Ground parcel line close-to-ground rendering method and system and computer readable storage medium

Abstract

The invention relates to the technical field of geographic information processing, in particular to a land parcel line close-to-the-ground rendering method and system and a computer readable storage medium, and the method comprises the steps: obtaining a 3D model of a topographic region, and extracting ground point cloud data representing the topography from the 3D model of the topographic region; converting the ground point cloud data into a continuous terrain surface model through digital terrain modeling; determining a land parcel boundary point and a gradient thereof based on the terrain surface model, and selecting a corresponding interpolation method according to the gradient to perform encryption and smoothing processing of terrain data; and performing close-to-ground rendering of the land parcel boundary through a three-dimensional graphic rendering technology based on the topographic data and the land parcel boundary points after interpolation processing. According to the implementation of the method, the land parcel line can be accurately attached to the ground, and a more real and natural visual effect is presented.

Description

Technical Field

[0001] The present invention relates to the technical field of geographic information processing, and particularly relates to a method, a system, and a computer-readable storage medium for rendering parcel lines on the ground. Background Art

[0002] The technology of rendering parcel lines on the ground has extensive applications in fields such as geographic information systems, digital twins, and 3D modeling. This technology is mainly used to render the boundary lines of parcels (i.e., the plots enclosed by land ownership boundaries) on 3D terrain or maps in a way that adheres to the ground, so as to more intuitively display the location and scope of the parcels. With the continuous development of 3D visualization technology, the method of rendering parcel lines on the ground is also constantly optimized and improved. Existing methods for rendering parcel lines on the ground include rendering based on height maps, rendering based on polygon meshes, etc. Although these methods can achieve the rendering of parcel lines on the ground to a certain extent, there are problems with insufficient matching of terrain height. Especially in complex terrains or places with large slopes, the shape of the parcel lines often cannot accurately conform to the ground, resulting in an unnatural display effect. These unnatural phenomena seriously affect the overall visual effect of the scene and reduce the realism and credibility of the 3D model. Therefore, in order to make the parcel lines accurately conform to the ground and present a more realistic and natural visual effect, it is necessary to study a new method for rendering parcel lines on the ground. This method can achieve the precise matching of parcel lines and terrain through high-precision terrain data and efficient rendering algorithms while fully considering complex factors such as terrain height changes and slopes. Summary of the Invention

[0003] In order to enable the parcel lines to accurately conform to the ground and present a more realistic and natural visual effect, the purpose of the present invention is to provide a method, a system, and a computer-readable storage medium for rendering parcel lines on the ground. The specific technical solutions adopted are as follows:

[0004] In a first aspect, the present application discloses a method for rendering parcel lines on the ground, and the method includes:

[0005] S1. Obtain a 3D model of a terrain area, and extract ground point cloud data representing the terrain and landforms from the 3D model of the terrain area;

[0006] S2. Through digital terrain modeling, convert the ground point cloud data into a continuous terrain surface model;

[0007] S3. Based on the terrain surface model, determine the parcel boundary points and their slopes, and select corresponding interpolation methods according to the slope magnitude for encryption and smoothing processing of terrain data;

[0008] S4. Based on the interpolated terrain data and parcel boundary points, perform ground rendering of the parcel boundary through 3D graphics rendering technology.

[0009] Further, in step S1, the extraction of the ground point cloud data representing the terrain and landform from the 3D model of the terrain area includes:

[0010] S11. Load the 3D model file of the terrain area and parse the three-dimensional information in the model;

[0011] S12. Sample the ground points of the model based on the three-dimensional information and calculate the spatial coordinates of each sampled point;

[0012] S13. Organize these sampled points and their coordinate information into the point cloud data format to obtain the ground point cloud data representing the terrain and landform.

[0013] Further, in step S2, the conversion of the ground point cloud data into a continuous terrain surface model through digital terrain modeling includes:

[0014] S21. Remove the noise points and non-ground points from the ground point cloud data through a data filtering algorithm to retain the effective point cloud data of the terrain surface;

[0015] S22. Based on rasterized modeling, project the point cloud data onto a regular raster grid to convert the filtered effective point cloud data into a continuous terrain surface model.

[0016] Further, in step S2, the conversion of the ground point cloud data into a continuous terrain surface model through digital terrain modeling includes:

[0017] S21. Remove the noise points and non-ground points from the ground point cloud data through a data filtering algorithm to retain the effective point cloud data of the terrain surface;

[0018] S22. Based on triangular mesh modeling, connect the filtered effective point cloud data into a continuous triangular mesh by constructing an irregular triangular network to obtain a continuous terrain surface model.

[0019] Further, in step S3, the determination of the parcel boundary points and their slopes based on the terrain surface model and the selection of the corresponding interpolation method for terrain data encryption and smoothing according to the slope magnitude include:

[0020] S31. Based on the terrain surface model, determine multiple pairs of adjacent parcel boundary points;

[0021] S32. For each pair of adjacent parcel boundary points, determine the slope between the adjacent boundary points by calculating the ratio of the elevation difference to the horizontal distance between the two points;

[0022] S33. When it is determined that the slope between the corresponding first adjacent boundary points is greater than a preset angle threshold, interpolation processing is performed based on the bisection interpolation method determined by the slope;

[0023] S34. When it is determined that the slope between the corresponding second adjacent boundary points is less than or equal to the preset angle threshold, the 2-meter interpolation method is used to sequentially insert corresponding interpolation points at intervals of 2 meters between the corresponding second adjacent boundary points.

[0024] Further, in step S33, the interpolation processing based on the bisection interpolation method determined by the slope includes:

[0025] S331. Calculate the initial midpoint between the first adjacent boundary points, and calculate the slope of the initial midpoint relative to each of the first adjacent boundary points;

[0026] S332. When it is determined that the slope of the initial midpoint relative to the corresponding first adjacent boundary point is greater than the angle threshold, perform bisection recursive interpolation on the line segment between the current two points;

[0027] S333. When it is determined that the slope of the initial midpoint relative to the corresponding first adjacent boundary point is less than or equal to the angle threshold, use the initial midpoint as the interpolation point, and use the 2-meter interpolation method to sequentially insert corresponding interpolation points at intervals of 2 meters between the initial midpoint and the corresponding first adjacent boundary point.

[0028] Further, in step S332, the bisection recursive interpolation of the line segment between the current two points includes:

[0029] S33321. When it is determined that the slope of the line segment between the two points is less than or equal to the angle threshold, use the 2-meter interpolation method to perform data interpolation calculation every 2 meters between the midpoint and the two end points;

[0030] S33322. When it is determined that the slope of the line segment between the two points is greater than the angle threshold, use the 1-meter interpolation method to perform data interpolation calculation every 1 meter between the midpoint and the two end points;

[0031] S33323. When it is determined that the horizontal distance between the two points is less than or equal to the preset distance threshold, stop interpolation and retain the currently calculated interpolation points.

[0032] Further, in step S4, the terrain data and the parcel boundary points after interpolation processing are used to perform ground rendering of the parcel boundary through three-dimensional graphics rendering technology, including:

[0033] S41. For each initial two-dimensional coordinate point after interpolation, obtain the true height of the initial two-dimensional coordinate point on the terrain, and combine the corresponding height information with the initial two-dimensional coordinates to obtain a target two-dimensional coordinate point containing height information;

[0034] S42. Based on the terrain surface model, convert each of the target two-dimensional coordinate points into three-dimensional coordinate points in the Cartesian coordinate system;

[0035] S43. Based on each of the three-dimensional coordinate points, perform ground rendering of the land parcel boundary through three-dimensional graphics rendering technology to visually display the actual position and shape of the land parcel boundary on the terrain.

[0036] In a second aspect, the present application discloses a system for ground rendering of land parcel lines. The system includes a ground point cloud data extraction module, a terrain surface modeling module, a terrain data processing and interpolation module, and a land parcel boundary ground rendering module, where:

[0037] The ground point cloud data extraction module is used to obtain a 3D model of the terrain area and extract ground point cloud data representing the terrain features from the 3D model of the terrain area;

[0038] The terrain surface modeling module is used to convert the ground point cloud data into a continuous terrain surface model through digital terrain modeling;

[0039] The terrain data processing and interpolation module is used to determine the land parcel boundary points and their slopes based on the terrain surface model, and select corresponding interpolation methods according to the slope magnitude for encryption and smoothing processing of the terrain data;

[0040] The land parcel boundary ground rendering module is used to perform ground rendering of the land parcel boundary through three-dimensional graphics rendering technology based on the interpolated terrain data and land parcel boundary points.

[0041] In a third aspect, the present application discloses a computer-readable storage medium storing a computer program, which when executed by a processor, implements the method for ground rendering of land parcel lines.

[0042] The present invention has the following beneficial effects:

[0043] 1) By obtaining the 3D model of the terrain area and extracting the ground point cloud data, the features such as the undulation and slope of the terrain can be accurately represented, providing accurate basic data for subsequent digital terrain modeling and ground rendering of land parcel lines;

[0044] 2) Using digital terrain modeling technology to convert discrete ground point cloud data into a continuous terrain surface model makes the terrain representation smoother and more continuous, which is beneficial for the subsequent determination and interpolation processing of land parcel boundary points;

[0045] 3) Determine the boundary points of the land parcel and their slopes determined according to the terrain surface model, and select the corresponding interpolation method for encrypting and smoothing the terrain data. This slope-adaptive interpolation processing can more accurately reflect the true situation of the terrain and avoid the phenomenon of the land parcel line "floating" or "penetrating" the ground in areas with large slopes or complex terrains;

[0046] 4) Based on the interpolated terrain data and the boundary points of the land parcel, use 3D graphics rendering technology to render the land parcel line close to the ground, which can present a more realistic and natural land parcel line shape and improve the fidelity and credibility of the 3D scene. Description of the Drawings

[0047] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1 It is a method flow chart of a method for rendering a land parcel line close to the ground provided by an embodiment of the present invention;

[0049] Figure 2 It is a schematic diagram of the effect of rendering the boundary of the land parcel;

[0050] Figure 3 (a) Schematic diagram of the rendering effect before being close to the ground;

[0051] Figure 3 (b) Schematic diagram of the rendering effect after being close to the ground;

[0052] Figure 4 It is a system structure diagram of a system for rendering a land parcel line close to the ground provided by an embodiment of the present invention. Detailed Embodiments

[0053] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following, in combination with the drawings and preferred embodiments, details the specific embodiments, structures, features, and effects of a method, system, and computer-readable storage medium for rendering a land parcel line close to the ground proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0055] The following specifically describes the specific solutions of a method, a system, and a computer-readable storage medium for rendering a lot line close to the ground provided by the present invention in conjunction with the accompanying drawings.

[0056] Please refer to Figure 1 , which shows a flowchart of a method for rendering a lot line close to the ground according to an embodiment of the present invention. The method includes:

[0057] Step S1: Obtain a 3D model of the terrain area and extract ground point cloud data representing the terrain and landforms from the 3D model of the terrain area.

[0058] Step S2: Convert the ground point cloud data into a continuous terrain surface model through digital terrain modeling.

[0059] Step S3: Determine the lot boundary points and their slopes based on the terrain surface model, and select corresponding interpolation methods for encryption and smoothing processing of terrain data according to the slope magnitude.

[0060] Step S4: Perform ground rendering of the lot boundary based on the interpolated terrain data and the lot boundary points through three-dimensional graphics rendering technology.

[0061] As can be seen from the above, a method for rendering a lot line close to the ground disclosed in the present application can accurately represent features such as the undulation and slope of the terrain by obtaining a 3D model of the terrain area and extracting ground point cloud data, providing accurate basic data for subsequent digital terrain modeling and lot line ground rendering; using digital terrain modeling technology to convert discrete ground point cloud data into a continuous terrain surface model, making the terrain representation smoother and more continuous, which is beneficial to the determination and interpolation processing of subsequent lot line boundary points; according to the lot boundary points and their slopes determined by the terrain surface model, select corresponding interpolation methods for encryption and smoothing processing of terrain data. This slope-adaptive interpolation processing can more accurately reflect the true situation of the terrain and avoid the phenomenon of the lot line "floating" or "penetrating" the ground in areas with large slopes or complex terrains; based on the interpolated terrain data and the lot boundary points, use three-dimensional graphics rendering technology to perform ground rendering of the lot line, which can present a more realistic and natural lot line shape, improving the fidelity and credibility of the three-dimensional scene.

[0062] In one embodiment, in step S1, the extracting the ground point cloud data representing the terrain and landforms from the 3D model of the terrain area includes:

[0063] Step S11: Load the 3D model file of the terrain area and parse the three-dimensional information in the model.

[0064] Specifically, this application uses the FME tool to load the 3D model file of the terrain area. After loading, the tool parses the three-dimensional information in the model, including the positions, sizes, and shapes of the vertices of the model. It should be noted that as a powerful data conversion and integration platform, the FME tool not only supports the reading and writing of multiple data formats but also can efficiently process and transform the loaded three-dimensional information through its built-in conversion rules and function libraries.

[0065] Step S12: Sample the ground points of the model based on the three-dimensional information and calculate the spatial coordinates of each sampled point.

[0066] Specifically, this application samples the ground points of the model based on the three-dimensional information through a sampling algorithm (such as uniform sampling, random sampling, and the specific sampling method is determined according to the complexity of the model, and this application does not limit it) to accurately and efficiently identify the ground points. After sampling, to ensure the accuracy of subsequent terrain rendering and analysis, this application also calculates the spatial coordinates of each sampled point, including longitude, latitude, and altitude. These coordinate information will serve as the basis for point cloud data to support the subsequent ground texture rendering technology, ensuring that the ground texture can seamlessly and realistically fit onto the terrain surface in a three-dimensional scene, thereby enhancing the realism and visual effect of terrain rendering.

[0067] Step S13: Organize these sampled points and their coordinate information into the point cloud data format to obtain the ground point cloud data representing the terrain and landforms.

[0068] Specifically, this application organizes and stores the sampled points and their coordinate information according to the standard format of point cloud data. These point cloud data will contain the longitude, latitude, and altitude information of each sampled point, as well as possible other attribute information (such as color, reflectivity, etc., depending on specific application requirements).

[0069] In one embodiment, in step S2, the conversion of the ground point cloud data into a continuous terrain surface model through digital terrain modeling includes:

[0070] Step S21: Remove the noise points and non-ground points from the ground point cloud data through a data filtering algorithm to retain the effective point cloud data of the terrain surface.

[0071] Specifically, this application is based on a statistical filtering algorithm. By analyzing the distribution of points in the neighborhood of each point in the point cloud, the points with abnormal distributions (such as outliers) are regarded as noise points and removed. Further, for the removal of non-ground points, this application is based on a ground filtering algorithm, such as a method based on elevation thresholds, to identify and remove the points that do not belong to the terrain surface (such as vegetation, buildings, etc.).

[0072] Step S22 , based on rasterization modeling, the point cloud data is projected onto a regular raster grid to convert the filtered valid point cloud data into a continuous terrain surface model.

[0073] Specifically, first, the application projects the point cloud data onto a regular grid and determines the coordinates of the center point of each grid. Then, based on the point cloud data around the center point, the selected interpolation method is used to calculate the elevation value of the center point. By traversing all grids, the continuous elevation data of the entire terrain surface can be obtained, thereby generating a continuous terrain surface model of the digital elevation model (DEM).

[0074] In one embodiment, in step S2, converting the ground point cloud data into a continuous terrain surface model by digital terrain modeling includes:

[0075] Step S21, removing noise points and non-ground points from the ground point cloud data through a data filtering algorithm to retain valid point cloud data of the terrain surface.

[0076] Specifically, this application will analyze the distribution of points in the neighborhood of each point in the point cloud based on a statistical filtering algorithm, so as to treat points with abnormal distribution (such as outliers) as noise points and remove them. Furthermore, for the removal of non-ground points, this application will identify and remove points that do not belong to the terrain surface (such as vegetation, buildings, etc.) based on a ground filtering algorithm, such as a method based on elevation thresholds.

[0077] Step S22, modeling based on triangular meshes, by constructing an irregular triangular network to connect the filtered valid point cloud data into a continuous triangular mesh, so as to obtain a continuous terrain surface model.

[0078] Specifically, first, this application will use the filtered valid point cloud data as input, and these points represent the key positions of the terrain surface. Then, the Delaunay triangulation algorithm is used to automatically generate a set of interconnected and non-overlapping triangles based on the spatial distribution of these points. The vertices of these triangles are the points in the input point cloud data. It should be noted that the Delaunay triangulation algorithm ensures that the generated triangular mesh has the characteristic of maximizing the minimum angle, thereby ensuring the uniformity and stability of the mesh. Finally, after mesh optimization and surface smoothing, a continuous terrain surface model can be obtained.

[0079] In one embodiment, in step S3, determining the boundary points and slopes of the plot based on the terrain surface model, and selecting a corresponding interpolation method according to the slope to perform encryption and smoothing of the terrain data includes:

[0080] Step S31: Based on the terrain surface model, determine multiple pairs of adjacent land parcel boundary points.

[0081] Specifically, the present application first identifies the boundary lines of the land parcels according to the grid structure of the terrain surface model. Then, along these boundary lines, based on the geometric features of the boundary lines (such as inflection points, curvature change points, etc.), multiple pairs of adjacent land parcel boundary points are identified.

[0082] Step S32: For each pair of adjacent land parcel boundary points, determine the slope between the adjacent boundary points by calculating the ratio of the elevation difference to the horizontal distance between the two points.

[0083] Specifically, when calculating the slope between each pair of adjacent boundary points, the present application first obtains the three-dimensional coordinate information of these two points, including longitude, latitude, and elevation. Then, using this coordinate information, the horizontal distance and elevation difference between the two points are calculated. Among them, the horizontal distance is accurately calculated through the longitude and latitude differences between the two points, combined with the geometric relationship or projection formula of the earth's surface; the elevation difference is the direct difference between the elevation values of the two points. Finally, dividing the elevation difference by the horizontal distance can obtain the slope value between this pair of adjacent boundary points, and this slope value specifically represents the vertical height change per unit length, indicating the inclination degree of the terrain between these two points.

[0084] Step S33: When it is determined that the slope between the corresponding first adjacent boundary points is greater than the preset angle threshold, perform interpolation processing based on the binary interpolation method for slope judgment.

[0085] Specifically, when it is determined that the slope between the corresponding first adjacent boundary points is greater than the preset angle threshold, it is considered that for the area where the slope is greater than the preset angle threshold, the terrain change is relatively drastic. Therefore, more data points need to be added in these areas through the binary interpolation method to more accurately describe and represent the subtle changes of the terrain.

[0086] It should be noted that the binary interpolation method gradually approaches the real terrain change by recursively dividing the line segment into smaller parts and inserting new data points at the midpoint of each part, thereby improving the resolution and accuracy of the terrain data.

[0087] Step S34: When it is determined that the slope between the corresponding second adjacent boundary points is less than or equal to the preset angle threshold, use the 2-meter interpolation method to sequentially insert corresponding interpolation points at intervals of 2 meters between the corresponding second adjacent boundary points.

[0088] Specifically, when it is determined that the slope between the corresponding second adjacent boundary points is less than or equal to the preset angle threshold, it is considered that for the area where the slope is less than or equal to the preset angle threshold, the terrain is relatively flat. Therefore, interpolation points can be inserted at a fixed interval of 2 meters between adjacent boundary points to maintain the smooth transition of the terrain.

[0089] This method can not only ensure the continuity of terrain data, but also effectively reduce the number of data points without sacrificing too much accuracy, thereby improving the efficiency of data processing and rendering. Through the 2-meter interpolation method, while ensuring the accurate overall shape of the terrain, the data can be reasonably sparsified to meet the performance requirements in different application scenarios.

[0090] In the above embodiments, by accurately identifying the boundary points of the land parcel and calculating their slopes, and then intelligently selecting the binary interpolation or 2-meter interpolation method according to the slope size, the refined encryption and smooth transition of terrain data are effectively realized, providing more accurate, continuous and efficient data support for subsequent terrain rendering.

[0091] In one of the embodiments, in step S33, the interpolation process using the binary interpolation method based on slope judgment includes:

[0092] Step S331, calculate the initial midpoint between the first adjacent boundary points, and calculate the slope of the initial midpoint relative to the first adjacent boundary points.

[0093] Specifically, first, the application will first determine the midpoint position of the adjacent boundary points and use it as the initial interpolation candidate point. Subsequently, by calculating the ratio of the elevation difference between the midpoint and the adjacent two boundary points to the horizontal distance, the slope of the midpoint to these two boundary points is obtained. Such processing is to evaluate the degree of change of the terrain in this small area and provide a basis for the selection of the subsequent interpolation method.

[0094] Step S332, when it is determined that the slope of the initial midpoint relative to the corresponding first adjacent boundary point is greater than the angle threshold, perform binary recursive interpolation on the line segment between the current two points.

[0095] Specifically, when it is determined that the slope of the initial midpoint exceeds the preset angle threshold, it is considered that the terrain change in this area is relatively drastic. In order to capture this change more precisely, the application uses binary recursive interpolation to capture more detailed terrain features. During the process, the current line segment will be divided into two halves, and the midpoint slope will be calculated, and then whether to continue to subdivide will be determined according to the slope size. By continuously subdividing and interpolating, more and denser data points can be generated in the area with a larger slope, so as to more accurately reflect the subtle changes of the terrain.

[0096] Step S333, when it is determined that the slope of the initial midpoint relative to the corresponding first adjacent boundary point is less than or equal to the angle threshold, use the initial midpoint as the interpolation point, and adopt the 2-meter interpolation method to insert corresponding interpolation points at intervals of 2 meters between the initial midpoint and the corresponding first adjacent boundary point.

[0097] Specifically, when it is determined that the slope of the initial midpoint meets or is lower than the preset angle threshold, the terrain in this area is considered relatively flat. To maintain the smooth transition of the terrain and reduce the number of data points, the present application will use this initial midpoint as an interpolation point, and insert new interpolation points at a fixed interval of 2 meters between this midpoint and the adjacent boundary points. In this way, while ensuring the accuracy of the overall terrain shape, the data can be reasonably thinned, improving the efficiency of data processing and rendering.

[0098] In the above embodiment, by intelligently judging the terrain slope and selecting the corresponding interpolation strategy, that is, using the dichotomy recursive interpolation in the area with a large slope to accurately capture the terrain changes, and using the 2-meter interpolation method in the area with a small slope to keep the terrain smooth and optimize the data density, the refined processing of the terrain data is realized, improving the accuracy and efficiency of terrain expression.

[0099] In one of the embodiments, in step S332, the dichotomy recursive interpolation of the line segment between the current two points includes:

[0100] Step S33321, when it is determined that the slope of the line segment between the two points is less than or equal to the angle threshold, use the 2-meter interpolation method to perform data interpolation calculation every 2 meters between the midpoint and the two end points.

[0101] Specifically, the interpolation process is realized by inserting a new data point at a distance of every 2 meters between the known two points. The value of this new data point is calculated by quadratic interpolation based on the values of the known points.

[0102] In one of the embodiments, the angle threshold is set to 15°, which means that when the slope of the line segment between the two points is less than or equal to 15°, the present application will use the 2-meter interpolation method for calculation. The selection of this angle threshold is based on the trade-off between terrain complexity and interpolation accuracy.

[0103] Step S33322, when it is determined that the slope of the line segment between the two points is greater than the angle threshold, use the 1-meter interpolation method to perform data interpolation calculation every 1 meter between the midpoint and the two end points.

[0104] Specifically, similar to the 2-meter interpolation method, the 1-meter interpolation method inserts a new data point at a distance of every 1 meter between the known two points. The value of this new data point is also calculated by the interpolation algorithm. Due to the large slope, using denser interpolation points (i.e., every 1 meter) can better capture the details of the terrain.

[0105] Step S33323, when it is determined that the horizontal distance between the two points is less than or equal to the preset distance threshold, stop the interpolation and retain the currently calculated interpolation points.

[0106] Specifically, when the horizontal distance between two points is less than or equal to a preset distance threshold, it means that the terrain between these two points is already flat or detailed enough, and no further interpolation calculation is required. At this time, the interpolation process will be stopped, and all the interpolated points that have been calculated currently will be retained as the final terrain data.

[0107] In one embodiment, the distance threshold is set to 2 meters, which means that when the horizontal distance between two points is less than or equal to 2 meters, the interpolation calculation will be stopped. The selection of this distance threshold is based on the trade-off between the requirements for terrain accuracy and calculation efficiency.

[0108] In one embodiment, in step S4, based on the interpolated terrain data and the parcel boundary points, the ground rendering of the parcel boundary is performed through 3D graphics rendering technology, including:

[0109] Step S41, for each initial two-dimensional coordinate point after interpolation, obtain the true height of the initial two-dimensional coordinate point on the terrain, and combine the corresponding height information with the initial two-dimensional coordinates to obtain a target two-dimensional coordinate point containing height information.

[0110] Specifically, this application will extract the height value corresponding to each initial two-dimensional coordinate point from the terrain height data through direct query (if the height data is in raster form, the height value is obtained by locating the corresponding raster through coordinates). Then, the extracted height value is combined with the initial two-dimensional coordinates (X, Y) to form a target two-dimensional coordinate point (X, Y, Z) containing height information, where Z represents the height.

[0111] In one embodiment, for each initial two-dimensional coordinate point after interpolation, this application uses the Cesium.sampleTerrainMostDetailed method to obtain the true height of each point on the terrain, so as to ensure that each coordinate point can accurately match the terrain surface. It should be noted that the Cesium.sampleTerrainMostDetailed method is an advanced function provided by the CesiumJS library, which uses terrain data services (such as the terrain tile service of Cesium Ion) to query the most detailed terrain height information at a given geographical location. By using the Cesium.sampleTerrainMostDetailed method, accurate query of the terrain height can be achieved, thus ensuring that the interpolated coordinate points can accurately reflect the undulation and changes of the terrain surface.

[0112] Step S42, based on the terrain surface model, convert each of the target two-dimensional coordinate points into three-dimensional coordinate points in the Cartesian coordinate system.

[0113] Specifically, this application will clearly define the reference coordinate system used for the terrain surface model and ensure that all coordinate points are in this coordinate system. Since the terrain surface model is often constructed based on the geographic coordinate system, while 3D graphics rendering usually needs to be carried out in the Cartesian coordinate system, it is necessary to convert each target 2D coordinate point from the geographic coordinate system to the Cartesian coordinate system. Specifically, the conversion parameters from the geographic coordinate system to the Cartesian coordinate system will be determined first, and the corresponding conversion formula from geographic coordinates to Cartesian coordinates will be used. Then, for each target 2D coordinate point (X, Y, Z), the above-mentioned conversion formula will be applied for conversion processing to obtain the 3D coordinate point in the Cartesian coordinate system.

[0114] In one of the embodiments, this application will use batch processing technology. By combining multiple coordinate points into a data batch, the conversion of multiple coordinate points will be processed centrally to avoid repeated calls to the conversion function and improve the calculation efficiency.

[0115] Step S43: Based on each of the above-mentioned 3D coordinate points, perform ground rendering of the land parcel boundary through 3D graphics rendering technology to visually display the actual position and shape of the land parcel boundary on the terrain.

[0116] Specifically, to improve performance and rendering efficiency, this application selects to use the Cesium.Primitive method to render the land parcel boundary. It should be noted that the Cesium.Primitive method is an advanced rendering interface provided by the CesiumJS library. It allows users to directly submit custom geometries and materials into the graphics rendering pipeline, so that it can be applicable to complex geometries that require efficient rendering. Especially in the scenario of large-scale geographic data, it can significantly reduce the calculation and rendering burden.

[0117] Furthermore, to create geometries that conform to the shape of the land parcel boundary and be able to efficiently manage and render these geometries, this application chooses to use the Cesium.PolylineVolumeGeometry method to create the geometric shape of the boundary. It should be noted that the Cesium.PolylineVolumeGeometry method allows users to define a series of line segments and generate a volume geometry around these line segments, which is very suitable for representing the geometric shape of the linear features of the land parcel boundary. Subsequently, the Cesium.GeometryInstance method is used to configure the attributes of the boundary (such as color, material, etc.), and these attributes determine the visual performance of the geometry in the scene. Finally, the configured geometry instances are added to the scene through the Cesium.Primitive method for rendering. It should be noted that the Cesium.GeometryInstance method not only improves the rendering efficiency but also enhances the flexibility and scalability of the scene. By dynamically creating and destroying Cesium.GeometryInstance objects, users can easily achieve dynamic updates and interactions of the scene, providing more possibilities for the display and management of the land parcel boundary.

[0118] In one embodiment, please refer to Figure 2 , to ensure that the land parcel boundary can be clearly visible in complex terrains, this application uses a semi-transparent filling method for boundary rendering. It should be noted that the semi-transparent filling gives the boundary a certain transparency, so that it can not only highlight the position and shape of the boundary but also avoid completely obscuring the terrain details, enabling the terrain and the boundary to be clearly displayed in the scene at the same time.

[0119] In a specific implementation case, this application chooses red for semi-transparent filling, so that the land parcel boundary can be prominently displayed against any terrain background. In addition, the setting of the transparency also avoids obscuring the terrain details, enabling both the terrain and the boundary to be displayed simultaneously, allowing users to observe the information of both the terrain and the boundary at the same time, thereby improving the overall readability of the scene and the user experience.

[0120] Please refer to Figure 3 , as can be seen from Figure 3 (a), the land parcel line only exists as a planarized boundary. The land parcel line does not consider the actual undulations of the terrain and is only displayed on a two-dimensional plane, so it cannot truly reflect the terrain changes. Especially in areas with large terrain undulations, the land parcel line may appear to float or penetrate the ground, resulting in obvious distortion. As can be seen from Figure 3As can be seen from (b), after interpolation, terrain height sampling, and coordinate transformation, the lot line can be accurately aligned with the terrain surface. Moreover, the lot line can precisely fit the ground in areas with different slopes and undulations, eliminating distortion or misalignment caused by terrain changes and ensuring that the lot boundary perfectly coincides with the terrain surface. This precise processing greatly improves the accuracy of the lot line, especially in complex terrains, where it can maintain the original appearance of the terrain and the clarity of the boundary.

[0121] In the above embodiments, by combining terrain height information to convert the initial two-dimensional coordinate points into three-dimensional coordinate points and using three-dimensional graphics rendering technology for ground rendering, the close fitting of the lot boundary with the terrain surface is achieved, presenting a natural three-dimensional effect. This makes the lot line clearly visible not only horizontally and vertically but also harmoniously integrated with the surrounding terrain and environment, making it more visually realistic and natural.

[0122] Please refer to Figure 4 , a lot line ground rendering system disclosed in this application. The system includes a ground point cloud data extraction module, a terrain surface modeling module, a terrain data processing and interpolation module, and a lot boundary ground rendering module, where:

[0123] The ground point cloud data extraction module is used to obtain a 3D model of the terrain area and extract the ground point cloud data representing the terrain features from the 3D model of the terrain area;

[0124] The terrain surface modeling module is used to convert the ground point cloud data into a continuous terrain surface model through digital terrain modeling;

[0125] The terrain data processing and interpolation module is used to determine the lot boundary points and their slopes based on the terrain surface model and select the corresponding interpolation method according to the slope magnitude for encryption and smoothing processing of the terrain data;

[0126] The lot boundary ground rendering module is used to perform ground rendering of the lot boundary through three-dimensional graphics rendering technology based on the interpolated terrain data and the lot boundary points.

[0127] In one of the embodiments, the above modules are also used to implement the lot line ground rendering method described in any one of the foregoing method embodiments, which is not limited in this application.

[0128] As can be seen from the above, a cadastral line ground rendering system disclosed in this application can accurately represent features such as the undulation and slope of the terrain by obtaining the 3D model of the terrain area and extracting the ground point cloud data, providing accurate basic data for subsequent digital terrain modeling and cadastral line ground rendering; using digital terrain modeling technology to convert discrete ground point cloud data into a continuous terrain surface model, making the terrain representation smoother and more continuous, which is beneficial to the determination and interpolation processing of subsequent cadastral line boundary points; according to the cadastral line boundary points determined by the terrain surface model and their slopes, select the corresponding interpolation method to encrypt and smooth the terrain data. This slope-adaptive interpolation processing can more accurately reflect the true situation of the terrain, avoiding the phenomenon of the cadastral line "floating" or "penetrating" the ground in areas with large slopes or complex terrains; based on the interpolated terrain data and cadastral line boundary points, using 3D graphics rendering technology for cadastral line ground rendering can present a more realistic and natural cadastral line form, improving the fidelity and credibility of the 3D scene.

[0129] A computer-readable storage medium disclosed in this application stores a computer program, which, when executed by a processor, implements the cadastral line ground rendering method described above.

[0130] As can be seen from the above, a computer-readable storage medium disclosed in this application can accurately represent features such as the undulation and slope of the terrain by obtaining the 3D model of the terrain area and extracting the ground point cloud data, providing accurate basic data for subsequent digital terrain modeling and cadastral line ground rendering; using digital terrain modeling technology to convert discrete ground point cloud data into a continuous terrain surface model, making the terrain representation smoother and more continuous, which is beneficial to the determination and interpolation processing of subsequent cadastral line boundary points; according to the cadastral line boundary points determined by the terrain surface model and their slopes, select the corresponding interpolation method to encrypt and smooth the terrain data. This slope-adaptive interpolation processing can more accurately reflect the true situation of the terrain, avoiding the phenomenon of the cadastral line "floating" or "penetrating" the ground in areas with large slopes or complex terrains; based on the interpolated terrain data and cadastral line boundary points, using 3D graphics rendering technology for cadastral line ground rendering can present a more realistic and natural cadastral line form, improving the fidelity and credibility of the 3D scene.

[0131] It should be noted that the above sequence of embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0132] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and the differences between each embodiment and other embodiments are emphasized.

Claims

1. A method for rendering a plot line close to the ground, characterized in that: The method comprises: S1, obtaining a 3D model of a terrain area, and extracting ground point cloud data representing the terrain from the 3D model of the terrain area; S2. converting the ground point cloud data into a continuous terrain surface model through digital terrain modeling; S3, determining the boundary points and slopes of the plot based on the terrain surface model, and selecting a corresponding interpolation method according to the slope to perform encryption and smoothing of the terrain data; S4. Based on the interpolated terrain data and the land parcel boundary points, the land parcel boundary is rendered close to the ground using three-dimensional graphics rendering technology.

2. The method according to claim 1, characterized in that: In step S1, extracting ground point cloud data representing the topography from the 3D model of the terrain area includes: S11, loading a 3D model file of the terrain area, and parsing the three-dimensional information in the model; S12, sampling ground points of the model based on the three-dimensional information, and calculating the spatial coordinates of each sampling point; S13, organizing these sampling points and their coordinate information into a point cloud data format to obtain ground point cloud data representing the topography.

3. The method according to claim 1, characterized in that In step S2, the ground point cloud data is converted into a continuous terrain surface model by digital terrain modeling, including: S21, removing noise points and non-ground points from the ground point cloud data by a data filtering algorithm to retain valid point cloud data of the terrain surface; S22. Based on rasterization modeling, the point cloud data is projected onto a regular raster grid to convert the filtered valid point cloud data into a continuous terrain surface model.

4. The method according to claim 1, characterized in that In step S2, the ground point cloud data is converted into a continuous terrain surface model by digital terrain modeling, including: S21, removing noise points and non-ground points from the ground point cloud data by a data filtering algorithm to retain valid point cloud data of the terrain surface; S22. Modeling based on triangular meshes: by constructing an irregular triangular network, the filtered valid point cloud data is connected into a continuous triangular mesh to obtain a continuous terrain surface model.

5. The method according to claim 1, characterized in that: In step S3, the boundary points and slopes of the plots are determined based on the terrain surface model, and a corresponding interpolation method is selected according to the slope to perform encryption and smoothing of the terrain data, including: S31, determining a plurality of pairs of adjacent parcel boundary points based on the terrain surface model; S32, for each pair of adjacent land boundary points, respectively determine the slope between the adjacent boundary points by calculating the ratio of the elevation difference between the two points to the horizontal distance; S33, when it is determined that the slope between the corresponding first adjacent boundary points is greater than a preset angle threshold, performing interpolation processing based on a bisection interpolation method for slope judgment; S34. When it is determined that the slope between the corresponding second adjacent boundary points is less than or equal to the preset angle threshold, a 2-meter interpolation method is used to sequentially insert corresponding interpolation points at intervals of 2 meters between the corresponding second adjacent boundary points.

6. The method according to claim 5, characterized in that In step S33, the interpolation process is performed using the binary interpolation method based on slope judgment, including: S331, calculating an initial midpoint between first adjacent boundary points, and calculating a slope of the initial midpoint relative to each first adjacent boundary point; S332: when it is determined that the slope of the initial midpoint relative to the corresponding first adjacent boundary point is greater than the angle threshold, perform a binary recursive interpolation on the line segment between the current two points; S333. When it is determined that the slope of the initial midpoint relative to the corresponding first adjacent boundary point is less than or equal to the angle threshold, the initial midpoint is used as an interpolation point, and the 2-meter interpolation method is adopted to insert corresponding interpolation points in sequence at intervals of 2 meters between the initial midpoint and the corresponding first adjacent boundary point.

7. The method according to claim 6, characterized in that In step S332, the bisection recursive interpolation is performed on the line segment between the current two points, including: S33321. When it is determined that the slope of the line segment between the two points is less than or equal to the angle threshold, a 2-meter interpolation method is used to perform data interpolation calculation every 2 meters between the midpoint and the two end points. S33322. When it is determined that the slope of the line segment between the two points is greater than the angle threshold, use the 1-meter interpolation method to perform data interpolation calculation every 1 meter between the midpoint and the two end points; S33323. When it is determined that the horizontal distance between the two points is less than or equal to a preset distance threshold, stop interpolation and retain the currently calculated interpolation point.

8. The method according to claim 1, characterized in that: In step S4, the rendering of the land parcel boundary using a three-dimensional graphics rendering technology based on the interpolated terrain data and the land parcel boundary points includes: S41, for each initial two-dimensional coordinate point after interpolation, obtaining the real height of the initial two-dimensional coordinate point on the terrain, and combining the corresponding height information with the initial two-dimensional coordinate to obtain a target two-dimensional coordinate point containing height information; S42, based on the terrain surface model, converting each of the target two-dimensional coordinate points into a three-dimensional coordinate point in a Cartesian coordinate system; S43. Based on each of the three-dimensional coordinate points, the boundary of the land parcel is rendered close to the ground through three-dimensional graphics rendering technology to intuitively display the actual position and shape of the boundary of the land parcel on the terrain.

9. A land parcel line rendering system, characterized in that: The system includes a ground point cloud data extraction module, a terrain surface modeling module, a terrain data processing and interpolation module, and a land parcel boundary ground rendering module, wherein: The ground point cloud data extraction module is used to obtain a 3D model of a terrain area and extract ground point cloud data representing the terrain from the 3D model of the terrain area; The terrain surface modeling module is used to convert the ground point cloud data into a continuous terrain surface model through digital terrain modeling; The terrain data processing and interpolation module is used to determine the boundary points of the plot and its slope based on the terrain surface model, and select a corresponding interpolation method according to the slope to perform encryption and smoothing of the terrain data; The plot boundary rendering module is used to render the plot boundary on the ground based on the interpolated terrain data and the plot boundary points by using three-dimensional graphics rendering technology.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for rendering the plot lines close to the ground is implemented.

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