Section data generation method and device

Abstract

The invention discloses a section data generation method and device. The method comprises the following steps: acquiring first earth surface point cloud data and a cross section arrangement diagram; the cross section arrangement diagram comprises cross section position lines; generating a buffer area according to the cross section position line, and cutting the first earth surface point cloud data by using the buffer area to obtain a plurality of second earth surface point cloud data; acquiring section point data of each piece of second earth surface point cloud data; the section point data are thinned, and target section point data meeting the section precision requirement are determined; and generating section data according to the target section point data, and outputting the section data. According to the technical scheme, the data of multiple sections can be automatically extracted in batches, the process is simple and efficient, the obtained section data are more accurate, and the shape of the surface section can be reflected more truly.

Description

Technical Field

[0001] The present application relates to the technical field of point cloud data processing, and in particular to a method and device for generating cross-sectional data. Background Art

[0002] In recent years, with the popularization of 3D laser scanning technology, this technology has become one of the main means of obtaining terrain data. This technology can quickly and efficiently obtain the 3D solid surface coordinate data in the scene, that is, point cloud data. Section data is a cross-sectional expression of the surface shape. It is the data obtained after obtaining point cloud data and surface terrain points and performing sectioning at specified locations.

[0003] Currently, there are two commonly used methods for obtaining cross-section data. One is to manually extract terrain key points according to the cross-section position, and then use the terrain key points on each cross-section to compile the cross-section. This method uses manual data extraction and is less efficient, but the extracted cross-section can more accurately reflect the cross-section shape; the other is to slice the surface point cloud at a certain distance according to the cross-section position, such as extracting surface point cloud data within 1 meter on both sides of the cross-section line, projecting it, obtaining cross-section data, and then performing uniform sampling at a certain interval to obtain cross-section result data. However, the problem with this method is that the obtained cross-section shape is affected by the size of the slicing range, and the cross-section data cannot truly reflect the cross-section shape at the cross-section position. When there are no surface points within the slicing range, it may cause a large cross-section deviation.

[0004] Therefore, how to provide a method for generating cross-sectional data to ensure the efficiency and accuracy of the generation has become a problem that needs to be solved in this field. Summary of the invention

[0005] In view of this, in a first aspect, the present application proposes a method for generating cross-sectional data, the method comprising:

[0006] Acquire first surface point cloud data and a cross-section layout diagram; the cross-section layout diagram includes: a cross-section position line;

[0007] Generate a buffer area according to the cross-section position line, and use the buffer area to cut the first surface point cloud data to obtain a plurality of second surface point cloud data;

[0008] Acquire cross-section point data of each of the second surface point cloud data;

[0009] Thinning the cross-section point data to determine target cross-section point data that meets cross-section accuracy requirements;

[0010] Generate section data according to the target section point data and output it.

[0011] Preferably, the section point data includes: the name of the section to which it belongs, the plane position data of the section point and the elevation of the section point.

[0012] Further preferably, obtaining the elevation of each cross-section point data of the second surface point cloud data comprises:

[0013] Creating a triangulated network model using the second surface point cloud data;

[0014] Performing an intersection operation on the cross-section position line of the second surface point cloud data and the triangulated network model to obtain plane position data of the cross-section point;

[0015] The elevation of the section point is obtained according to the plane position data of the section point and the triangulated network model.

[0016] Further preferably, a vertical distance between a point cloud within each triangle in the triangulated mesh model and a corresponding triangular facet is less than a profile accuracy threshold.

[0017] Further preferably, performing an intersection operation on the cross-section position line of the second surface point cloud data and the triangulated network model to obtain the plane position data of the cross-section point includes:

[0018] Performing an intersection operation with the cross-section position line of the second surface point cloud and the triangulated network model to obtain an intersection point between the cross-section position line and the triangulated network;

[0019] The plane position data of the cross-section point are obtained according to the plane coordinates of the intersection point and the plane coordinates of the nodes of the cross-section position line.

[0020] Preferably, the thinning of the section point data to determine the target section point that meets the section accuracy requirement includes:

[0021] Obtaining the section points at both ends of the same cross-section position line as initial reserved section points;

[0022] Connecting two of the initial reserved section points to form a line segment;

[0023] In the line segment, the section point with the largest vertical distance to the line segment and the vertical distance greater than the section accuracy threshold is added as a reserved section point;

[0024] Connecting the newly added reserved section points and the initial reserved section points to form a plurality of new line segments, and determining new newly added reserved section points in the new line segments until there are no section points in the new line segments whose vertical distance is greater than the section accuracy threshold;

[0025] The initial reserved section point and all newly added reserved section points are taken as target section points.

[0026] Preferably, each of the cross-section position lines corresponds to a cross-section name.

[0027] In a second aspect, the present application further provides a device for generating cross-sectional data, the device comprising:

[0028] The file acquisition module is configured to acquire the first surface point cloud data and the cross-section layout diagram; the cross-section layout diagram includes: a cross-section position line;

[0029] a cutting module, configured to generate a buffer area according to the cross-section position line, and use the buffer area to cut the first surface point cloud data to obtain a plurality of second surface point cloud data;

[0030] A section point acquisition module, configured to acquire section point data of each of the second surface point cloud data;

[0031] A thinning module is configured to thin the section point data to determine target section point data that meets the section accuracy requirement;

[0032] The output module is configured to generate cross-section data according to the target cross-section point data and output the cross-section data.

[0033] Preferably, the section point acquisition module is also used for:

[0034] Creating a triangulated network model using the second surface point cloud data;

[0035] Performing an intersection operation on the cross-section position line of the second surface point cloud data and the triangulated network model to obtain plane position data of the cross-section point;

[0036] The elevation of the section point is obtained according to the plane position data of the section point and the triangulated network model.

[0037] Preferably, the thinning module is also used for:

[0038] Obtaining the section points at both ends of the same cross-section position line as initial reserved section points;

[0039] Connecting two of the initial reserved section points to form a line segment;

[0040] In the line segment, the section point with the largest vertical distance to the line segment and the vertical distance greater than the section accuracy threshold is added as a reserved section point;

[0041] Connecting the newly added reserved section points and the initial reserved section points to form a plurality of new line segments, and determining new newly added reserved section points in the new line segments until there are no section points in the new line segments whose vertical distance is greater than the section accuracy threshold;

[0042] The initial reserved section point and all newly added reserved section points are taken as target section points.

[0043] According to the method for generating section data provided in the present application, a buffer area is generated using the cross-section position line, and the buffer area is used to cut the original surface point cloud data to obtain a plurality of segmented surface point cloud data. The section points of these segmented surface point cloud data are then thinned to obtain target section point data that meet the section accuracy requirements. This process can realize batch automated extraction of multiple section data. The process is simple and efficient, and the obtained section data is more accurate and can more truly reflect the surface section shape.

[0044] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present application, and the schematic implementation modes and descriptions of the present application are used to explain the present application. In the accompanying drawings:

[0046] Figure 1 A method flow chart of a method for generating cross-sectional data according to a preferred embodiment of the present application;

[0047] Figure 2 A flow chart of a method for calculating the plane position and elevation of a cross-section point according to a preferred embodiment of the present application;

[0048] Figure 3 A schematic diagram of a cross-sectional position line and a triangulated network model of a preferred embodiment of the present application;

[0049] Figure 4 A method flow chart of a thinning method according to a preferred embodiment of the present application;

[0050] Figure 5 A schematic diagram of thinning out cross-section points in a preferred embodiment of the present application;

[0051] Figure 6 This is a schematic diagram of the structure of a device for generating cross-sectional data according to a preferred embodiment of the present application. DETAILED DESCRIPTION

[0052] The technical solution of the present application will be described in detail below with reference to the accompanying drawings and in combination with the implementation modes.

[0053] First, the present application provides a method for generating cross-sectional data, such as Figure 1 As shown, the method includes steps 110-150:

[0054] Step 110, obtaining first surface point cloud data and a cross-section layout diagram;

[0055] Specifically, the first surface point cloud data in the present application is preprocessed point cloud data, and the preprocessing step at least includes benchmark conversion and unification of point cloud coordinates, noise removal, ground point filtering, etc., to finally obtain point cloud data containing only surface topography.

[0056] The cross-section layout diagram in this application includes: cross-section position lines and the cross-section name corresponding to each cross-section position line. There may be multiple cross-section position lines, and the cross-section name should be annotated near the corresponding cross-section position line, and the distance from other cross-section position lines should not be less than the distance of the buffer zone created in step 120 below, so as to ensure that each buffer zone has and only corresponds to one cross-section name.

[0057] In a specific example, the cross-sectional layout drawing may be a cross-sectional layout drawing vector file drawn by CAD.

[0058] Step 120, generating a buffer area according to the cross-section position line, and using the buffer area to cut the first surface point cloud data to obtain a plurality of second surface point cloud data;

[0059] Specifically, read the cross-section position line in the cross-section layout diagram, and use the cross-section position line to create a buffer zone. Take the two end points of the cross-section position line as the starting point and extend to both ends of the cross-section position line, and take the extended cross-section position line as the center, expand a rectangular buffer zone containing the cross-section position line in the area on both sides of the line, and then perform point-to-surface overlay analysis on the cross-section name and the created buffer zone, so that the newly established buffer zone corresponds to the cross-section name. Of course, if there are multiple cross-section position lines, there are also multiple buffer zones corresponding to them. Finally, use the buffer zone to cut the first surface point cloud data, and use the boundaries of each buffer zone as the boundary to divide the first surface point cloud data into multiple second surface point cloud data. The boundaries of these second surface point cloud data are the boundaries of the corresponding buffer zones. Of course, each second surface point cloud data corresponds to a corresponding cross-section name to indicate the section to which it belongs. In a specific embodiment, the extension length and expanded length of both ends of the cross-sectional position line can be set as needed. For example, the extension lengths of both ends of the cross-sectional position line are ten meters, and the expanded distances of the areas on both sides of the extended cross-sectional position line are five meters each.

[0060] Step 130, obtaining cross-section point data of each second surface point cloud data;

[0061] Specifically, the section point data includes: the name of the section to which it belongs, the plane position data of the section point, and the elevation of the section point. For the name of the section to which it belongs, directly inherit the name of the section to which the point cloud belongs, and you can get the name of the section to which it belongs. As for the plane position data of the section point and the elevation of the section point, the method of obtaining it is as follows: Figure 2 As shown, the following steps 210-230 are included:

[0062] Step 210, creating a triangulated network model using the second surface point cloud data;

[0063] To be more specific, the irregular triangulated network (TIN) model is a model that uses a series of connected triangles to fit the ground surface or other irregular surfaces. The corresponding triangulated network model can be generated using the second surface point cloud data. It should be noted that in the created triangulated network model, the vertical distance between the point cloud within each triangle range and its corresponding triangle face should be less than the corresponding profile accuracy threshold, so that the triangle face is close enough to the point cloud data to ensure that the triangulated network model maintains a certain accuracy.

[0064] Step 220, performing an intersection operation on the cross-section position line of the second surface point cloud data and the triangulated network model to obtain the plane position data of the cross-section point;

[0065] More specifically, Figure 3 As shown, the cross-section position line and the triangulated network are used to perform intersection operations to obtain the intersection points of the cross-section position line and the triangulated network, and the plane coordinates of these intersection points and the nodes on the cross-section position line are used as the plane position data of the cross-section points. Here, the nodes on the cross-section position line are the points in the cross-section position line.

[0066] In a specific embodiment, the intersection operation is performed with the cross-sectional position line and the triangulated network. The two are first projected onto the horizontal XY plane, and then the elevation Z coordinates are all set to 0. Then, the cross-sectional position line is intersected with each constituent edge of the triangulated network to obtain the plane coordinates of the intersection point and the plane coordinates of the nodes of the cross-sectional position. The plane coordinates of the intersection point and the plane coordinates of the nodes are both used as the plane position data of the section point.

[0067] Step 230, obtaining the elevation of the section point according to the plane position data of the section point and the triangulated network model;

[0068] More specifically, the elevation of the section point can be obtained by interpolating the triangulated network model, that is, by determining the spatial plane equation of the section point and a specific triangle in the triangulated network where it is located, the elevation of the section point can be interpolated.

[0069] Step 140, thinning the cross-section point data to determine target cross-section point data that meets the cross-section accuracy requirements;

[0070] Specifically, in the process of processing vector data, we often encounter situations where the records contain a large amount of duplicate data. These redundant data not only take up valuable storage space, but may also cause the presented graphics to be not smooth enough or not meet the established standards. Under the premise of ensuring that the shape of the vector curve does not change, the number of data points is reduced as much as possible. This process is called thinning. The specific steps of thinning are as follows: Figure 4 As shown, the following steps 410-450 are included:

[0071] Step 410, obtaining the cross-section points at both ends of the same cross-section position line as initial reserved cross-section points;

[0072] More specifically, combined Figure 5 In the specific embodiment shown, in a cross-sectional position line, its two ends are taken as the initial section points that need to be retained.

[0073] Step 420, connecting two initially retained section points to form a line segment;

[0074] More specifically, two initially retained section points are connected to form a straight line segment.

[0075] Step 430, within the line segment, the section point with the largest vertical distance to the line segment and a vertical distance greater than the section accuracy threshold is added as a reserved section point;

[0076] More specifically, in the line segment formed in step 420, two cross-section points whose vertical distance to the line segment is the largest and whose vertical distance is greater than the cross-section accuracy threshold are determined, and these two cross-section points are used as newly added reserved cross-section points. Here, if the cross-section accuracy of the vertical distance between the surface point and the line segment is greater than the cross-section accuracy threshold, it meets the cross-section accuracy requirement, and the accuracy requirement can be set according to the cross-section measurement scale.

[0077] Step 440, connecting the newly added reserved section point and the initial reserved section point, as well as the two newly added reserved section points, to form a plurality of new line segments, and determining new newly added reserved section points in the new line segments until there are no two section points in the new line segments whose vertical distance is greater than the profile accuracy threshold;

[0078] More specifically, the newly added reserved section point and the initial reserved section point, as well as the two newly added reserved section points, are connected to form multiple new line segments. Of course, the newly added reserved section point and the initial reserved section point can only be connected once as the endpoints of one direction of the line segment. Then, a new newly added reserved section is determined in these new line segments. The determination method is the same as step 430. The section point with the largest vertical distance to the corresponding line segment and a vertical distance greater than the profile accuracy threshold is still used as the new newly added reserved section. This process is repeated until there is no section point in the currently divided line segment whose vertical distance to the corresponding line segment is greater than the profile accuracy threshold.

[0079] Step 450, taking the initial reserved section point and all newly added reserved section points as target section points;

[0080] More specifically, the initial reserved section points obtained in step 410 and all newly added reserved section points obtained in subsequent steps 430 - 440 are reserved as target section points.

[0081] In the above process, thinning and simplifying the section points can minimize the extracted section point data within a certain accuracy threshold, that is, using the least section point data to reflect the most accurate surface profile shape within the specified accuracy.

[0082] It can be understood that if in step 430, there is no section point with a vertical distance greater than the profile accuracy threshold in the initial line segment, then in the cross-sectional position line, only two endpoints are retained as initial retained section points.

[0083] Step 150, generating cross-section data according to target cross-section point data and outputting the data;

[0084] Specifically, the data of the target section point that is retained is used as the final section point result data to generate section data output, which includes the name and elevation information of the section point that is retained.

[0085] According to the method for generating section data provided in the present application, a buffer area is generated using the cross-section position line, and the buffer area is used to cut the original surface point cloud data to obtain a plurality of segmented surface point cloud data. The section points of these segmented surface point cloud data are then thinned to obtain target section point data that meet the section accuracy requirements. This process can realize batch automated extraction of multiple section data. The process is simple and efficient, and the obtained section data is more accurate and can more truly reflect the surface section shape.

[0086] In a second aspect, the present application further provides a device for generating cross-sectional data, the device being used to implement the method for generating cross-sectional data in the first aspect, such as Figure 6 As shown, the device comprises:

[0087] The file acquisition module 610 is configured to acquire first surface point cloud data and a cross-section layout diagram; the cross-section layout diagram includes: a cross-section position line;

[0088] The cutting module 620 is configured to generate a buffer area according to the cross-section position line, and use the buffer area to cut the first surface point cloud data to obtain a plurality of second surface point cloud data;

[0089] The section point acquisition module 630 is configured to acquire section point data of each second surface point cloud data;

[0090] A thinning module 640 is configured to thin the cross-section point data to determine target cross-section points that meet the cross-section accuracy requirements;

[0091] The output module 650 is configured to generate cross-sectional data according to the target cross-sectional point data and output the generated cross-sectional data.

[0092] Preferably, the section point acquisition module 630 is further used for:

[0093] Creating a triangulated network model using the second surface point cloud data;

[0094] Performing an intersection operation on the cross-section position line of the second surface point cloud data and the triangulated network model to obtain the plane position data of the cross-section point;

[0095] The elevation of the section point is obtained according to the plane position data of the section point.

[0096] Preferably, the thinning module 640 is further used for:

[0097] Obtain the section points at both ends of the same cross-section position line as the initial reserved section points;

[0098] Connect the two initial reserved section points to form a line segment;

[0099] In the line segment, the section point with the largest vertical distance to the line segment and whose vertical distance is greater than the profile accuracy threshold is added as the reserved section point;

[0100] Connect the newly added reserved section points and the initial reserved section points to form multiple new line segments, and determine new newly added reserved section points in the new line segments until there are no section points in the new line segments whose vertical distance is greater than the profile accuracy threshold;

[0101] The initial reserved section point and all newly added reserved section points are taken as target section points.

[0102] Other preferred embodiments of the device for generating cross-sectional data provided in the present application, the technical problems that can be solved, and the technical effects that can be achieved are the same as those of the above-mentioned method for generating cross-sectional data, and will not be described in detail here.

[0103] The preferred embodiments of the present application are described in detail above; however, the present application is not limited to the specific details in the above embodiments. Within the technical concept of the present application, a variety of simple modifications can be made to the technical solution of the present application, and these simple modifications all fall within the protection scope of the present application.

[0104] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not further describe various possible combinations.

[0105] In addition, the various implementation modes of the present application may be arbitrarily combined, and as long as they do not violate the concept of the present application, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for generating cross-sectional data, characterized in that: The method comprises: Acquire first surface point cloud data and a cross-section layout diagram; the cross-section layout diagram includes: a cross-section position line; Generate a buffer area according to the cross-section position line, and use the buffer area to cut the first surface point cloud data to obtain a plurality of second surface point cloud data; Acquire cross-section point data of each of the second surface point cloud data; Thinning the cross-section point data to determine target cross-section point data that meets cross-section accuracy requirements; Generate section data according to the target section point data and output it.

2. The method according to claim 1, characterized in that: The section point data include: the name of the section to which it belongs, the plane position data of the section point and the elevation of the section point.

3. The method according to claim 2, characterized in that: Acquiring the elevation of each cross-section point data of the second surface point cloud data, including: Creating a triangulated network model using the second surface point cloud data; Performing an intersection operation on the cross-section position line of the second surface point cloud data and the triangulated network model to obtain plane position data of the cross-section point; The elevation of the section point is obtained according to the plane position data of the section point and the triangulated network model.

4. The method according to claim 3, characterized in that: The vertical distance between the point cloud within each triangle in the triangulated network model and the corresponding triangular face is less than the profile accuracy threshold.

5. The method according to claim 3, characterized in that: The performing an intersection operation on the cross-section position line of the second surface point cloud data and the triangulated network model to obtain the plane position data of the cross-section point includes: Performing an intersection operation with the cross-section position line of the second surface point cloud and the triangulated network model to obtain an intersection point between the cross-section position line and the triangulated network; The plane position data of the cross-section point are obtained according to the plane coordinates of the intersection point and the plane coordinates of the nodes of the cross-section position line.

6. The method according to claim 1, characterized in that The thinning out of the cross-section point data to determine target cross-section point data that meets the cross-section accuracy requirement includes: Obtaining the section points at both ends of the same cross-section position line as initial reserved section points; Connecting two of the initial reserved section points to form a line segment; In the line segment, the section point with the largest vertical distance to the line segment and the vertical distance greater than the section accuracy threshold is added as a reserved section point; Connecting the newly added reserved section points and the initial reserved section points to form a plurality of new line segments, and determining new newly added reserved section points in the new line segments until there are no section points in the new line segments whose vertical distance is greater than the section accuracy threshold; The initial reserved section point and all newly added reserved section points are taken as target section points.

7. The method according to claim 1, characterized in that: Each of the cross-section position lines corresponds to a cross-section name.

8. A device for generating cross-sectional data, characterized in that: The device comprises: The file acquisition module is configured to acquire the first surface point cloud data and the cross-section layout diagram; the cross-section layout diagram includes: a cross-section position line; a cutting module, configured to generate a buffer area according to the cross-section position line, and use the buffer area to cut the first surface point cloud data to obtain a plurality of second surface point cloud data; A section point acquisition module, configured to acquire section point data of each of the second surface point cloud data; A thinning module is configured to thin the section point data to determine target section point data that meets the section accuracy requirements; The output module is configured to generate cross-section data according to the target cross-section point data and output the cross-section data.

9. The device according to claim 8, characterized in that: The cross-section point acquisition module is also used for: Creating a triangulated network model using the second surface point cloud data; Performing an intersection operation on the cross-section position line of the second surface point cloud data and the triangulated network model to obtain plane position data of the cross-section point; The elevation of the section point is obtained according to the plane position data of the section point and the triangulated network model.

10. The device according to claim 8, characterized in that: The thinning module is also used for: Obtaining the section points at both ends of the same cross-section position line as initial reserved section points; Connecting two of the initial reserved section points to form a line segment; In the line segment, the section point with the largest vertical distance to the line segment and the vertical distance greater than the section accuracy threshold is added as a reserved section point; Connecting the newly added reserved section points and the initial reserved section points to form a plurality of new line segments, and determining new newly added reserved section points in the new line segments until there are no section points in the new line segments whose vertical distance is greater than the section accuracy threshold; The initial reserved section point and all newly added reserved section points are taken as target section points.

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