Method for determining maximum range of three-dimensional scanning based on measurement accuracy and stability

Abstract

This invention discloses a method for determining the maximum distance of a three-dimensional scanning device based on measurement accuracy and stability, comprising the following steps: Step 1: Prepare the site and set up the three-dimensional scanning device and total station at intervals, establishing several measuring points within the site, with the distances from the measuring points to the three-dimensional scanning device forming an arithmetic sequence; Step 2: Obtain the three-dimensional coordinates of the three-dimensional scanning device relative to the total station; erect a hemispherical prism at each measuring point, with the height of the hemispherical prism matching the height of the three-dimensional scanning device; Step 3: Determine the maximum distance L1 of the three-dimensional scanning device based on stability; Step 4: Determine the maximum distance L2 of the three-dimensional scanning device based on measurement accuracy; Step 5: Determine the maximum distance L of the three-dimensional scanning device based on both stability and measurement accuracy, where L = min(L1, L2). In engineering surveying, using the maximum distance L to set up measuring points can minimize the number of measuring stations and improve measurement efficiency while meeting the requirements of measurement accuracy and stability.

Description

TECHNICAL FIELD

[0001] The application relates to a three-dimensional scanning maximum ranging determination method based on measurement accuracy and stability, and belongs to the technical field of engineering measurement. BACKGROUND

[0002] Three-dimensional scanning technology has a wide application range in domestic engineering measurement due to the advantages of massive point cloud data acquisition, fast measurement speed and less labor demand. However, factors such as the instrument itself, the distance of the measurement object and the scanning point cloud density will affect the point cloud collection quality and the point cloud accuracy, and therefore, the measurement accuracy needs to be paid more attention to compared with total station and level.

[0003] There are two common error control methods at present: one is to increase the number of measurement stations, reduce the distance from the measurement object, and measure the same area multiple times at a short distance to improve stability and data accuracy. The disadvantage of this method is that the number of measurements is increased and the measurement time is improved. The other is to increase the density of the measurement point cloud and use high-density scanning mode for scanning. The disadvantage of this method is that although the number of measurements is not increased, the time of single scanning is increased, the scanning file is very large, and the difficulty of later data processing is increased. It is very meaningful to find a method that can guarantee the monitoring accuracy and data stability and at the same time can reduce the measurement time as much as possible. SUMMARY

[0004] In view of the contradiction between the measurement accuracy and efficiency of the existing three-dimensional scanning in engineering measurement, the application provides a three-dimensional scanning maximum ranging determination method based on measurement accuracy and stability, which can find the maximum ranging under the premise of meeting the measurement accuracy and stability and improve the measurement efficiency.

[0005] To solve the above technical problems, the application comprises the following technical scheme:

[0006] A three-dimensional scanning maximum ranging determination method based on measurement accuracy and stability comprises the following steps:

[0007] Step 1: Prepare the site, and erect three-dimensional scanning equipment and a total station at intervals, set up a plurality of measurement points in the site, and the distance from the measurement points to the three-dimensional scanning equipment point position forms an arithmetic sequence with a tolerance of d;

[0008] Step 2: An identification mark is arranged on the main body of the three-dimensional scanning equipment, and the total station measures the identification mark of the three-dimensional scanning equipment to obtain three-dimensional coordinates (Xa, Ya, Za) relative to the total station; a half-sphere prism is arranged at the measurement point, and the height of the half-sphere prism is matched with the height of the main body of the three-dimensional scanning equipment;

[0009] Step 3: Determine the three-dimensional scanning maximum ranging L1 based on stability;

[0010] Step 4: Determine the maximum distance L2 for 3D scanning based on measurement accuracy;

[0011] Step 5: Determine the maximum distance L for 3D scanning based on stability and measurement accuracy, where L = min(L1, L2).

[0012] Furthermore, in step three, the maximum 3D scanning distance L1 is determined based on stability, specifically as follows:

[0013] Align the hemispherical surface of the hemispherical prism with the 3D scanning device, and scan the hemispherical prism every half hour for a total of m scans. Obtain the coordinates (x, y, y) of the hemispherical prism at the i-th scan and the n-th coordinate. in y in , z in ), where i = 1, 2, ..., m, n = 1, 2, ..., N, and N is the number of measurement points;

[0014] The standard deviation of the X-coordinate of the nth hemispherical prism is S. xn ,in,

[0015]

[0016] The relative standard deviation of the X-coordinate of the nth hemispherical prism is RSD. X ,in,

[0017] Similarly, the relative standard deviation of the Y-coordinate of the nth hemispherical prism is calculated as RSD. Y The relative standard deviation of the Z-coordinate of the nth hemispherical prism is RSD. Z ;

[0018] If RSD X RSD Y RSD Z All less than or equal to RSD 允 Then the distance measurement at the measuring point of the nth hemispherical prism satisfies the stability requirement, where RSD 允 The value is known and can be determined according to the specifications or preset as needed; among the measuring points that meet the stability requirements, find the largest distance L1.

[0019] Furthermore, to eliminate the influence of displacement of the 3D scanning equipment, the specific method is to move the position of the 3D scanning equipment by 2-3m, measure the height of the lens of the 3D scanning equipment after displacement with a total station, and adjust the height of the 3D scanning equipment to ensure that the elevation difference is less than 5mm; then repeat step three to analyze the data stability under different distance conditions, and redetermine the maximum measurement distance L1' that meets the stability requirements. If L1' is less than L1, the maximum distance is corrected to L1'; if L1' is greater than or equal to L1, the maximum distance remains L1.

[0020] Furthermore, in step four, the maximum 3D scanning distance L2 is determined based on the measurement accuracy. Specifically,

[0021] The prism face of the hemispherical prism is aligned with the total station. The total station scans the hemispherical prism to obtain the relative coordinates (Xn', Yn', Zn') of the nth hemispherical prism relative to the total station, where n = 1, 2, ..., N, and N is the number of measuring points.

[0022] The spherical surface of the hemispherical prism is aligned with the 3D scanner to obtain the relative coordinates (Xn, Yn, Zn) of the nth hemispherical prism relative to the 3D scanning device. The measurement error (dXn, dYn, dZn) of the nth hemispherical prism is calculated, where dXn is the accuracy in the X direction, dYn is the accuracy in the Y direction, dZn is the accuracy in the Z direction, dXn = Xn + Xa - Xn', dYn = Yn + Ya - Yn', and dZn = Zn + Za - Zn'.

[0023] By converting between three-dimensional polar coordinates and three-dimensional rectangular coordinates, the equipment accuracy error is obtained. Considering that the center height of the hemispherical prism and the elevation of the three-dimensional scanning equipment are basically the same during measurement, the vertical angle can be approximated as 0, and the coordinate transformation formula can be simplified to:

[0024]

[0025] Among them, ds n The ranging error of the device scanning the nth hemispherical prism is dα. n The horizontal angle error of the device scanning the nth hemispherical prism is given by dβ. n The vertical angle error of the device scanning the nth hemispherical prism;

[0026] ρ=180°×3600" / π=206265";

[0027] If ds n dα n dβ n If all values ​​meet the allowable values, then the measurement data of the nth hemispherical prism meets the measurement accuracy requirements. Among the measurement points that meet the measurement accuracy requirements, find the largest distance L2.

[0028] Furthermore, the identification mark consists of two patterns: a circle and a square. The center of the circle is the center of the square. The circle has a diameter of 5cm and is made of reflective glass microbeads. The square has a side length of 8cm, and the rest of the square is made of black hard rubber material that does not reflect light.

[0029] Furthermore, matching the height of the hemispherical prism with the height of the main body of the 3D scanning equipment means that the error between the center height and Za of the hemispherical prism is no greater than 5mm.

[0030] The present invention, by adopting the above technical solution, has the following advantages and positive effects compared with the prior art: The present invention provides a method for determining the accuracy and stability of three-dimensional scanning measurement based on measurement distance. By setting up a three-dimensional scanning device, a total station, and several measuring points in the site, the distances from the measuring points to the three-dimensional scanning device point form an arithmetic sequence. Then, the maximum three-dimensional scanning distance L1 is determined based on stability, the maximum three-dimensional scanning distance L2 is determined based on measurement accuracy, and finally, the maximum three-dimensional scanning distance L is determined based on stability and measurement accuracy. Under the premise of meeting the requirements of measurement accuracy and stability, the number of measuring stations is reduced as much as possible, which can both ensure monitoring accuracy and data stability and improve measurement efficiency. Attached Figure Description

[0031] Fig. 1 This is a flowchart of the method for determining the maximum distance of a three-dimensional scan based on measurement accuracy and stability in this invention.

[0032] Fig. 2 This is a schematic diagram of the three-dimensional scanning equipment, total station, and measuring point layout in this invention;

[0033] Fig. 3 This is a schematic diagram of the identification representation in this invention.

[0034] The numbers in the diagram are as follows:

[0035] 1-Site; 2-3D scanning equipment location; 3-Total station location; 4-Surveying point; 5-3D scanning equipment location after adjustment. Detailed Implementation

[0036] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a more comprehensive understanding of the three-dimensional scanning maximum distance determination method based on measurement accuracy and stability provided by the present invention. The advantages and features of the present invention will become clearer with the following description. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0037] Combination Figs. 1 to 3 As shown, the method for determining the maximum distance in three-dimensional scanning based on measurement accuracy and stability provided in this embodiment includes the following steps:

[0038] Step 1: Prepare site 1 and set up 3D scanning equipment and total station at intervals. Establish several measuring points 4 in the site. The distances from measuring points 4 to the 3D scanning equipment points form an arithmetic sequence with a tolerance of d.

[0039] For example, the site is a rectangle of 50m×35m, and the distances from the measuring points to the 3D scanning equipment are 10m, 15m, 20m, ..., 50m, respectively. The distance between the 3D scanning equipment point 2 and the total station point 3 is about 10m.

[0040] Step 2: Set up identification marks on the main body of the 3D scanning equipment, measure the identification marks of the 3D scanning equipment with a total station to obtain the 3D coordinates (Xa, Ya, Za) relative to the total station; set up a hemispherical prism on a pole at measuring point 4, with the height of the hemispherical prism matching the height of the main body of the 3D scanning equipment.

[0041] For example, such as Fig. 3 As shown, the identification mark consists of two patterns: a circle and a square. The center of the circle is the center of the square, and the circle has a diameter of 5cm. It is composed of a diamond-grade reflective material in the form of glass microbeads. The background is a common hard rubber material, black in color, with a side length of 8cm. There is no backlight reflection signal in this area, which will form point cloud holes after scanning, facilitating center extraction. When affixing the identification mark, the scanning lens should be horizontal to ensure that the center of the identification mark and the center of the scanning lens are at the same height. The height of the hemispherical prism is matched with the height of the main body of the 3D scanning equipment. That is, the length of the hemispherical prism rod is adjusted so that the prism center position is basically controlled near Za. Specifically, the prism face of the hemispherical prism is aligned with the total station, and the total station measures the elevation of each hemispherical prism to ensure that the elevation error between the prism center height and the identification mark on the 3D scanning equipment is no more than 5mm.

[0042] Step 3: Determine the maximum 3D scanning distance L1 based on stability. Specifically, align the hemispherical surface of the hemispherical prism with the 3D scanning device, scan the hemispherical prism every half hour for a total of m scans, and import the scan information into the device's built-in software to extract the spherical coordinates, thereby obtaining the coordinates (x, y, y) of the i-th and n-th hemispherical prisms. in y in , z in ), where i = 1, 2, ..., m, n = 1, 2, ..., N, and N is the number of measurement points.

[0043] The standard deviation of the X-coordinate of the nth hemispherical prism is S. xn The standard deviation of the Y coordinate is S yn The standard deviation of the Z-coordinate is S zn ,in,

[0044]

[0045] The relative standard deviation of the X-coordinate of the nth hemispherical prism is RSD. X The relative standard deviation of the Y-coordinate is RSDy, and the relative standard deviation of the Z-coordinate is RSDz, where...

[0046]

[0047] If RSD X RSD Y RSD Z All less than or equal to RSD允 Then the distance measurement at the measuring point of the nth hemispherical prism satisfies the stability requirement, where RSD 允 Given a known value, L1 can be determined according to specifications or preset as needed. Among the measuring points that meet the stability requirements, find the maximum distance L1.

[0048] As a preferred implementation, it is necessary to eliminate the influence of displacement factors of the 3D scanning equipment. Specifically, the position of the 3D scanning equipment is changed by 2-3m, from point 2 to point 5 after adjustment. The height of the lens of the 3D scanning equipment after displacement is measured with a total station, and the height of the 3D scanning equipment is adjusted to ensure that the difference in elevation between before and after adjustment is less than 5mm. Then, step three is repeated to analyze the data stability under different distance conditions and redetermine the maximum measurement distance L1' that meets the stability requirements. If L1' is less than L1, the maximum distance is corrected to L1'. If L1' is greater than or equal to L1, the maximum distance is still L1.

[0049] Step 4: Determine the maximum 3D scanning distance L2 based on measurement accuracy; specifically,

[0050] After completing step one, align the prism face of the hemispherical prism with the total station. The total station scans the hemispherical prism to obtain the relative coordinates (Xn', Yn', Zn') of the nth hemispherical prism relative to the total station, where n = 1, 2, ..., N, and N is the number of measuring points.

[0051] The spherical surface of the hemispherical prism is aligned with the 3D scanner to obtain the relative coordinates (Xn, Yn, Zn) of the nth hemispherical prism relative to the 3D scanning device. The measurement error (dXn, dYn, dZn) of the nth hemispherical prism is calculated, where dXn is the accuracy in the X direction, dYn is the accuracy in the Y direction, dZn is the accuracy in the Z direction, dXn = Xn + Xa - Xn', dYn = Yn + Ya - Yn', and dZn = Zn + Za - Zn'.

[0052] By converting between three-dimensional polar coordinates and three-dimensional rectangular coordinates, the equipment accuracy error is obtained. Considering that the height of the prism center and the elevation of the three-dimensional scanning equipment are basically the same during measurement, the vertical angle can be approximated as 0, and the coordinate transformation formula can be simplified to:

[0053]

[0054] Among them, ds n The ranging error of the device scanning the nth hemispherical prism is dα. n The horizontal angle error of the device scanning the nth hemispherical prism is given by dβ. n The vertical angle error of the device scanning the nth hemispherical prism;

[0055] ρ=180°×3600" / π=206265";

[0056] If ds n dα n dβ n If all values ​​meet the allowable values, then the measurement data of the nth hemispherical prism meets the measurement accuracy requirements. Among the measurement points that meet the measurement accuracy requirements, find the largest distance L2.

[0057] Step 5: Determine the maximum distance L for 3D scanning based on stability and measurement accuracy, where L = min(L1, L2).

[0058] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for determining the maximum distance in three-dimensional scanning based on measurement accuracy and stability, characterized in that, Includes the following steps: Step 1: Prepare the site and set up 3D scanning equipment and total station at intervals. Establish several measuring points in the site. The distances from the measuring points to the 3D scanning equipment points form an arithmetic sequence with a tolerance of d. Step 2: Set up identification marks on the main body of the 3D scanning equipment, measure the identification marks of the 3D scanning equipment with a total station to obtain the 3D coordinates (Xa, Ya, Za) relative to the total station; set up hemispherical prisms on the pole at the measuring points, and match the height of the hemispherical prisms with the height of the main body of the 3D scanning equipment. Step 3: Determine the maximum 3D scanning distance L1 based on stability; Step 4: Determine the maximum distance L2 for 3D scanning based on measurement accuracy; Step 5: Determine the maximum distance L for 3D scanning based on stability and measurement accuracy, where L = min(L1, L2); In step three, determining the maximum 3D scanning distance L1 based on stability is specifically as follows: Align the hemispherical surface of the hemispherical prism with the 3D scanning device, and scan the hemispherical prism every half hour for a total of m scans. Obtain the coordinates (x, y, y) of the hemispherical prism at the i-th scan and the n-th coordinate. in y in , z in ), where i = 1, 2, ..., m, n = 1, 2, ..., N, and N is the number of measurement points; The standard deviation of the X-coordinate of the nth hemispherical prism is S. xn ,in, The relative standard deviation of the X-coordinate of the nth hemispherical prism is RSD. X ,in, Similarly, the relative standard deviation of the Y-coordinate of the nth hemispherical prism is calculated as RSD. Y The relative standard deviation of the Z-coordinate of the nth hemispherical prism is RSD. Z ; If RSD X RSD Y RSD Z All less than or equal to RSD 允 Then the distance measurement at the measuring point of the nth hemispherical prism satisfies the stability requirement, where RSD 允 The value is known and can be determined according to the specifications or preset as needed; among the measuring points that meet the stability requirements, find the largest distance L1.

2. The method for determining the maximum distance in three-dimensional scanning based on measurement accuracy and stability as described in claim 1, characterized in that, To eliminate the influence of displacement of the 3D scanning equipment, the specific steps are as follows: move the 3D scanning equipment to a position of 2-3m, measure the height of the lens of the 3D scanning equipment after the displacement using a total station, and adjust the height of the 3D scanning equipment to ensure that the elevation difference is less than 5mm; then repeat step three to analyze the data stability under different distance conditions, and redetermine the maximum measurement distance L1' that meets the stability requirements. If L1' is less than L1, the maximum distance is corrected to L1'; if L1' is greater than or equal to L1, the maximum distance remains L1.

3. The method for determining the maximum distance in three-dimensional scanning based on measurement accuracy and stability as described in claim 1, characterized in that, In step four, the maximum 3D scanning distance L2 is determined based on the measurement accuracy. Specifically, The prism face of the hemispherical prism is aligned with the total station. The total station scans the hemispherical prism to obtain the relative coordinates (Xn', Yn', Zn') of the nth hemispherical prism relative to the total station, where n = 1, 2, ..., N, and N is the number of measuring points. The spherical surface of the hemispherical prism is aligned with the 3D scanner to obtain the relative coordinates (Xn, Yn, Zn) of the nth hemispherical prism relative to the 3D scanning device. The measurement error (dXn, dYn, dZn) of the nth hemispherical prism is calculated, where dXn is the accuracy in the X direction, dYn is the accuracy in the Y direction, dZn is the accuracy in the Z direction, dXn = Xn + Xa - Xn', dYn = Yn + Ya - Yn', and dZn = Zn + Za - Zn'. By converting between three-dimensional polar coordinates and three-dimensional rectangular coordinates, the equipment accuracy error is obtained. Considering that the center height of the hemispherical prism and the elevation of the three-dimensional scanning equipment are basically the same during measurement, the vertical angle can be approximated as 0, and the coordinate transformation formula can be simplified to: Among them, ds n The ranging error of the device scanning the nth hemispherical prism is dα. n The horizontal angle error of the device scanning the nth hemispherical prism is given by dβ. n The vertical angle error of the device scanning the nth hemispherical prism; ρ=180°×3600" / π=206265"; If ds n dα n dβ n If all values ​​meet the allowable values, then the measurement data of the nth hemispherical prism meets the measurement accuracy requirements. Among the measurement points that meet the measurement accuracy requirements, find the largest distance L2.

4. The method for determining the maximum distance in three-dimensional scanning based on measurement accuracy and stability as described in claim 1, characterized in that, The identification mark consists of two patterns: a circle and a square. The center of the circle is the center of the square. The circle has a diameter of 5cm and is made of reflective glass microbeads. The square has a side length of 8cm, and the rest of the square is made of black hard rubber material that does not reflect light.

5. The method for determining the maximum distance in three-dimensional scanning based on measurement accuracy and stability as described in claim 1, characterized in that, Matching the height of the hemispherical prism with the height of the main body of the 3D scanning equipment means that the error between the center height and Za of the hemispherical prism is no more than 5mm.

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