Free image control photogrammetric device
By integrating a laser rangefinder and camera equipment onto a drone, combined with a differential positioning module, high-precision image-free photogrammetry is achieved, solving the problems of low elevation accuracy and difficulty in setting up ground control points in existing technologies, and improving the accuracy of aerial surveying and the quality of 3D modeling under special terrain.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- NORTHWEST ENGINEERING CORPORATION LIMITED
- Filing Date
- 2025-09-04
- Publication Date
- 2026-06-23
AI Technical Summary
Existing image-free control technology has low accuracy in the elevation direction and cannot meet the accuracy requirements in special terrains such as poor RTK signal, steep cliffs, reservoirs, canyons, etc., and requires the deployment of multiple ground control points to achieve positioning accuracy.
A multi-rotor UAV equipped with a single-beam laser rangefinder and camera equipment is used. Combined with an airborne GNSS differential and RTK differential positioning module, synchronous measurement of elevation and planar data is achieved. The flight platform is controlled by an autopilot module. The camera equipment is fixedly connected to the laser rangefinder. A second RTK differential positioning module is added to improve positioning accuracy and stability.
It enables high-precision aerial surveying and positioning in special terrains, reduces fieldwork workload, improves the accuracy of elevation and planar measurements, solves the problem of difficult ground control point layout, and enhances the integrity and accuracy of 3D modeling.
Smart Images
Figure CN224398663U_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of flight platform photogrammetry technology, and more specifically, to an image-control-free photogrammetry device. Background Technology
[0002] The image control-free technology in related technologies has some problems:
[0003] (1) Its accuracy in the elevation direction is slightly lower than its accuracy in the plane geometry direction.
[0004] (2) For application scenarios where conventional ground control points cannot be set up, such as poor RTK signal, or special terrain such as steep cliffs, reservoirs, and canyons in the survey area, the accuracy of the results is difficult to meet the requirements.
[0005] (3) In the production process, multiple GCPs are often required to achieve the positioning accuracy of conventional ground control points.
[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0007] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a cameraless photogrammetry device that can improve the accuracy of the elevation direction of the results and completely eliminate the need for setting up ground control points, directly obtaining high-precision aerial positioning data, thereby significantly reducing the workload of fieldwork.
[0008] According to one aspect of this disclosure, an image-free photogrammetry apparatus is provided, comprising:
[0009] Flight platform;
[0010] The first differential positioning module is located at the upper end of the flight platform;
[0011] A laser rangefinder is used to acquire the first elevation data of the object being measured; the laser rangefinder is connected to the lower end of the flight platform.
[0012] A camera device is used to acquire planar data of the object being measured; the camera device is disposed on one side of the laser rangefinder and is fixed relative to the position of the laser rangefinder, and the field of view of the laser rangefinder at least partially overlaps with the camera area of the camera device.
[0013] In one embodiment of this disclosure, the laser rangefinder is a single-beam laser rangefinder, and the field of view of the laser rangefinder is located within the imaging area of the camera device; the main optical axis of the camera device is parallel to the laser beam emitted by the laser rangefinder.
[0014] The repeatability of the laser rangefinder is less than 5 centimeters.
[0015] In one embodiment of this disclosure, the image-free photogrammetry device further includes a second RTK differential positioning module, which is disposed on the laser rangefinder or the camera device, and the position of the second RTK differential positioning module is relatively fixed relative to the position of the laser rangefinder.
[0016] In one embodiment of this disclosure, the second RTK differential positioning module has a history data storage, and the acquisition frequency of the history data storage is not less than 20Hz.
[0017] In one embodiment of this disclosure, the flight platform has an autopilot module;
[0018] The self-driving device module has a coordinate transformation unit, which is configured to generate second elevation data based on the position of the camera device, based on the relative position of the laser rangefinder and the camera device and the first elevation data.
[0019] In one embodiment of this disclosure, the first differential positioning module is an airborne GNSS differential and RTK differential positioning module.
[0020] In one embodiment of this disclosure, the measuring range of the laser rangefinder is not less than 200 meters.
[0021] In one embodiment of this disclosure, the laser rangefinder is configured to have at least some of its acquisition times coincide with the acquisition times of the camera device.
[0022] In one embodiment of this disclosure, the flight platform has a power module connected to the laser rangefinder and the camera device, and the power module is used to supply power to the laser rangefinder and the camera device;
[0023] The power consumption of the laser rangefinder is no more than 35 watts and the weight is no more than 1 kilogram; the power consumption of the camera device is no more than 35 watts and the weight is no more than 0.5 kilograms.
[0024] In one embodiment of this disclosure, the flight platform is a multi-rotor unmanned aerial vehicle (UAV) flight platform.
[0025] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description
[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.
[0027] Figure 1 This is a schematic diagram of the structure of an image-free photogrammetry device in one embodiment of the present disclosure.
[0028] Figure 2 This is a schematic diagram of the structure of an image-free photogrammetry device in one embodiment of the present disclosure.
[0029] Figure 3 This is a schematic diagram illustrating the coordinate calibration principle of a camera device and a laser rangefinder in one embodiment of this disclosure.
[0030] Figure 4 This is a schematic diagram of the structure of an image-free photogrammetry device in one embodiment of the present disclosure.
[0031] Figure 5 This is a schematic diagram of the structure of an image-free photogrammetry device in one embodiment of the present disclosure.
[0032] Figure 6 This is a schematic diagram of the structure of an image-free photogrammetry device in one embodiment of the present disclosure. Detailed Implementation
[0033] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore detailed descriptions of them will be omitted. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.
[0034] Although relative terms such as "up" and "down" are used in this specification to describe the relative relationship of one component of an icon to another, these terms are used only for convenience, such as according to the orientation of the examples shown in the accompanying drawings. It is understood that if the device of the icon is flipped upside down, the component described as "up" will become the component described as "down." When a structure is "up" of another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is "directly" mounted on the other structure, or that the structure is "indirectly" mounted on the other structure through another structure.
[0035] The terms “a,” “one,” “the,” and “the” are used to indicate the existence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to the listed elements / components / etc.; the terms “first,” “second,” etc. are used only as markers and are not a limitation on the number of objects.
[0036] In this application, unless otherwise expressly specified and limited, the term "connection" shall be interpreted broadly. For example, "connection" may be a fixed connection, a detachable connection, or an integral part; it may be a direct connection or an indirect connection through an intermediate medium.
[0037] The image control-free technology in related technologies has some problems:
[0038] (1) Its accuracy in the elevation direction is slightly lower than its accuracy in the plane geometry direction.
[0039] (2) For application scenarios where conventional ground control points cannot be set up, such as poor RTK signal, or special terrain such as steep cliffs, reservoirs, and canyons in the survey area, the accuracy of the results is difficult to meet the requirements.
[0040] (3) In the production process, multiple GCPs are often required to achieve the positioning accuracy of conventional ground control points.
[0041] To address at least one of the aforementioned problems, this disclosure provides an image-controlled photogrammetry apparatus, see [link to relevant documentation]. Figure 1 , Figure 2 , Figure 4 and Figure 5 It includes a flight platform 1, a first differential positioning module 2, a laser rangefinder 3, and a camera device 5.
[0042] Among them, the flight platform 1 is used to carry the laser rangefinder 3 and the camera device 5. The laser rangefinder 3 is used to acquire the first elevation data of the object being measured, and the camera device 5 is used to acquire the planar data (planar geometric data) of the object being measured.
[0043] In one embodiment of this disclosure, the flight platform 1 is a multi-rotor flight platform such as a quadcopter, hexacopter, or octagon, which is used to carry a laser rangefinder 3 and a camera device 5.
[0044] See in this example. Figure 1 and Figure 6 The flight platform 1 is connected to a first differential positioning module 2, a laser rangefinder 3, a camera device 5, an autopilot module, a communication module, and a power module.
[0045] Optional, see Figure 6The laser rangefinder 3, camera device 5, first differential positioning module 2, autopilot module, and communication module are all electrically connected to the power supply module, which supplies power to the laser rangefinder 3, camera device 5, first differential positioning module 2, autopilot module, and communication module. The autopilot module is also electrically connected to the first differential positioning module 2, communication module, laser rangefinder 3, and camera device 5.
[0046] In this embodiment, the first differential positioning module 2 is used for positioning. In this example, the first differential positioning module 2 is an airborne GNSS differential and RTK differential positioning module, which can realize real-time differential positioning calculation. Of course, in other embodiments, the first differential positioning module 2 can also be an airborne GNSS differential and PPK differential positioning module. The autopilot module is responsible for controlling the flight of the entire flight platform 1, acquiring the first elevation data of the laser rangefinder 3, and acquiring the planar data of the camera device 5. The communication module is used to receive external commands, and the power supply module is responsible for supplying power to the flight platform 1 and its various electronic modules.
[0047] In one embodiment of this disclosure, the first differential positioning module 2 is an airborne GNSS differential and RTK differential positioning module. The first differential positioning module 2 includes at least an airborne multimode GNSS receiver, a GNSS receiving antenna, a history data storage, an RTK communication link radio, and electronic coupling accessories. In one example, the airborne GNSS differential and RTK differential positioning module consists of an airborne multimode GNSS receiver, a GNSS receiving antenna, a history data storage, an RTK communication link radio, and electronic coupling accessories.
[0048] The airborne multi-mode GNSS receiver is electrically connected to the GNSS receiving antenna; the historical data storage is connected to the airborne multi-mode GNSS receiver; the RTK communication link radio is electrically connected to the airborne multi-mode GNSS receiver; and an electronic coupling connector connects one end to the airborne multi-mode GNSS receiver and the other end to the autopilot module. See also... Figure 4 and Figure 5 The airborne multi-mode GNSS receiver can receive broadcast signals from four commonly used satellite navigation systems, including GPS, GLONASS, GALILEO, and BDS. The data acquisition frequency of the historical data storage is no less than 20Hz, thereby obtaining and storing accurate position information, enabling the multi-rotor flight platform 1 to perform image-controlled measurements, and providing accurate observation data for the three-dimensional reconstruction of the flight platform 1 images.
[0049] Optionally, the autopilot module in this disclosure can adopt the existing autopilot equipment of the flight platform 1 for automatic flight control and pulse signal transmission and control of aerial photography operations. In actual use, it enables the flight platform 1 to fly autonomously along a preset route, while simultaneously driving the laser rangefinder 3, camera equipment 5, and airborne multi-mode GNSS receiver to record and collect data.
[0050] Optionally, the communication module in this disclosure adopts the existing GNSS-RTK field base station and rover signal transmission module, which is used for real-time positioning information communication between the laser rangefinder 3 and the camera equipment 5 and the ground base station, realizing stable and efficient transmission of data transmission signals and positioning coordinate signals between the flight platform 1 and the ground control system in real time.
[0051] Optionally, the first differential positioning module 2 can accurately acquire the spatial information of the flight platform 1 during aerial photography, enabling control-free measurement in complex terrain where it is difficult to set up image control points. In this embodiment, the first differential positioning module 2 is located at the upper end of the flight platform 1.
[0052] In one embodiment of this disclosure, a laser rangefinder 3 is disposed at the lower end of the flight platform 1 to acquire first elevation data of the object being measured. The first elevation data is acquired based on the position of the laser rangefinder 3. In this embodiment, the laser rangefinder 3 is a single-beam laser rangefinder. The repeatability of this single-beam laser rangefinder is less than 5 centimeters. This disclosure utilizes a high-precision single-beam laser rangefinder, which not only acquires accurate first elevation data but also reduces the overall mass of the measuring device and lowers power consumption.
[0053] In one embodiment of this disclosure, the camera device 5 is connected to one side of the laser rangefinder 3 and is fixedly connected to the laser rangefinder 3. This allows for a fixed relative position between the camera device 5 and the laser rangefinder 3. With the relative positions of the camera device 5 and the laser rangefinder 3 fixed, it is easier to calculate the exposure point difference position of the camera device 5 and the system correction parameters. In other words, it is possible to determine the system error correction values between each module more accurately.
[0054] In this embodiment, the field of view of the laser rangefinder 3 at least partially overlaps with the imaging area of the camera device 5. Thus, the camera device 5 and the laser rangefinder 3 can measure the same object.
[0055] In one example, when the laser rangefinder 3 is a single-beam laser rangefinder, the field of view of the laser rangefinder 3 is located within the imaging area of the camera device 5; the main optical axis of the camera device 5 is parallel to the laser beam emitted by the laser rangefinder 3, that is, the observation directions of the camera device 5 and the laser rangefinder 3 are basically the same.
[0056] In this disclosure, the laser rangefinder 3, camera device 5, and first differential positioning module 2 enable simultaneous data measurement of different dimensions of the object under test, improving the accuracy of spatial position measurement. In actual operation of the measuring device, for scenarios where conventional ground control points cannot be deployed, such as poor RTK signal, steep cliffs, deserts, large reservoirs, major transportation routes, or military-controlled areas, this disclosure, through multiple sensors (laser rangefinder 3, camera device 5, and first differential positioning module 2), can completely eliminate the need for ground control point deployment, acquiring high-precision positioning information from aerial survey data, significantly reducing fieldwork workload. Similarly, for application scenarios where ground control points cannot be deployed, high-precision ground control-free photogrammetry products can be obtained, solving industry pain points such as the difficulty of deploying ground control points and unstable GNSS receiver signals during aerial survey production.
[0057] In addition, this disclosure includes a laser rangefinder to measure the first elevation data of the object being measured. The high-precision laser altimetry data (first elevation data) is introduced into the subsequent aerial triangulation calculation process, which is beneficial to obtain the calibration parameters of the camera device 5 more accurately. At the same time, it can provide more accurate elevation data in the vertical direction, strengthen the vertical horizontal difference constraint, reduce the vertical error, and improve the vertical measurement accuracy.
[0058] In addition, the solution disclosed herein, through camera device 5 and laser rangefinder 3, can simultaneously acquire highly overlapping photographic data from multiple angles, including top, level, and bottom views, when the camera is obstructed by downward tilting objects such as cliffs. Furthermore, the ground resolution and color tone are consistent, effectively reducing aerial photography loopholes, significantly improving the integrity and accuracy of 3D real-world modeling, and effectively reducing the frequency of rework in aerial photography and indoor modeling for 3D modeling.
[0059] In one embodiment of this disclosure, the camera device 5 has an interface communication protocol that meets common communication interfaces, can be replaced with common aerial photography focal length lenses, can be set to acquire high-pixel images at equal time intervals, can automatically store acquired photos, the camera device 5 is used to record the time information of the exposure time of the camera device 5, and can acquire high-pixel image data to achieve high-resolution results.
[0060] In one embodiment of this disclosure, the camera device 5 is a digital camera.
[0061] In one embodiment of this disclosure, see [link to relevant documentation]. Figure 1 In the flight direction of flight platform 1, laser rangefinder 3 is located in front, and laser rangefinder 3 and camera equipment 5 do not obstruct each other.
[0062] In one embodiment of this disclosure, see [link to relevant documentation]. Figure 1 and Figure 2 The image-controlled photogrammetry device also includes a second RTK differential positioning module 4, which is mounted on the laser rangefinder 3 or the camera device 5. The position of the second RTK differential positioning module 4 is relatively fixed to the position of the laser rangefinder 3 (a relatively fixed position can more accurately determine the system error correction between modules). The second RTK differential positioning module 4 is used to provide accurate positioning data for the exposure time of the camera device 5.
[0063] In one embodiment of this disclosure, the second RTK differential positioning module 4 includes at least an airborne multimode GNSS receiver, a GNSS receiving antenna, a history data storage, an RTK communication link radio, and electronic coupling accessories. In one example, the airborne GNSS differential and RTK module consists of an airborne multimode GNSS receiver, a GNSS receiving antenna, a history data storage, an RTK communication link radio, and electronic coupling accessories.
[0064] The system comprises an airborne multi-mode GNSS receiver electrically connected to the GNSS receiving antenna, a history data storage device connected to the airborne multi-mode GNSS receiver, an RTK communication link radio electrically connected to the airborne multi-mode GNSS receiver, and an electronic coupling connector connected to the airborne multi-mode GNSS receiver at one end and to the autopilot module at the other. The airborne multi-mode GNSS receiver can receive broadcast signals from four commonly used satellite navigation systems: GPS, GLONASS, GALILEO, and BDS, providing a unified time reference and real-time GNSS position information. The history data storage device has a sampling frequency of no less than 20Hz to acquire and store accurate position information.
[0065] In this disclosure, a second RTK differential positioning module 4 is added to form a dual differential antenna with the first differential positioning module 2, which effectively improves the positioning accuracy and stability during operation, solves the problem of unstable single RTK signal, and improves the stability of RTK signal and differential positioning accuracy during operation.
[0066] In this disclosure, the relative positions of the second RTK differential positioning module 4, the laser rangefinder 3, and the camera device 5 are fixed, which can be used to calculate the structural system error correction number. The three are arranged reasonably, and the appropriate offset is adjusted according to the center of the camera device 5, which is used as the exposure point differential position correction parameter. The purpose is to ensure that the overall center of gravity of the flight platform 1 is below the multi-axis intersection of the flight platform 1.
[0067] In this disclosure, the second RTK differential positioning module 4 is positioned on the side of the camera device 5 to avoid signal obstruction. It also provides timestamps for the exposure time of the camera device 5, the echo time of the laser rangefinder 3, and the positioning time of the second RTK differential positioning module 4, thus constructing a unified time coordinate system. Under the same timestamp, the first elevation data and planar data of the object under test can be acquired to obtain the coordinate position positioning data of the object under test.
[0068] In one embodiment of this disclosure, the weight of the second RTK differential positioning module 4 is no more than 0.3 kg. This reduces weight while simultaneously lowering power consumption and extending the battery life of the power module.
[0069] In one embodiment of this disclosure, the laser rangefinder 3 has a measurement range of not less than 200 meters, the measured object is a natural object, the repeatability is less than 5 centimeters, the repeat measurement period is less than 4 milliseconds, the communication interface has at least one commonly used real-time communication interface, it can measure the measured object in the flight state of the flight platform 1, and meet performance indicators such as maximum height and minimum period; it can record millimeter-level ranging data, millisecond-level laser emission time and laser echo intensity information.
[0070] In one embodiment of this disclosure, the autonomous driving module further includes a coordinate transformation unit. This unit is configured to convert the position of the laser rangefinder 3 into second elevation data based on the position of the camera device 5. In other words, it is used to determine the pixel position of the first elevation data obtained by the laser rangefinder 3 in the planar image acquired by the camera device 5, perform precise spatial calibration between the camera device 5 and the laser rangefinder 3, and obtain second elevation data based on the position of the camera device 5. That is, based on the relative position of the camera device 5 and the laser rangefinder 3, the first elevation data is converted into second elevation data. See also... Figure 3 The position calibration of the camera device 5 and the laser rangefinder 3 is as follows: In the spatial relative pose calibration, six parameters of the camera device 5 and the laser rangefinder 3 need to be obtained. In the formula, (tX, tY, tZ) represents the displacement of the laser rangefinder 3 relative to the camera device 5 in the coordinate system (Xc, Yc, Zc), and (θx, θy, θz) represents the rotation angle of the laser light from the laser rangefinder 3 relative to the principal optical axis of the camera device 5 in the coordinate system (Xc, Yc, Zc).
[0071] In one embodiment of this disclosure, the laser rangefinder 3 is configured to acquire data at least partially at the same time as the camera device 5. Thus, at any given time, the first elevation data acquired by the laser rangefinder 3 will always match the planar data acquired by the camera device 5, for use in locating the object under test.
[0072] In one embodiment of this disclosure, the power consumption of the laser rangefinder 3 is no more than 35 watts and its weight is no more than 1 kg, while the power consumption of the camera device 5 is no more than 35 watts and its weight is no more than 0.5 kg. This reduces weight while lowering power consumption and extending the battery life of the power module.
[0073] The surveying apparatus disclosed herein is particularly suitable for contour flight paths and terrain-following flight paths. Contour flight paths are suitable for surveying areas with flat or gently undulating terrain, urban and town areas, linear engineering line surveys, and initial assessments. Terrain-following flight paths are widely used in mountainous and hilly areas with dramatic topographic relief, deeply dissected landforms such as canyons, gullies, and karst peaks, small-scale surveying of complex terrain, and detailed investigations of forests and nature reserves.
[0074] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.
Claims
1. A cameraless photogrammetry device, characterized in that, include: Flight platform (1); The first differential positioning module (2) is located at the upper end of the flight platform (1); A laser rangefinder (3) is used to acquire the first elevation data of the object being measured; the laser rangefinder (3) is connected to the lower end of the flight platform (1); A camera device (5) is used to acquire planar data of the object being measured. The camera device (5) is located on one side of the laser rangefinder (3) and is fixed relative to the position of the laser rangefinder (3). The field of view of the laser rangefinder (3) at least partially overlaps with the camera area of the camera device (5).
2. The image-controlled photogrammetry device according to claim 1, characterized in that, The laser rangefinder (3) is a single-beam laser rangefinder, and the field of view of the laser rangefinder (3) is located within the imaging area of the camera device (5); the main optical axis of the camera device (5) is parallel to the laser beam emitted by the laser rangefinder (3); The repeatability of the laser rangefinder (3) is less than 5 cm.
3. The image-free photogrammetry device according to claim 2, characterized in that, The image-free photogrammetric device further includes a second RTK differential positioning module (4), which is mounted on the laser rangefinder (3) or the camera device (5). The position of the second RTK differential positioning module (4) is relatively fixed relative to the position of the laser rangefinder (3).
4. The image-free photogrammetry device according to claim 3, characterized in that, The second RTK differential positioning module (4) has a history data storage, and the acquisition frequency of the history data storage is not less than 20Hz.
5. The image-free photogrammetry apparatus according to claim 1, characterized in that, The flight platform (1) has an autopilot module; The self-driving device module has a coordinate transformation unit, which is configured to generate a second elevation data based on the position of the camera device (5) based on the relative position of the laser rangefinder (3) and the camera device (5) and the first elevation data.
6. The image-controlled photogrammetry device according to claim 1, characterized in that, The first differential positioning module (2) is an airborne GNSS differential and RTK differential positioning module.
7. The image-free photogrammetry apparatus according to claim 1, characterized in that, The laser rangefinder (3) has a measurement range of not less than 200 meters.
8. The image-free photogrammetry apparatus according to claim 1, characterized in that, The laser rangefinder (3) is configured to have at least some of its acquisition times the same as those of the camera device (5).
9. The image-free photogrammetry apparatus according to any one of claims 1-8, characterized in that, The flight platform (1) has a power module, which is connected to the laser rangefinder (3) and the camera device (5). The power module is used to supply power to the laser rangefinder (3) and the camera device (5). The power consumption of the laser rangefinder (3) is no more than 35 watts and the weight is no more than 1 kg; the power consumption of the camera device (5) is no more than 35 watts and the weight is no more than 0.5 kg.
10. The image-controlled photogrammetry device according to claim 9, characterized in that, The flight platform (1) is a multi-rotor unmanned aerial vehicle (UAV) flight platform (1).