Concealed area surface three-dimensional model construction method

Abstract

The invention discloses a method for constructing a three-dimensional model on the surface of a hidden area. The method comprises the following steps: performing low-altitude oblique photography on a hidden area at a low-altitude position to obtain a low-altitude photography data set carrying first POS data; hidden area textures which cannot be obtained by low-altitude unmanned aerial vehicle oblique photography are collected at the ground position in a ground supplementary photography mode, and a ground photography data set carrying second POS data is obtained; matching RTK positioning coordinates, namely second pos data, corresponding to each photo through the shooting time of terrestrial photography; and based on the terrestrial photography data set and the low-altitude photography data set, combined aerial triangulation adjustment is carried out under the assistance of POS data, and a hidden area surface model is constructed. The invention aims to provide the method for constructing the hidden area surface three-dimensional model, the full-scene dead-corner-free surface three-dimensional model can be duplicated, digital twinning in the real world can be truly realized, the modeling quality and the mapping efficiency can be greatly improved for the surveying and mapping industry, and the investment cost of equipment personnel is reduced.

Description

Technical Field

[0001] The present invention relates to the field of real-scene three-dimensional technology, and in particular to a method for constructing a three-dimensional model of a hidden area surface. Background Art

[0002] Oblique photography 3D modeling technology has been widely used in many fields. Its core advantage is that high-resolution aerial images can significantly improve the absolute accuracy and texture clarity of the generated 3D model. However, this technology still faces challenges when facing occluded areas, because these areas are often difficult to capture images through conventional photography. Although a variety of sophisticated photography techniques have emerged in recent years, such as fine route planning, close-up photography, optimal view photography, and DJI's oblique routes, which aim to solve problems such as deformation, streaks, and holes in 3D models, the effectiveness of these methods is often limited by environmental conditions where there are no obstacles around the target.

[0003] In actual surveying work, this case often encounters complex and changeable scenes, such as densely populated areas, hidden areas with dense trees, and large areas of shantytowns, which are often difficult to observe comprehensively from an aerial perspective. Therefore, for the field supplementary survey of these hidden areas, this case has to invest a lot of manpower and material resources. Although handheld laser scanners can assist in measurement to a certain extent, in order to build a comprehensive 3D surface model without blind spots, it is still necessary to explore and apply more advanced technologies. Summary of the invention

[0004] In view of this, the purpose of the present invention is to propose a method for constructing a three-dimensional surface model of a hidden area, which can reproduce a three-dimensional surface model of the entire scene without blind spots, truly realize the digital twin of the real world, and greatly improve the modeling quality and mapping efficiency for the surveying and mapping industry, and reduce the investment cost of equipment and personnel.

[0005] According to one aspect of the present invention, a method for constructing a three-dimensional model of a hidden area surface is provided, the method comprising the following steps:

[0006] Perform low-altitude oblique photography of the concealed area at a low-altitude position to obtain a low-altitude photography data set carrying first POS data;

[0007] The texture of the hidden area that cannot be obtained by low-altitude UAV oblique photography is collected at the ground position through ground supplementary photography, and a ground photography data set carrying the second POS data is obtained;

[0008] Match the RTK positioning coordinates corresponding to each photo through the shooting time of ground photography, that is, the second POS data;

[0009] Based on the ground photography dataset and the low-altitude photography dataset, joint aerial triangulation is performed with the assistance of POS data to construct a surface three-dimensional model of the hidden area.

[0010] In the above technical scheme, through many tests, this case proposes a ground supplementary photography combined with drone oblique photography to construct a three-dimensional model of the whole scene without blind spots, which greatly reduces the investment cost of equipment and personnel, and improves the efficiency of measurement and mapping. This case considers the construction of equipment for ground supplementary photography, mainly at least one camera and an RTK positioning module. The camera can be an ordinary camera, a sports camera, a mobile phone or other image shooting device. The device can be carried handheld and walked through the streets, or it can be mounted in a car, which is very convenient. As long as there are enough continuous photos obtained by ground supplementary photography, and the photos have positioning accuracy, they can be combined with the aerial drone oblique photography data for aerial triangulation to construct a surface three-dimensional model of the whole scene without blind spots. The above method can be used to collect textures in hidden areas that cannot be obtained by conventional photography, such as under trees, under eaves, and other scenes.

[0011] In some embodiments, the first POS data is obtained based on an RTK positioning module.

[0012] In the above technical solution, the traditional method is to use a manned aircraft equipped with a UCD aerial camera to obtain digital images with a resolution better than 5cm in the survey area. Although it has POS data, the coordinate positioning accuracy is poor and cannot meet the requirements of aerial triangulation encryption. Therefore, this case considers the use of RTK technology. RTK (Real-time Dynamic Carrier Phase Differential) technology is usually used to improve the accuracy of GPS positioning. It can correct GPS measurements through differential GPS signals to achieve centimeter-level positioning accuracy. In the field of drone surveying and mapping, RTK technology can be used in conjunction with aerial cameras to obtain more accurate geospatial data. Each step in the aerial triangulation operation is very critical, and each parameter configuration must be correct. Images from different periods have different color differences, textures, and terrain elements, and the matching error increases accordingly. Therefore, high-precision POS data is more needed as an aid to improve the reliability of matching points and increase the matching speed.

[0013] In some embodiments, the texture of the hidden area that cannot be obtained by the low-altitude UAV oblique photography is collected at the ground position by ground supplementary photography, and a ground photography data set carrying the second POS data is obtained, specifically:

[0014] Based on several cameras and RTK positioning modules, the hidden area is traversed from the ground to obtain ground photography data sets;

[0015] Moreover, the combined viewing angle of the photos output by several cameras after stitching satisfies 720°;

[0016] Furthermore, the overlapping area between two consecutive photos is greater than 40%.

[0017] In the above technical solution, the camera layout is preferably able to take photos with a full 720-degree viewing angle, that is, covering 360 degrees horizontally and 360 degrees vertically, and the two photos in each group should have an overlap of about 50%. In this way, the camera layout position and lens direction can be specifically calculated.

[0018] In some embodiments, based on the ground photography dataset and the low-altitude photography dataset, a joint aerial triangulation is performed with the assistance of POS data, specifically:

[0019] Aerial triangulation is performed based on the ground photography dataset and the low-altitude photography dataset. Specifically:

[0020] Preprocess the first POS data and the second POS data, and perform data import and parameter configuration;

[0021] Based on the pre-processed first POS data and second POS data, the image points with the same name in the low-altitude photography data set and the ground photography data set are automatically matched.

[0022] In the above technical solution, due to the inconsistent shooting heights of the ground and low-altitude shots, and different shooting times, the image color difference is large. However, after the high-precision POS data-assisted aerial triangulation matching, the image matching connection points are large and the matching accuracy is high, which meets the aerial triangulation encryption accuracy index requirements.

[0023] In some embodiments, based on the pre-processed first POS data and the second POS data, the automatic matching of the same-name points in the low-altitude photography dataset and the ground photography dataset is specifically:

[0024] After manual inspection and elimination of error points, the camera on the drone is self-calibrated to obtain accurate camera parameters relative to before calibration;

[0025] Import the updated camera parameters and then optimize the alignment of all images:

[0026] Repeat the above steps until the preset conditions are met and then output the adjustment results.

[0027] In the above technical solutions, the conventional solution is to only use low-altitude oblique aerial photography. We added ground supplementary photography to obtain image data of hidden areas, and then constructed such a full-scene surface 3D model without blind spots by combining encryption adjustment with low-altitude photography data.

[0028] According to another aspect of the present invention, a camera bracket is provided for use in the above-mentioned method for constructing a three-dimensional model of a surface of a hidden area, the bracket comprising:

[0029] A support rod, a plurality of mounting plates are fixed on the top of the support rod; the first mounting plate takes the top as the origin, and a plurality of support seats are extended at any direction of the origin, and the support seats are used to fix the camera.

[0030] In the above technical solution, in order to better use the above method, the present application proposes a camera bracket to facilitate the collection of ground data. The specific principle has been described above and will not be repeated here.

[0031] In some embodiments, the method for using the camera bracket includes:

[0032] The RTK positioning module and the camera are turned on simultaneously, and the bracket is manually held to traverse the hidden area from the ground to obtain additional ground texture.

[0033] In the above technical solution, as an optional example, the entire hidden area can be traversed manually, and images with higher accuracy can be taken at a close distance according to actual needs.

[0034] In some embodiments, the method for using the camera bracket includes:

[0035] The RTK positioning module and the camera are turned on simultaneously, and the bracket is placed on top of a mobile device. The mobile device is used to traverse the hidden area from the ground to supplement the ground texture.

[0036] In the above technical solution, as an optional example, a vehicle-mounted method can be used to traverse the entire hidden area, which can collect data more quickly. The vehicle-mounted device can be a car, an unmanned vehicle, or other tool with a mobile function.

[0037] According to another aspect of the present invention, a system for constructing a three-dimensional model of a hidden area surface is provided, based on the above method; comprising:

[0038] A low-altitude module, used to perform low-altitude oblique photography of a concealed area at a low-altitude position to obtain a low-altitude photography data set carrying first POS data;

[0039] The ground module is used to collect the texture of the hidden area that cannot be obtained by the low-altitude UAV oblique photography at the ground position through ground supplementary photography, and obtain a ground photography data set carrying the second POS data;

[0040] A matching module, used to match the RTK positioning coordinates corresponding to each photo according to the shooting time of the ground photography, that is, the second POS data;

[0041] The construction module is used to perform joint aerial triangulation based on the ground photography dataset and the low-altitude photography dataset with the assistance of POS data to construct a surface three-dimensional model of the hidden area.

[0042] In the above technical scheme, in order to better use the above method, the present application proposes a system for constructing a three-dimensional model of the surface of a hidden area, and each module corresponds to each step of the above method. The specific principles have been described above and will not be repeated here.

[0043] According to another aspect of the present invention, a computer-readable storage medium is provided, storing a computer program, wherein the computer program implements the above method when executed by a processor.

[0044] In the above technical solution, in order to better run and use the method, the above method is stored in a computer-readable storage medium, and the above method is implemented by a processor. It should be noted that the principle and effect of each step have been described above and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 It is a flow chart of an embodiment of a method for constructing a three-dimensional model of a hidden area surface according to the present invention;

[0047] Figure 2 It is a structural schematic diagram of a camera bracket of the present invention;

[0048] Figure 3 This is an example diagram of a complex scene;

[0049] Figure 4 It is a hand-held schematic diagram of a camera stand of the present invention;

[0050] Figure 5 It is a schematic diagram of placing a camera bracket of the present invention;

[0051] Figure 6 It is a schematic diagram of a vehicle-mounted camera bracket of the present invention;

[0052] Figure 7 This is the first exemplary model of the present invention;

[0053] Figure 8 This is the second exemplary model of the present invention;

[0054] Fig. 9 It is a structural schematic diagram of an embodiment of a system for constructing a three-dimensional model of a hidden area surface according to the present invention. DETAILED DESCRIPTION

[0055] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0056] The present invention provides a method for constructing a three-dimensional surface model of a hidden area, which can replicate a three-dimensional surface model of the entire scene without blind spots, truly realizing the digital twin of the real world. For the surveying and mapping industry, it can greatly improve the modeling quality and mapping efficiency, and reduce the investment cost of equipment and personnel.

[0057] Embodiment 1

[0058] See also Figure 1 , a method for constructing a three-dimensional model of a hidden area surface, the method comprising the following steps:

[0059] S1, performing low-altitude oblique photography of a concealed area at a low altitude position to obtain a low-altitude photography data set carrying first POS data;

[0060] In this embodiment, the first POS data is obtained based on the RTK positioning module. Traditionally, a manned aircraft equipped with a UCD aerial camera is used to obtain digital images with a resolution better than 5 cm in the survey area. Although it has POS data, the coordinate positioning accuracy is poor and cannot meet the requirements of aerial triangulation encryption. Therefore, this case considers the use of RTK technology. RTK (real-time dynamic carrier phase difference) technology is usually used to improve the accuracy of GPS positioning. It can correct GPS measurements through differential GPS signals to achieve centimeter-level positioning accuracy. In the field of drone surveying and mapping, RTK technology can be used in conjunction with aerial cameras to obtain more accurate geospatial data. Each step in the aerial triangulation operation is very critical, and each parameter configuration cannot be wrong. Images from different periods have different color differences, textures, and ground features, and the matching error increases accordingly. Therefore, high-precision POS data is more needed as an aid to improve the reliability of matching points and increase the matching speed.

[0061] S2. Collect the texture of the hidden area that cannot be obtained by the oblique photography of the low-altitude UAV by using the ground supplementary photography method at the ground position to obtain a ground photography data set carrying the second POS data;

[0062] In this embodiment, S2, the texture of the hidden area that cannot be obtained by the oblique photography of the low-altitude UAV is collected at the ground position by ground supplementary photography, and a ground photography data set carrying the second POS data is obtained. Specifically: based on several cameras and RTK positioning modules, the hidden area is traversed from the ground to obtain the ground photography data set; and the combined viewing angle of the photos spliced ​​by the output of several cameras meets 720°; and the overlapping area between two consecutive photos is greater than 40%. The camera layout is preferably able to take photos with a full 720-degree viewing angle, that is, covering the horizontal 360° and vertical 360° viewing angles, and the two photos in each group should have an overlap of about 50%. In this way, the position of the camera layout and the direction of the lens can be specifically calculated.

[0063] S3, matching the RTK positioning coordinates corresponding to each photo by the shooting time of the ground photography, i.e., the second POS data;

[0064] S4. Based on the ground photography dataset and the low-altitude photography dataset, a joint aerial triangulation is performed with the assistance of POS data to construct a surface three-dimensional model of the hidden area.

[0065] In this embodiment, based on the ground photography dataset and the low-altitude photography dataset, a joint aerial triangulation adjustment is performed with the assistance of POS data, specifically:

[0066] S41, pre-processing the first and second POS data, and importing the data and configuring parameters;

[0067] S42: Automatically match the image points with the same name in the low-altitude photography dataset and the ground photography dataset based on the pre-processed first POS data and the second POS data.

[0068] Due to the inconsistent shooting heights and shooting times of the ground and low-altitude images, the image color difference is large. However, after the high-precision POS data-assisted aerial triangulation matching, the image matching connection points are more and the matching accuracy is high, which meets the aerial triangulation encryption accuracy index requirements.

[0069] In this embodiment, S42, based on the pre-processed first POS data and the second POS data, automatically matching the image points with the same name in the low-altitude photography data set and the ground photography data set, specifically:

[0070] S421, after manual inspection and elimination of error points, the camera carried by the drone is self-calibrated to obtain accurate camera parameters relative to those before calibration;

[0071] S422, import the updated camera parameters, and then optimize the alignment of all images:

[0072] S423, repeat the above steps until the preset conditions are met and then output the adjustment results.

[0073] In this embodiment, the specific method of adjustment can be found in "CN113607134B A method for auxiliary aerial triangulation and encryption joint adjustment based on high-precision POS framework routes" or "Chen Xiaohai. Research on auxiliary aerial triangulation and encryption joint adjustment based on high-precision POS framework routes [C] / / Jiangsu Society of Surveying, Mapping and Geographic Information. Proceedings of the 22nd Academic Exchange Conference of the Surveying and Mapping Society of Six Provinces and One City in East China (I). Xiamen Tuchen Information Technology Co., Ltd.;, 2021:4.DOI:10.26914 / c.cnkihy.2021.019229." No further explanation is given here.

[0074] In this embodiment, through many tests, this case proposes a ground supplementary photography combined with drone oblique photography to construct a three-dimensional model of the whole scene without blind spots, which greatly reduces the investment cost of equipment and personnel, and improves the efficiency of measurement and mapping. This case considers the construction of equipment for ground supplementary photography, mainly at least one camera and an RTK positioning module. The camera can be an ordinary camera, a sports camera, a mobile phone or other image capture device. The device can be carried handheld in the streets or mounted in a car, which is very convenient. As long as there are enough continuous photos obtained by ground supplementary photography and the photos have positioning accuracy, they can be combined with the aerial drone oblique photography data for aerial triangulation to construct a surface three-dimensional model of the whole scene without blind spots.

[0075] Embodiment 2

[0076] See also Figure 2 A camera bracket is used in a method for constructing a three-dimensional model of a surface of a hidden area as described in one of the embodiments. The bracket comprises: a support rod 1, on the top of which a plurality of mounting plates 2 are fixed; the first mounting plate 2 takes the top as the origin, and a plurality of support seats 3 are extended at any direction of the origin, and the support seats 3 are used to fix the camera.

[0077] In order to better use the above method, the present application proposes a camera bracket to facilitate the collection of ground data. The specific principle has been described above and will not be repeated here.

[0078] In this embodiment, as an optional example, the method for using the camera bracket includes: synchronously turning on the RTK positioning module and the camera, manually holding the bracket to traverse the hidden area from the ground, and supplementing the ground texture on the ground. By manually traversing the entire hidden area, higher-precision images can be taken at close range according to actual needs.

[0079] In this embodiment, as an optional example, the method for using the camera bracket includes: synchronously turning on the RTK positioning module and the camera, placing the bracket on top of a mobile device, traversing the hidden area from the ground through the mobile device, and supplementing the ground texture on the ground. Traversing the entire hidden area in a vehicle-mounted manner can collect data more quickly. The vehicle-mounted device can be a car, an unmanned vehicle, or other tool with a mobile function.

[0080] In order to better explain the present invention, the following will be specifically described:

[0081] Oblique photography 3D modeling technology has been widely used. As long as the resolution of the aerial photographs obtained in this case is high enough, the obtained 3D model will be clearer. However, the problem is that there are still many blocked parts that cannot be imaged. Although many fine photography methods have emerged in recent years to improve the deformation, lamination and leakage of 3D models, such as fine flight routes, close-up photography, excellent vision photography, DJI's inclined flight routes, etc., the application conditions of these technologies all require scenes with no obstacles around the target objects. Please refer to Figure 3 The measurement in this case faces a variety of complex scenes, such as densely populated areas, hidden areas under trees, large shed areas, and many other hidden areas that cannot be seen from an aerial perspective. The field survey work in these areas requires a lot of manpower and material resources. Although handheld laser scanners can supplement the measurement well, new technologies are still needed to build a three-dimensional surface model of the entire scene without blind spots.

[0082] To this end, this case has conducted many tests and proposed a method of combining ground supplementary photography with drone oblique photography to construct a 3D model of the entire scene without blind spots, which greatly reduces the investment cost of equipment and personnel, while improving the efficiency of measurement and mapping. Figure 4 , Figure 5 , Figure 6 This is the ground supplementary photography equipment assembled in this case. It is mainly a Mavic 3E plus multiple cameras at different angles. The camera can be an ordinary camera, a sports camera, or a mobile phone. It can be held in the street or mounted in a car, which is very convenient. As long as there are enough continuous photos obtained by ground supplementary photography and the photos have positioning accuracy, they can be combined with the oblique photography data of aerial drones for aerial triangulation to construct a surface 3D model of the entire scene without blind spots.

[0083] Two examples are shown below. The first 3D scene is a hidden area under a dense forest. Figure 7 We use ground-based supplementary photography to build a seamless 3D model from aerial to ground perspective, which can directly measure each feature under the trees. The second is the cultural heritage buildings in densely populated areas. Please refer to Figure 8, and also uses ground supplementary photography equipment to obtain the texture of objects that cannot be photographed by drones, and constructs a photo-level 3D model of outdoor and indoor holography, with clear texture and very high precision. Compared with the prior art, the method provided by the present invention will greatly improve the efficiency of surveying and mapping of buildings and structures, and greatly improve the accuracy of mapping.

[0084] Embodiment 3

[0085] See also Fig. 9 , a system for constructing a two-dimensional model of a hidden area surface, based on the method described in one of the embodiments; comprising:

[0086] A low-altitude module, used to perform low-altitude oblique photography of a concealed area at a low-altitude position to obtain a low-altitude photography data set carrying first POS data;

[0087] The ground module is used to collect the texture of the hidden area that cannot be obtained by the low-altitude UAV oblique photography at the ground position through ground supplementary photography, and obtain a ground photography data set carrying the second POS data;

[0088] A matching module, used to match the RTK positioning coordinates corresponding to each photo according to the shooting time of the ground photography, that is, the second POS data;

[0089] The construction module is used to perform joint aerial triangulation based on the ground photography dataset and the low-altitude photography dataset with the assistance of POS data to construct a surface three-dimensional model of the hidden area.

[0090] In the above technical scheme, in order to better use the method described in one of the embodiments, the present application proposes a system for constructing a two-dimensional surface model of a hidden area. Each module corresponds to each step of the method described in one of the embodiments. The specific principles have been described above and will not be repeated here.

[0091] Embodiment 4

[0092] A computer-readable storage medium stores a computer program, wherein when the computer program is executed by a processor, the method described in one of the embodiments is implemented.

[0093] In the above technical solution, in order to better run and use the method described in one of the embodiments, the above method is stored in a computer-readable storage medium, and a processor is used to implement the method described in one of the embodiments. It should be noted that the principle and effect of each step have been described above and will not be described in detail here.

[0094] The above descriptions are only some embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for constructing a three-dimensional model of a hidden area surface, characterized in that: The method comprises: Perform low-altitude oblique photography of the concealed area at a low-altitude position to obtain a low-altitude photography data set carrying first POS data; The texture of the hidden area that cannot be obtained by low-altitude UAV oblique photography is collected at the ground position through ground supplementary photography, and a ground photography data set carrying the second POS data is obtained; Match the RTK positioning coordinates corresponding to each photo through the shooting time of ground photography, that is, the second POS data; Based on the ground photography dataset and the low-altitude photography dataset, joint aerial triangulation is performed with the assistance of POS data to construct a surface three-dimensional model of the hidden area.

2. A method for constructing a three-dimensional model of a hidden area surface as claimed in claim 1, characterized in that: The first POS data is obtained based on an RTK positioning module.

3. The method for constructing a three-dimensional model of a hidden area surface according to claim 1, characterized in that: At the ground position, the texture of the hidden area that cannot be obtained by the low-altitude UAV oblique photography is collected by ground supplementary photography to obtain a ground photography dataset carrying the second POS data, specifically: Based on several cameras and RTK positioning modules, the hidden area is traversed from the ground to obtain ground photography data sets; Moreover, the combined viewing angle of the photos output by several cameras after stitching satisfies 720°; Furthermore, the overlapping area between two consecutive photos is greater than 40%.

4. The method for constructing a three-dimensional model of a hidden area surface according to claim 1, characterized in that: Based on the ground photography dataset and the low-altitude photography dataset, a joint aerial triangulation adjustment is performed with the assistance of POS data. Specifically: Preprocess the first POS data and the second POS data, and perform data import and parameter configuration; Based on the pre-processed first POS data and second POS data, the image points with the same name in the low-altitude photography data set and the ground photography data set are automatically matched.

5. The method for constructing a three-dimensional model of a hidden area surface according to claim 4, characterized in that: Based on the pre-processed first POS data and second POS data, the image points with the same name in the low-altitude photography dataset and the ground photography dataset are automatically matched, specifically: After manual inspection and elimination of error points, the camera on the drone is self-calibrated to obtain accurate camera parameters relative to before calibration; Import the updated camera parameters and then optimize the alignment of all images: Repeat the above steps until the preset conditions are met and then output the adjustment results.

6. A camera stand, characterized in that: A method for constructing a three-dimensional model of a surface of a hidden area according to any one of claims 1 to 5, characterized in that the support comprises: A bracket, a plurality of mounting plates are fixed on the top of the support rod; the first mounting plate takes the top as the origin, and a plurality of supporting seats are extended at any direction of the origin, and the supporting seats are used to fix the camera.

7. A camera bracket as claimed in claim 6, characterized in that: The method for using the camera bracket includes: The RTK positioning module and the camera are turned on simultaneously, and the bracket is manually held to traverse the hidden area from the ground to obtain additional ground texture.

8. A camera bracket as claimed in claim 6, characterized in that: The method for using the camera bracket includes: The RTK positioning module and the camera are turned on simultaneously, and the bracket is placed on top of a mobile device. The mobile device is used to traverse the hidden area from the ground to supplement the ground texture.

9. A system for constructing a two-dimensional model of a hidden area surface, characterized in that: The method according to any one of claims 1 to 5; comprising: A low-altitude module is used to perform low-altitude oblique photography of a concealed area at a low-altitude position to obtain a low-altitude photography data set carrying first POS data; The ground module is used to collect the texture of the hidden area that cannot be obtained by the low-altitude UAV oblique photography at the ground position through ground supplementary photography, and obtain a ground photography data set carrying the second POS data; A matching module, used to match the RTK positioning coordinates corresponding to each photo according to the shooting time of the ground photography, that is, the second POS data; The construction module is used to perform joint aerial triangulation based on the ground photography dataset and the low-altitude photography dataset with the assistance of POS data to construct a surface three-dimensional model of the hidden area.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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