阅读说明：本技术 一种地面三维激光扫描无标靶监测矿区地表沉陷的方法 (Method for monitoring surface subsidence of mining area by ground three-dimensional laser scanning and without target ) 是由 周大伟 张德民 顾元元 周宝慧 郭良林 亓立壮 李昱昊 于 2019-11-01 设计创作，主要内容包括：本发明涉及一种地面三维激光扫描无标靶监测矿区地表沉陷的方法,属于矿区开采沉陷技术领域,解决了现有技术中矿区开采沉陷监测外业劳动强度大、标靶布设困难、效率低且存在人身安全风险的问题。本发明的方法步骤包括：在矿区工作面布设地面三维激光扫描仪测站点位置；使用三维激光扫描仪对矿区工作面进行多站点扫描,获得同期多站点云数据；对点云数据预处理；利用预处理后的各期点云数据建立地表DEM；通过多期地表DEM相减,得到观测期间地表动态下沉值。本发明无需布设标靶对矿区地表沉陷进行监测,使用特征点完成同期多站点云数据拼接,将整体点云统一转换到大地坐标系下,简化了野外作业流程,降低了工作的危险性,提高了工作效率。(The invention relates to a method for monitoring mining area ground surface subsidence without a target by ground three-dimensional laser scanning, belongs to the technical field of mining area subsidence, and solves the problems of high labor intensity, difficulty in target arrangement, low efficiency and personal safety risk in mining area subsidence monitoring field in the prior art. The method comprises the following steps: laying ground three-dimensional laser scanner station measuring positions on a working surface of a mine area; performing multi-station scanning on a working surface of a mine area by using a three-dimensional laser scanner to obtain synchronous multi-station point cloud data; preprocessing point cloud data; establishing a ground surface DEM (digital elevation model) by utilizing the preprocessed point cloud data of each stage; and subtracting through a multi-phase earth surface DEM to obtain an earth surface dynamic subsidence value during observation. According to the invention, the monitoring of the ground surface subsidence of the mining area is not required to be carried out by arranging targets, the characteristic points are used for completing the simultaneous multi-station point cloud data splicing, and the integral point cloud is uniformly converted into a geodetic coordinate system, so that the field operation process is simplified, the work risk is reduced, and the work efficiency is improved.)

1. A method for monitoring surface subsidence of a mining area by ground three-dimensional laser scanning and without targets is characterized by comprising the following steps:

step 1: laying ground three-dimensional laser scanner station measuring positions on a working surface of a mine area;

step 2: performing multi-station scanning on a working surface of a mine area by using a three-dimensional laser scanner to obtain synchronous multi-station point cloud data;

and step 3: preprocessing point cloud data;

and 4, step 4: establishing a ground surface DEM (digital elevation model) by utilizing the preprocessed point cloud data of each stage;

and 5: and subtracting through a multi-phase earth surface DEM to obtain an earth surface dynamic subsidence value during observation.

2. The method for target-free surface subsidence monitoring of a mining area through ground three-dimensional laser scanning as claimed in claim 1, wherein in the step 1, the ground three-dimensional laser scanner stations are arranged, and targets are not required to be arranged between the stations.

3. The method for target-free surface subsidence monitoring of a mine area through ground three-dimensional laser scanning according to claim 1, wherein the point cloud data preprocessing comprises point cloud data splicing and converting the simultaneous multi-station point cloud data into a scanner coordinate system in the step 3.

4. The method of claim 3, wherein the point cloud data stitching is performed by selecting common feature points.

5. The method of claim 4, wherein the common feature points are common points with well-defined corners of the building or structure.

6. The method for target-free monitoring of surface subsidence in a mine area through ground three-dimensional laser scanning according to claim 3, wherein a Boolean sand model is used for the point cloud data stitching.

7. The method for target-free surface subsidence monitoring of a mine area through ground three-dimensional laser scanning according to claim 3, wherein the point cloud data preprocessing further comprises point cloud data geodetic coordinate conversion, and converting a scanner coordinate system to be below the geodetic coordinate system in the step 3.

8. The method of claim 7, wherein the geodetic coordinate transformation is performed by using an observation station geodetic coordinate system measured by a total station to obtain coordinate translation and rotation transformation parameters, and transforming the whole point cloud into the geodetic coordinate system of the survey area.

9. The method for target-free surface subsidence monitoring of mining area through ground three-dimensional laser scanning according to claim 1, wherein in the step 4, the ground surface DEM is established by using a discrete point network method, and the steps comprise:

s1. calculating observation area range, namely maximum and minimum coordinates in the obtained scanning range;

s2, setting grid intervals, and circularly dividing grids in a range formed by the maximum coordinate and the minimum coordinate;

s3. interpolating grid node elevation values;

s4. store three-dimensional grid elevation values.

10. The method for target-free monitoring of surface subsidence of a mine area through ground three-dimensional laser scanning according to claims 1 to 9, wherein the method further comprises the step of performing error analysis on the coordinate-converted point cloud data between step 3 and step 4.

Technical Field

The invention relates to the technical field of mining subsidence in mining areas, in particular to a method for monitoring surface subsidence in a mining area by ground three-dimensional laser scanning and without a target.

Background

The three-dimensional laser scanning technology belongs to a surface type measuring mode, and is widely applied to the fields of deformation monitoring, geological disaster protection, industry and building modeling and the like in recent years due to the characteristics of high efficiency, high precision and non-contact, wherein the defect and the defect of monitoring the ground surface subsidence of a traditional main section cross linear observation station are overcome in the field of ground surface subsidence monitoring, and the practice shows that the method can effectively acquire deformation information of buildings, the ground surface and the like.

When data acquisition is carried out on a target by using three-dimensional laser scanning, due to the reasons of limited visual angle or shielding of other objects and the like, observation stations need to be reasonably arranged, and the target is scanned in an all-round manner by multiple stations. The traditional splicing method is characterized in that three or more than three non-collinear targets are manually laid, common targets are regarded as homonymous points by data among multiple stations, forced alignment of coordinates is completed, the data of the multiple stations are unified to an independent three-dimensional coordinate system, the method is time-consuming and labor-consuming, particularly in the field with complex terrain and large measuring area range, the problems that the targets are difficult to lay and the geodetic coordinates of the centers of the targets are difficult to measure exist, the field labor capacity is large, the efficiency is low, and the working risk is increased.

Disclosure of Invention

In view of the foregoing analysis, an embodiment of the present invention is directed to providing a method for monitoring surface subsidence of a mining area without a target by ground three-dimensional laser scanning, so as to solve the problems of high labor intensity, difficulty in target arrangement, low efficiency and personal safety risk in mining subsidence monitoring field in the existing mining area.

The purpose of the invention is mainly realized by the following technical scheme:

a method for monitoring surface subsidence of a mining area without a target by ground three-dimensional laser scanning comprises the following steps:

step 1: laying ground three-dimensional laser scanner station measuring positions on a working surface of a mine area;

step 2: performing multi-station scanning on a working surface of a mine area by using a three-dimensional laser scanner to obtain synchronous multi-station point cloud data;

and step 3: preprocessing point cloud data;

and 4, step 4: establishing a ground surface DEM (digital elevation model) by utilizing the preprocessed point cloud data of each stage;

and 5: and subtracting through a multi-phase earth surface DEM to obtain an earth surface dynamic subsidence value during observation.

Further, in the present invention,

in the step 1, the positions of the measuring stations of the ground three-dimensional laser scanner are arranged, and targets do not need to be arranged among the measuring stations.

Further, in the step 3, the point cloud data preprocessing includes point cloud data splicing, and the synchronous multi-station point cloud data is converted into a scanner coordinate system.

Further, the point cloud data is spliced by selecting common characteristic points.

Further, the common characteristic point refers to a common point with well-defined edges and corners of the building or the structure.

Further, a Boolean sand model is used for splicing the point cloud data.

Further, in step 3, the point cloud data preprocessing further includes point cloud data geodetic coordinate conversion, and converting the scanner coordinate system into a geodetic coordinate system.

Further, the geodetic coordinate conversion is to use an observation station geodetic coordinate system measured by a total station to calculate coordinate translation and rotation conversion parameters, and transfer the whole point cloud to a measuring area geodetic coordinate system.

Further, in the step 4, the establishing of the surface DEM uses a discrete point network construction method, and the steps include:

s1. calculating observation area range, namely maximum and minimum coordinates in the obtained scanning range;

s2, setting grid intervals, and circularly dividing grids in a range formed by the maximum coordinate and the minimum coordinate;

s3. interpolating grid node elevation values;

s4. store three-dimensional grid elevation values.

Further, the method also comprises the step of carrying out error analysis on the point cloud data after coordinate conversion between the step 3 and the step 4.

Compared with the prior art, the invention can realize at least one of the following beneficial effects:

(1) by establishing a ground three-dimensional laser scanner observation station and performing multi-station scanning on a working surface of a mining area by using a three-dimensional laser scanner to obtain synchronous multi-station point cloud data, the field measurement process is simplified, the labor intensity of field measurement is reduced, and main work is converted into field treatment;

(2) the method has the advantages that the field operation abandons the laying of targets, the splicing is completed by using the characteristic points, the coordinate conversion parameters are solved by using the site geodetic coordinates to form a rotation matrix, and the integral point cloud data are converted into a geodetic coordinate system in a unified manner, so that the monitoring precision is ensured, the field operation process is simplified, the working risk is reduced, and the working efficiency is improved.

In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.

FIG. 1 is a schematic diagram of three-dimensional laser scanning applied to monitoring surface subsidence;

FIG. 2 is a schematic diagram of the layout of the stations of the scanner;

FIG. 3 is a diagram of a standard grid digital elevation model;

FIG. 4 is a map of a surface DEM established using grid points;

fig. 5 is a mine ground surface DEM and sink basin map.

Reference numerals:

100-first scan; 200-second scanning; 300-the earth's surface; 400-a working surface; 500-sink the basin.

Detailed Description

The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention and not to limit its scope.

The embodiment discloses a method for monitoring surface subsidence of a mining area by ground three-dimensional laser scanning and without targets, as shown in fig. 1-5, the method mainly comprises the following steps: laying ground three-dimensional laser scanner station measuring positions on a working surface of a mining area → using the three-dimensional laser scanner to perform multi-station scanning on the working surface of the mining area, obtaining synchronous multi-station point cloud data → preprocessing point cloud data → establishing a ground surface DEM by utilizing the preprocessed point cloud data of each stage → subtracting through the multi-stage ground surface DEM to obtain a dynamic subsidence value of the ground surface during observation.

Three-dimensional laser scanning applied to surface subsidence monitoring process as shown in fig. 1, when mining work is performed for a period of time, that is, the working face 400 is advanced to a certain position, the working face 400 is scanned 100 a first time by using the three-dimensional laser scanner, and data of the surface 300 is extracted to establish or update a subsidence area DEM₁When the mining work continues for a period of time, i.e., the working face 400 advances to another location, the three-dimensional laser scanner is used to scan 200 the surface 300 of the earth at the same location for a second time, and the digital ground model of the subsidence area is updated to obtain the DEM₂Using DEM₁Subtract DEM₂A measured subsidence of the surface 300 between the time of mining of the monitored area, i.e., the subsidence basin 500, may be obtained.

Illustratively, this method is applied to the inner Mongolia King Hota coal mine, studying regional profiles: the ground elevation of the working surface of the Wangjiata coal mine 2S201 is 1300m, the trend length is 1200m on average, the trend length is 260m on average, the average coal thickness is 3260mm, the average inclination angle is 5 degrees, and the mining starting time is 2018, 7 months and 11 days.

The 2S201 working surface is provided with 14 scanner stations, the scanner stations are arranged as shown in FIG. 2, the arrangement of the scanner stations is mainly used for determining the boundary range of the subsidence basin, and the point of 10mm subsidence is generally taken as the outermost boundary of the movable basin. Because the laser emitted by the instrument has divergence, the laser facula increases along with the increase of the distance, the station-measuring station is reasonably controlled to set the distance, the data quality is ensured, the operation efficiency is improved as much as possible, each station is prevented from being shielded as much as possible within the scanning distance of the scanner, the marking target points are not distributed between the stations, the field operation gives up the distribution of the target, the labor intensity of the field operation is reduced, the field operation process is simplified, the field time of personnel is reduced, and the working risk is reduced. The method comprises the steps of scanning the working surface of the Wangjiata coal mine 2S201 twice by using a ReiglVZ-1000 ground three-dimensional laser scanner in 6 months and 9 months in 2018 respectively to obtain multi-station point cloud data, collecting field work data by using the ground three-dimensional laser scanner, transferring main work to interior work, simplifying the field work operation process and effectively reducing the labor intensity of field work.

When the same-period data is subjected to multi-site scanning, point cloud data obtained by each site needs to be spliced under an independent coordinate system of a scanner in order to convert the point cloud data into a unified coordinate system, and a Boolean model converted by any angle space coordinate is used for registration in the splicing process, wherein the Boolean model is as follows:

wherein, X₀、Y₀、Z₀α, β and gamma are rotation angles converted from the SOCS1 coordinate system to the SOCS0 coordinate system respectively;

setting the Boolean model at six-parameter initial value X₀ ⁰、Y₀ ⁰、Z₀ ⁰、α⁰、β⁰、γ⁰And the Taylor expansion is processed, a first order term is kept, the truncation error is reduced through iterative calculation,

finally, an error equation can be obtained:

wherein the content of the first and second substances,

and selecting at least four pairs of homonymous points for the seven parameter correction numbers, and carrying out iterative computation by a least square method to obtain the optimal estimation of the parameters.

By adopting the method, the multi-station data in the same period can be uniformly converted into the coordinate system of the scanner.

Exemplarily, in a Wangjiata coal mine, a three-dimensional laser scanner is used for multi-site scanning on a working surface of a mine area to obtain synchronous multi-site point cloud data, and point cloud data are preprocessed, wherein the point cloud data preprocessing comprises splicing of the multi-site point cloud data, and geodetic coordinate conversion of the point cloud data after splicing. Because the research area range is large, the number of the stations is large, and the two stations are spliced by selecting common characteristic points. The method comprises the steps of completing point cloud splicing by selecting more than three buildings, structures or other common points with clear edges, exemplarily, taking house corner points, power transmission line tower corner points and telegraph pole corner points as common characteristic points, using geodetic coordinates of a measuring station measured by a total station to calculate translation and rotation parameters converted by two coordinate systems in the process of converting the coordinate systems, and converting integral point cloud data into a geodetic coordinate system of an observation area.

Since the mine surface monitoring is a time sequence work of deformation, the coordinate systems of the scanners in the two phases are not uniform, and the spliced data in each phase needs to be converted into a uniform geodetic coordinate system, such as a WGS84 coordinate system for example; extraction ofAfter registration, the three-dimensional coordinates of the 3 stations in the scanner coordinate system correspond to the high-precision geodetic coordinates measured by the total station, and the corresponding coordinate conversion parameters X are solved according to a point cloud data splicing method₁，Y₁，Z₁α, gamma, rotating the registered point cloud coordinate system around the Z axis to obtain a rotation matrix R₃(γ)，

Similarly, rotation β of the coordinate system about the Y-axis yields a rotation matrix R₂(β)，

The coordinate system is rotated α about the X-axis to obtain a rotation matrix R₁(α)，

Then the overall rotation matrix M_sopComprises the following steps:

the coordinate system conversion formula is:

in the formula, M_sopFor the overall rotation matrix, the SOCS is a scanner coordinate system, the GLCS is a geodetic coordinate system, and the overall point cloud data can be converted into the geodetic coordinate system through a coordinate system conversion formula.

In the embodiment, the characteristic points are used for completing splicing, less stations, at least 3 stations, and exemplarily 3 stations are used for solving coordinate conversion parameters to form a rotation matrix, and the integral point cloud is uniformly converted into a geodetic coordinate system.

In order to ensure the precision of the point cloud data converted into the geodetic coordinate system, after the point cloud data is preprocessed, before the earth surface DEM is established by utilizing the preprocessed point cloud data in each period, the method also comprises the step of analyzing the error and the precision of the point cloud data. The point cloud error source after the geodetic coordinate conversion mainly comprises a scanning error m of a three-dimensional laser three-dimensional scanner₁Registration error m₂And geodetic coordinate conversion error m₃Point location error m_pThe estimation formula is as follows:

note that the scanning error m₁Including angle measurement and distance measurement errors, calibration of the instrument, external environment, scanned target and other errors all affect the accuracy of point cloud. Illustratively, in the embodiment, the Reigl VZ-1000 three-dimensional laser scanner is used for field data acquisition, the main performance index of the three-dimensional laser scanner is shown in the following table, the Reigl VZ-1000 factory report and quality inspection report indicate that the nominal accuracy of the scanner is 5mm/100, and in the embodiment, the average effective distance between the scanner and the target is about 100m due to topographic relief and vegetation shielding in the field, so that the error of the scanner is considered to be about 5 mm.

Performance index	Parameter(s)
		Measuring distance	2.5m＜d＜1400m
Nominal accuracy	5mm/100m
		Angle of view	100deg×360deg
Angular resolution	0.0005°

The error in the registration stage mainly comes from the corresponding relation of the selected points, iterative calculation is carried out on at least 3 pairs of homologous points which are uniformly distributed by using a least square method, the optimal parameter is solved, and the error sigma in unit weight for coarse registration precision is₀And (3) evaluation:

where 3n-6 represents the degree of freedom and n is the number of common points.

In this embodiment, the error σ in the splicing of each station is recorded₀Using Bessel's formula

Wherein n is the error sigma in the calculation₀And (4) the number. 7-month data integral splicing error m in 2018₂Is 22 mm; the data of 9 months in 2018 has an integral splicing error of 11mm and an average error of 16.5mm in two months, namely m₂＝16.5mm。

It should be noted that, the geodetic coordinate transformation is similar to the registration principle in nature, and is also a process of solving seven parameters and constructing a rotation matrix, the main error sources are the extraction of the coordinates of the stations and the measurement of the corresponding geodetic coordinates, and the selected stations should be uniformly distributed to avoid being on a straight line. In the embodiment, the geodetic coordinate measurement of the measuring station is arranged in a closed wire form, the measurement is carried out according to the accuracy of the wire, come TM30 measurement robot (the angle measurement accuracy is 0.5s, and the distance measurement accuracy is 1mm +/-1 ppm) is used for observation, and the simple adjustment and other work are carried out after the measurement of the control network is finished.

In order to verify the coordinate conversion precision, the coordinates of the station under the scanner coordinate system are multiplied by a rotation matrix, the converted coordinate system is compared with the directly observed geodetic coordinates, the following table shows the 9 month point cloud data coordinate conversion precision, and the error value is obtained by comparing the randomly selected station coordinates after the coordinate conversion with the data measured by the high-precision total station. The result shows that the precision is less than 5mm in the x and y directions, the elevation precision is less than 40mm in the z direction, and the point position precision is realized for each station

Average point location accuracy:

mean accuracy m of point location₃This accuracy is 32mm, which meets engineering requirements.

Number of observation station	Difference of X DeltaX/m	Difference of Y DeltaY/m	Difference of Z Δ Z/m
				T8	0.0007	0.0005	0.0375
T9	0.0008	0.0002	0.0370
				T10	0.0012	0.0006	0.0381
T14	0.0011	0.0021	0.0370
				T1	0.0016	0.0000	0.0107

In this embodiment, the wang jiata coal mine: m is₁＝5mm，m₂＝16.5mm，m₃Using a point cloud error estimation formula of 32mm

Obtaining point location error m of point cloud_p＝36.349mm。

In order to obtain the DEM of the ground surface of a mining area, after removing non-ground point data such as vegetation, buildings, structures and the like from point cloud data subjected to coordinate conversion, establishing a square grid according to a generation algorithm of an elevation model and according to a resolution of 0.5m, only reserving one lowest point in each grid, constructing a discrete point network, and mainly comprising the following steps of:

(1) calculating the observation area range to obtain the maximum and minimum coordinates in the scanning range;

(2) setting a grid interval D to divide the grid circularly;

(3) interpolating the elevation value of the grid node;

finding the distance d from each discrete point S to the grid point_lL belongs to (1-N), and N is the number of discrete points; get each discrete pointWeight of elevation Q_l＝(1/d_l)^kK is the average value of the data amount; grid point P (i, j) elevation value Z_pEqual to the elevation Z of a nearby point_lInverse distance weighted averages, the larger k the smoother the result.

(4) Storing the three-dimensional grid DEM;

wherein

And (4) corresponding the x and y values of the three-dimensional coordinate points derived after modeling the data in each period to one by one according to the sequence of traversing from small to large. And subtracting the elevations of corresponding points of the same absolute coordinate to obtain the true value of settlement of each point after DEM modeling, which is acquired by the three-dimensional laser scanner.

In a Wangjiata coal mine, the ground DEM is generated by utilizing preprocessed point cloud data of each period, after denoising and sampling are carried out on the ground point cloud, discrete point networking is carried out according to the resolution of 0.5m, scanning observation is carried out on the working face from 6 months in 2018 to 9 months in 2019 for two times, and the ground DEM is established by taking the data scanned for the first time before mining (30 days 6 months in 2018) as the reference₁As shown in fig. 5 (a); establishing a DEM (dynamic elevation model) of the ground surface of the mining area by using data scanned for the second time (9 months and 3 days in 2018)₂As shown in fig. 5(b), it can be seen from fig. 5(a) and 5(b) that the ground surface elevation is constantly changing from 6 months in 2018 to 9 months in 2018, wherein the ground surface area with lower elevation gradually increases.

In order to verify the accuracy of the ground three-dimensional laser scanner for obtaining the earth surface DEM model, measuring stations of the erected instrument by using a total station so as to obtain earth coordinates and elevations of the stations, wherein the measured elevation value and the DEM elevation value of the total station are shown in the following table.

By comparing the elevation values of the 9 set stations measured by the measuring total station with the elevation values of the generated corresponding points of the DEM, the calculation formula of the labeling difference of the DEM precision can be calculated as follows:

wherein vv is an error value, n is the number of stations, and the marking difference sigma for evaluating DEM precision₁＝46.48mm。

DEM of mine ground surface obtained in 6, 11 and 2018₁DEM obtained in 2018, 9, 3₂Subtracting, obtaining the subsidence basins of the earth surface for 84 days from 11 days in 2018 and 6 months to 3 days in 2018 and 9 months, as shown in fig. 5(c), the maximum subsidence of the earth surface reaches 2.5m from the Wangma coal mine to 3 days in 2018 and 9 months.

And (3) evaluating the accuracy of the obtained subsidence basin by taking the subsidence value measured by the high-accuracy total station as a true value, measuring the subsidence value of the set site by the total station in the second period of 6 months and 9 months in 2018, and comparing the measured subsidence value of the set site with the corresponding subsidence value of the point obtained by subtracting the DEM, wherein the obtained subsidence value of each point is shown in the following table.

By comparing the measured subsidence value with the model corresponding point subsidence value, the labeling difference of the subsidence basin model can be calculated as follows:

wherein vv is errorThe difference value n is the number of the measuring stations, and the labeling difference sigma of the precision of the subsidence basin model is evaluated₂＝67mm。

The point cloud measurement accuracy is obtained through analysis and reaches 36mm, the DEM elevation accuracy established by the point cloud can reach 46mm, the point cloud data is used for establishing a ground surface DEM of a mining area, a ground surface subsidence basin in the time period is obtained through subtraction of the two-stage DEM, the accuracy can reach 67mm, the accuracy of a subsidence basin model is about 2.5m of ground surface deformation relative to the maximum subsidence value, the relative error is 2.7%, the accuracy meets the application requirement in the aspect of mining subsidence monitoring, and the reliability of a three-dimensional laser scanning target-free ground surface deformation monitoring scheme is explained.

The traditional measuring method comprises total station instrument control measurement, three-dimensional laser scanner scanning, total station instrument data adjustment processing and point cloud data processing. Taking the inner Mongolia king house tower coal mine as an example in the embodiment, the traditional method is adopted to control the measurement part to measure 40 control points (the target is erected on the control point) along the trend and the inclination of the working surface by using a total station, the time is 3 days, the three-dimensional laser scanning needs to scan 40 measurement stations according to the positions of the control points, the time is 5 days, the data adjustment of the total station for interior data processing needs 3 days, the point cloud data processing needs 15 days, and the accumulation needs 26 days; under the same manpower and other conditions, by adopting the method of the embodiment, the control and measurement only need to measure the position coordinates of 6 points (more than 3 points are needed), the time is 0.5 day, the three-dimensional laser scanning does not need to control the points, the stations are randomly set, only 14 measuring stations need to be scanned, the time is 2 days, the total station internal work data processing is 0.5 day, the point cloud data processing is 6 days, the accumulation is 9 days, and compared with the traditional method, the efficiency is improved by 65%.

In the embodiment, the three-dimensional laser scanning is used for monitoring the subsidence ground surface subsidence of the mining area, the target does not need to be arranged, and the step of arranging the target is avoided, so that a large number of instruments do not need to be carried to reach the field operation, the difficulties of carrying a large number of instruments and arranging the target in the prior art are avoided, the field operation process is simplified, and the limitation of the field topography is overcome; the characteristic points are used for completing the multi-site point cloud data splicing in the same period, the site geodetic coordinates are used for solving coordinate conversion parameters to form a rotation matrix, and the whole point cloud is converted into a geodetic coordinate system in a unified manner, so that the monitoring precision is ensured, the field operation process is simplified, the working risk is reduced, and the working efficiency is improved.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.