A ground photogrammetry mark for observing fault activity and its use method

Abstract

The present invention discloses a ground photogrammetry mark for observing fault activity and a method for using the same. The ground photogrammetry mark is composed of a base plate, a reflection identification plate, a connecting rod and a level. The geometric center of the reflection identification plate and the base plate have a predetermined spatial relationship. The method for using the mark for fault measurement includes four parts: making the ground photogrammetry mark, laying out the ground photogrammetry mark, observing and identifying the point position of the measurement mark, and a fault observation method based on the ground photogrammetry mark. At least two marks are laid out on each of the two plates of the fault, and at least two periods of observation are performed. The photogrammetry mark can provide redundant observation values ​​to improve the observation accuracy, and has the advantages of flexible layout and labor saving.

Description

Technical Field

[0001] The present invention relates to the technical field of fault activity observation, and in particular to a ground photogrammetry mark for observing fault activity and a use method thereof. Background Art

[0002] The methods used to observe the horizontal or vertical movement of the two plates of the fault mainly include theodolite + rangefinder / total station trilateration or triangulation, lidar, InSAR, GNSS, precision leveling, etc.

[0003] The observation system of fault activity based on theodolite + rangefinder / total station trilateration or triangulation (triangulation network) requires the burial of ground observation marks, and has always relied on manual repeated measurements under the observation points, and the line of sight problem must be solved. The line of sight between two opposite observation points cannot be too large, generally less than 3000m. Therefore, this method has low working efficiency and is greatly affected by line of sight conditions, which often results in unsatisfactory network layout.

[0004] For air-based LiDAR, there is no need to bury ground observation marks, there is no problem of surface visibility conditions, and it has the advantages of high efficiency and large operating area, but it is expensive and not conducive to repeated observation. If the ground observation mark is not buried, it will be impossible to determine the vector direction of the relative movement of the two plates of the fault and the amount of movement in the vector direction, and it will not be possible to determine the absolute movement of the two plates of the fault through joint measurement with the regional satellite positioning network. Ground-based LiDAR also does not need to bury ground observation marks, but there is a problem of needing to have visibility between surface traverse points. This method has high accuracy, but low efficiency, small operating area, and relatively expensive costs. If the ground observation mark is not buried, it will be impossible to determine the vector direction of the relative movement of the two plates of the fault and the amount of movement in the vector direction, and it will not be possible to determine the absolute movement of the two plates of the fault through joint measurement with the regional satellite positioning network.

[0005] The InSAR method uses the interference fringes of two or more periods of surface deformation to untangle and calculate the activity amplitude of the two sides of the fault in different directions. This method requires the installation of ground angle radiators. The measurement area is large, but it is dependent on the area covered by the satellite flight trajectory, which affects the scope of application.

[0006] The GNSS crustal deformation observation network requires the burial of ground observation markers. It does not have the problem of surface visibility restrictions and is suitable for large-scale crustal deformation observation. It has good signal continuity and can calculate the horizontal displacement of the relative movement of the two plates of the fault. However, the calculation of the vertical or vertical component is weak, and the network deployment cost is high.

[0007] To achieve multi-period, high-precision observation of fault activity, a simple, cheap and easy-to-operate method is an important one. With the launch of consumer-grade drones, it has become possible to achieve low-cost, multi-period photogrammetric observations.

[0008] With the emergence of oblique photogrammetry technology, oblique photogrammetry with drones equipped with multiple lenses has multiple shooting angles and is convenient for repeated observation. If drones equipped with satellite positioning systems are used but ground observation marks are not buried, the vector direction of the relative movement of the two plates of the fault and the amount of movement in the vector direction cannot be determined. Therefore, the arrangement of ground photogrammetry marks is a necessary condition for achieving high-precision observation of surface deformation or fault activity.

[0009] The photogrammetric marks that are currently used more are mostly multi-ring center type. The essence of this type of photogrammetric mark is to capture the mark through multiple rings and use a single-point plane photogrammetric mark positioned by the center point. If the center point is blocked, the data of the point will be unusable. Then, by setting multiple corner points, the capture efficiency of the photogrammetric mark in the image can be improved, and redundant observation values ​​can be increased, thereby improving the observation accuracy.

[0010] Existing research and observations have shown that the intensity of activity of a large-scale or medium-scale regional fault zone is often uneven, thus forming a localized deformation image. This phenomenon provides a new idea for observing the state of fault activity. That is, by deploying a small regional network in areas with high fault activity intensity or large activity amplitude, using drones to observe the point changes of ground photogrammetry marks for multiple periods, local dynamic observation of small areas can be achieved. The observation data of the small regional network can also be connected to the regional deformation observation network for solution and used as an encrypted observation network for the large regional network. Summary of the invention

[0011] In order to solve the problems raised in the above background technology, the present invention provides a ground photogrammetry mark for observing fault activity and a method of using the same.

[0012] To achieve the above-mentioned purpose, the present invention provides a ground photogrammetric marker for observing fault activity.

[0013] It includes: a bottom plate, wherein the bottom plate is an isosceles right triangle;

[0014] At least two isosceles right triangle reflection identification plates of the same shape and equal length; the two reflection identification plates are fixed on the base plate, and the two reflection identification plates and the one isosceles right triangle base plate have a predetermined spatial position relationship, so that when the photogrammetric mark is placed in a space, the position of the geometric center in the space can be calculated based on the position of at least one reflection identification plate in the space and the predetermined spatial relationship;

[0015] The connecting rod is connected to the bottom plate so that the geometric center of the connecting rod and the geometric center of the bottom plate have a preset spatial relationship. The geometric center of the bottom connecting rod or the position of a specific part of the connecting rod can be calculated by marking the corner point of the upper bottom plate or the corner point of the reflector. The corresponding position of the connecting rod and the bottom plate is the position of the ground observation point.

[0016] Level, installed on the connecting rod or base plate, used to level the base plate and make the connecting rod vertical during the first observation;

[0017] The overall outline of the logo is a triangular pyramid at the top and a connecting rod at the bottom.

[0018] The method for using the ground photogrammetry mark for observing fault activity comprises the following steps:

[0019] Ground photogrammetry mark layout:

[0020] (1) Determination of active fault areas: by reading existing data or conducting field surveys, we can identify active fault areas, such as areas with high activity intensity or obvious landform deformation;

[0021] (2) The layout of ground photogrammetry marks: In the active fault section, at least 4 ground photogrammetry marks of the present invention are laid on both sides of the fault, and at least 2 marks are laid on each side. The connecting rod at the bottom of the mark needs to be fixed on the bedrock, and the upper part has low or medium shielding;

[0022] Observation and point identification methods of measurement marks:

[0023] (1) Flight preparation, including: ① GNSS base station setup; ② aircraft communication link radio setup; ③ aircraft assembly and commissioning; ④ mission area route design; ⑤ aircraft and ground control station joint commissioning;

[0024] (2) Test flight to determine safe altitude and shooting parameters;

[0025] (3) Rapid DSM production of orthophotos. After the flight preparation is completed, orthophotos are acquired at a safe altitude above the mission area. After the orthophoto acquisition mission is completed, the GNSS base station data, the aircraft's onboard GNSS mobile station data, the aircraft's flight control inertial navigation and photography information data, and the orthophotos taken by the onboard camera are copied to the computer at the mission site for rapid DSM production.

[0026] (4) Oblique photography

[0027] After the rapid DSM is produced, a high-resolution oblique photography route is designed based on the DSM data of the mission area. The UAV follows the ground and takes close-up photos. Through multiple flights, high-resolution oblique photography aerial photos of the mission area are obtained.

[0028] (5) Aerial triangulation and real-scene 3D data production

[0029] Copy the data from the mobile hard disk to the computer processing cluster and process it using professional processing software (Smart3D or ContextCapture or Mirauge3D, etc.). First, perform aerial triangulation to obtain accurate POS information for each photo, then perform real-scene 3D reconstruction to obtain real-scene 3D model data of the mission area;

[0030] (6) Orthophoto production

[0031] Based on the real-scene 3D data produced, vertical image acquisition and processing are performed to obtain the true orthogonal image results of the mission area;

[0032] (7) Three-dimensional coordinates of corner points: Read the three-dimensional coordinates of any corner point in the measurement mark in ContextCapture4.4.9.516 software or Smart3D;

[0033] (8) Two-dimensional coordinates of corner points: In ArcGIS software, manually obtain the two-dimensional coordinates of any corner point on the ground survey mark;

[0034] (9) When point O in the logo is blocked, the coordinates of other corner points in the logo, such as A, B, or O, can be identified. 1 .

[0035] The geometric center can also capture any corner point of the radiation identification plate in the space where it is located to deduce the spatial positions of the remaining corner points.

[0036] The bottom plate or the reflective plate is pre-sprayed with a characteristic color to improve the recognition rate of the ground measurement mark in the image.

[0037] The application of the ground photogrammetry mark for observing fault activity in fault observation is characterized by comprising the following steps:

[0038] (1) Point identification: (1) to (6) of the above-mentioned survey mark observation and point identification methods can obtain the two-dimensional or three-dimensional coordinates of each corner point of each ground photogrammetric mark;

[0039] (2) Distance measurement: Use the two-point distance formula to calculate the length between any two points; you can also measure the length of the side between corner points with the same number on different measurement marks;

[0040] (3) Distance adjustment: Adjust the combined side lengths in (2) to obtain the adjusted side lengths;

[0041] (4) Azimuth measurement of the observation side: connect the measurement mark of one plate of the fault with the corresponding numbered corner points of the two measurement marks of the opposite plate of the fault to obtain multiple sets of azimuths of the observation side;

[0042] (5) Multi-period observation: After the first phase of observation is obtained through steps (1) to (4), the subsequent multi-period observation needs to repeat steps (1) to (4) to obtain the change in side length and azimuth of the observed side between each subsequent observation and the first observation, or the change in side length and azimuth of the observed side between any two phases. In this way, the relative activity amplitude and relative activity azimuth of the two plates of the fault over a period of time can be observed.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. The ground photogrammetry marks used can provide more redundant observation values ​​in one flight, thereby reducing the layout of ground measurement marks, saving costs and improving the accuracy of single measurement solutions.

[0045] 2. The use of drones has flexible operation time, a wide range of flight altitude options, and more flexible re-measurement cycles and flight altitudes than the InSAR method.

[0046] 3. The image of the survey area is obtained by drone photogrammetry, which greatly improves the work efficiency compared with other ground manual measurement methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The present invention provides a vertical view (a), a side view (b), a base plate (including a level) and a reflective identification plate view (c) of the ground photogrammetry mark.

[0048] Figure 2 The physical map of the ground photogrammetry mark described in the present invention.

[0049] Figure 3 It is a relationship diagram between the measurement marks and faults described in the present invention and a field oblique photography operation diagram.

[0050] Figure 4 This is the orthophoto map described in the present invention.

[0051] Figure 5 This is the two-dimensional point identification diagram of the measurement mark described in the present invention.

[0052] Figure 6 This is the three-dimensional point identification diagram of the measurement mark described in the present invention.

[0053] Figure 7 This is a diagram of the fault activity monitoring method described in the present invention. DETAILED DESCRIPTION

[0054] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0055] Example 1

[0056] This embodiment is a ground photogrammetry mark for observing fault activity according to the present invention, including: 1 base plate, 2 triangular reflection identification plates, 1 connecting rod and 1 circular level. The overall outline of the mark is a triangular cone at the top and a long square rod at the bottom. That is, it is composed of 1 isosceles right triangle base plate, 2 isosceles right triangle reflection identification plates, 1 connecting rod with a square cross section and 1 circular level. The overall outline is as follows Figure 1 As shown in (a), the upper O 1 OAB triangular pyramid, the lower part is the connecting rod. Figure 1 shown.

[0057] Welding of measuring marks. OAB is an isosceles right triangle base plate, O 1 OA and O 1 OB is two isosceles right triangle reflectors, OO 2 A connecting rod with a square cross section. 1 is a corner point at the top of the logo, O is the geometric center point of the logo, and O 2 Weld the right-angled side OA of the isosceles right triangle reflection identification plate to the right-angled side OA of the isosceles right triangle of the bottom plate at the same point, weld the right-angled side OB of the other isosceles right triangle reflection identification plate to the right-angled side OB of the isosceles right triangle of the bottom plate at the same point, and weld the right-angled sides OO of the two isosceles right triangle reflection identification plates at the same point. 1 The right angles of the bottom plate and the two reflectors in this embodiment are 20 cm long, and the hypotenuse is 28.28 cm long. Figure 2 shown.

[0058] The method of connecting the connecting rod to the upper triangular pyramid mark. This embodiment uses a stainless steel tube with a square cross section, a side length of 2 cm, and a length of 1 m. One of the ribs of the square stainless steel tube is OO 2 , will be OO 2 The common right angle side OO of the two triangular reflective identification plates in the logo 1 On the same straight line, Figure 2 . So that in obtaining A, B, O or O 1 When the corner point is 2 point.

[0059] The circular level in this embodiment uses a compass circular level and is placed on the bottom plate, such as Figure 2 shown.

[0060] In order to quickly identify the ground photogrammetry mark during the oblique photogrammetry process, in this embodiment, the base plate of the mark is painted red, and the two isosceles right-angled triangle reflective identification plates are painted green and yellow. Figure 2 .

[0061] Example 2

[0062] This embodiment is an example of the ground photogrammetry mark layout of the present invention. After the on-site inspection, a medium-shaded area is selected, and a steel tape measure is used to represent the fault ground trace. Photogrammetry marks are buried on the two plates of the assumed fault, and two marks of the same specifications are buried in each plate, such as Figure 3 shown.

[0063] Example 3

[0064] This embodiment is a method for observing and identifying a measurement mark in the present invention, comprising the following steps:

[0065] (1) Flight preparation

[0066] Before the flight, choose a weather with calm wind, thin clouds and uniform light to carry out field operations. This embodiment uses a DJI Phantom 4RTK single-lens drone. Aircraft assembly and debugging, mission area route design, and aircraft and ground control station joint debugging were carried out in the field.

[0067] (2) Test flight

[0068] After two test flights, the safe altitude was set to 7.5m, aperture 2.8, shutter speed 1 / 160S, ISO100, the planned route was a tic-tac-toe route, and the tilt photography shooting mode was selected.

[0069] (3) Rapid DSM production of orthophotos

[0070] After the orthophoto acquisition mission flight is completed, the aircraft's onboard GNSS mobile station data, aircraft flight control inertial navigation and photography information data, and orthophotos taken by the onboard camera are copied to the computer at the mission site for rapid DSM production;

[0071] (4) Oblique photography

[0072] After the fast DSM of oblique photography is produced, a high-resolution oblique photography route is designed based on the DSM data of the mission area, so that the drone can follow the ground and take close-up photos, such as Figure 3 shown.

[0073] (5) Aerial triangulation solution and 3D model reconstruction

[0074] After the aerial photography is completed, the aircraft's onboard GNSS mobile station data, aircraft flight control inertial navigation and photography information data, and photos taken by the onboard camera are copied to the mobile hard disk for storage. The data on the mobile hard disk is copied to the computer processing cluster, and Smart3D is used to perform aerial triangulation and solve to obtain the precise POS information of each photo, and then the real scene 3D reconstruction is performed to obtain the real scene 3D model data of the mission area.

[0075] (6) Orthophoto production

[0076] Based on the real-scene 3D data produced, vertical image acquisition and processing are carried out to obtain the orthophoto results of the mission area. Figure 4 .

[0077] (7) Reading the 2D coordinates of the corner points of the measurement mark

[0078] Import the orthophoto into ArcGIS or other remote sensing software, zoom in on a corner point in the image to a pixel and read its two-dimensional coordinates; Figure 5 shown.

[0079] (8) Reading the three-dimensional coordinates of the corner points of the measurement mark

[0080] Import the DSM image into Smart3D or other software, zoom in on a corner point in the image, and read its 3D coordinates, such as Figure 6 shown.

[0081] (9) Repeat steps (7) and (8) to measure the two-dimensional or three-dimensional coordinates of any other corner point in the ground survey mark, and then perform two-dimensional or three-dimensional coordinate adjustment to obtain the coordinates of the center o of the survey mark, or derive the coordinates of the center point based on the preset geometric relationship between the corner point and the center point o.

[0082] Here, the measurement results after a flight mission are provided. If fault activity observation is required, steps (1) to (8) in Example 3 need to be repeated, and then data comparison is performed to obtain the point position changes of each marker itself during the time interval of the flight missions on both sides, as well as the relative changes between the points, so that the relative movement mode and amplitude of the two plates of the fault can be calculated.

[0083] Example 4

[0084] This embodiment is an application of the ground photogrammetry mark for observing fault activity in the present invention in fault observation, including the following steps:

[0085] like Figure 1 As shown, the four measurement marks in Example 3 are named T 1 , T2 , T 3 and T 4 , the corner points and connecting rod numbers of each mark,

[0086] (1) After the first observation, the two-dimensional or three-dimensional coordinates of point o of each mark can be obtained. The side length between each mark in the first period can be calculated by the coordinate formula between two points, as follows: Figure 7 Assume that after a period of time, one side of the fault undergoes left-handed activity, resulting in T 3 and T 4 There is a relative shift to the left;

[0087] (2) Repeat the steps (1) to (8) in Example 3 in the second phase of flight to obtain T 1 , T 2 , T 3 and T 4 , the two-dimensional or three-dimensional coordinates of the second phase o point. The side length between each mark in the second phase can be calculated by the coordinate formula between two points, such as Figure 7 As shown by the short dashed line in;

[0088] (3) Change in side length. By comparing the side lengths of the same-name lines in (1) and (2), the change in side length can be obtained, such as Figure 7 Medium S 1 and S 2 ;

[0089] (4) Elevation change. The elevation change of each mark in the two observation time interval can be obtained by comparing the three-dimensional coordinates of each mark o point. Figure 7 The middle curve shows the T caused by fault activity between two observation periods. 4 Changes in elevation;

[0090] (5) Azimuth change. Determine the azimuth of the line segment between the first two points in (1) ( Figure 7 α), and then determine the azimuth of the line segment between the two points after observation (2) Figure 7 By comparing the azimuth changes of the same-name line segments in two periods, the azimuth changes of the relative movement of the two plates of the fault can be obtained.

Claims

1. A ground photogrammetric marker for observing fault activity, characterized in that: include: A bottom plate, wherein the bottom plate is an isosceles right triangle; At least two isosceles right triangle reflection identification plates of the same shape and equal length; the two reflection identification plates are fixed on the bottom plate, the common right angle sides of the two reflection identification plates are perpendicular to the bottom plate, and the two reflection identification plates and the one isosceles right triangle bottom plate have a predetermined spatial position relationship, so that when the photogrammetric mark is placed in a space, the position of the geometric center in the space can be calculated based on the position of at least one reflection identification plate in the space and the predetermined spatial relationship; A connecting rod, the connecting rod is connected to the bottom plate, the connecting rod is square, and a rib in the connecting rod is on the same straight line as the common right-angled side, so that the geometric center of the connecting rod and the geometric center of the bottom plate have a preset spatial relationship, and the geometric center of the bottom connecting rod or the position of a specific part of the connecting rod can be calculated by marking the corner point of the upper bottom plate or reflecting the position of the flat plate corner point, and the corresponding position of the connecting rod and the bottom plate is the position of the ground observation point; Level, installed on the connecting rod or base plate, used to level the base plate and make the connecting rod vertical during the first observation; The overall outline of the logo is a triangular pyramid at the top and a connecting rod at the bottom.

2. The method for using the ground photogrammetry mark for observing fault activity according to claim 1, characterized in that: The steps include: Ground photogrammetry mark layout: a. Determination of active fault sections, by reading existing data or field investigation to sort out the active fault sections; b. The layout of ground photogrammetry marks. In the active fault section, at least 4 ground photogrammetry marks are laid on both sides of the fault, with at least 2 marks on each side. The connecting rod at the bottom of the mark needs to be fixed on the bedrock, and the upper part has low shielding; Observation and point identification methods of measurement marks: (1) Flight preparation, including: ① GNSS base station setup; ② aircraft communication link radio setup; ③ aircraft assembly and commissioning; ④ mission area route design; ⑤ aircraft and ground control station joint commissioning; (2) Test flight to determine safe altitude and shooting parameters; (3) Rapid DSM production of orthophotos. After the flight preparation is completed, orthophotos are acquired at a safe altitude above the mission area. After the orthophoto acquisition mission is completed, the GNSS base station data, the aircraft's onboard GNSS mobile station data, the aircraft's flight control inertial navigation and photography information data, and the orthophotos taken by the onboard camera are copied to the computer at the mission site for rapid DSM production. (4) Oblique photography After the rapid DSM is produced, a high-resolution oblique photography route is designed based on the DSM data of the mission area, so that the UAV follows the ground and takes close-up photos. Through multiple flights, high-resolution oblique photography aerial photos of the mission area are obtained. (5) Aerial triangulation and real-life 3D data production The data from the mobile hard disk is copied to the computer processing cluster and processed using professional processing software. First, aerial triangulation is performed to obtain the precise POS information of each photo, and then real-scene 3D reconstruction is performed to obtain real-scene 3D model data of the mission area. (6) Orthophoto production Based on the real-scene 3D data produced, vertical image acquisition and processing are performed to obtain the true orthogonal image results of the mission area; (7) 3D coordinates of corner points: Read the 3D coordinates of any corner point in the measurement mark in ContextCapture software or Smart3D; (8) Two-dimensional coordinates of corner points: Manually obtain the two-dimensional coordinates of any corner point on the ground survey mark using ArcGIS software; (9) When point O in the mark is blocked, the coordinates of point O can be obtained by adjusting the coordinates of other corner points in the mark.

3. The ground photogrammetric marker for observing fault activity according to claim 1, characterized in that: The geometric center can also capture any corner point of the radiation identification plate in the space where it is located to deduce the spatial positions of the remaining corner points.

4. The ground photogrammetric marker for observing fault activity according to claim 1, characterized in that: The bottom plate or the reflective identification plate is pre-sprayed with a characteristic color to improve the recognition rate of the ground measurement mark in the image.

5. The method for using the ground photogrammetry mark for observing fault activity according to claim 2, characterized in that: The steps include: (C1) Point identification: (1) to (6) of the above-mentioned survey mark observation and point identification methods can obtain the two-dimensional or three-dimensional coordinates of each corner point of each ground photogrammetric mark; (C2) Distance measurement: Use the two-point distance formula to calculate the length between any two points; you can also measure the length of the side between corner points with the same number but different measurement marks; (C3) Distance adjustment: adjust the combined side lengths in (C2) to obtain the adjusted side lengths; (C4) Azimuth measurement of the observation side: connect the measurement mark of one plate of the fault with the corresponding numbered corner points of the two measurement marks of the opposite plate of the fault to obtain multiple sets of azimuths of the observation side; (C5) Multi-period observation: After the steps (C1) to (C4), the results of one phase of observation are obtained. When the subsequent multi-period observation is carried out after a period of time, the steps (C1) to (C4) need to be repeated to obtain the change in side length and the change in azimuth of the observed side between each subsequent observation and the first observation, or the change in side length and the change in azimuth of the observed side between any two phases, so as to observe the relative activity amplitude and relative activity orientation of the two plates of the fault over a period of time.

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