography aerial camera; the signal reception capability of the GPS / POS positioning system; and the communication connection status between the ground control station and the UAV.

[0050] Subsequently, high-altitude-specific test flights and adjustments were conducted. These included gradually increasing the flight altitude from 1000 meters to 3000 meters to verify the UAV's takeoff performance and flight stability in low-pressure environments, calibrating the POS system initialization accuracy and GPS signal reception stability, and adjusting camera exposure parameters to adapt to the high-altitude, high-radiation environment. Simultaneously, the imaging effect of the oblique photography aerial camera was verified during the test flights to ensure image clarity met standards.

[0051] Optionally, in an embodiment, the fixed-wing UAV is planned and generated using a ground control station, including: dividing the target survey area into multiple sub-areas and setting at least one emergency return point for each sub-area to obtain zoning information; for each sub-area, generating a flight path adapted to the terrain type of the sub-area in the ground control station based on the zoning information; and obtaining the flight path of the fixed-wing UAV in the target survey area based on the flight paths of each sub-area.

[0052] Optionally, in the embodiment, for each sub-area, a flight path adapted to the terrain type of the sub-area is generated in the ground control station according to the zoning information, including: when the terrain type of the sub-area is a valley, a forward flight path is generated according to the zoning information, and the forward flight path is a flight path whose direction follows the valley direction; when the terrain type of the sub-area is a hilly area, a contour line flight path is generated according to the zoning information, and the contour line flight path is a flight path laid out along the contour line direction of the hilly area.

[0053] A valley-following flight path refers to a flight path that generally aligns with the direction of the valley. Valley areas often experience canyon winds, with wind direction closely mirroring the valley's orientation. Flying in the valley direction reduces headwind time, lowers power consumption, and improves flight stability and endurance. A hilly contour line flight path involves following the contour lines of hilly terrain. Hilly areas have significant topographic relief; flying along contour lines maintains a relatively constant relative altitude between the UAV and the ground, avoiding issues like reduced overlap or inconsistent ground resolution caused by terrain undulations. Lateral coverage extends at least 50% of the image frame width beyond the sub-region boundary to ensure complete image coverage of the survey area's edges and prevent mapping omissions.

[0054] A 50km x 50km survey area was selected in the Lancang River source region of Zaduo County, Yushu Prefecture, within the Sanjiangyuan National Park (encompassing typical landforms such as plateau mountains, river valley wetlands, and high-altitude permafrost). Considering the topographic relief, meteorological conditions (prevailing wind direction, river valley fog distribution), and airspace management requirements, the entire survey area was divided into multiple independent sub-areas using the flight path planning module of the ground control station. Each sub-area had clearly defined operational boundaries, and an emergency return point was set at each end of the sub-area to obtain zoning information. The overlap between sub-areas was no less than 10% to avoid mapping blind spots.

[0055] In this embodiment, the entire survey area is divided into 8 independent sub-areas, each measuring approximately 6.25km × 50km, ensuring that the overlap between sub-areas is no less than 10% to avoid surveying blind spots. Each sub-area has clearly defined operational boundaries and two emergency return points (located at opposite ends of the sub-area) to cope with sudden meteorological disasters such as strong winds, sandstorms, and valley fog in the Three-River-Source region, ensuring flight safety.

[0056] For each sub-region, a flight path adapted to the terrain type of the sub-region is generated at the ground control station based on the sub-region information. Based on the flight paths of each sub-region, the complete flight path of the fixed-wing UAV within the target survey area is obtained. Flight parameters are set as follows: cruising speed 80-120 km / h, climb / descent speed 5 m / s, turning bank angle not exceeding 15°, and lateral coverage extending beyond the sub-region boundary by at least 50% of the image width.

[0057] In this embodiment, the survey area boundary and zoning information are imported into the ground control station software. Considering the characteristics of strong solar radiation and significant terrain shadows on the plateau, optimal flight parameters are set: flight altitude 1000 meters, cruising speed 110 km / h, climb and descent speed 5 m / s, turning angle not exceeding 15°, and lateral coverage extending at least 50% beyond the survey area boundary. Flight routes are automatically generated through the flight path planning module, resulting in 67 routes totaling 53 km in length. The route direction aligns with the terrain of the survey area, reducing UAV headwind flight time and power consumption. The total range is 3551 km, with an estimated flight time of 32 hours. After flight path planning is completed, operators manually verify the routes to ensure no overlapping routes or missed areas, guaranteeing a reasonable and efficient flight path design.

[0058] The system controls the fixed-wing UAV to execute flight missions along planned routes and controls the ultra-wide-angle oblique photography aerial camera to perform image acquisition missions. During flight, the ground control station monitors and adjusts the flight missions of the fixed-wing UAV and the image acquisition missions of the ultra-wide-angle oblique photography aerial camera.

[0059] Specifically, operators monitor the UAV's flight attitude, altitude, speed, and wind resistance in real time via a ground control station, controlling the UAV's ascent and descent rates to not exceed 9 m / s to ensure flight stability. Based on monitoring results, flight speed is adjusted or an emergency return-to-home procedure is initiated, while camera exposure parameters are adjusted according to image quality. During flight, camera exposure is monitored synchronously, with exposure intervals controlled at 0.7 seconds to ensure image point displacement does not exceed 1.5 pixels. In response to the strong radiation environment of the Three-River-Source region, camera white balance parameters are adjusted in real time to avoid image overexposure.

[0060] For example, if a sudden gale of level 5 is encountered during flight, the drone's flight speed is adjusted to 80 km / h to maintain stability; if a sudden strong wind exceeding level 7 is encountered, the emergency return procedure is immediately initiated to control the drone to return to the nearest emergency return point, and operations can continue after the weather conditions stabilize.

[0061] The preferred flight times are 8:30-11:00 AM and 2:30-5:00 PM, when atmospheric visibility is ≥10km, solar altitude angle is >20°, and shadow ratio is <2.5, which can effectively avoid the impact of shadows, dust, and valley fog on image quality.

[0062] Optionally, in the embodiments, before importing the oblique images acquired by the ultra-wide-angle oblique photography aerial camera into the data processor for 3D modeling, the method further includes: performing a quality check on the oblique images acquired by the ultra-wide-angle oblique photography aerial camera, the quality check including at least checking for the existence of mapping loopholes; when mapping loopholes exist and the mapping loopholes are located in plateau and hilly areas, formulating a first supplementary photography route based on a first supplementary photography rule, and controlling the fixed-wing UAV to perform supplementary photography flights according to the first supplementary photography route, the first supplementary photography rule being that the supplementary photography range exceeds the area where the mapping loophole is located by three baselines; when mapping loopholes exist and the mapping loopholes are located in river valley wetland areas, formulating a second supplementary photography route based on a second supplementary photography rule, and controlling the fixed-wing UAV to perform supplementary photography flights according to the second supplementary photography route, the second supplementary photography rule being that the supplementary photography range exceeds the area where the mapping loophole is located by two baselines.

[0063] Optionally, in the embodiments, the quality check further includes: checking the image clarity, checking whether the forward overlap reaches a first preset threshold, and checking whether the lateral overlap reaches a second preset threshold.

[0064] After each sub-area flight is completed, the acquired image data is immediately subjected to a quality check, focusing on verifying image sharpness, whether the forward overlap is no less than 80%, the lateral overlap is no less than 60%, and mapping omissions. Supplementary flight parameters are kept consistent with the original flight path. After supplementary shooting, image quality is checked again to ensure the integrity of image data in areas with defects.

[0065] In aerial photogrammetry, a baseline refers to the horizontal distance between the shooting positions of two adjacent images. Extending the supplementary imagery beyond the gap area by three baselines means extending the imagery forward and backward along the flight path by the equivalent of three baselines from the gap area. This ensures sufficient overlap between the supplementary and original images, meeting the requirements for matching corresponding points in aerial triangulation.

[0066] In this embodiment, after the flight in the third sub-region (plateau and hilly region) was completed, an area of ​​approximately 0.5 km² was found on the edge of the region. 2 To identify the relative vulnerability, a supplementary imagery route was immediately planned using the route planning module. In accordance with the special supplementary imagery rules for the Sanjiangyuan hilly area, the supplementary imagery range exceeded the vulnerability area by three baselines. The supplementary imagery flight altitude was 1000 meters and the speed was 110 km / h. After the supplementary imagery was completed, the image quality was checked again to ensure that the image data of the vulnerability area was complete and met the requirements for subsequent processing.

[0067] All qualified image data (approximately 12,000 images in total) were imported into a 50-node data processor, and the automatic stitching and 3D modeling program was started. The data processing software automatically identified and removed cloud shadows, blemishes, overexposed areas, or hazy areas from the acquired oblique images, resulting in preprocessed images. 3D modeling was then performed based on the preprocessed images to generate 3D point clouds. Point cloud filtering was applied to areas in the 3D point cloud corresponding to plateau permafrost or wetland landforms, with a filtering threshold set to 0.3m. During processing, positioning data acquired by the POS system was used to calibrate the image positioning accuracy, improving the accuracy of the 3D model. After processing, the accuracy of the 3D model and surveying data was verified, confirming a ground resolution of 7.8cm. The planar and elevation accuracy of the 3D model met the requirements for 1:500 topographic mapping and the exploration and ecological monitoring of resources in the Three-River-Source region. Finally, a qualified 3D model and surveying results were output.

[0068] This method, through optimized aerial photography techniques, specifically proposes zoning, valley-to-hill contour line planning, optimal flight time selection, and specialized supplementary photography mechanisms, ensuring operational safety and data continuity. The output results can be directly applied to topographic mapping, resource exploration, and ecological monitoring, and are suitable for large-scale mapping in prefecture-level cities and counties, with easier promotion and application in plateau regions.

[0069] Specifically, the output 3D model and surveying results will be seamlessly integrated with the Sanjiangyuan National Park GIS geographic database, enabling overlay analysis with geographical elements such as the survey area's water system, topography, protected area boundaries, and wildlife habitats. This will provide data support for ecological monitoring and resource exploration in the Lancang River source area. Aerial photography and data processing results will be standardized and categorized by region, with topographic and meteorological adaptation parameters labeled for each sub-region, providing data reference for routine aerial photography operations in Sanjiangyuan. After the operation, the UAVs will undergo specialized maintenance for Sanjiangyuan, including cleaning dust from the fuselage and lenses, checking for UV protection coating wear, and calibrating the power system and POS system to ensure the equipment is repeatedly adaptable to the Sanjiangyuan operating environment.

[0070] The plateau unmanned aerial vehicle (UAV) wide-swath oblique photography system and operation method of the present invention can effectively solve the technical problems of poor adaptability, low operation efficiency and difficulty in ensuring data quality in high-altitude, low-pressure, strong wind and complex terrain environments. It is fully adapted to the complex terrain and meteorological conditions of plateau areas, has good feasibility and superiority, and can meet the actual needs of large-area topographic mapping, alpine wetland resource exploration and ecological monitoring in plateau areas. It is easy to promote and apply in plateau areas.

[0071] The core operating scenario of this invention is the Sanjiangyuan National Park (Yushu, Guoluo, and Zaduo areas) on the Qinghai-Tibet Plateau. This area is the source region of the Yangtze River, the Yellow River, and the Lancang River. The typical landforms are plateau hills, alpine meadows, river valley wetlands, and alpine permafrost at an altitude of 4000-4800m. The meteorological characteristics are low air pressure (air pressure value 60-65kPa), instantaneous strong winds of level 7 or above, strong solar radiation (annual sunshine hours 2500-2800h), frequent sandstorms in spring, and frequent fog in the river valleys in summer.

[0072] All technical parameters, equipment configurations, and operational procedures of this invention have been verified through on-site test flights in the Sanjiangyuan region. Although direct aerial photographs of the core protected area have not yet been obtained, measured data of similar terrain in the surrounding areas can be transferred to the core area at a 1:1 scale. Furthermore, the test flight registration with the Sanjiangyuan National Park Administration has been completed, ensuring the legality and feasibility of the operation. This invention is particularly suitable for large-area, high-precision aerial photogrammetry operations in complex environments characterized by high altitude, low air pressure, and strong winds.

[0073] Example 3 This embodiment verifies the technical effects, feasibility, and superiority of the present invention by applying the system described in Embodiment 1 and the method described in Embodiment 2 in a real-world scenario within the Sanjiangyuan National Park. The specific verification process and results are as follows: The Lancang River source area (93°00′-93°30′E, 32°40′-33°10′N) in Zaduo County, Yushu Prefecture, Sanjiangyuan National Park was selected as the experimental survey area. The survey area covers 50km×50km and includes the typical plateau mountains, river valley meadows, alpine wetlands, and alpine permafrost of Sanjiangyuan. The meteorological conditions are low pressure (62kPa), frequent strong winds (maximum instantaneous wind force 7.5), spring dust storms, and summer river valley fog, which are consistent with the routine aerial photography operation environment of Sanjiangyuan National Park.

[0074] The verification objectives are: the adaptability of UAVs to the Sanjiangyuan region, image acquisition accuracy, operational efficiency, and data processing performance, and to compare the operational performance with that of traditional 3-5 lens oblique photography systems.

[0075] Specifically, the aerial photography operation was carried out using the DM150 fixed-wing UAV and KG661 6-camera aerial camera system described in Example 1, strictly following the special operation steps for the Three Rivers Source area as described in Example 2. The flight altitude was set at 1000 meters and the cruising speed at 110 km / h, generating 67 long flight routes of 53 km each, with a total flight distance of 3551 km, completing the entire process of image acquisition, quality inspection, supplementary photography, and data processing for the entire survey area.

[0076] The verification results are explained from the following aspects: 1. UAV adaptability: The UAV took off normally at an altitude of 4400m in the Lancang River source area of ​​the Sanjiangyuan region. It had good stability during flight and could effectively resist instantaneous gale-force winds of level 5. The measured wind resistance reached level 7.5. There were no problems such as difficulty in takeoff or flight turbulence. The sand and dust protection modification and anti-ultraviolet coating are effectively adapted to the sand and dust and strong radiation environment of the Sanjiangyuan region. It ensures the continuity of image acquisition throughout the process. The adaptability fully meets the operation requirements of the Sanjiangyuan region.

[0077] 2. Image quality: The acquired images meet the standards for clarity. The average forward overlap of the Sanjiangyuan region is 79% and the average lateral overlap is 66%, with no obvious stitching gaps. The ground resolution is 7.8cm, which is better than 8cm, fully meeting the requirements for 1:500 high-precision topographic mapping and detailed 3D modeling.

[0078] 3. Operational efficiency: The total flight time for the entire survey area is 32 hours, which is 66.3% higher than the traditional 3-5 lens oblique photography system (which requires 95 hours of flight time). The amount of data collected is about 1 / 3 of that of the traditional solution, which greatly reduces data redundancy and post-processing time, and significantly reduces the time and manpower costs of field operations in the Sanjiangyuan Plateau.

[0079] 4. Data processing effect: The 50-node server completed the processing of 680G of image data within 36 hours, automatically removing interference factors such as strong radiation and fog in the Sanjiangyuan area, and the stitching was seamless; the newly added topographic freeze-thaw zone point cloud filtering function effectively improved the accuracy of the permafrost area model, and the output three-dimensional model had a planar accuracy of 0.18m and an elevation accuracy of 0.22m, which fully meets the actual needs of resource exploration and ecological monitoring in the Sanjiangyuan area.

[0080] 5. Practicality: All parameters of this invention have been verified by on-site test flights in the Sanjiangyuan area and have been registered with the Sanjiangyuan National Park Administration. Although no direct aerial photographs of the core protected area have been obtained yet, the measured data of similar landforms in the surrounding area can be transferred to the core area at a 1:1 scale, which meets the conditions for direct on-site operation.

[0081] This invention addresses the technical bottlenecks of existing UAV oblique photogrammetry technology in complex high-altitude environments, including poor adaptability of the power system, significant contradictions between payload and service ceiling, and low efficiency and data quality assurance in large-area operations due to the small swath width and insufficient resolution of traditional image acquisition equipment. It proposes a systematic solution that effectively solves the technical problems of poor adaptability, low operational efficiency, and unreliable data quality in the Sanjiangyuan environment. The solution is fully adaptable to the complex terrain and meteorological conditions of the Sanjiangyuan National Park, possessing excellent feasibility and superiority. It can meet the practical needs of large-area topographic mapping, alpine wetland resource exploration, and ecological monitoring in the Sanjiangyuan region and is easily promoted and applied in high-altitude areas.

[0082] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-disclosed concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

[0083] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and represent a limitation on a specific order or sequence. Where appropriate, the order of use for similar objects can be interchanged so that the embodiments of this application described herein can be implemented in an order other than that shown or described.

[0084] Those skilled in the art will recognize that this invention can be implemented as a system, method, or computer program product. Therefore, this invention can be specifically implemented in the following forms: it can be entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software, generally referred to herein as a "circuit," "module," or "system." Furthermore, in some embodiments, this invention can also be implemented as a computer program product contained in one or more computer-readable media, which includes computer-readable program code.

[0085] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A wide-swath oblique photography system for unmanned aerial vehicles (UAVs) suitable for high-altitude environments, characterized in that, Includes fixed-wing unmanned aerial vehicles, ultra-wide-angle oblique photography aerial cameras, ground control stations, and data processors; The fixed-wing UAV is used to carry the ultra-wide-angle oblique photography aerial camera; The ultra-wide-angle oblique photography aerial camera is used to acquire oblique images of the target survey area. The ultra-wide-angle oblique photography aerial camera includes multiple cameras, which are divided into two groups, front and rear, along the flight direction of the fixed-wing UAV and are configured at multiple angles to form an ultra-wide-angle image acquisition range. The ground control station is used to plan and generate the flight path of the fixed-wing UAV in the target survey area, and to monitor and adjust the flight mission of the fixed-wing UAV and the image acquisition mission of the ultra-wide-angle oblique photography aerial camera. The data processor is used to perform three-dimensional modeling on the oblique images acquired by the ultra-wide-angle oblique photography aerial camera, so as to generate three-dimensional mapping results for the target survey area.

2. The UAV wide-swath oblique photography system suitable for plateau environments according to claim 1, characterized in that, The multiple cameras consist of six cameras, each a full-frame CMOS camera. The six cameras are divided into a front group and a rear group along the flight direction of the fixed-wing UAV, with three cameras in each group. The middle camera in the front group is tilted forward by 30° relative to the vertical downward direction, and the two side cameras in the front group are tilted forward by 30° and then tilted to the left and right by 29° respectively, so that the image overlap between the side cameras and the middle camera is greater than or equal to 20%. The three cameras in the rear group are arranged symmetrically and in reverse to the three cameras in the front group.

3. The UAV wide-swath oblique photography system suitable for plateau environments according to claim 1, characterized in that, The fixed-wing UAV uses a full carbon fiber composite fuselage and is equipped with a sand and dust protection structure. The power system of the fixed-wing UAV includes a high-altitude-adaptive electronic fuel injection engine.

4. The UAV wide-swath oblique photography system suitable for plateau environments according to claim 1, characterized in that, Each camera lens is equipped with UV protection coating.

5. The UAV wide-swath oblique photography system suitable for plateau environments according to claim 1, characterized in that, The data processor is equipped with data processing software, which is used to identify and remove cloud shadows, blemishes, overexposed areas or fog-blurred areas in the acquired oblique images to obtain pre-processed images; and to perform three-dimensional modeling based on the pre-processed images to generate three-dimensional point clouds, and to perform point cloud filtering processing on the areas in the three-dimensional point clouds that correspond to plateau permafrost or wetland landforms.

6. A method for wide-swath oblique photography using unmanned aerial vehicles (UAVs) suitable for high-altitude environments, characterized in that: The UAV wide-swath oblique photography system suitable for high-altitude environments, as described in any one of claims 1 to 5, comprises: After transporting the fixed-wing UAV and the ultra-wide-angle oblique photography aerial camera to the plateau operation base, a plateau-specific test flight and debugging were conducted. The ground control station is used to plan and generate the flight path of the fixed-wing UAV within the target survey area; Control the fixed-wing UAV to perform flight missions according to the flight path, and control the ultra-wide-angle oblique photography aerial camera to perform image acquisition missions; During the flight of the fixed-wing UAV, the ground control station is used to monitor and adjust the flight mission of the fixed-wing UAV and the image acquisition mission of the ultra-wide-angle oblique photography aerial camera. The oblique images acquired by the ultra-wide-angle oblique photography aerial camera are imported into the data processor for three-dimensional modeling, and the three-dimensional mapping results for the target survey area are output.

7. The method for unmanned aerial vehicle (UAV) wide-swath oblique photography suitable for plateau environments according to claim 6, characterized in that, The step of using the ground control station to plan and generate the flight path of the fixed-wing UAV within the target survey area includes: The target survey area is divided into multiple sub-areas, and at least one emergency return point is set for each sub-area to obtain the zoning information; For each sub-area, a flight path adapted to the terrain type of the sub-area is generated in the ground control station based on the partition information; Based on the flight paths of each sub-region, the flight path of the fixed-wing UAV within the target survey area is obtained.

8. The method for wide-swath oblique photography using a UAV suitable for plateau environments according to claim 7, characterized in that, For each sub-area, based on the partition information, a flight path adapted to the terrain type of the sub-area is generated in the ground control station, including: When the terrain type of the sub-region is a river valley, a forward route is generated based on the partition information. The forward route is a route whose direction follows the direction of the river valley. When the terrain type of the sub-region is hilly terrain, a contour line route is generated based on the partition information. The contour line route is a route laid out along the contour line direction of the hilly terrain.

9. The method for unmanned aerial vehicle (UAV) wide-swath oblique photography suitable for plateau environments according to claim 6, characterized in that, Before importing the oblique images acquired by the ultra-wide-angle oblique photography aerial camera into the data processor for 3D modeling, the process also includes: The quality of the oblique images acquired by the ultra-wide-angle oblique photography aerial camera is checked, and the quality check includes at least checking for the existence of mapping loopholes. When a mapping vulnerability exists and the mapping vulnerability is located in a plateau or hilly area, a first supplementary photography route is formulated based on a first supplementary photography rule, and the fixed-wing UAV is controlled to perform supplementary photography flight according to the first supplementary photography route. The first supplementary photography rule is that the supplementary photography range exceeds three baselines in the area where the mapping vulnerability is located. When a mapping vulnerability exists and the vulnerability is located in a river valley wetland area, a second supplementary photography route is formulated based on the second supplementary photography rule, and the fixed-wing UAV is controlled to perform supplementary photography flight according to the second supplementary photography route. The second supplementary photography rule is that the supplementary photography range exceeds two baselines in the area where the mapping vulnerability is located.

10. The method for unmanned aerial vehicle (UAV) wide-swath oblique photography suitable for plateau environments according to claim 9, characterized in that, The quality check also includes: checking the image clarity, checking whether the forward overlap reaches a first preset threshold, and checking whether the lateral overlap reaches a second preset threshold.

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