A method for determining three-dimensional scanning distance and range under given precision conditions

Abstract

The present invention relates to the field of three-dimensional scanning technology, and particularly to a method for determining the three-dimensional scanning distance and range under given precision conditions. Through systematic calibration tests and detailed data analysis, the precision of the three-dimensional scanner within a specified range at different distances is determined, reliable scanning parameter selection is provided, and it is widely applied in fields such as building surveying, industrial inspection, and cultural heritage protection. The present invention avoids the subjectivity and blindness of scanning parameter selection through a scientific parameter selection method, and at the same time improves the working efficiency of scanning operations. Multiple tests and data averaging reduce accidental errors, provide comprehensive data, clarify the influencing factors and laws of scanning precision, optimize the scanning process, improve the efficiency and the accuracy of the results, and solve the problem that limits the precision reliability of existing three-dimensional scanning systems in practical applications.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional scanning, and particularly to a method for determining the three-dimensional scanning distance and range under given accuracy conditions. Background Art

[0002] In the technical field of three-dimensional scanning, a point cloud is the output result of three-dimensional scanning technology, which consists of a large number of discrete points. Each point has a definite three-dimensional coordinate (x, y, z). These points together describe the surface features of an object and represent the detailed three-dimensional information of the scanned object. Through the point cloud data, it can be further used for applications such as modeling, analysis, measurement, and visualization. Among them, the measurement accuracy of the point cloud is an important index for judging the scanning accuracy of the scanner.

[0003] In terms of point cloud accuracy, the accuracy of the scanner is an important factor affecting the measurement reliability. Existing three-dimensional scanning systems usually rely on the specification parameters and test data provided by the manufacturer, and these data may have deviations in actual applications and cannot reflect the actual measurement accuracy of the scanner. The existing technologies mainly have the following problems and disadvantages: incomplete data: most of the current accuracy verifications are carried out only under limited test conditions, lacking comprehensive verification under different distances, ranges, and complex environments; strong subjectivity in parameter selection: there is no specific reference for parameter selection at present, and users cannot select appropriate scanning distances and effective ranges according to specific accuracy requirements, and can only subjectively select based on experience and cannot judge whether the accuracy meets the requirements; the accuracy range provided by the manufacturer is vague: the manufacturer cannot provide a detailed accuracy gradient range, and can only give the accuracy data under a single condition, lacking the accuracy change under multiple working conditions; insufficient optimization: existing technologies fail to provide an effective method for optimizing scanning parameters, and it is difficult for users to adjust scanning parameters according to specific measurement requirements to achieve the required accuracy.

[0004] To sum up, in the existing three-dimensional scanning system, the above-mentioned problems and disadvantages limit the accuracy reliability of three-dimensional scanning technology in practical applications. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for determining the three-dimensional scanning distance and range under given accuracy conditions, aiming to solve the problem of limiting the accuracy reliability of the existing three-dimensional scanning system in practical applications.

[0006] To achieve the above purpose, a method for determining the three-dimensional scanning distance and range under given accuracy conditions adopted by the present invention includes: conducting an accuracy calibration test based on a three-dimensional scanner;

[0007] identifying the influence law of scanning accuracy with scanning distance and range;

[0008] selecting scanning parameters according to specific accuracy requirements.

[0009] Among them, the specific method for conducting the accuracy calibration test based on a 3D scanner is as follows:

[0010] Based on the standard flat plate test, 3D point cloud modeling of the standard flat plate is performed at different scanning distances;

[0011] For each scanning distance situation, investigate the distribution law of the standard flat plate size recognition accuracy at different positions, and draw a distribution map of the recognition accuracy on the plane, then the accuracy calibration test based on the 3D scanner can be completed.

[0012] Among them, the specific method for identifying the influence law of the scanning accuracy with the scanning distance and range is as follows:

[0013] After completing the accuracy calibration test based on the 3D scanner, the scanned data is registered into the computer in the form of a point cloud model and data processing is performed, and then the average point position error is calculated;

[0014] Draw according to the recognition accuracy distribution law based on the average point position error calculation result.

[0015] Among them, after completing the accuracy calibration test based on the 3D scanner, the scanned data is registered into the computer in the form of a point cloud model and data processing is performed, and then the specific method for calculating the average point position error is as follows:

[0016] Taking the scanned data under a set station as an example, first find the central plate scanned under this station, and then find the plates that diverge outward from the central plate and present a shape, and the number of plates in each divergence direction is equal. Use these plates as the selected calibration range;

[0017] Then, measure the four-side dimensions of all selected plates in the point cloud model, calculate the difference from the actually measured dimensions, and then average to obtain the corresponding error of a point position;

[0018] Repeat the above steps multiple times, and average the errors obtained multiple times to obtain the average error of the point positions within a certain distance range to eliminate accidental errors.

[0019] Among them, in repeating the above steps multiple times, and averaging the errors obtained multiple times to obtain the average error of the point positions within a certain distance range to eliminate accidental errors, the repeated steps are not less than 10 times.

[0020] Among them, according to the average point position error calculation result, the recognition accuracy distribution shows the following law:

[0021] For all points within the range, as the distance increases, the density of the point cloud and the overall accuracy will decrease as a whole; at a fixed distance, the accuracy of the points extending from the center outwards will form a gradient, and overall, it shows a trend of high accuracy in the middle and lower accuracy closer to the edge of the range.

[0022] Among them, the specific method for selecting scanning parameters according to specific accuracy requirements is as follows:

[0023] After determining the accuracy gradient within the range, the user can select scanning parameters according to specific accuracy requirements;

[0024] Within the selected accuracy gradient range, the range that meets the accuracy requirements is defined as the effective range.

[0025] A method for determining the three-dimensional scanning distance and range under given accuracy conditions according to the present invention, through systematic calibration tests and detailed data analysis, determines the accuracy of the three-dimensional scanner within a specified range at different distances, provides reliable selection of scanning parameters; is applicable to three-dimensional scanners of various models and brands, and users can flexibly select scanning parameters according to accuracy requirements, and is widely used in fields such as building measurement, industrial inspection, and cultural heritage protection; the present invention avoids subjectivity and blindness in the selection of scanning parameters through a scientific parameter selection method, and at the same time improves the work efficiency of the scanning operation. Multiple tests and data averaging reduce accidental errors, provide comprehensive data, enable users to intuitively understand the accuracy change law, accurately control the scanning range, ensure the accuracy and reliability of the scanning results. The present invention clarifies the influencing factors and laws of scanning accuracy, optimizes the scanning process, further improves the accuracy of the results, and solves the problem of restricting the accuracy and reliability in the actual application of the existing three-dimensional scanning system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 It is the design drawing of the test model of the present invention.

[0028] Figure 2 It is of the present invention Schematic diagram of the situation of the selection and absence of the font-shaped measuring plate positions.

[0029] Figure 3 It is the distribution diagram of the average station accuracy at different distances of the present invention.

[0030] Figure 4It is a schematic diagram of case selection according to the accuracy range of the present invention. Detailed implementation manners

[0031] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] Please refer to Figures 1 to 4 , wherein Figure 1 is the design drawing of the test model of the present invention, Figure 2 is of the present invention schematic diagram of the selection and absence of the glyph measurement plate position, Figure 3 is the distribution diagram of the average station accuracy at different distances of the present invention, Figure 4 is the schematic diagram of case selection according to the accuracy range of the present invention. The present invention provides a method for determining the three-dimensional scanning distance and range under given accuracy conditions, including the following steps:

[0033] S101. Conduct an accuracy calibration test based on a three-dimensional scanner;

[0034] For this specific implementation manner, based on the standard flat plate test, three-dimensional point cloud modeling is performed on the standard flat plate at different scanning distances;

[0035] For each scanning distance case, investigate the distribution law of the standard flat plate size recognition accuracy at different positions, and draw the distribution diagram of the recognition accuracy on the plane, then the accuracy calibration test based on the three-dimensional scanner can be completed; in order to reduce the interference of accidental errors, the recognition accuracy here is usually the average value of multiple tests, and it is recommended that the number of tests is not less than 10 times;

[0036] Please refer to Figure 1 , the center of each standard plate in the middle row will be used as the point position where the scanner is vertically incident, so that the obtained standard plate model data is uniformly symmetric up and down; the user first determines the approximate scanning distance and the distance segmentation according to his own needs, such as the segmentation is 1m, 2m, 3m, to be applicable to scanned objects of different sizes; secondly, at the distance of each segmentation, the scanner is directed at all the standard plates in the middle row in turn to collect data; thus, the data collection stage is completed.

[0037] S102. Identify the influence law of the scanning accuracy with the scanning distance and range;

[0038] For this specific implementation manner, after completing the accuracy calibration test based on the three-dimensional scanner, the scanned data is registered into the computer in the form of a point cloud model and data processing is performed, and then the average point position error is calculated;

[0039] It is drawn according to the recognition accuracy distribution law calculated from the average point position error results.

[0040] Among them, after completing the accuracy calibration test based on the 3D scanner, the scanned data is registered into the computer in the form of a point cloud model and data processing is performed. Subsequently, the specific method for calculating the average point position error is as follows:

[0041] Taking the scanned data under the set station as an example, first find the central plate scanned under this station, and then find the plates that diverge outward from the central plate and present a shape, with an equal number of plates in each divergent direction. These plates are used as the selected calibration range;

[0042] Then, measure the four-side dimensions of all the selected plates in the point cloud model, calculate the difference from the actually measured dimensions, and then average to obtain the corresponding error of one point position;

[0043] Repeat the above steps no less than 10 times, and average the errors obtained multiple times to obtain the average error of the point positions within a certain distance range to eliminate accidental errors; if the scanning center is close to the edge of the standard plate matrix, there will be a shape missing situation, as shown in Figure 2 . In this case, the plates that are not missing in the shape can also be used as the objects for averaging the error;

[0044] According to the calculation results of the average point position error, the accuracy distribution shows the following law:

[0045] Within the range, the accuracy of all point positions decreases as the distance increases, and the density of the point cloud and the overall accuracy will decrease as a whole; at a fixed distance, the accuracy of the point positions extending outward from the center will form a gradient, showing a trend of high accuracy in the middle and lower accuracy closer to the edge of the range.

[0046] S103. Select scanning parameters according to specific accuracy requirements;

[0047] For this specific embodiment, after determining the accuracy gradient within the range, the user can select scanning parameters according to specific accuracy requirements;

[0048] In the selected accuracy gradient range, the range that meets the accuracy requirements is defined as the effective range;

[0049] If the user has high accuracy requirements, it is recommended to select a site with a smaller distance. The reason is that the smaller the distance, the larger the accuracy gradient range that can meet the accuracy requirements. A position close to the scanning center can also be selected one level farther away, so that the scanning range is wider, but the effective range will decrease accordingly, so more sites are needed; if the selected accuracy requirements are lower, it is recommended to select a site with a larger distance. The reason is that the larger the distance, the more stable the accuracy error within the effective range and the wider range can be scanned, improving the overall scanning efficiency.

[0050] For example:

[0051] In this case, the Leica RTC360 3D scanner is used for precision calibration and parameter selection. The test materials are composed of a standard flat plate, a background white plate, and a 3D scanner to be calibrated. The test design uses standard plates with a size of 300mm×300mm and a thickness of 20mm. The plates are arranged in a 15×7 matrix. The vertical and horizontal spacing between each plate is 150mm to ensure that the plates are evenly distributed in the test range. The centroid of the standard plate in the middle row is used as the scanning center. By selecting the center position, it can be ensured that the scanning covers the entire test area and the symmetry and comprehensiveness of the data are guaranteed. In the test, four different scanning distances (1m, 2m, 3m, 4m) are set. At each distance, each standard plate in the middle row is scanned, so that data of 15 standard plates will be obtained at each meter, and finally 4×15=60 sets of data will be obtained.

[0052] These data record the scanner parameter settings and the point cloud data obtained by scanning for subsequent data processing and error analysis. Figure 1 The black plate in the figure is the standard plate that needs to be scanned at each meter. After scanning, the point cloud data of the standard plate will be obtained.

[0053] According to the above method, the standard plate error analysis is carried out to obtain the error of each meter. The average accuracy distribution diagram of the shape is as follows: Figure 3 As shown; overall, the average error increases with the increase of distance, and the accuracy decreases accordingly; the range error near the center varies greatly, and the error decreases by about 1 to 1.5 mm for every increase of 1 m in distance; while the regional error near the edge varies less; from a single distance, when the distance is 1 m, the accuracy fluctuation from the center board to the edge in the range is large, from the minimum error of 1.41 mm to the maximum error of 4.94 mm; when the distance is 4 m, the error of all boards in the range is maintained at about 5 mm, and it can be seen that the accuracy fluctuation is small.

[0054] Select cases based on range of precision:

[0055] ①If the user requires an accuracy of about 2mm:

[0056] The second precision gradient at a distance of 1 m can be selected, such as Figure 4 as shown by the range within the white frame in (a), and this range is a square with a side length of 1.20 m.

[0057] ② If the precision required by the user is about 3 mm:

[0058] The third precision gradient at a distance of 1 m can be selected, such as Figure 4 as shown by the range within the black frame in (a), and this range is a square with a side length of 1.95 m.

[0059] The second precision gradient at a distance of 2 m can also be selected, such as Figure 4 as shown by the range within the white frame in (b), and this range is a square with a side length of 1.20 m.

[0060] ③ If the user's precision requirement is about 4 mm:

[0061] The fourth precision gradient at a distance of 2 m can be selected, such as Figure 4 as shown by the range within the black frame in (b), and this range is a square with a side length of 2.85 m.

[0062] ④ If the user's precision requirement is about 5 mm:

[0063] The fourth precision gradient at a distance of 3 m can be selected, such as Figure 4 as shown by the range within the black frame in (c), and this range is a square with a side length of 2.85 m.

[0064] Using a method for determining the three-dimensional scanning distance and range under given precision conditions in this embodiment, through the calibration test of the system and detailed data analysis, the precision of the three-dimensional scanner within a specified range at different distances is determined, providing reliable scanning parameter selection; it is applicable to three-dimensional scanners of various models and brands. Users can flexibly select scanning parameters according to precision requirements and it is widely used in fields such as building measurement, industrial inspection, and cultural heritage protection. Through a scientific parameter selection method, this invention avoids the subjectivity and blindness of scanning parameter selection, improves the work efficiency of scanning operations at the same time. Multiple tests and data averaging reduce accidental errors, provide comprehensive data, enable users to intuitively understand the precision change law, accurately control the scanning range, ensure the precision and reliability of the scanning results. This invention clarifies the influencing factors and laws of scanning precision, optimizes the scanning process, further improves the precision of the results, and solves the problem that restricts the precision and reliability of the existing three-dimensional scanning system in practical applications.

[0065] The above-disclosed is only a preferred embodiment of the present invention. Of course, it cannot be used to limit the scope of rights of the present invention. Those of ordinary skill in the art can understand the entire or partial processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.

Claims

1. A method for determining the three-dimensional scanning distance and range under given accuracy conditions, characterized in that, Including: Conducting accuracy calibration tests based on a 3D scanner; Identifying the influence rules of scanning accuracy with respect to scanning distance and range; Selecting scanning parameters according to specific accuracy requirements; The specific method for conducting accuracy calibration tests based on a 3D scanner is as follows: Based on a standard flat plate test, 3D point cloud modeling of the standard flat plate is performed at different scanning distances; For each scanning distance case, investigate the distribution law of the recognition accuracy of the standard flat plate size at different positions, and draw a distribution map of the recognition accuracy on the plane, then the accuracy calibration test based on the 3D scanner can be completed; The specific method for identifying the influence rules of scanning accuracy with respect to scanning distance and range is as follows: After completing the accuracy calibration test based on the 3D scanner, the scanned data is registered into the computer in the form of a point cloud model and data processing is performed, and then the average point position error is calculated; Draw the accuracy distribution law according to the calculation result of the average point position error; After completing the accuracy calibration test based on the 3D scanner, the specific method for registering the scanned data into the computer in the form of a point cloud model and performing data processing and then calculating the average point position error is as follows: Taking the scanning data under a set station as an example, first find the central plate scanned under this station, and then find the plates in a "✳" shape diverging outward from the central plate, with an equal number of plates in each diverging direction, and use these plates as the selected calibration range; Then, measure the four-side dimensions of all the selected plates in the point cloud model, subtract the actual measured dimensions, and then average to obtain the corresponding error of one point position; Repeat the above steps multiple times, average the errors obtained multiple times, and the average error of the point positions within a certain distance range can be obtained to eliminate accidental errors, and the repeated steps are not less than 10 times; According to the calculation result of the average point position error, the accuracy distribution shows the following rules: The accuracy of all point positions within the range decreases as the distance increases, and the density of the point cloud and the overall accuracy will decrease as a whole; at a fixed distance, the accuracy of the point positions extending from the center outward will form a gradient, and overall shows a trend of high accuracy in the middle and lower accuracy closer to the range edge.

2. The method for determining the 3D scanning distance and range under a given accuracy condition according to claim 1, wherein The specific method for selecting scanning parameters according to specific accuracy requirements is as follows: After determining the accuracy gradient within the range, the user can select scanning parameters according to specific accuracy requirements; In the selected accuracy gradient range, the range that meets the accuracy requirements is defined as the effective range.

Images