Method and system for evaluating plane precision without directional digital line drawing

Abstract

The invention discloses an evaluation method and system for plane precision of a non-directional digital line map, and relates to the technical field of digital line map quality evaluation, and the method comprises a collection unit which is used for obtaining a field undirectional ground feature check point, a positioning unit which is used for obtaining the real-time coordinate of an observation station and the initial azimuth angle of the observation station when the ground feature check point is measured, and a processing unit which is used for processing the real-time coordinate. The processing unit is used for correcting the coordinates of the ground feature check points acquired for the first time in a non-directional manner, so that the quadratic sum of a plane difference value between the corrected coordinates of the ground feature check points and the coordinates of the homonymy points on the digital line graph is minimum, and the quality management system is used for receiving the corrected coordinates of the ground feature check points, and managing the quality of the ground feature check points. Carrying out precision evaluation on the corrected coordinates of the ground feature check points; through the device, inspection data under a free coordinate system is directly collected without orientation, the obtained data is sorted and analyzed, the plane precision of a digital line drawing is evaluated, manpower resource allocation is reduced, precious field operation time is saved, and then working efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of digital line drawing quality evaluation technology, specifically relating to a method and system for evaluating the planar accuracy of digital line drawings without orientation. Background Technology

[0002] According to GB / T 24356-2009 "Quality Inspection and Acceptance of Surveying and Mapping Results" and CH / T 1025-2011 "Technical Specification for Quality Inspection of Digital Line Maps (DLG)," when evaluating the planar positional accuracy of digital line map results, each map generally requires 20-50 checkpoints. These checkpoints should be evenly distributed and located on prominent landmarks such as communication poles, low-voltage poles, streetlights, manhole cover centers, building corners, and flower bed corners. Planar checkpoints can be collected using methods such as field surveying, aerial triangulation, and photogrammetry. However, in actual accuracy assessment, field surveying is generally preferred. Depending on the workload and map complexity, a single checkpoint collection session (including station orientation and point acquisition) typically takes half an hour, with station orientation accounting for one-third of the time. Furthermore, in traditional inspection processes, office and field work are conducted in separate steps, resulting in low automation and drawbacks such as long data processing times and susceptibility to operational errors.

[0003] Currently, the process of collecting planar inspection data in the field requires steps such as collecting station coordinates, manual orientation, and orientation verification, which requires at least two people. This is especially true in urban areas, underground areas, and other locations with poor visibility, severe obstruction, or unfavorable visibility conditions, where even greater manpower and time costs are incurred. Furthermore, the inconvenience caused by the separation of the two important steps of field data collection and office statistics in the planar accuracy assessment of digital line maps in terms of location and time results in defects such as long office data processing time and the inability to promptly review and verify errors. Summary of the Invention

[0004] To address the shortcomings of existing technologies in field data collection for planar inspection, which involves high labor and time costs and lengthy data processing times, this invention provides a method and system for evaluating the planar accuracy of digital line drawings without the need for orientation. This method allows for data collection, processing, evaluation, and analysis without orientation, resulting in high efficiency and real-time detection and evaluation. This solves the problems of long data processing times and high labor and time costs in existing technologies.

[0005] A method for evaluating the planar accuracy of non-orientation digital line drawings includes the following steps:

[0006] Identify unmarked checkpoints in the field;

[0007] When measuring ground feature checkpoints, obtain the real-time coordinates of the station and the initial orientation azimuth of the station;

[0008] The coordinates of the checkpoints that were initially obtained without orientation were corrected by using the orientation azimuth angle, so that the sum of the squares of the plane differences between the corrected checkpoint coordinates and the coordinates of the corresponding points on the digital line drawing was minimized.

[0009] Receive the corrected checkpoint coordinates, calculate the difference between the checkpoint and the corresponding point on the digital line map, and calculate the map sheet accuracy of the digital line map based on the difference.

[0010] Furthermore, the steps for correcting the coordinates of the checkpoints acquired during the initial non-directional data collection include:

[0011] Determine the positional error of the ground feature point; the positional error is the planar error between the checkpoint collected in the field and the corresponding point on the digital line map;

[0012] The planar position error of the digital line map is calculated based on the positional errors of multiple ground features.

[0013] Furthermore, the calculation steps for the planar position error include:

[0014] Assuming an accurate orientation azimuth θ is determined, the sum of squares D(θ) of the planar differences between the coordinates of all checkpoints after correction by the orientation azimuth θ and the coordinates of their corresponding points on the digital line drawing is minimized. The calculation process is as follows:

[0015]

[0016] Among them, (X) i ,Y i (X) represents the coordinates of the measurement checkpoint after orientation correction. i ′,Y i (′) represents the coordinates of the corresponding point on the graph;

[0017] Since the coordinate correction of the measurement checkpoint is affected by the orientation angle θ of the station, finding the extreme value of D(θ) is equivalent to finding the best estimate of θ. The calculation process is as follows:

[0018] A second-order expansion of D(θ) yields:

[0019]

[0020] D′(θ)+D″(θ)Δθ=0 holds if and only if Δθ approaches 0 infinitely;

[0021] The iterative formula is then:

[0022]

[0023] Set the convergence condition of the iterative formula as follows: δ = 0.00001.

[0024] Furthermore, the accuracy of the corrected coordinates of the ground feature checkpoints is assessed, and the assessment calculation process is as follows:

[0025] The error at the checkpoint is calculated using the following formula:

[0026]

[0027] Among them, (x A ,y A (x) represents the coordinates of point A after processing by the processing unit. A' ,y A' ) represents the coordinates of the corresponding point A′ on the digital line graph, Δ i This represents the difference between coordinates A and A′.

[0028] The formula for calculating the map sheet accuracy of a digital line drawing is as follows:

[0029]

[0030] Where M represents the mean error of the digital line plot results; n represents the total number of detection points.

[0031] Furthermore, an evaluation system based on an assessment method for the planar accuracy of non-orientation digital line drawing includes:

[0032] The data collection unit is used to identify unoriented checkpoints in the field.

[0033] The positioning unit is used to obtain the real-time coordinates of the station when measuring ground feature checkpoints and the initial orientation azimuth of the station.

[0034] The processing unit is used to correct the coordinates of the checkpoints that were initially acquired without orientation by using the orientation azimuth angle, so as to minimize the sum of the squares of the plane differences between the corrected checkpoint coordinates and the coordinates of the corresponding points on the digital line drawing.

[0035] The quality management system is used to receive the corrected coordinates of the checkpoints, calculate the difference between the checkpoints and the corresponding points on the digital line drawing, and calculate the map sheet accuracy of the digital line drawing based on the difference.

[0036] Furthermore, it also includes a communication unit, which includes communication equipment and wiring harness, for transmitting the coordinate data of the ground features processed by the processing unit to the quality management system.

[0037] Furthermore, the positioning unit includes a GNSS-RTK and an IMU; the GNSS-RTK is used to acquire the real-time coordinates of the station, and the IMU is used to acquire the initial azimuth angle of the station.

[0038] Furthermore, the GNSS-RTK terminal is a GPS, GLONASS, or BeiDou terminal, wherein the RTK mode is a single base station mode or CORS mode.

[0039] Furthermore, the IMU is an inertial navigation sensor, including a three-axis gyroscope and a three-axis accelerometer.

[0040] This invention provides a method and system for evaluating the planar accuracy of digital line drawings without the need for orientation, which has the following advantages:

[0041] When the data acquisition unit collects data in this invention, the processing unit associates the positioning information, ground feature checkpoints, and digital line maps to calculate the orientation azimuth. Absolute orientation is not required. By correcting the coordinates of checkpoints obtained without initial orientation, the accuracy of the digital line map sheet can be assessed. This is particularly effective in reducing manpower, material resources, and time consumption in urban areas, underground areas, and other areas with poor visibility and severe obstruction. The quality evaluation unit organizes and analyzes the obtained data to assess the planar accuracy of the digital line map, realizing the integration of field and office work in digital line map quality assessment. Quality problems can be promptly re-checked on-site, avoiding the inability to trace and analyze gross errors in a timely manner in traditional processes, saving valuable fieldwork time, thereby saving economic costs and improving work efficiency. Attached Figure Description

[0042] Figure 1 This is a structural diagram of a planar accuracy assessment system for non-directional digital line drawing according to an embodiment of the present invention;

[0043] Figure 2 This is a flowchart of the non-directional acquisition of ground feature point coordinate correction algorithm in an embodiment of the present invention;

[0044] Figure 3 This is a flowchart of the digital line drawing planar accuracy evaluation in an embodiment of the present invention;

[0045] Figure 4 This is a structural diagram of an evaluation system without an IMU sensor in an embodiment of the present invention;

[0046] Figure 5 This is a structural diagram of an evaluation system with an IMU sensor in an embodiment of the present invention. Detailed Implementation

[0047] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0048] This invention discloses a system for evaluating the planar accuracy of digital line drawings without the need for orientation. For example... Figure 1As shown, the device consists of an orientation unit composed of sensors such as GNSS-RTK and IMU, an acquisition unit composed of a total station, a processing unit composed of a CPU, and a management unit composed of a quality evaluation system. The GNSS-RTK in the positioning unit acquires the real-time coordinates of the device, the IMU acquires the initial orientation values, and the acquisition unit acquires unoriented ground feature checkpoints. The processing unit correlates the positioning information, ground feature checkpoints, and digital line map, and obtains the orientation angle of the station through a finite-step approximation method, thereby obtaining the plane error of the checkpoints. The quality evaluation unit processes and analyzes the obtained data to assess the plane accuracy of the digital line map.

[0049] Data acquisition unit: mainly includes total station and its supporting equipment, responsible for collecting data on field feature checkpoints.

[0050] Positioning Unit: Mainly includes positioning sensors such as GNSS-RTK and IMU. The GNSS-RTK terminal can be a GPS, GLONASS, or BeiDou terminal, or a free combination of the three. The RTK mode can be a single base station mode or CORS mode. The IMU is an inertial navigation sensor, which generally includes a three-axis gyroscope and a three-axis accelerometer. The IMU is not necessary in the device. The IMU mainly provides the processing unit with the initial azimuth angle of the station, which facilitates faster convergence to the true azimuth angle.

[0051] Processing unit: Composed of CPU, and may also include GPU or other processing units, used to calculate the azimuth of the station and correct the coordinates of the initially collected ground features.

[0052] Communication unit: mainly includes communication equipment and wiring harness, which can transmit wirelessly or via wired means, and is used to download single-point positioning errors to the quality management system.

[0053] The quality management system mainly includes modules for data processing and analysis, digital line drawing plane accuracy assessment, and manual review, such as... Figure 3 As shown.

[0054] A method for evaluating the planar accuracy of non-orientation digital line drawings includes the following steps:

[0055] Identify undefined checkpoints in the field;

[0056] When measuring ground feature checkpoints, obtain the real-time coordinates of the station and the initial azimuth of the station;

[0057] The coordinates of the checkpoints collected in the initial non-directional survey are corrected to minimize the sum of the squares of the planar differences between the corrected coordinates of the checkpoints and the coordinates of the corresponding points on the digital line map.

[0058] Receive the corrected checkpoint coordinates and evaluate their accuracy.

[0059] Among them, the algorithm for correcting the coordinates of ground features collected without orientation is as follows: Figure 2 As shown: The planar difference between the checkpoints collected in the field and their corresponding points on the map is the positional error of the ground feature. The planar positional error of the map can be estimated by the positional errors of multiple points (planar error is the difference of a single point, while planar positional error describes the dispersion of multiple points (differences)). Assume that there exists an accurate orientation azimuth angle θ such that the sum of the squares D(θ) of the planar differences between the coordinates of all measured checkpoints after orientation angle correction and the coordinates of their corresponding points on the map is minimized, as shown in equation (1):

[0060]

[0061] Where (X) i ,Y i (X) represents the coordinates of the measurement checkpoint after orientation correction. i ′,Y i ′) represents the coordinates of the corresponding point on the graph.

[0062] Since the coordinate correction of the measurement checkpoint is mainly affected by the orientation angle θ of the station, finding the extreme value of D(θ) is also the best estimate of θ.

[0063] Expanding D(θ) by order 2 yields equation (2):

[0064]

[0065] The expression holds if and only if Δθ approaches 0 infinitely.

[0066] D′(θ)+D″(θ)Δθ=0 (3)

[0067] The iterative formula is then:

[0068]

[0069] The convergence condition for equation (4) is set as follows: δ = 0.00001.

[0070] This includes receiving the corrected checkpoint coordinates and evaluating the accuracy of the corrected checkpoint coordinates, including:

[0071] (1) Calculate the checkpoint error. The checkpoint error is the difference between the coordinates of point A after processing by the processing unit and the coordinates of the corresponding point A′ on the digital line drawing; the calculation formula is:

[0072]

[0073] (2) Calculate map sheet accuracy. During high-precision inspection, error values ​​at checkpoints within twice the allowable mean square error (inclusive) are included in the mathematical accuracy statistics; errors exceeding twice the allowable mean square error are considered to exceed the accuracy limit. During the same-precision inspection, within the allowable mean square error... Within 10 times (inclusive) Error values ​​exceeding (times) should all be included in the mathematical precision statistics; those exceeding (times) should be included in the statistics. An error exceeding a factor of 1 is considered to exceed the accuracy limit. If the number of detection points (edges) is less than 20, the arithmetic mean of the errors is used instead of the mean error; if it is greater than 20, the mean error is used for statistical purposes.

[0074] In this invention, when high-precision detection is used, the mean error is calculated according to formula (1).

[0075]

[0076] Where M represents the mean square error of the result; n represents the total number of detection points (edges); Δ i This indicates a poor result.

[0077] Example 1: As Figure 4 As shown, the acquisition unit consists of a total station, and the positioning unit only contains a GNSS-RTK sensor. This embodiment can achieve basic functions. However, since there is no IMU to provide initial values, the processing unit will converge slowly when calculating the station azimuth angle. In extreme cases, it may fail to converge correctly.

[0078] Example 2: As Figure 5 As shown, the acquisition unit consists of a total station. Each unit contains a GNSS-RTK sensor and an IMU sensor. In this embodiment, the IMU provides the initial value, and the processing unit is highly efficient in calculating the station azimuth.

[0079] Current research in this field mainly focuses on the automation of product manufacturing, which requires vehicles to be equipped with expensive equipment such as 3D laser scanners or gyroscopes. Firstly, this device is smaller and lighter, and vehicle-mounted devices are not suitable for entering narrow alleys such as shantytowns and old urban areas. Secondly, the total station costs about one-tenth of the price of a 3D laser scanner, making it more cost-effective.

[0080] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for evaluating the planar accuracy of non-orientation digital line drawings, characterized in that, Includes the following steps: Identify unmarked checkpoints in the field; When measuring ground feature checkpoints, obtain the real-time coordinates of the station and the initial orientation azimuth of the station; The coordinates of the checkpoints that were initially obtained without orientation were corrected by using the orientation azimuth angle, so that the sum of the squares of the plane differences between the corrected checkpoint coordinates and the coordinates of the corresponding points on the digital line drawing was minimized. Receive the corrected checkpoint coordinates, calculate the difference between the checkpoint and the corresponding point on the digital line map, and calculate the map sheet accuracy of the digital line map based on the difference.

2. The method for evaluating the planar accuracy of a non-orientable digital line drawing according to claim 1, characterized in that, The steps for correcting the coordinates of the checkpoints obtained during the initial haphazard data collection include: Determine the positional error of the ground feature point; the positional error is the planar error between the checkpoint collected in the field and the corresponding point on the digital line map; The planar position error of the digital line map is calculated based on the positional errors of multiple ground features.

3. The method for evaluating the planar accuracy of a non-orientable digital line drawing according to claim 2, characterized in that, The calculation steps for the planar position error include: Assuming an accurate orientation azimuth θ is determined, the sum of squares D(θ) of the planar differences between the coordinates of all checkpoints after correction by the orientation azimuth θ and the coordinates of their corresponding points on the digital line drawing is minimized. The calculation process is as follows: Among them, (X) t Y t (X) represents the coordinates of the measurement checkpoint after orientation correction. t ′, X t (′) represents the coordinates of the corresponding point on the graph; Since the coordinate correction of the measurement checkpoint is affected by the orientation angle θ of the station, finding the extreme value of D(θ) is equivalent to finding the best estimate of θ. The calculation process is as follows: A second-order expansion of D(θ) yields: D′(θ)+D″(θ)Δθ=0 holds if and only if Δθ approaches 0 infinitely; The iterative formula is then: Set the convergence condition of the iterative formula as follows:

4. The method for evaluating the planar accuracy of a non-orientable digital line drawing according to claim 3, characterized in that, The accuracy of the corrected coordinates of the ground feature checkpoints is assessed, and the assessment calculation process is as follows: The error at the checkpoint is calculated using the following formula: Among them, (x A ,y A (x) represents the coordinates of point A after processing by the processing unit. A' ,y A' ) represents the coordinates of the corresponding point A′ on the digital line graph, Δ i This represents the difference between coordinates A and A′. The formula for calculating the map sheet accuracy of a digital line drawing is as follows: Where M represents the mean error of the digital line plot results; n represents the total number of detection points.

5. An evaluation system based on the method for evaluating the planar accuracy of non-orientation digital line drawing as described in claim 1, characterized in that, include: The data collection unit is used to identify unoriented checkpoints in the field. The positioning unit is used to obtain the real-time coordinates of the station when measuring ground feature checkpoints and the initial orientation azimuth of the station; The processing unit is used to correct the coordinates of the checkpoints that were initially acquired without orientation by using the orientation azimuth angle, so as to minimize the sum of the squares of the plane differences between the corrected checkpoint coordinates and the coordinates of the corresponding points on the digital line drawing. The quality management system is used to receive the corrected coordinates of the checkpoints, calculate the difference between the checkpoints and the corresponding points on the digital line drawing, and calculate the map sheet accuracy of the digital line drawing based on the difference.

6. The system for evaluating the planar accuracy of a non-orientable digital line drawing according to claim 5, characterized in that, It also includes a communication unit, which includes communication equipment and wiring harness, for transmitting the coordinate data of the ground features processed by the processing unit to the quality management system.

7. The system for evaluating the planar accuracy of a non-orientable digital line drawing according to claim 5, characterized in that, The positioning unit includes a GNSS-RTK and an IMU; the GNSS-RTK is used to obtain the real-time coordinates of the station, and the IMU is used to obtain the initial azimuth angle of the station.

8. The system for evaluating the planar accuracy of a non-orientable digital line drawing according to claim 8, characterized in that, The GNSS-RTK terminal is a GPS, GLONASS, or BeiDou terminal, wherein the RTK mode is a single base station mode or CORS mode.

9. The system for evaluating the planar accuracy of a non-orientable digital line drawing according to claim 8, characterized in that, The IMU is an inertial navigation sensor, which includes a three-axis gyroscope and a three-axis accelerometer.

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