Method, system and electronic device for obtaining a state of protection of a curbstone opening

Abstract

The application provides an edge hole protection state acquisition method and system and an electronic device. The edge hole protection state acquisition method comprises: acquiring point cloud data of an area where an edge hole is located by using a three-dimensional laser scanning device, wherein the area where the edge hole is located is an area where a falling risk exists in a construction site; and acquiring an installation state of a guardrail in the area where the edge hole is located according to the point cloud data of the area where the edge hole is located. The above scheme can not only improve the monitoring efficiency of the edge hole protection state, but also ensure accurate determination of the edge hole position, so as to accurately grasp the installation state of the guardrail.

Description

Technical Field

[0001] This application relates to the field of engineering construction safety monitoring technology, specifically to a method, system, and electronic equipment for obtaining the protection status of edge openings. Background Technology

[0002] To rectify situations where protective devices are not installed or are improperly installed, it is necessary to monitor the protective status of edge openings. Currently, there are two main methods for monitoring the protective status of edge openings: manual inspection or monitoring based on image recognition technology.

[0003] Manual inspection involves assigning dedicated personnel to conduct regular on-site checks of construction sites to assess the protection status of perimeter openings. However, manual inspection has the following drawbacks: First, it inevitably carries subjectivity, potentially leading to inconsistent assessment results; second, limited human resources often prevent the frequency and coverage of inspections from reaching the ideal level, potentially overlooking potential safety hazards; third, manual inspection is relatively expensive and inefficient, hindering optimal resource allocation.

[0004] Image recognition-based monitoring methods utilize cameras to capture images of the construction site and employ image recognition algorithms to determine the protective status of edge protection devices. However, this method also has certain drawbacks: First, the accuracy of image recognition technology in monitoring edge protection devices is easily affected by various environmental factors, especially lighting conditions and weather conditions (such as fog, rain, and snow), which can significantly impact image quality and introduce recognition errors. Second, since image recognition technology typically relies on deep learning frameworks, this approach requires powerful computing hardware and finely tuned advanced algorithms, undoubtedly increasing the system's implementation cost and the complexity of deployment and maintenance. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a method, system, and electronic device for acquiring the protection status of edge openings. This method improves the accuracy and frequency of monitoring the installation status of edge opening guardrails, thereby enhancing the efficiency of monitoring edge opening protection status. Furthermore, this application exhibits stronger environmental adaptability and can more accurately determine the location of edge openings to effectively acquire the installation status of guardrails.

[0006] According to a first aspect of this disclosure, a method for obtaining the protection status of an edge opening is provided. The method includes: acquiring point cloud data of the area where the edge opening is located using a three-dimensional laser scanning device, wherein the area where the edge opening is located is an area in the construction site where there is a risk of falling; and acquiring the installation status of the guardrail in the area where the edge opening is located based on the point cloud data.

[0007] In one implementation of the first aspect, point cloud data of the area where the adjacent opening is located is obtained using a three-dimensional laser scanning device, including: scanning the construction area using the three-dimensional laser scanning device to obtain original scanned point cloud data, and fusing the original scanned point cloud data based on Simultaneous Localization and Mapping (SLAM) technology to obtain original point cloud data of the construction area; processing the original point cloud data of the construction area to obtain horizontal point cloud data of the construction area in a horizontal coordinate system; and obtaining point cloud data of the area where the adjacent opening is located from the horizontal point cloud data of the construction area.

[0008] In one implementation of the first aspect, processing the original point cloud data of the construction area to obtain horizontal point cloud data of the construction area in a horizontal coordinate system includes: downsampling the original point cloud data of the construction area to obtain downsampled point cloud data; extracting planar point cloud data from the downsampled point cloud data and fitting it to obtain a fitted plane, and calculating the normal vector of the fitted plane; calculating the rotation matrix between the normal vector of the fitted plane and the unit vector of the Z-axis direction of the horizontal coordinate system, and rotating the original point cloud data of the construction area to the horizontal coordinate system based on the rotation matrix to obtain horizontal point cloud data of the construction area in a horizontal coordinate system.

[0009] In one implementation of the first aspect, obtaining point cloud data of the area where the edge opening is located from the horizontal point cloud data of the construction area includes: displaying the horizontal point cloud data of the construction area through point cloud display software; obtaining a polygonal region containing the edge opening as the area where the edge opening is located; and obtaining the point cloud data of the area where the edge opening is located based on the area where the edge opening is located.

[0010] In one implementation of the first aspect, obtaining point cloud data of the area where the edge opening is located from the horizontal point cloud data of the construction area includes: obtaining at least two spatial points through the design drawings of the construction area and determining the design drawing coordinates of the at least two spatial points; determining the horizontal coordinate system coordinates corresponding to the at least two spatial points in the horizontal point cloud data of the construction area; calculating the rotation and translation transformation relationship between the design drawing coordinate system and the horizontal coordinate system; obtaining the position and size information of the edge opening through the design drawings of the construction area and calculating the minimum enclosing rectangle of the edge opening; using the rotation and translation transformation relationship, performing a rotation and translation transformation on the minimum enclosing rectangle of the edge opening to obtain the area of ​​the edge opening contained in the horizontal point cloud data of the construction area; calculating the center point coordinates of the area of ​​the edge opening, and proportionally enlarging the area of ​​the edge opening to a preset area multiple with the center point coordinates as the center, as the area where the edge opening is located; and obtaining the point cloud data of the area where the edge opening is located based on the area where the edge opening is located.

[0011] In one implementation of the first aspect, the installation status of the guardrail in the area where the edge opening is located is obtained based on the point cloud data of the area where the edge opening is located, including: extracting the point cloud data of the guardrail inspection area of ​​the edge opening based on the point cloud data of the area where the edge opening is located; and determining the installation status of the guardrail in the area where the edge opening is located.

[0012] In one implementation of the first aspect, point cloud data of the inspection area of ​​the protective fence at the edge opening is extracted based on the point cloud data of the area where the edge opening is located. This includes: performing planar fitting on the point cloud data of the area where the edge opening is located to determine a planar model; removing point cloud data that conforms to the characteristics of the planar model and point cloud data whose elevation is lower than the center point height of the planar model from the point cloud data of the area where the edge opening is located, and using the remaining point cloud data as the point cloud data of the inspection area of ​​the protective fence at the edge opening.

[0013] In one implementation of the first aspect, determining the installation status of the guardrail in the area where the edge opening is located includes: dividing the point cloud data of the guardrail inspection area of ​​the edge opening into multiple grids according to the horizontal XY coordinates, according to a pre-set grid size, to obtain the number of grids W in the X-axis direction and the number of grids H in the Y-axis direction; creating an image whose width and height are equal to W and H, respectively, wherein each pixel of the image corresponds one-to-one with each grid; calculating the maximum height of the point cloud data in each grid, if the maximum height is less than a preset height, then setting the grayscale value of the pixels of the image corresponding to the grid to black, otherwise setting it to white; using an image algorithm to identify contours in the image, if any contour exists whose area is greater than a preset area threshold, then the installation status of the guardrail in the area where the edge opening is located is that the guardrail is installed, otherwise it is that the guardrail is not installed.

[0014] According to a second aspect of this disclosure, a system for acquiring the protection status of an edge opening is provided. The system includes: an acquisition module for acquiring point cloud data of the area where the edge opening is located using a three-dimensional laser scanning device, wherein the area where the edge opening is located is an area in the construction site where there is a risk of falling; and a processing module for acquiring the installation status of the guardrail in the area where the edge opening is located based on the point cloud data.

[0015] According to a third aspect of this application, an electronic device is provided, comprising a memory and a processor, the memory for storing a computer program, the processor for running the computer program to cause the electronic device to perform the method for obtaining the protection status of an edge opening as provided in the first aspect of this application.

[0016] According to a fourth aspect of this application, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the method for obtaining the protection status of an edge opening as provided in the first aspect of this application.

[0017] According to a fifth aspect of this application, a computer program product is provided, the computer program product including instructions that, when executed by a processor of an electronic device provided in a third aspect of this application, enable the electronic device to implement the method for obtaining the protection status of an edge opening as provided in the first aspect of this application.

[0018] This application provides a method, system, and electronic device for acquiring the protection status of edge openings. The method automatically monitors the installation status of guardrails in the area where the edge opening is located based on point cloud data, reducing manual intervention, thereby minimizing human error and lowering labor costs. Reduced human error improves monitoring accuracy, and lower labor costs allow for increased monitoring frequency, ultimately improving the efficiency of edge opening protection status monitoring. Furthermore, since this application utilizes laser technology for point cloud data acquisition, the acquisition process effectively resists interference from external factors such as lighting conditions and weather conditions, giving the solution excellent environmental adaptability. This further ensures the accurate determination of the edge opening location, facilitating accurate understanding of the guardrail installation status. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1The diagram shown is a flowchart illustrating a method for obtaining the protection status of an edge opening according to an embodiment of this application.

[0021] Figure 2 The diagram shown is a flowchart illustrating a method for acquiring point cloud data of an area near an edge opening using a three-dimensional laser scanning device, according to an embodiment of this application.

[0022] Figure 3 The diagram shown is a flowchart illustrating a method for obtaining horizontal point cloud data of a construction area from the original point cloud data of the construction area according to an embodiment of this application.

[0023] Figure 4 The diagram shown is a flowchart illustrating a method for obtaining point cloud data of an area near an edge opening, according to an embodiment of this application.

[0024] Figure 5 The diagram shown is a flowchart illustrating a method for obtaining point cloud data of an area near an edge opening, according to another embodiment of this application.

[0025] Figure 6 The diagram shown is a flowchart illustrating a method for obtaining the installation status of guardrails in the area where an edge opening is located, according to an embodiment of this application.

[0026] Figure 7 The diagram shown is a flowchart illustrating a method for extracting point cloud data of a protective railing inspection area near an edge opening, according to an embodiment of this application.

[0027] Figure 8 The diagram shown is a flowchart illustrating a method for determining the status of a protective railing at an edge opening according to an embodiment of this application.

[0028] Figure 9 The diagram shown is a schematic diagram of a system for obtaining the protection status of an edge opening according to an embodiment of this application.

[0029] Figure 10 The diagram shown is a block diagram of an exemplary electronic device provided in an embodiment of this application. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.

[0031] This application embodiment can be applied to scenarios where point cloud data of the area where the edge opening is located is obtained using a three-dimensional laser scanning device, and then the installation status of the guardrail in the area where the edge opening is located is monitored. For ease of understanding, the edge opening mentioned in this application embodiment will be described in detail first.

[0032] An edge opening refers to an edge formed during construction work, created by excavation or construction at ground level or height. Edge openings are typically referred to as "edges" or "openings." An edge can be a building edge, roof edge, balcony edge, elevator shaft edge, or foundation pit edge, while an opening can be a reserved opening, elevator shaft opening, passageway opening, or stairwell opening. Edge openings are among the most common locations for fall accidents on construction sites. If protective measures are inadequate, workers may easily fall through these openings, as may items on the construction site, causing serious injuries or fatalities. This can also lead to project delays, increased costs, and damage to the company's reputation. Therefore, to ensure the safety of personnel and equipment on construction sites, it is necessary not only to install protective devices around edge openings but also to regularly monitor the installation status of these devices.

[0033] It should be noted that, in the embodiments of this application, the protective device for the edge opening mainly refers to the guardrail.

[0034] However, the current installation and management of guardrails at openings near edges have the following problems:

[0035] 1. No installation or inaccurate installation location: In order to shorten the construction period or reduce costs, some construction workers often fail to install guardrails or neglect the installation location of guardrails, which fails to fully cover the edge openings and leaves safety hazards.

[0036] 2. Insecure Fixing Methods: Traditional fixing methods such as bolts and welding are not only complex to install, but their effectiveness is also easily affected by environmental and human factors. In addition, long-term exposure to wind and sun, as well as construction vibrations, may cause the guardrails to loosen or fall off, losing their protective function and easily creating safety hazards.

[0037] 3. Lack of monitoring mechanism: Due to the lack of effective monitoring methods, construction management personnel have difficulty keeping track of the installation status of guardrails in real time, and cannot promptly detect and rectify edge openings with safety hazards, resulting in the continued existence of safety hazards.

[0038] In view of this, this application provides a method, system and electronic device for obtaining the protection status of edge openings, which can not only automatically and effectively obtain the installation status of edge opening guardrails, i.e. the protection status of edge openings, but also improve the monitoring efficiency of edge opening protection status, thereby helping to eliminate safety hazards of edge openings.

[0039] Figure 1 The diagram shown is a flowchart illustrating a method for obtaining the protection status of an edge opening according to an embodiment of this application.

[0040] like Figure 1 As shown, the method may include the following steps S110 to S120.

[0041] Step S110: Use a three-dimensional laser scanning device to obtain point cloud data of the area where the edge opening is located, where the edge opening is located in an area of ​​the construction site where there is a risk of falling.

[0042] Currently, point cloud data acquisition mainly relies on 3D laser scanning devices. This application can use a 3D laser scanning device to acquire point cloud data of the area where the edge opening is located. The 3D laser scanning device obtains the 3D coordinate information of the target object by emitting and receiving laser beams and utilizing the principle of laser reflection. Since laser technology is not affected by external factors such as lighting conditions (e.g., fog, rain, snow) and weather conditions (e.g., fog, rain, snow), the solution provided in this application has stronger environmental adaptability, and can more accurately determine the location of the edge opening in order to effectively obtain the installation status of the guardrail.

[0043] Specifically, 3D laser scanning devices can be either stand-alone or mobile, each with its own advantages and disadvantages. The appropriate 3D laser scanning device can be selected based on actual needs (e.g., resolution, scanning frequency, and accuracy).

[0044] The specific implementation method of using a 3D laser scanning device to obtain point cloud data of the area where the edge of the opening is located will be described below. Figures 2-5 The specific implementation examples are illustrated below.

[0045] Step S120: Based on the point cloud data of the area where the edge opening is located, obtain the installation status of the guardrail in the area where the edge opening is located.

[0046] The installation status of guardrails in areas near edge openings is divided into two states: guardrails installed and guardrails not installed. Installed guardrails refer to guardrails whose height meets industry standards and whose width is not less than the width of the edge opening. Other states that do not meet the installation requirements refer to the state of not having guardrails installed, such as: no guardrails installed at all, guardrails installed but whose height is not up to standard, guardrails installed but not effectively surrounding the edge opening, etc.

[0047] Furthermore, after obtaining the installation status of the guardrail in the area where the edge opening is located, if an edge opening that is not installed is found, in some embodiments, a warning message can be issued to the relevant construction management personnel to prompt them to rectify the edge opening in a timely manner. The warning message may include the location information of the edge opening. In other embodiments, edge openings that are not installed can be recorded in a log for construction management personnel to check regularly so as to facilitate subsequent rectification of the edge opening.

[0048] Specifically, the detailed implementation method for obtaining the installation status of the guardrail in the area where the edge opening is located, based on the point cloud data, will be discussed below. Figures 6-8 The specific implementation examples are illustrated below.

[0049] Figure 1 The proposed solution automatically monitors the installation status of guardrails in the area of ​​edge openings based on point cloud data, reducing manual intervention, thus minimizing human error and lowering labor costs. Reduced human error improves monitoring accuracy, while lower labor costs allow for increased monitoring frequency, ultimately improving the efficiency of edge opening protection status monitoring. Furthermore, since this application utilizes laser technology for point cloud data acquisition, the acquisition process effectively resists interference from external factors such as lighting conditions and weather, giving the solution excellent environmental adaptability. This further ensures accurate determination of the edge opening location, facilitating precise understanding of the guardrail installation status.

[0050] Figure 2 The diagram shown is a flowchart illustrating a method for acquiring point cloud data of an area near an edge opening using a three-dimensional laser scanning device, according to an embodiment of this application.

[0051] In such Figure 1In step S110, to obtain the point cloud data of the area where the edge opening is located, the point cloud data of the entire construction area must first be obtained, and then a series of processes are performed on the point cloud data of the entire construction area. Specifically, as shown... Figure 2 As shown, the method may include the following steps S210 to S240:

[0052] Step S210: Use a 3D laser scanning device to scan the construction area to obtain the original scanned point cloud data, and fuse the original scanned point cloud data based on SLAM technology to obtain the original point cloud data of the construction area.

[0053] It should be understood that the construction area includes the area where the opening is located.

[0054] Specifically, at least one three-dimensional laser scanning device is used to scan the construction area to obtain the original scanned point cloud data of the construction area. The original scanned point cloud data records relevant information of the construction area, such as three-dimensional coordinate information, color information, and reflection intensity information. Since three-dimensional point cloud data has the characteristics of high precision and high realism, it is more conducive to the present application to make a more accurate and effective judgment on the installation status of the guardrail based on the three-dimensional point cloud data.

[0055] Optionally, if multiple 3D laser scanning devices are used to scan the construction area, multiple original scan point cloud data will be obtained. In this case, it is also necessary to register and stitch the multiple original scan point cloud data.

[0056] Specifically, the frequency of scanning the construction area using a three-dimensional laser scanning device can be determined according to actual needs. For example, scanning once every morning before construction, or once each morning, noon and evening before construction, or random inspections every day. This application does not impose any restrictions on this.

[0057] Step S220: Process the original point cloud data of the construction area to obtain the horizontal point cloud data of the construction area in the horizontal coordinate system.

[0058] In practical applications, the original point cloud data of the construction area may come from point cloud data in multiple different coordinate systems for the following reasons: First, the original point cloud data of the construction area may come from different acquisition devices, and each acquisition device has its own coordinate system. The acquired point cloud data is stored according to the coordinate system of its respective acquisition device. Therefore, the original point cloud data of the construction area may be point cloud data in multiple different coordinate systems. Second, even if the same acquisition device is used, if the same construction area is scanned multiple times from multiple angles, the point cloud data obtained from different scanning positions may still be in different coordinate systems.

[0059] Therefore, in order to facilitate subsequent data processing and visualization operations on point cloud data, it is usually necessary to convert the point cloud data to a unified coordinate system to ensure the consistency of the point cloud data.

[0060] Preferably, in this embodiment of the application, the original point cloud data of the construction area will be converted to a horizontal coordinate system to obtain the horizontal point cloud data of the construction area in the horizontal coordinate system.

[0061] Specifically, the method for obtaining the horizontal point cloud data of the construction area from the raw point cloud data of the construction area will be described below. Figure 3 The embodiments are illustrated below. Figure 3 The diagram shown is a flowchart illustrating a method for obtaining horizontal point cloud data of a construction area from the original point cloud data of the construction area according to an embodiment of this application.

[0062] like Figure 3 As shown, step S220 above includes the following steps:

[0063] Step S310: Downsample the original point cloud data of the construction area to obtain downsampled point cloud data.

[0064] The original point cloud data of the construction area is very large and contains a lot of redundant data. This not only leads to huge storage requirements, but also makes processing time-consuming and labor-intensive. Therefore, in one embodiment of this application, the original point cloud data of the construction area will be downsampled to retain key information while reducing the amount of data, thereby reducing storage requirements, reducing computational complexity and improving computational efficiency.

[0065] There are various downsampling algorithms for point cloud data, such as random downsampling algorithm, uniform downsampling algorithm, voxel downsampling algorithm, farthest point downsampling algorithm, moving least squares downsampling algorithm, etc. This application does not limit the selection of downsampling algorithms for point cloud data. Preferably, in one embodiment of this application, a voxel downsampling algorithm is used to downsample the original point cloud data of the construction area to obtain downsampled point cloud data.

[0066] To transform the original point cloud data of the construction area to a horizontal coordinate system, the key is to find the corresponding rotation matrix. Therefore, step S220 above also includes the following steps S320 to S330:

[0067] Step S320: Extract planar point cloud data from the downsampled point cloud data and fit it to obtain a fitted plane, and calculate the normal vector of the fitted plane.

[0068] Specifically, in one embodiment of this application, a planar point cloud can be extracted from downsampled point cloud data and fitted to a plane using a random consistency sampling algorithm, and the normal vector of the resulting plane can be calculated. It should be noted that, in addition to the random consistency sampling algorithm, other methods such as least squares or direct methods can also be used to fit the plane; the choice can be made according to the actual situation, and this application does not impose any restrictions on this.

[0069] Step S330: Calculate the rotation matrix between the normal vector of the fitting plane and the unit vector of the Z-axis direction of the horizontal coordinate system, and rotate the original point cloud data of the construction area to the horizontal coordinate system based on the rotation matrix to obtain the horizontal point cloud data of the construction area in the horizontal coordinate system.

[0070] Back to Figure 2 After obtaining the horizontal point cloud data of the construction area in the horizontal coordinate system in step S220, the following step S230 is a method for obtaining the point cloud data of the area where the adjacent opening is located from the horizontal point cloud data of the construction area:

[0071] Step S230: Obtain the point cloud data of the area where the adjacent opening is located from the horizontal point cloud data of the construction area.

[0072] In some embodiments, step S230 can be performed using point cloud display software; the specific implementation of this solution will be described below. Figure 4 The specific details are illustrated in the examples shown.

[0073] In some other embodiments, step S230 can also be accomplished using design drawings of the construction area; the specific implementation of this solution will be described below. Figure 5 The specific details are illustrated in the examples shown.

[0074] Figure 4 The diagram shown is a flowchart illustrating a method for obtaining point cloud data of an area near an edge opening, according to an embodiment of this application. Figure 4 As shown, step S230 includes the following steps:

[0075] Step S410: Display the horizontal point cloud data of the construction area using point cloud display software.

[0076] Point cloud display software refers to point cloud data visualization tools. Some mainstream point cloud display software includes CloudCompare and MeshLab. In practical applications, the selection of suitable point cloud display software can be based on a comprehensive consideration of factors such as data type, processing requirements, user technical level, and budget. This application embodiment does not impose any limitations on these factors.

[0077] Step S420: Obtain the polygonal region containing the adjacent opening as the region where the adjacent opening is located.

[0078] Specifically, on the corresponding operation interface of the point cloud display software, users can visually see the image corresponding to the point cloud data, and thus can directly and manually select the polygonal area containing the edge opening as the area where the edge opening is located.

[0079] Preferably, to avoid selection errors, the area of ​​the polygonal region containing the edge opening can be 2-4 times the actual area of ​​the edge opening, and it is ensured that there are no other buildings or debris in the area where the edge opening is located, while ensuring that the edge opening is located at the center of the polygonal region it is located in.

[0080] Step S430: Based on the area where the adjacent opening is located, obtain the point cloud data of the area where the adjacent opening is located.

[0081] It should be noted that there may be one or more edge openings in the construction area. If there are multiple edge openings in the construction area, steps S410 to S430 above can be executed sequentially for each edge opening, or they can be executed at once to obtain point cloud data of the areas where multiple edge openings are located.

[0082] Figure 5 The diagram shown is a flowchart illustrating a method for obtaining point cloud data of an area near an edge opening, according to another embodiment of this application. Figure 5 As shown, step S240 includes the following steps:

[0083] Step S510: Obtain at least two spatial points from the design drawings of the construction area and determine the design drawing coordinates of the at least two spatial points. Determine the horizontal coordinate system coordinates corresponding to the at least two spatial points in the horizontal point cloud data of the construction area. Calculate the rotation and translation transformation relationship between the design drawing coordinate system and the horizontal coordinate system.

[0084] Specifically, the design drawings for the construction area can be CAD drawings. When the design drawings for the construction area are CAD drawings, users can read the CAD drawings using CAD software, select at least two spatial points, and determine their design drawing coordinates.

[0085] Specifically, in step S510, the least squares fitting method can be used to calculate the rotation and translation transformation relationship between the design drawing coordinate system and the horizontal coordinate system. It should be noted that, in addition to the least squares fitting method, other methods can also be used to calculate the rotation and translation transformation relationship between the design drawing coordinate system and the horizontal coordinate system. The choice can be made according to the actual situation, and this application does not impose any restrictions on this.

[0086] Step S520: Obtain the location and size information of the edge opening through the design drawings of the construction area and calculate the minimum outer rectangle of the edge opening.

[0087] In some embodiments, after a user reads a CAD drawing using CAD software, they can manually select the location and size information of each adjacent opening in the design drawing and calculate its minimum axial enclosing rectangle.

[0088] In other embodiments, after the user parses the CAD drawings, the location and size information of each edge opening are automatically identified (e.g., by reading the parameters of each component in the CAD drawings and filtering according to the parameters to obtain the area coordinates of each edge opening in the design drawings) and its minimum enclosing rectangle is calculated.

[0089] Step S530: Using the rotation and translation transformation relationship, perform a rotation and translation transformation on the minimum outer rectangle of the adjacent opening to obtain the area of ​​the adjacent opening contained in the horizontal point cloud data of the construction area.

[0090] To minimize errors in determining the installation status of guardrails in areas with adjacent openings, the area containing the openings needs to be enlarged proportionally. The specific implementation method is shown in step S540 below:

[0091] Step S540: Calculate the coordinates of the center point of the area adjacent to the opening, and enlarge the area of ​​the adjacent opening proportionally to a preset area multiple with the center point coordinates as the center, and take it as the area where the adjacent opening is located.

[0092] Preferably, the preset area multiplier is 2-4 times, that is, the area of ​​the adjacent opening is enlarged proportionally to 2-4 times the original area with the center point coordinates as the center.

[0093] Step S550: Based on the area where the adjacent opening is located, obtain the point cloud data of the area where the adjacent opening is located.

[0094] It should be noted that there may be one or more edge openings in the construction area. If there are multiple edge openings in the construction area, steps S510 to S550 above can be executed sequentially for each edge opening, or they can be executed at once to obtain point cloud data of the areas where multiple edge openings are located.

[0095] It should be understood that in practical applications, it is necessary to monitor the protection status of edge openings frequently and multiple times. In multiple monitoring tasks of edge opening protection status, the location of edge openings is basically fixed for the same floor or even different floors. Moreover, the construction site conditions are complex, and the amount of point cloud data is extremely large. If the area where the edge opening is located is re-determined for each round of detection tasks, the consumption of computing resources will be huge.

[0096] Therefore, optionally, in order to reduce the amount of data processing, based on the horizontal point cloud data of the construction area in the horizontal coordinate system obtained in the first scan and the area where the edge opening is located determined during the first scan, in the subsequent acquisition of the edge opening protection status, for each current round in subsequent rounds, after scanning the construction area using a 3D laser scanning device, and before obtaining the installation status of the guardrail in the area where the edge opening is located based on the point cloud data of the area where the edge opening is located, the point cloud data of the area where the edge opening is located in the current round can also be obtained in the following way:

[0097] The horizontal point cloud data of the construction area in the horizontal coordinate system obtained in the first scan is used as the global point cloud data; the point cloud data obtained by scanning the construction area using a 3D laser scanning device in the current round is used as the scanning point cloud data of the current round; the scanning point cloud data of the current round is registered to the global point cloud coordinate system where the global point cloud data is located to obtain the real-time point cloud data of the current round in the global point cloud coordinate system; the real-time point cloud data of the current round in the global point cloud coordinate system is fused to generate the horizontal point cloud data of the construction area in the horizontal coordinate system of the current round; based on the area where the edge opening is located determined during the first scan, the point cloud data of the area where the edge opening is located in the current round is obtained.

[0098] Among them, SLAM relocalization technology can be used to register the scanned point cloud data of the current round to the global point cloud coordinate system where the global point cloud data is located.

[0099] In addition, voxel downsampling can be performed on the point cloud data of the area where the edge opening is located in the current round, and filtering methods can be used to remove noise, so as to facilitate the subsequent acquisition of the installation status of the guardrail in the area where the edge opening is located based on the point cloud data.

[0100] Therefore, when it is necessary to frequently monitor the protection status of the edge opening, based on the horizontal point cloud data of the construction area in the horizontal coordinate system obtained in the first scan and the area where the edge opening is located determined in the first scan, for each current round in subsequent rounds, the above method of determining the point cloud data of the area where the edge opening is located in the current round can reduce the amount of data processing, thereby reducing the consumption of computing resources and improving computing efficiency.

[0101] The above-mentioned options can reduce the amount of data processing, increase the data processing speed, and thus improve monitoring efficiency; since the consumption of computing resources is reduced, monitoring expenses can also be saved to a certain extent.

[0102] Figure 6 The diagram shown is a flowchart illustrating a method for obtaining the installation status of guardrails in the area where an edge opening is located, according to an embodiment of this application.

[0103] like Figure 6As shown, the aforementioned step S120: Based on the point cloud data of the area where the edge opening is located, obtain the installation status of the guardrail in the area where the edge opening is located, including steps S610 to S620:

[0104] Step S610: Extract point cloud data of the inspection area of ​​the protective railing at the edge opening based on the point cloud data of the area where the edge opening is located.

[0105] Specifically, Figure 7 The diagram shown is a flowchart illustrating a method for extracting point cloud data from an inspection area of ​​a protective fence at an edge opening, according to an embodiment of this application. Figure 7 As shown, step S610 includes the following steps S710 to S720:

[0106] Step S710: Perform plane fitting on the point cloud data of the area where the adjacent opening is located to determine a planar model.

[0107] Specifically, the random consistency sampling algorithm can be used to fit the point cloud data of the area where the edge opening is located to the plane. It should be noted that, in addition to the random consistency sampling algorithm, the least squares method, the direct method, and other methods can also be used to fit the plane. The choice can be made according to the actual situation, and this application does not impose any restrictions on this.

[0108] Step S720: Remove point cloud data that matches the characteristics of the planar model and point cloud data whose elevation is lower than the center point height of the planar model from the point cloud data of the area where the edge opening is located, and use the remaining point cloud data as the point cloud data of the edge opening guardrail inspection area.

[0109] Step S620: Determine the installation status of the guardrail in the area where the edge opening is located.

[0110] Specifically, Figure 8 The diagram shown is a flowchart illustrating a method for determining the state of a protective railing at an edge opening according to an embodiment of this application. Figure 8 As shown, step S620 includes the following steps S810 to S820:

[0111] Step S810: According to the preset grid size, divide the point cloud data of the edge opening protection railing inspection area into multiple grids according to the horizontal XY coordinates, and obtain the number of grids W in the X-axis direction and the number of grids H in the Y-axis direction respectively.

[0112] It should be noted that the preset grid size can be selected according to the actual situation (e.g., monitoring accuracy, computing power, etc.); preferably, the preset grid size can be 5cm.

[0113] Step S820: Create an image with a width and height equal to W and H respectively, where each pixel of the image corresponds one-to-one with each grid.

[0114] Step S830: Calculate the maximum height of the point cloud data within each grid. If the maximum height is less than the preset height, set the grayscale value of the pixels in the image corresponding to the grid to black; otherwise, set it to white.

[0115] It should be noted that the preset height should be consistent with the height of the guardrail, and the height of the guardrail should comply with national regulations; specifically, the preset height can be in the range of 1.1-1.2 meters; preferably, the preset height is 1.2 meters.

[0116] Step S840: Use image algorithms to identify contours in the image. If any contour exists and its area is greater than a preset area threshold, the installation status of the guardrail in the area where the edge opening is located is "guardrail installed"; otherwise, it is "guardrail not installed".

[0117] Specifically, the calculation method for the preset area threshold is as follows:

[0118] Preset area threshold = 0.5 × actual area of ​​adjacent opening / horizontal area of ​​each grid.

[0119] In other embodiments, the aforementioned step S620: determining the installation status of the guardrail in the area where the edge opening is located can also be achieved by the following method: classifying the point cloud data of the guardrail inspection area based on a three-dimensional target classification framework to determine the installation status of the guardrail in the area where the edge opening is located.

[0120] Specifically, the 3D object classification framework can be PointNet++.

[0121] Specifically, when training the three-dimensional target classification framework, the input training samples are the point cloud data and state categories of the inspection area of ​​the protective fence at the edge of the opening, and the output categories are: protective fence installed or protective fence not installed.

[0122] The above describes a method for obtaining the protection status of an edge opening according to an embodiment of this application. The above solution can automatically monitor the installation status of the guardrail in the area where the edge opening is located based on point cloud data, reducing manual intervention, thereby reducing human error and lowering labor costs. The reduction in human error improves monitoring accuracy, and the reduction in labor costs allows for increased monitoring frequency, thus improving the efficiency of edge opening protection status monitoring. Furthermore, since this application utilizes laser technology for point cloud data acquisition, the point cloud data acquisition process can effectively resist interference from external factors such as lighting conditions and weather conditions, giving the solution excellent environmental adaptability. This further ensures the accurate determination of the edge opening location, facilitating accurate understanding of the guardrail installation status.

[0123] The method for obtaining the protection status of the aforementioned edge openings can be derived from... Figure 9 The system for obtaining the protection status of the adjacent openings is executed as shown.

[0124] Figure 9 The diagram shown is a schematic diagram of a system for obtaining the protection status of an edge opening according to an embodiment of this application. Figure 9 As shown, the system 900 includes:

[0125] The acquisition module 910 is used to acquire point cloud data of the area where the edge opening is located using a three-dimensional laser scanning device. The area where the edge opening is located is an area in the construction site where there is a risk of falling.

[0126] The processing module 920 is used to obtain the installation status of the guardrail in the area where the edge opening is located based on the point cloud data of the area.

[0127] It should be understood that, for the sake of convenience and brevity, the specific working scenarios, processes, effects, and other details of each module in the above system 900 can be referred to the corresponding processes in the aforementioned method embodiments, and will not be repeated here.

[0128] This application also provides an electronic device. Figure 10 The diagram shown is a block diagram of an exemplary electronic device provided in an embodiment of this application. (Refer to...) Figure 10 The electronic device 1000 includes a memory 1010 and a processor 1020. The memory 1010 stores a computer program, and the processor 1020 runs the computer program to enable the electronic device 1000 to implement the method for obtaining the protection status of the edge opening provided in any of the foregoing embodiments.

[0129] Electronic device 1000 may also include a power supply component configured to perform power management of electronic device 1000, a wired or wireless network interface configured to connect electronic device 1000 to a network, and an input / output (I / O) interface. Electronic device 500 may operate based on an operating system stored in memory 1010, such as Windows Server™, MacOS X™, Unix™, Linux™, FreeBSD™, or similar.

[0130] This application also provides a computer-readable storage medium storing a computer program thereon. When the computer program in the storage medium is executed by the processor 1020 of the electronic device 1000, the electronic device 1000 is able to implement the method for obtaining the protection status of the edge opening provided in any of the foregoing embodiments.

[0131] This application also provides a computer program product, which includes instructions that, when executed by the processor 1020 of the electronic device 1000, enable the electronic device 1000 to implement the method for obtaining the protection status of the edge opening provided in any of the foregoing embodiments.

[0132] The prompting method in this application can be implemented, in whole or in part, by software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. This computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in this application are performed, in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, network equipment, user equipment, core network equipment, OAM, or other programmable device.

[0133] The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device, a core network device, an OAM (Operational Information Management) system, or other programmable devices.

[0134] The computer program or instructions may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions may be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium may be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; an optical medium, such as a digital video optical disc; or a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both volatile and non-volatile types of storage media.

[0135] It is understood that the specific examples provided in this application are only intended to help those skilled in the art better understand the embodiments of this application, and are not intended to limit the scope of the invention.

[0136] It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0137] It is understood that the various embodiments described in this application can be implemented individually or in combination, and the embodiments of this application are not limited in this respect.

[0138] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0139] It is understood that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiments can be completed by the integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above method.

[0140] It is understood that the memory in the embodiments of this application may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Specifically, non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may be random access memory (RAM). It should be noted that the memory in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0141] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0142] For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual couplings, direct couplings, or communication connections may be indirect couplings or communication connections between devices or units through some interfaces, and may be electrical, mechanical, or other forms.

[0143] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0144] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0145] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0146] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A method for obtaining the protection status of an opening near an edge, characterized in that, include: Point cloud data of the area where the edge opening is located is obtained using a three-dimensional laser scanning device. The area where the edge opening is located is an area in the construction site where there is a risk of falling. Extract point cloud data of the inspection area of ​​the protective railing at the edge of the opening based on the point cloud data of the area where the edge opening is located; The installation status of the guardrail in the area where the edge opening is located is determined based on the point cloud data of the inspection area; wherein, The step of acquiring point cloud data of the area where the adjacent opening is located using a three-dimensional laser scanning device includes: scanning the construction area using a three-dimensional laser scanning device to obtain raw scanned point cloud data, and fusing the raw scanned point cloud data based on SLAM technology to obtain raw point cloud data of the construction area; processing the raw point cloud data of the construction area to obtain horizontal point cloud data of the construction area in a horizontal coordinate system; and obtaining the point cloud data of the area where the adjacent opening is located from the horizontal point cloud data of the construction area. The step of obtaining point cloud data of the area where the adjacent opening is located from the horizontal point cloud data of the construction area includes: obtaining at least two spatial points from the design drawings of the construction area and determining the design coordinates of the at least two spatial points; determining the horizontal coordinate system coordinates corresponding to the at least two spatial points in the horizontal point cloud data of the construction area; calculating the rotation and translation transformation relationship between the design coordinate system and the horizontal coordinate system; obtaining the position and size information of the adjacent opening from the design drawings of the construction area and calculating the minimum enclosing rectangle of the adjacent opening; using the rotation and translation transformation relationship, performing a rotation and translation transformation on the minimum enclosing rectangle of the adjacent opening to obtain the area of ​​the adjacent opening contained in the horizontal point cloud data of the construction area; calculating the center point coordinates of the area of ​​the adjacent opening, and proportionally enlarging the area of ​​the adjacent opening to a preset area multiple with the center point coordinates as the center, as the area where the adjacent opening is located; and obtaining the point cloud data of the area where the adjacent opening is located based on the area where the adjacent opening is located. Specifically, when acquiring the protection status of the edge opening multiple times in subsequent rounds, for each current round, after scanning the construction area using a 3D laser scanning device, and before acquiring the installation status of the guardrail in the area where the edge opening is located based on the point cloud data of the area, acquiring the point cloud data of the area where the edge opening is located includes: using the horizontal point cloud data of the construction area in the horizontal coordinate system obtained in the first scan as global point cloud data; using the point cloud data obtained in the current round by scanning the construction area using the 3D laser scanning device as the scan point cloud data of the current round; registering the scan point cloud data of the current round to the global point cloud coordinate system where the global point cloud data is located to obtain the real-time point cloud data of the current round in the global point cloud coordinate system; fusing the real-time point cloud data of the current round in the global point cloud coordinate system to generate the horizontal point cloud data of the construction area in the horizontal coordinate system of the current round; and acquiring the point cloud data of the area where the edge opening is located in the current round based on the area where the edge opening is located determined in the first scan.

2. The method according to claim 1, characterized in that, The process of processing the original point cloud data of the construction area to obtain horizontal point cloud data of the construction area in a horizontal coordinate system includes: The original point cloud data of the construction area is downsampled to obtain downsampled point cloud data; Planar point cloud data is extracted from the downsampled point cloud data and fitted to obtain a fitted plane, and the normal vector of the fitted plane is calculated. Calculate the rotation matrix between the normal vector of the fitted plane and the unit vector of the Z-axis direction of the horizontal coordinate system, and rotate the original point cloud data of the construction area to the horizontal coordinate system based on the rotation matrix to obtain the horizontal point cloud data of the construction area in the horizontal coordinate system.

3. The method according to claim 1, characterized in that, The step of extracting point cloud data for the inspection area of ​​the protective fence at the edge opening based on the point cloud data of the area where the edge opening is located includes: A planar model is determined by performing plane fitting on the point cloud data of the area where the adjacent opening is located. Remove point cloud data that match the characteristics of the planar model and point cloud data whose elevation is lower than the center point height of the planar model from the point cloud data of the area where the edge opening is located, and use the remaining point cloud data as the point cloud data of the edge opening guardrail inspection area.

4. The method according to claim 3, characterized in that, The determination of the installation status of the guardrail in the area where the adjacent opening is located includes: According to the pre-set grid size, the point cloud data of the inspection area of ​​the edge opening guardrail is divided into multiple grids according to the horizontal XY coordinates, and the number of grids W in the X-axis direction and the number of grids H in the Y-axis direction are obtained respectively. Create an image with a width and height equal to W and H, respectively, wherein each pixel of the image corresponds one-to-one with each of the grids; Calculate the maximum height of the point cloud data within each grid. If the maximum height is less than a preset height, set the grayscale value of the pixels of the image corresponding to the grid to black; otherwise, set it to white. Image algorithms are used to identify contours in an image. If any contour exists whose area is greater than a preset area threshold, then the guardrail in the area where the opening is located is considered to be installed; otherwise, it is considered to be installed without guardrails.

5. A system for acquiring the protection status of an edge opening, characterized in that, include: The acquisition module is used to acquire point cloud data of the area where the edge opening is located using a three-dimensional laser scanning device, wherein the area where the edge opening is located is an area in the construction site where there is a risk of falling. The processing module is used to extract point cloud data of the inspection area of ​​the protective fence of the edge opening based on the point cloud data of the area where the edge opening is located; and to determine the installation status of the protective fence in the area where the edge opening is located based on the point cloud data of the inspection area of ​​the protective fence of the edge opening. Specifically, when the acquisition module is used to acquire point cloud data of the area where the adjacent opening is located using a three-dimensional laser scanning device, the acquisition module is further used to: scan the construction area using a three-dimensional laser scanning device to obtain original scanned point cloud data, and fuse the original scanned point cloud data based on SLAM technology to obtain original point cloud data of the construction area; process the original point cloud data of the construction area to obtain horizontal point cloud data of the construction area in a horizontal coordinate system; and acquire the point cloud data of the area where the adjacent opening is located from the horizontal point cloud data of the construction area. Wherein, when the acquisition module is used to acquire point cloud data of the area where the edge opening is located from the horizontal point cloud data of the construction area, the acquisition module is further used to: obtain at least two spatial points through the design drawings of the construction area and determine the design drawing coordinates of the at least two spatial points; determine the horizontal coordinate system coordinates corresponding to the at least two spatial points in the horizontal point cloud data of the construction area; calculate the rotation and translation transformation relationship between the design drawing coordinate system and the horizontal coordinate system; obtain the position and size information of the edge opening through the design drawings of the construction area and calculate the minimum enclosing rectangle of the edge opening; use the rotation and translation transformation relationship to perform rotation and translation transformation on the minimum enclosing rectangle of the edge opening to obtain the area of ​​the edge opening contained in the horizontal point cloud data of the construction area; calculate the center point coordinates of the area of ​​the edge opening, and enlarge the area of ​​the edge opening proportionally to a preset area multiple with the center point coordinates as the center, as the area where the edge opening is located; acquire the point cloud data of the area where the edge opening is located based on the area where the edge opening is located. Specifically, when acquiring the protection status of the edge opening multiple times in subsequent rounds, for each current round, after scanning the construction area using a 3D laser scanning device, and before acquiring the installation status of the guardrail in the area where the edge opening is located based on the point cloud data of the area, the acquisition module is further configured to: use the horizontal point cloud data of the construction area in the horizontal coordinate system obtained in the first scan as global point cloud data; use the point cloud data obtained in the current round by scanning the construction area using the 3D laser scanning device as the scanned point cloud data of the current round; register the scanned point cloud data of the current round to the global point cloud coordinate system where the global point cloud data is located to obtain the real-time point cloud data of the current round in the global point cloud coordinate system; fuse the real-time point cloud data of the current round in the global point cloud coordinate system to generate the horizontal point cloud data of the construction area in the horizontal coordinate system of the current round; and acquire the point cloud data of the area where the edge opening is located in the current round based on the area where the edge opening is located determined in the first scan.

6. An electronic device, characterized in that, include: Memory; A processor, wherein the memory is used to store a computer program, the processor running the computer program to cause the electronic device to perform an automatic detection method for the protection status of an edge opening as described in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that, It stores a computer program, which, when executed by a processor, implements an automatic detection method for the protection status of the edge opening as described in any one of claims 1 to 4.

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