An unmanned aerial vehicle pier positioning hole accurate measurement device and method

Abstract

This invention discloses a precise measurement device for bridge pier positioning holes based on a drone, comprising a drone, a total station, a control unit, an intelligent measurement and calibration device, and an image acquisition device. The intelligent measurement and calibration device includes an attitude sensor, a rod, a prism, and a ranging and marking module. The control unit controls the drone to land on the bridge pier surface near the positioning hole to be measured, controls the total station to measure the center coordinates of the prism, controls the attitude sensor to measure the attitude information of the equipment, and controls the ranging and marking module to measure the distance from the bottom of the drone to the bridge pier surface and spray marking points onto the bridge pier surface. The center coordinates of the markings are calculated by combining the center coordinates of the prism, the attitude information of the equipment, and the distance measured by laser. The image acquisition device is controlled to acquire images of the bridge pier surface, and the coordinates of the positioning hole to be measured are calculated by combining the center coordinates of the markings and the bridge pier surface image. Based on this, this invention achieves safe, efficient, non-contact measurement of bridge pier positioning holes using a drone with millimeter-level absolute accuracy.

Description

Technical Field

[0001] This invention relates to the field of precision engineering measurement and UAV application technology, specifically to a device and method for precise measurement of bridge pier positioning holes based on UAVs. Background Technology

[0002] In bridge construction, accurately obtaining the absolute coordinates of the pre-drilled positioning holes on the top of the piers is a prerequisite for ensuring the precise installation of the bridge beams, with accuracy requirements often reaching the millimeter level (e.g., ±2mm). Current methods primarily rely on surveyors carrying prisms to climb to the top of the piers and use a total station for measurement. This method has three major drawbacks:

[0003] High risk: The risk of personnel working at heights is extremely high.

[0004] Inefficiency: The climbing and station setting process is cumbersome and time-consuming.

[0005] Visibility: The structure of the bridge piers themselves can easily obstruct the line of sight of the total station.

[0006] Existing alternatives, such as UAV photogrammetry, are safe and convenient, but their absolute coordinate accuracy is limited by the difficulty of setting up image control points and the accuracy of aerial triangulation, making it difficult to consistently achieve millimeter-level accuracy. Furthermore, using UAVs to suspend prisms for dynamic measurements is affected by hovering stability and wind conditions, resulting in measurement accuracy and reliability that fail to meet requirements. Summary of the Invention

[0007] To overcome the shortcomings of existing UAV measurement schemes in terms of measurement accuracy and reliability, this invention provides a UAV-based device and method for precise measurement of bridge pier positioning holes, enabling safe, efficient, non-contact measurement of bridge pier positioning holes with millimeter-level absolute accuracy.

[0008] According to one aspect of this invention, a precise measurement device for bridge pier positioning holes based on a drone is provided, comprising a drone, an intelligent measurement and calibration device, a ground detection device, an image acquisition device, and a control unit. The intelligent measurement and calibration device and the image acquisition device are mounted on the drone. The intelligent measurement and calibration device includes an attitude sensor, a prism, and a ranging and marking module. The ranging and marking module is located at the bottom of the drone. The attitude sensor is used to measure the device's attitude information in real time. The control unit controls the drone to land on the bridge pier surface within a preset range from the positioning hole to be measured, and controls the ground detection device to measure the prism's center coordinates. The control unit controls the ranging and marking module to measure the distance from the bottom of the drone to the bridge pier surface and sprays marking points from the bottom of the drone onto the bridge pier surface. The control unit calculates the marking center coordinates by combining the prism's center coordinates, the device's attitude information, and the measured distance, and binds them to the markings. The control unit also controls the image acquisition device to acquire images of the bridge pier surface covering the marking points and the positioning hole to be measured. Finally, the control unit calculates the coordinates of the positioning hole to be measured by combining the marking center coordinates and the bridge pier surface images.

[0009] Furthermore, the prism is located on top of the drone.

[0010] Furthermore, the intelligent measurement and calibration device also includes a rod, through which the prism is mounted on top of the drone.

[0011] Furthermore, the device attitude information is the tilt angle of the UAV in a stable state.

[0012] Furthermore, the ranging and marking module integrates a spraying device and a laser ranging device. The spraying device is used to spray marking points from the bottom of the UAV onto the surface of the bridge pier, and the laser ranging device is used to measure the distance from the bottom of the UAV to the center of the marking point.

[0013] According to one aspect of the present invention, a method for accurately measuring bridge pier positioning holes based on a drone is provided, which is implemented using a drone-based device for accurately measuring bridge pier positioning holes as described above. The measurement method includes: Step S1: Controlling the drone to fly and land on the surface of the bridge pier within a preset range from the positioning hole to be measured; Step S2: Controlling a ground detection device to measure the coordinates of the prism center, using an intelligent measurement and calibration device mounted on the drone to obtain the distance from the bottom of the drone to the bridge pier surface and the device attitude information, and spraying a mark from the bottom of the drone to the bridge pier surface, calculating the center coordinates of the mark by combining the prism center coordinates, the device attitude information, and the distance measured by laser, and binding it to the mark; Step S3: Controlling the drone to move to another position and repeating the above steps to set up several marking points on the top surface of the bridge pier; Step S4: Controlling an image acquisition device mounted on the drone to acquire an image of the bridge pier surface covering the several markings and the positioning hole to be measured, and calculating the coordinates of the positioning hole to be measured by combining the coordinates of the several marking points and the bridge pier surface image.

[0014] Further, step S2 includes: setting up a ground detection device on the ground, controlling the ground detection device to aim at the stationary pole-top prism and perform multiple measurements to calculate the prism center coordinates; controlling the attitude sensor to measure the attitude information of the device, controlling the laser rangefinder to measure the distance from the bottom of the UAV to the center of the marker point, and controlling the spraying device to spray the marker point from the bottom of the UAV to the surface of the pier; combining the preset pole geometry parameters, prism center coordinates, laser-measured distance, and device attitude information to calculate the marker center coordinates and bind them to the marker, so that the marker center is given known millimeter-level absolute coordinates.

[0015] Further, step S4 includes: controlling the drone to ascend to a height where all marked points and the positioning hole to be measured can be photographed; controlling the image acquisition device mounted on the drone to take a series of overlapping images of the bridge pier surface; generating a millimeter-precision true coordinate three-dimensional model of the top surface of the bridge pier based on the series of overlapping bridge pier surface images; and measuring the three-dimensional absolute coordinates of the positioning hole to be measured in the generated millimeter-precision true coordinate three-dimensional model.

[0016] Furthermore, generating a millimeter-precision true coordinate 3D model of the top surface of the bridge pier based on the set of overlapping bridge pier surface images includes: automatically identifying all marker points from the set of overlapping bridge pier surface images using image processing software; calling the marker center coordinates bound to each marker point as strong constraint control points, performing aerial triangulation using bundle adjustment, and calculating the high-precision exterior orientation elements of each bridge pier surface image; and generating a millimeter-precision true coordinate 3D model of the top surface of the bridge pier based on the high-precision exterior orientation elements of each bridge pier surface image.

[0017] Furthermore, in step S3, at least three or more marking points are sprayed on the surface of the bridge pier.

[0018] The above technical solution, firstly, involves the precise establishment and coordinate binding of marker points on the bridge pier surface: A drone equipped with an intelligent measurement and calibration device is controlled to fly and land on the bridge pier surface near the positioning hole to be measured. A ground-based detection device measures the coordinates of the prism center. These prism center coordinates are the absolute coordinates of the prism center and serve as the reference for subsequent marker point coordinate calculations. An attitude sensor measures the device's attitude information, and a ranging and marking module measures the distance from the bottom of the drone to the bridge pier surface. Marker points are then sprayed from the bottom of the drone onto the bridge pier surface. Understandably, using the prism center coordinates as a reference, combined with the device's attitude information and the geometric information between the prism and the ranging and marking module, the coordinates of the marking module can be obtained. Then, combined with the measured distance, the precise marker center coordinates can be calculated, and these coordinates are bound to the marker points for subsequent coordinate calculations of the positioning hole to be measured. The second stage: 3D reconstruction and target extraction: Using a drone equipped with an image acquisition device, images of the bridge pier surface covering all marked points and the positioning holes to be measured are collected. Then, a 3D model of the bridge pier surface is created based on the bridge pier surface images. Finally, the 3D absolute coordinates of the positioning holes to be measured are extracted based on the millimeter-precision true coordinate 3D model of the bridge pier top surface obtained by the modeling.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) Revolutionary improvement in safety: Completely eliminates personnel working at height.

[0021] (2) The accuracy reaches the millimeter level: ① Static measurement is achieved by using a drone to carry a prism and land on the surface of the bridge pier. The measurement is simple, reliable, and the accuracy is guaranteed; ② Through attitude perception and distance compensation, the errors of the equipment not being absolutely vertical and the non-contact distance are solved, ensuring the mathematical rigor of the coordinates transferred from the prism to the center of the mark.

[0022] (3) High efficiency and reliability: The take-off, landing, measurement and marking operations of UAVs are simple and can be automated.

[0023] (4) Systematic solution: seamlessly integrate the mobility of UAVs, the absolute accuracy of traditional geodetic surveying, and the efficiency of modern visual measurement to form a closed-loop workflow.

[0024] (5) Digitalization and visualization of results: The final output is a precise three-dimensional model with absolute coordinates, which is intuitive and reliable, and easy to archive, verify and digitally construct. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a first structural schematic diagram of a precise measuring device for bridge pier positioning holes based on a drone, provided as an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the second structure of a precise measuring device for bridge pier positioning holes based on a drone, provided as an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram illustrating the control of a drone to fly onto a bridge pier and land, as provided in an embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of a total station measuring instrument mounted on a drone, provided as an embodiment of the present invention.

[0030] Figure 5 A printing or spraying device for the bottom of a drone provided in an embodiment of the present invention.

[0031] Figure 6 This is a schematic diagram of high-precision image control points on the surface of a bridge pier captured by a drone, provided in an embodiment of the present invention.

[0032] Figure 7 A flowchart illustrating a method for precise measurement of bridge pier positioning holes based on unmanned aerial vehicles (UAVs) is provided for an embodiment of the present invention. Detailed Implementation

[0033] It should be noted that:

[0034] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0035] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices. The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be decomposed, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0037] Please refer to the appendix. Figure 1 and Figure 2 This invention provides a precise measurement device for bridge pier positioning holes based on a drone, comprising a drone, an intelligent measurement and calibration device, a ground detection device (in this embodiment, a total station), an image acquisition device, and a control unit. The intelligent measurement and calibration device and the image acquisition device are mounted on the drone. The intelligent measurement and calibration device includes an attitude sensor, a prism, and a ranging and marking module. The ranging and marking module is located at the bottom of the drone. The attitude sensor is used to measure the device's attitude information in real time. The control unit controls the drone to land on the bridge pier surface near the positioning hole to be measured, and controls the total station to measure the center coordinates of the prism. The control unit controls the ranging and marking module to measure the distance from the bottom of the drone to the bridge pier surface and sprays marking points from the bottom of the drone onto the bridge pier surface. The center coordinates of the markings are calculated by combining the prism center coordinates, the device attitude information, and the distance measured by the laser, and then the coordinates of the positioning holes are bound to the markings. The control unit also controls the image acquisition device to acquire images of the bridge pier surface covering the marking points and the positioning holes to be measured. Finally, the coordinates of the positioning holes to be measured are calculated by combining the center coordinates of the markings and the bridge pier surface images.

[0038] In this embodiment, the intelligent measurement and calibration device further includes a rod, with the prism and ranging and marking module integrated onto the rod. The drone has a through hole through which the top of the rod extends upwards to the top of the drone, and the prism is mounted on the top of the rod so that the prism is located at the top of the drone. The bottom of the rod extends downwards to the bottom of the drone through the through hole, and the ranging and marking module is located at the bottom of the rod so that the ranging and marking module is located at the bottom of the drone. In this case, the geometric information between the prism and the ranging and marking module is the geometric information of the rod. The control unit can calculate the marker center coordinates by combining the rod geometric information, the prism center coordinates, the device attitude information, and the distance measured by the laser. In another embodiment, only the prism is integrated onto the rod, the bottom of the rod is fixed to the top of the drone, and the prism is mounted on the top of the rod. The ranging and marking module is fixed at any position on the bottom of the drone. In this case, the control unit calculates the marker center coordinates by combining the geometric information between the prism and the ranging and marking module, the prism center coordinates, the device attitude information, and the distance measured by the laser.

[0039] In this embodiment, the pole is made of lightweight, high-strength material, and the prism is a circular prism. An attitude sensor is located on the pole or the drone, providing attitude information as the tilt angle of the pole or drone in a stable state. The attitude sensor incorporates a high-precision MEMS accelerometer for real-time measurement of the tilt angle of the pole or drone in a stable state. The ranging and marking module integrates a spraying device and a laser rangefinder. The spraying device sprays marking points from the bottom of the drone onto the surface of the bridge pier, and the laser rangefinder measures the distance from the bottom of the drone to the surface of the bridge pier. The spraying device is either an inkjet module or a printing module, used for printing or imprinting marks on the surface of the bridge pier.

[0040] Please refer to the appendix for details. Figure 7 Based on the same technical concept as the foregoing embodiments, the present invention also provides a method for accurately measuring the positioning holes of bridge piers using unmanned aerial vehicles (UAVs), which is implemented using the aforementioned device for accurately measuring the positioning holes of bridge piers using UAVs. The measurement method includes:

[0041] Step S1: Control the drone to fly and land on the surface of the bridge pier near the positioning hole to be measured (please refer to the attached document). Figure 3 It should be noted that only one drone is needed. Figure 3 The multiple drones shown are for illustrative purposes only and are not required to be operating simultaneously.

[0042] Step S2: Control the total station to measure the coordinates of the prism center, use the intelligent measurement and calibration device mounted on the UAV to obtain the distance from the bottom of the pole to the surface of the pier and the equipment attitude information, and spray a mark from the bottom of the pole to the surface of the pier. Combine the coordinates of the prism center, the equipment attitude information and the distance measured by the laser to calculate the coordinates of the mark center and bind it to the mark.

[0043] In step S2, the control unit controls the drone to fly to the top of the bridge pier and land at a suitable location. A total station is then set up on the ground. After the intelligent measurement and calibration device mounted on the drone stabilizes, the control unit controls the total station to aim at the stationary prism on the top of the pier and perform multiple measurements (please refer to the appendix). Figure 4 The coordinates of the prism center are calculated; the attitude sensor measures the device's attitude information in real time and transmits it to the control unit; the control unit controls the laser rangefinder to measure the distance from the bottom of the pole to the center of the marker point; the control unit controls the spraying device to spray the marker point from the bottom of the pole onto the surface of the pier (please refer to the appendix). Figure 5 The control unit combines the preset rod geometry parameters, prism center coordinates, laser-measured distance, and device attitude information to calculate the marker center coordinates and bind them to the marker, so that the marker center is given known millimeter-level absolute coordinates.

[0044] Step S3: Control the drone to move to another location and repeat the above steps to set up several marker points on the top surface of the bridge pier.

[0045] In step S3, at least three or more marking points are sprayed on the surface of the bridge pier.

[0046] Step S4: Control the image acquisition device mounted on the UAV to acquire images of the bridge pier surface covering several markers and the hole to be measured, and calculate the coordinates of the hole to be measured by combining the coordinates of several marker points and the bridge pier surface images.

[0047] In step S4, the control unit controls the drone to ascend to a height that allows for clear imaging of all marked points and the positioning holes to be measured (e.g., 5-10 meters relative to the pier surface), and takes a series of high-overlap images of the pier surface (see attached image). Figure 6 The process involves generating a millimeter-precision 3D model of the pier top surface based on a set of highly overlapping images; then measuring the 3D absolute coordinates of the positioning hole to be measured within the generated millimeter-precision 3D model. It should be noted that the overlap rate of the pier surface images can be set according to requirements and is not limited here.

[0048] Furthermore, a millimeter-precision true coordinate 3D model of the top surface of the bridge pier is generated based on a set of bridge pier surface images with a high overlap rate. This includes: automatically identifying all marker points from a set of bridge pier surface images with a high overlap rate using image processing software; calling the marker center coordinates bound to each marker point as strong constraint control points, and performing aerial triangulation using bundle adjustment to calculate the high-precision exterior orientation elements of each bridge pier surface image; and generating a millimeter-precision true coordinate 3D model of the top surface of the bridge pier based on the high-precision exterior orientation elements of each bridge pier surface image.

[0049] In summary, the first stage involves the precise establishment and coordinate binding of marker points on the bridge pier surface: A drone equipped with an intelligent measurement and calibration device is controlled to fly and land on the bridge pier surface near the positioning hole to be measured. A ground-based detection device measures the coordinates of the prism center, which are the absolute coordinates of the prism center and serve as the reference for subsequent marker point coordinate calculations. An attitude sensor measures the device's attitude information, and a ranging and marking module measures the distance from the bottom of the drone to the bridge pier surface. Marking points are then sprayed from the bottom of the drone onto the bridge pier surface. Understandably, using the prism center coordinates as a reference, combined with the device attitude information and the geometric information between the prism and the ranging and marking module, the coordinates of the marking module can be obtained. Then, combined with the measured distance, the precise marker center coordinates can be calculated, and these coordinates are bound to the marker points for subsequent coordinate calculations of the positioning hole to be measured. The second stage: 3D reconstruction and target extraction: Using a drone equipped with an image acquisition device, images of the bridge pier surface covering all marked points and the positioning holes to be measured are collected. Then, a 3D model of the bridge pier surface is created based on the bridge pier surface images. Finally, the 3D absolute coordinates of the positioning holes to be measured are extracted based on the millimeter-precision true coordinate 3D model of the bridge pier top surface obtained by the modeling.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A precise measuring device for bridge pier positioning holes based on unmanned aerial vehicles (UAVs), characterized in that, The system includes a drone, an intelligent measurement and calibration device, a ground detection device, an image acquisition device, and a control unit. The intelligent measurement and calibration device and the image acquisition device are mounted on the drone. The intelligent measurement and calibration device includes an attitude sensor, a prism, and a ranging and marking module. The ranging and marking module is located at the bottom of the drone. The attitude sensor is used to measure the device's attitude information in real time. The control unit controls the drone to land on the surface of a bridge pier within a preset distance from the hole to be measured, and controls the ground detection device to measure the center coordinates of the prism. The control unit controls the ranging and marking module to measure the distance from the bottom of the drone to the surface of the bridge pier and sprays marking points from the bottom of the drone onto the surface of the bridge pier. The control unit calculates the center coordinates of the markings by combining the center coordinates of the prism, the device's attitude information, and the measured distance, and binds them to the markings. The control unit also controls the image acquisition device to acquire images of the bridge pier surface covering the markings and the hole to be measured. Finally, the coordinates of the hole to be measured are calculated by combining the center coordinates of the markings and the images of the bridge pier surface.

2. The precise measuring device for bridge pier positioning holes based on unmanned aerial vehicles as described in claim 1, characterized in that, The prism is located on top of the drone.

3. The precise measuring device for bridge pier positioning holes based on unmanned aerial vehicles as described in claim 2, characterized in that, The intelligent measurement and calibration device also includes a rod, through which the prism is mounted on top of the drone.

4. The precise measuring device for bridge pier positioning holes based on unmanned aerial vehicles as described in claim 1, characterized in that, The device attitude information refers to the tilt angle of the UAV in a stable state.

5. The precise measuring device for bridge pier positioning holes based on unmanned aerial vehicles as described in claim 1, characterized in that, The ranging and marking module integrates a spraying device and a laser ranging device. The spraying device is used to spray marking points from the bottom of the UAV onto the surface of the bridge pier, and the laser ranging device is used to measure the distance from the bottom of the UAV to the center of the marking point.

6. A method for accurately measuring bridge pier positioning holes based on unmanned aerial vehicles (UAVs), implemented using a UAV-based device for accurately measuring bridge pier positioning holes as described in any one of claims 1 to 5, characterized in that... The measurement method includes: Step S1: Control the drone to fly and land on the surface of the bridge pier within a preset range of the distance to be measured positioning hole; Step S2: Control the ground detection device to measure the center coordinates of the prism, use the intelligent measurement and calibration device mounted on the UAV to obtain the distance from the bottom of the UAV to the surface of the bridge pier and the equipment attitude information, and spray a mark from the bottom of the UAV to the surface of the bridge pier. Combine the center coordinates of the prism, the equipment attitude information and the distance measured by the laser to calculate the center coordinates of the mark and bind it to the mark. Step S3: Control the drone to move to another location and repeat the above steps to set up several marker points on the top surface of the bridge pier; Step S4: Control the image acquisition device mounted on the UAV to acquire images of the bridge pier surface covering the several markers and the hole to be measured, and calculate the coordinates of the hole to be measured by combining the coordinates of the several marker points and the bridge pier surface images.

7. The method for precise measurement of bridge pier positioning holes based on unmanned aerial vehicles (UAVs) as described in claim 6, characterized in that, Step S2 includes: A ground detection device is set up on the ground, and the ground detection device is controlled to aim at the pole-top prism in a stationary state and perform multiple measurements to calculate the coordinates of the prism center. The attitude sensor measures the attitude information of the device, the laser rangefinder measures the distance from the bottom of the drone to the center of the marker point, and the spraying device sprays the marker point from the bottom of the drone to the surface of the bridge pier. The coordinates of the mark center are calculated by combining the preset rod geometry parameters, prism center coordinates, laser-measured distance, and device attitude information, and then bound to the mark so that the mark center is given known millimeter-level absolute coordinates.

8. The method for precise measurement of bridge pier positioning holes based on unmanned aerial vehicles (UAVs) as described in claim 6, characterized in that, Step S4 includes: Control the drone to fly to a height that can capture all the marked points and the positioning holes to be measured, and control the image acquisition device mounted on the drone to take a series of overlapping images of the bridge pier surface. A millimeter-precision 3D model of the top surface of the bridge pier is generated based on the set of overlapping bridge pier surface images. The three-dimensional absolute coordinates of the hole to be measured are obtained in the generated millimeter-precision true coordinate three-dimensional model.

9. The method for precise measurement of bridge pier positioning holes based on unmanned aerial vehicles as described in claim 8, characterized in that, Based on the set of overlapping bridge pier surface images, a millimeter-precision 3D model of the bridge pier top surface is generated, including: Image processing software was used to automatically identify all the marker points from the set of overlapping bridge pier surface images; The coordinates of the marker center bound to each marker point are used as strong constraint control points. Aerial triangulation is performed using bundle adjustment to calculate the high-precision exterior orientation elements of each pier surface image. A 3D model of the top surface of the bridge pier with millimeter-level accuracy in real coordinates is generated based on high-precision exterior orientation elements of images of each bridge pier surface.

10. The method for precise measurement of bridge pier positioning holes based on unmanned aerial vehicles (UAVs) as described in claim 6, characterized in that, In step S3, at least three or more marking points are sprayed on the surface of the bridge pier.

Images