Ground laser scanner precision detection method

Abstract

The invention discloses a ground laser scanner precision detection method, and belongs to the technical field of measurement, and the method comprises the following steps: taking a tripod, placing the tripod on a flat ground, and then taking a ground laser scanner and installing the ground laser scanner on the tripod; carrying out standard deviation detection in the horizontal direction; placing at least six targets around the ground laser scanner, wherein each target and the ground laser scanner are positioned on the same horizontal plane; a ground laser scanner is started to obtain point cloud data of each target, three groups of measurement are carried out, and each group of measurement comprises four measurement loops; processing data in the horizontal direction; standard deviation detection in the vertical direction is carried out; geometric centers of at least six targets are collinearly arranged in the vertical direction; starting a ground laser scanner to measure data in the vertical direction; and processing data in the vertical direction. Through precision detection in the horizontal direction and the vertical direction, the scanning result can be effectively connected with existing civil engineering measurement data, and data support is provided for engineering evaluation and decision making.

Description

Technical Field

[0001] The present invention relates to the field of measurement technology, and in particular to a method for detecting the accuracy of a terrestrial laser scanner. Background Art

[0002] As a core piece of modern 3D spatial information acquisition equipment, terrestrial laser scanners achieve digital modeling of measured targets through laser ranging and precision angle measurement technology. Their operating principle relies on a servo motor driving the high-speed rotation of a reflective prism and the horizontal rotation of the instrument, controlling the laser beam to systematically scan horizontally and vertically. This system then combines distance, horizontal, and vertical angle observations through coordinate conversion to generate 3D point cloud data. In civil engineering, this technology has become a crucial support for key processes such as structural deformation monitoring, tunnel axis control, and construction quality verification. Its measurement accuracy is directly related to the reliability of project safety assessments and quality control.

[0003] The reliance on measurement accuracy in civil engineering is significantly higher than in other application areas. In engineering practices such as bridge monitoring, high-rise building deformation analysis, and tunnel penetration, measurement accuracy is directly related to the accuracy of structural safety and stability assessments.

[0004] However, the current terrestrial laser scanner accuracy detection system has the following significant deficiencies:

[0005] Inadequate Angular Accuracy Detection Systems: Existing detection methods focus excessively on radial distance accuracy and point cloud registration accuracy, while systematic methods for detecting angular measurement accuracy are severely inadequate. Because scanners utilize high-speed rotation mechanisms to achieve 360° scanning, the accuracy of their horizontal and vertical angular measurements directly impacts the geometric and spatial positional accuracy of point cloud data. Especially in long-distance measurement scenarios common in civil engineering, the cumulative effect of small angular errors can lead to significant misjudgments in critical applications such as structural deformation monitoring.

[0006] Lack of standardized testing methods: Existing specifications have relatively rough requirements for target spatial distribution, stipulating only basic angular range requirements and not detailed regulations for detection distance. Because the measurement accuracy of a scanner is closely related to the scanning distance, significant distance differences will affect the horizontal comparability of test results, making it difficult to provide a standardized basis for equipment selection and quality assessment. At the same time, there is a lack of unified angular accuracy testing standards and standardized processes for specific civil engineering application scenarios. Different testing agencies and research institutions use different methods, resulting in a lack of comparability and traceability between different evaluation results, making it difficult to provide a reliable scientific basis and quality assurance for engineering practice.

[0007] The assessment system is not compatible with engineering requirements: Existing testing methods fail to effectively control key influencing factors such as distance, horizontal angle, and vertical angle during accuracy assessment. Instead, they perform tests under conditions where multiple factors vary simultaneously. As a result, the accuracy results obtained are actually a comprehensive reflection of the coupled effects of multiple factors, including distance measurement, horizontal angle measurement, and vertical angle measurement. This coupled accuracy assessment method cannot accurately identify and quantify the specific contribution of each individual factor to the final measurement accuracy, making it difficult for the test results to provide effective technical guidance for equipment stability assessment, performance improvement, and measurement quality control, severely limiting the guiding value of the test results for civil engineering practice.

[0008] Therefore, there is an urgent need to develop a terrestrial laser scanner accuracy detection method specifically tailored to the characteristics of civil engineering applications, in order to evaluate the instrument's horizontal and vertical angle measurement accuracy in various complex engineering environments, and to establish a standardized detection process applicable to the civil engineering field, providing reliable technical support for scanner accuracy evaluation, performance improvement, equipment selection, and measurement quality control in engineering applications. Summary of the Invention

[0009] The purpose of the present invention is to provide a terrestrial laser scanner accuracy detection method, which solves the problem that existing terrestrial laser scanners lack angle accuracy detection and evaluation means in engineering measurements, and at the same time constructs a set of evaluation systems so that the scanning data obtained in the project has a reliable accuracy reference basis.

[0010] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0011] A method for detecting the accuracy of a terrestrial laser scanner comprises the following steps:

[0012] S1. Place the tripod on a flat surface and install the terrestrial laser scanner on the tripod.

[0013] S2. Perform horizontal standard deviation detection: Place at least six targets around the terrestrial laser scanner, with each target on the same horizontal plane as the terrestrial laser scanner.

[0014] S3. Start the terrestrial laser scanner. The terrestrial laser scanner automatically rotates around the vertical axis. At the same time, the reflective prism on the terrestrial laser scanner automatically rotates around the horizontal axis to obtain point cloud data of each target. The terrestrial laser scanner scans all targets one by one to form a measurement round. A total of three groups of measurements are performed. Each group of measurements includes four measurement rounds. S1 needs to be repeated before each group of measurements.

[0015] When performing each set of measurements, the reflective prism rotates around the horizontal axis to form an initial laser scanning plane. The initial laser scanning plane divides the space into two areas, the left and the right. It is necessary to ensure that the initial laser scanning plane is located in the space between any two adjacent targets and does not cut any target. Ensure that all targets can be completely scanned in their respective areas. Then, any target adjacent to the initial laser scanning plane is selected as the starting target I.

[0016] After completing the first and second rounds of measurement, the terrestrial laser scanner is rotated 180° around the vertical axis so that the initial orientation of the reflective prism is opposite to that of the first and second rounds of measurement, and then the third and fourth rounds of scanning are performed;

[0017] S4. Horizontal scanning data processing: Calculate the horizontal standard deviation m H ;

[0018] S5. Perform vertical standard deviation test: Arrange the geometric centers of at least six targets in a collinear manner in the vertical direction. There is no requirement for the spacing between the targets.

[0019] S6. Start the terrestrial laser scanner to perform at least three sets of data measurements. Each set of measurements includes four rounds, and each round includes all targets. S1 must be repeated before each set of measurements.

[0020] When performing each set of measurements, the reflective prism rotates around the horizontal axis to form the initial laser scanning plane. It is necessary to ensure that the initial laser scanning plane does not cut any target, and select the bottom or top target as the starting target I;

[0021] After completing the fifth and sixth rounds of measurement, the terrestrial laser scanner is rotated 180° around the vertical axis so that the initial orientation of the reflective prism is opposite to that of the fifth and sixth rounds of measurement, and the seventh and eighth rounds of scanning are performed;

[0022] S7. Vertical scanning data processing: Calculate the vertical standard deviation m V By conducting horizontal and vertical accuracy tests on the ground laser scanner, we can determine whether the scanner's scanning results can be effectively connected with the existing civil engineering measurement data, providing data support for engineering evaluation and decision-making, and giving full play to the application value of laser scanning technology in civil engineering.

[0023] Preferably, the target is a geometric target that can be identified by a terrestrial laser scanner and extract coordinate information. The target arrangement in existing projects can be used to arrange the measurement site, which is convenient to arrange and has low cost.

[0024] Preferably, in S2, each target maintains the same horizontal distance from the ground laser scanner, and the distance value is within a set range of 5m to 10m. The fixed distance value range facilitates on-site arrangement and re-measurement.

[0025] Preferably, in S5, each target maintains the same horizontal distance from the ground laser scanner, and the distance value is within a set range of 5m to 10m. The fixed distance value range is convenient for on-site arrangement and re-measurement.

[0026] Preferably, in S1, the basic operating environment requirements for the terrestrial laser scanner are a temperature of 5°C to 40°C and a humidity in the air less than condensation humidity, to ensure that the instrument is in normal working condition.

[0027] Preferably, in S2, at least six targets are evenly distributed around the terrestrial laser scanner, so as to comprehensively evaluate the scanning accuracy of the terrestrial laser scanner in various directions.

[0028] More preferably, in S3 and S6, the terrestrial laser scanner needs to be preheated for a period of time before each set of measurements, and the feedback after the terrestrial laser scanner runs the self-test program indicates that there is no fault, thereby ensuring the stable state of the measurement scanner and improving the accuracy of the measurement data.

[0029] Furthermore, in S3, the coordinates of the target in the i-th direction during the J-th measurement are:

[0030] The absolute angles of the targets in each direction in the Jth round Calculate as follows:

[0031]

[0032] The relative angles between the targets in each direction and the starting target I in the Jth round Calculate as follows:

[0033]

[0034] The average value of each relative angle Calculate as follows:

[0035]

[0036] The error of each relative angle in each measurement round Calculate as follows:

[0037]

[0038] The arithmetic mean of the relative angle errors in each measurement round Calculate as follows:

[0039]

[0040] Residuals of relative angles Calculate as follows:

[0041]

[0042] The residual sum of squares of each group of measurements Calculate as follows:

[0043]

[0044] The degrees of freedom of each state in 4 directions Calculate as follows:

[0045]

[0046] A set of relative angle measurements Standard deviation Calculate as follows:

[0047]

[0048] The degrees of freedom f of the three sets of measurements H Calculate as follows:

[0049]

[0050] Horizontal standard deviation m H Calculate as follows:

[0051]

[0052] Where n is the number of targets, which is a dimensionless integer. The unit is ° squared, and f H is dimensionless, and all other units are in °.

[0053] Furthermore, in S6, the coordinates of the target in the i-th direction of the J-th measurement are:

[0054] The absolute angles of the targets in each direction in the Jth round with the starting target I Calculate as follows:

[0055]

[0056] The relative angles between the targets in each direction and the starting target I in the Jth round Calculate as follows:

[0057]

[0058] The average value of each relative angle Calculate as follows:

[0059]

[0060] The error of each relative angle in each measurement round Calculate as follows:

[0061]

[0062] The arithmetic mean of the relative angle errors in each measurement round Calculate as follows:

[0063]

[0064] Residuals of relative angles Calculate as follows:

[0065]

[0066] The residual sum of squares of each group of measurements Calculate as follows:

[0067]

[0068] The degrees of freedom of each state in 4 directions Calculate as follows:

[0069]

[0070] A set of measured coordinates Standard deviation Calculate as follows:

[0071]

[0072] The degrees of freedom f of the three sets of measurements V Calculate as follows:

[0073]

[0074] Vertical standard deviation m V Calculate as follows:

[0075]

[0076] Where n is the number of targets, which is a dimensionless integer. The unit is ° squared, and f V is dimensionless, and all other units are in °.

[0077] Furthermore, the accuracy of the terrestrial laser scanner is evaluated by measuring the horizontal standard deviation m H and vertical standard deviation m V Grading of laser scanning accuracy:

[0078] Horizontal and vertical classification basis: high precision <2.78×10 -3 °≤Medium precision≤5.56×10 -3 °<low accuracy;

[0079] When the horizontal and vertical deviations belong to the same level, the same level is determined as the accuracy level of the terrestrial laser scanner; otherwise, it is determined as a lower level, which is convenient for measurement and use in different projects.

[0080] The beneficial effects of the present invention are:

[0081] (1) Establishing an angular accuracy evaluation system: This terrestrial laser scanner accuracy detection method uses two-dimensional detection in the horizontal and vertical directions to calculate the standard deviation in the horizontal and vertical directions respectively, which can systematically evaluate the angular accuracy performance of the scanner and ensure the integrity of the angular accuracy characterization; multiple groups of measurements are used, and each group of measurements contains four measurement rounds, and each measurement round covers at least six directions, so that the angular errors in each direction are fully involved in the accuracy calculation, providing more objective accuracy evaluation results; by rotating the scanner 180° for symmetrical measurement, the actual error state of the instrument axis system is more comprehensively reflected, thereby enhancing the representativeness and reliability of the evaluation results.

[0082] (2) Establishment of standardized detection methods: This terrestrial laser scanner accuracy detection method establishes a complete detection process including temperature and humidity control, preheating self-test, and standardization of target spatial distribution, which solves the problem of rough provisions on detection conditions in existing specifications; the horizontal targets are evenly distributed and the vertical targets are arranged with a fixed horizontal projection distance to form a reproducible benchmark scene, which enables horizontal comparison between different devices and data docking with the existing measurement system of civil engineering; statistical methods are used to quantify errors for analysis to ensure the objectivity and comparability of the detection results.

[0083] (3) Realize engineering-oriented accuracy evaluation: The terrestrial laser scanner accuracy detection method is compatible with multiple types of targets and can adapt to the needs of different scenarios; the test process can be repeated in a variety of actual engineering environments, such as various weather conditions, vibration interference, and dust environments, to systematically evaluate the actual impact of external factors on angle accuracy; by independently controlling error influencing factors, a separate evaluation of angle accuracy can be achieved, providing precise technical guidance for equipment calibration and error compensation; through grading standards, the horizontal and vertical accuracy are divided into three levels: high, medium, and low, providing users with an intuitive basis for equipment selection to meet the measurement needs of different projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 A diagram showing the horizontal target arrangement of the terrestrial laser scanner accuracy detection method provided by the present invention;

[0085] Figure 2 A diagram showing the vertical target arrangement for the terrestrial laser scanner accuracy detection method provided by the present invention;

[0086] Figure 3 Scanning direction diagram of the terrestrial laser scanner accuracy detection method provided by the present invention Figure 1 ;

[0087] Figure 4 Scanning direction diagram of the terrestrial laser scanner accuracy detection method provided by the present invention Figure 2 . DETAILED DESCRIPTION

[0088] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the application without making any creative efforts shall fall within the scope of protection of the present invention.

[0089] like Figures 1-4 As shown, this embodiment discloses a method for detecting the accuracy of a terrestrial laser scanner, comprising the following steps:

[0090] S1. Place the tripod on a flat surface, then install the terrestrial laser scanner on the tripod, ensuring that the terrestrial laser scanner is in a horizontal state;

[0091] S2. Horizontal standard deviation test: Place six targets around the terrestrial laser scanner, with each target on the same horizontal plane as the terrestrial laser scanner. The more targets there are, the more accurate the measurement data will be, but the more difficult the target placement will be. Choose an appropriate number of targets based on the actual site environment and requirements.

[0092] S3. Start the terrestrial laser scanner. The terrestrial laser scanner automatically rotates around the vertical axis. At the same time, the reflective prism on the terrestrial laser scanner automatically rotates around the horizontal axis to obtain point cloud data for each target. The terrestrial laser scanner scans all targets one by one to form a measurement round. A total of three groups of measurements are performed. Each group of measurements contains four measurement rounds. S1 must be repeated before each group of measurements. By performing multiple measurements, the number of samples can be increased, the interference of accidental errors can be reduced, and the accuracy of the results can be enhanced, thereby obtaining a more realistic evaluation of the instrument accuracy.

[0093] When performing each set of measurements, the reflective prism rotates around the horizontal axis to form an initial laser scanning plane, which divides the space into two areas: left and right. It is necessary to ensure that the initial laser scanning plane is located in the space between any two adjacent targets and does not cut any target. This ensures that all targets can be completely scanned within their respective areas. Any target adjacent to the initial laser scanning plane is then selected as the starting target I. By preventing the targets from being artificially segmented, the integrity and quality of the point cloud data for each target is guaranteed.

[0094] After completing the first and second rounds of measurement, rotate the terrestrial laser scanner 180° around the vertical axis so that the initial orientation of the reflective prism is opposite to that of the first and second rounds of measurement. Then perform the third and fourth rounds of scanning. This can more comprehensively reflect the actual error status of the instrument axis system and enhance the representativeness and reliability of the evaluation results.

[0095] S4. Horizontal scanning data processing: Calculate the horizontal standard deviation m H ,Standardize the collected data to obtain accurate evaluation results;

[0096] S5. Perform vertical standard deviation test: Arrange the geometric centers of the six targets collinearly in the vertical direction. There is no requirement for the spacing between the targets. The targets are arranged by vertical lines, laser marking, or projection onto the ground to ensure the reliability of the target positions. At the same time, there is no requirement for the distance between the targets, which makes the arrangement easy, has low requirements for site layout, and is easy to reproduce.

[0097] S6. Start the terrestrial laser scanner and perform at least three sets of data measurements. Each set of measurements includes four rounds, and each round includes all targets. S1 must be repeated before each set of measurements. By performing multiple measurements, the number of samples can be increased, the interference of accidental errors can be reduced, and the accuracy of the results can be enhanced, thereby obtaining a more realistic evaluation of the instrument's accuracy.

[0098] During each set of measurements, the reflective prism rotates around the horizontal axis to form the initial laser scanning plane. Ensure that the initial laser scanning plane does not cut any targets, and select the bottom or top target as the starting target I. This prevents the targets from being artificially segmented, ensuring the integrity and quality of the point cloud data for each target.

[0099] After completing the fifth and sixth rounds, rotate the terrestrial laser scanner 180° around the vertical axis so that the initial orientation of the reflective prism is opposite to that of the fifth and sixth rounds. Perform the seventh and eighth rounds of scanning to more comprehensively reflect the actual error status of the instrument axis system and enhance the representativeness and reliability of the evaluation results.

[0100] S7. Vertical scanning data processing: Calculate the vertical standard deviation mV , the collected data is standardized, and the accuracy of the scanner is evaluated comprehensively in the horizontal and vertical directions, so that the evaluation results are more comprehensive.

[0101] More preferably, the target is a geometric target that can be identified by a terrestrial laser scanner and extract coordinate information. Specifically, the target is a spherical target commonly used by terrestrial laser scanners for site splicing, which is easy to arrange and has low cost.

[0102] Furthermore, in S2, each target maintains the same horizontal distance from the terrestrial laser scanner. This distance is within a set range of 5m to 10m and is evenly distributed around the terrestrial laser scanner in the same plane to improve the reliability of the collected data. A preferred horizontal distance of 9m is used for each target. To ensure measurement accuracy, the deviation between the actual distance value of each target and the set value is controlled within 10%, that is, the actual distance value is 9m ± 0.9m.

[0103] Furthermore, in S5, each target maintains the same horizontal distance from the terrestrial laser scanner. This distance is within a set range of 5m to 10m, with 5m being preferred. To ensure measurement accuracy, the deviation between the actual distance value of each target and the set value is controlled within 10%, i.e., the actual distance value is 5m ± 0.5m.

[0104] Preferably, in S1, the operating environment of the terrestrial laser scanner is required to be a temperature of 5°C to 40°C and the humidity in the air is less than the condensation humidity, to ensure stable operation of the equipment, prevent the external environment from affecting the operating status of the equipment, and ensure that the entire measurement process can be carried out stably.

[0105] More preferably, in S2, at least six spherical targets are evenly distributed around the terrestrial laser scanner to improve the accuracy of the measurement results.

[0106] Preferably, in S3 and S6, the terrestrial laser scanner needs to be preheated for a period of time before performing each set of measurements, and the feedback after the terrestrial laser scanner runs the self-test program indicates that there is no fault, so that the scanner is in a stable temperature range when working to prevent internal temperature changes from affecting the measurement results.

[0107] Furthermore, in S3, the coordinates of the target in the i-th direction during the J-th measurement are:

[0108] The absolute angles of the targets in each direction in the Jth round Calculate as follows:

[0109]

[0110] The relative angles between the targets in each direction and the starting target I in the Jth round Calculate as follows:

[0111]

[0112] The average value of each relative angle Calculate as follows:

[0113]

[0114] The error of each relative angle in each measurement round Calculate as follows:

[0115]

[0116] The arithmetic mean of the relative angle errors in each measurement round Calculate as follows:

[0117]

[0118] Residuals of relative angles Calculate as follows:

[0119]

[0120] The residual sum of squares of each group of measurements Calculate as follows:

[0121]

[0122] Degrees of freedom for each state in 4 measurements and 6 directions Calculate as follows:

[0123]

[0124] A set of relative angle measurements Standard deviation Calculate as follows:

[0125]

[0126] The degrees of freedom f of the three sets of measurements H Calculate as follows:

[0127]

[0128] Horizontal standard deviation m H Calculate as follows:

[0129]

[0130] in, The unit is ° squared, and fH is dimensionless, and all other units are in °.

[0131] The horizontal standard deviation is calculated by the residual square and the degrees of freedom, and the error is quantified using statistical methods. The data is then processed to make the evaluation results more objective.

[0132] Furthermore, in S6, the coordinates of the target in the i-th direction of the J-th measurement are:

[0133] The absolute angles of the targets in each direction in the Jth round with the starting target I Calculate as follows:

[0134]

[0135] The relative angles between the targets in each direction and the starting target I in the Jth round Calculate as follows:

[0136]

[0137] The average value of each relative angle Calculate as follows:

[0138]

[0139] The error of each relative angle in each measurement round Calculate as follows:

[0140]

[0141] The arithmetic mean of the relative angle errors in each measurement round Calculate as follows:

[0142]

[0143] Residuals of relative angles Calculate as follows:

[0144]

[0145] The residual sum of squares of each group of measurements Calculate as follows:

[0146]

[0147] Degrees of freedom for each state in 4 measurements and 6 directions Calculate as follows:

[0148]

[0149] A set of measured coordinates Standard deviation Calculate as follows:

[0150]

[0151] The degrees of freedom f of the three sets of measurements V Calculate as follows:

[0152]

[0153] Vertical standard deviation m V Calculate as follows:

[0154]

[0155] in, The unit is ° squared, and f V is dimensionless, and all other units are in °.

[0156] The vertical standard deviation is calculated by the residual square and the degree of freedom. Statistical methods are used to quantify the error and the data are processed to make the evaluation results more objective.

[0157] Furthermore, the accuracy of the terrestrial laser scanner is evaluated by measuring the horizontal standard deviation m H and vertical standard deviation m V Grading of laser scanning accuracy:

[0158] Horizontal and vertical classification basis: high precision <2.78×10 -3 °≤Medium precision≤5.56×10 -3 °<low accuracy;

[0159] When the horizontal and vertical deviations belong to the same level, the same level is determined as the accuracy level of the terrestrial laser scanner; otherwise, it is determined at a lower level. By detecting and evaluating the accuracy in the horizontal and vertical directions, the accuracy status of the scanner can be objectively evaluated, and the scanner can be connected with the data in the existing project under the same evaluation standard, providing an objective basis for using the scanner for measurement in the project.

[0160] The horizontal measurement and processing data of the terrestrial laser scanner accuracy detection method are as follows:

[0161] Table 1-1 Horizontal direction measurement group 1 data table

[0162]

[0163] Table 1-2 Calculation table for horizontal direction measurement group 1

[0164]

[0165] Table 1-3 Horizontal direction measurement group 2 data table

[0166]

[0167] Table 1-4 Calculation table for horizontal direction measurement group 2

[0168]

[0169] Table 1-5 Horizontal direction measurement group 3 data table

[0170]

[0171] Table 1-6 Calculation table for horizontal direction measurement group 3

[0172]

[0173] The vertical measurement and processing data of the terrestrial laser scanner accuracy detection method are as follows:

[0174] Table 1-7 Vertical direction measurement group 1 data table

[0175]

[0176] Table 1-8 Calculation table for vertical direction measurement group 1

[0177]

[0178] Table 1-9 Vertical direction measurement group 2 data table

[0179]

[0180] Table 1-10 Calculation table for vertical direction measurement group 2

[0181]

[0182] Table 1-11 Vertical direction measurement group 3 data table

[0183]

[0184] Table 1-12 Calculation table for vertical direction measurement group 3

[0185]

[0186] Horizontal standard deviation m H Final calculation results:

[0187]

[0188] Among them, 2.78×10-3 °<0.005425°<5.56×10 -3 °, meeting the requirements of medium precision use.

[0189] Vertical standard deviation m V Final calculation results:

[0190]

[0191] Among them, 2.78×10 -3 °<0.004494°<5.56×10 -3 °, meeting the requirements of medium precision use.

[0192] Based on the disclosure and teachings of the above description, those skilled in the art may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and any modifications and variations of the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although certain specific terms are used in this description, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for detecting the accuracy of a terrestrial laser scanner, characterized in that: The following steps are involved: S1. Place the tripod on a flat surface and install the terrestrial laser scanner on the tripod. S2. Perform horizontal standard deviation detection: Place at least six targets around the terrestrial laser scanner, with each target on the same horizontal plane as the terrestrial laser scanner. S3. Start the terrestrial laser scanner. The terrestrial laser scanner automatically rotates around the vertical axis. At the same time, the reflective prism on the terrestrial laser scanner automatically rotates around the horizontal axis to obtain point cloud data of each target. The terrestrial laser scanner scans all targets one by one to form a measurement round. A total of three groups of measurements are performed. Each group of measurements includes four measurement rounds. S1 needs to be repeated before each group of measurements. When performing each set of measurements, the reflective prism rotates around the horizontal axis to form an initial laser scanning plane. The initial laser scanning plane divides the space into two areas, the left and the right. It is necessary to ensure that the initial laser scanning plane is located in the space between any two adjacent targets and does not cut any target. Ensure that all targets can be completely scanned in their respective areas. Then, any target adjacent to the initial laser scanning plane is selected as the starting target I. After completing the first and second rounds of measurement, the terrestrial laser scanner is rotated 180° around the vertical axis so that the initial orientation of the reflective prism is opposite to that of the first and second rounds of measurement, and then the third and fourth rounds of scanning are performed; S4. Horizontal scanning data processing: Calculate the horizontal standard deviation m H ; S5. Perform vertical standard deviation test: Arrange the geometric centers of at least six targets collinearly in the vertical direction. There is no requirement for the spacing between the targets. S6. Start the terrestrial laser scanner to perform at least three sets of data measurements. Each set of measurements includes four rounds, and each round includes all targets. S1 must be repeated before each set of measurements. When performing each set of measurements, the reflective prism rotates around the horizontal axis to form the initial laser scanning plane. It is necessary to ensure that the initial laser scanning plane does not cut any target, and select the bottom or top target as the starting target I; After completing the fifth and sixth rounds of measurement, the terrestrial laser scanner is rotated 180° around the vertical axis so that the initial orientation of the reflective prism is opposite to that of the fifth and sixth rounds of measurement, and the seventh and eighth rounds of scanning are performed; S7. Vertical scanning data processing: Calculate the vertical standard deviation m V .

2. The terrestrial laser scanner accuracy detection method according to claim 1, characterized in that: The target is a geometric target that can be recognized by a terrestrial laser scanner and its coordinate information can be extracted.

3. The terrestrial laser scanner accuracy detection method according to claim 1, characterized in that: In S2, each target maintains the same horizontal distance from the ground laser scanner, and the distance value is within a set range of 5m to 10m.

4. The terrestrial laser scanner accuracy detection method according to claim 1, characterized in that: In S5 , each target maintains the same horizontal distance from the terrestrial laser scanner, and the distance value is within a set range of 5 m to 10 m.

5. The terrestrial laser scanner accuracy detection method according to claim 1, characterized in that: In S1, the operating environment of the terrestrial laser scanner is required to have a temperature of 5°C to 40°C and an air humidity less than condensation humidity.

6. The terrestrial laser scanner accuracy detection method according to claim 5, characterized in that: In S2, at least six targets are evenly distributed around the terrestrial laser scanner.

7. The terrestrial laser scanner accuracy detection method according to claim 6, characterized in that: In S3 and S6, the terrestrial laser scanner needs to be warmed up for a period of time before each set of measurements, and the feedback after the terrestrial laser scanner runs the self-test program indicates that there is no fault.

8. The terrestrial laser scanner accuracy detection method according to claim 1, characterized in that: In S3, the coordinates of the target in the i-th direction of the J-th measurement are: The absolute angles of the targets in each direction in the Jth round Calculate as follows: The relative angles between the targets in each direction and the starting target I in the Jth round Calculate as follows: The average value of each relative angle Calculate as follows: The error of each relative angle in each measurement round Calculate as follows: The arithmetic mean of the relative angle errors in each measurement round Calculate as follows: Residuals of relative angles Calculate as follows: The residual sum of squares of each group of measurements Calculate as follows: The degrees of freedom of each state in 4 directions Calculate as follows: A set of relative angle measurements Standard deviation Calculate as follows: The degrees of freedom f of the three sets of measurements H Calculate as follows: Horizontal standard deviation m H Calculate as follows: Where n is the number of targets, which is a dimensionless integer. The unit is ° squared, and f H is dimensionless, and all other units are in °.

9. The terrestrial laser scanner accuracy detection method according to claim 1, characterized in that: In S6, the coordinates of the target in the i-th direction of the J-th measurement are: The absolute angles of the targets in each direction in the Jth round with the starting target I Calculate as follows: The relative angles between the targets in each direction and the starting target I in the Jth round Calculate as follows: The average value of each relative angle Calculate as follows: The error of each relative angle in each measurement round Calculate as follows: The arithmetic mean of the relative angle errors in each measurement round Calculate as follows: Residuals of relative angles Calculate as follows: The residual sum of squares of each group of measurements Calculate as follows: The degrees of freedom of each state in 4 directions Calculate as follows: A set of measured coordinates Standard deviation Calculate as follows: The degrees of freedom f of the three sets of measurements V Calculate as follows: Vertical standard deviation m V Calculate as follows: Where n is the number of targets, which is a dimensionless integer. The unit is ° squared, and f V is dimensionless, and all other units are in °.

10. The terrestrial laser scanner accuracy detection method according to claim 1, characterized in that: Terrestrial laser scanner accuracy assessment: Based on the measured horizontal standard deviation m H and vertical standard deviation m V Grading of laser scanning accuracy: Horizontal and vertical classification basis: high precision <2.78×10 -3 °≤Medium precision≤5.56×10 -3 °<Low precision. When the horizontal and vertical deviations belong to the same level, the same level is determined as the accuracy level of the terrestrial laser scanner; otherwise, it is determined at a lower level.

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