Smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method and system

Abstract

The invention provides a smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method and system, which are mainly applied to the field of pumped storage power station engineering and realize efficient conversion from a two-dimensional contour line to a smooth terrain entity. According to the method, a technical route of an NURBS terrain entity is finally generated by establishing a triangulation network curved surface, specifying a boundary, converting DEM data, creating a grid curved surface, extracting control points and fitting an NURBS curve in a UV direction. Converting the contour line into DEM data and creating a grid curved surface; extracting control points and respectively fitting NURBS curve groups according to U / V directions; a complete NURBS three-dimensional terrain entity is formed by enclosing the surface curved surface, the bottom plane and the four side curved surfaces. According to the method, on-demand adjustment of terrain precision can be achieved, the generated entity can be directly used for CAE simulation calculation and can be combined with a panel dam partition amount calculation algorithm, and the engineering design efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pumped storage power station engineering, and in particular to a method and system for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting. Background Art

[0002] Non-Uniform Rational B-Splines (NURBS) are an excellent modeling method, supported by advanced 3D software. They offer superior control over surface curvature compared to traditional mesh modeling methods, enabling the creation of more realistic and vivid shapes. In engineering design, particularly for water conservancy and hydropower projects, the ability to quickly, efficiently, and smoothly fit 3D terrain entities is crucial for BIM digital design. When using Civil 3D, a 3D civil engineering design software, it is possible to quickly fit terrain triangulated surfaces and directly extruded 3D terrain entities based on these triangulated surfaces. However, in actual engineering applications, these 3D terrain entities are not smooth, but rather consist of countless triangular facets directly extruded. This results in redundant lines during model sectioning and display, hindering the usability of the model.

[0003] Prior art 1, a Chinese patent with the patent number 202110127452.6, belongs to the technical field of geological modeling and specifically relates to a BIM-based 3D geological automatic modeling method. The method includes acquiring multi-source geological exploration data, performing data fusion processing on the multi-source geological exploration data, expressing the terrain surface and the interfaces of various strata using non-uniform rational B-spline surfaces, analyzing the multi-source geological exploration data, obtaining the stratigraphic regularity of various strata, and determining the Boolean logic operation sequence between the various stratigraphic interfaces and the 3D geological model based on the stratigraphic regularity, obtaining the generation logic of the 3D geological model, and performing parametric geological modeling. The method enables real-time updating of the 3D geological model and the output files for various uses of the 3D geological model, and outputs the desired 3D geological model. Although the method achieves real-time global or local updates of the stratigraphic model, automates the modeling process, and implements parametric modeling, it is a multi-party collaborative modeling method; however, it lacks parametric modeling capabilities.

[0004] Prior art two, a Chinese patent, patent number: 202510218626.8, relates to the field of bridge mold technology and discloses a long-distance bridge modeling method based on Civil 3D, Revit, and Dynamo, including step 1: using Civil 3D to construct the centerline of the bridge, generating a set format and then importing it into the Revit project; sorting out the bridge modeling process, dividing the required components into layout components and adaptive components; and calculating the point information required for the adaptive components; establishing layout component families and adaptive component families respectively and importing them into the project; using Dynamo in Revit to convert the centerline into a spline curve; using Dynamo to complete the batch placement of layout components and adaptive components along the spline curve, thereby completing the batch modeling of the bridge. Although this method greatly reduces manpower input and operation time, achieves highly automated and precise modeling, can quickly update the entire model, and significantly improves modeling efficiency; however, the data processing process is complex.

[0005] Prior art three, Chinese patent, patent number: 202411659868.2 discloses a method for calculating earthwork volume in complex terrain based on Civil 3D software, which relates to the field of earthwork calculation technology. Specifically, it aims to solve the problem existing in the background technology that calculations require a lot of time and energy, and it is difficult to ensure the accuracy of calculations. By providing a method for calculating earthwork volume in complex terrain based on Civil 3D software. Although the powerful functions of Civil 3D are used to establish a three-dimensional digital terrain model of the trench and then calculate the earthwork, which greatly shortens the working time while ensuring the accuracy of calculations, the processing ability of large-scale terrain is limited.

[0006] Currently, existing technologies 1, 2, and 3 suffer from a lack of parametric modeling capabilities, complex data processing procedures, and limited ability to handle large-scale terrain. To address these issues, the present invention provides a smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method. Summary of the Invention

[0007] The main purpose of the present invention is to provide a method and system for creating smooth non-uniform rational B-spline three-dimensional terrain entity fitting, so as to solve the problems of limited parametric modeling capabilities, complex data processing procedures and limited processing capabilities for large-scale terrain in the existing technology.

[0008] To achieve the above object, the present invention provides the following technical solutions: A method for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting, the process of the method comprising the following steps: Construct a triangulated surface in civil engineering 3D design software based on terrain contours and determine the rectangular plane boundary required for non-uniform rational B-spline terrain solid fitting. Convert the contours into digital elevation model data, generate and extract control point datasets through raster surfaces, and provide basic geometric parameters for non-uniform rational B-spline surface fitting. Create a bottom plane to enclose a non-uniform rational B-spline 3D terrain entity; create four side surfaces to enclose a non-uniform rational B-spline 3D terrain entity: use the 3D surface surface, the bottom plane and the four side surfaces to enclose a non-uniform rational B-spline 3D terrain entity.

[0009] As a further improvement of the present invention, the process of creating a bottom plane for enclosing and generating a non-uniform rational B-spline three-dimensional terrain entity includes the following steps: Create a bottom plane surfaced that encloses and generates a non-uniform rational B-spline three-dimensional terrain entity; create four control points of the bottom plane; Obtain the minimum elevation value in the control point dataset, define the minimum thickness of a non-uniform rational B-spline 3D terrain entity, and the elevation of the bottom plane; create four control lines of the bottom plane and the elevation values ​​of the four lines; create the bottom plane using the four control lines; Create four side surfaces that enclose a non-uniform rational B-spline three-dimensional terrain entity; use the three-dimensional surface surfacet, the bottom plane surfaced and the four side surfaces to enclose the non-uniform rational B-spline three-dimensional terrain entity.

[0010] As a further improvement of the present invention, the process of creating four side surfaces that enclose and generate a non-uniform rational B-spline three-dimensional terrain entity includes the following steps: Create four side surfaces that enclose a non-uniform rational B-spline three-dimensional terrain entity; obtain the maximum elevation value in the control point data set; Use line1 as the stretching object, the normal of surface2 as the stretching direction, and the stretching height to create the stretching surface surface1 of line1; using the same method, create the stretching surfaces surface2, surface3, and surface4 of line2, line3, and line4 respectively; A non-uniform rational B-spline three-dimensional terrain entity is enclosed by a three-dimensional surface surfacet, a bottom plane surfaced and four side surfaces.

[0011] As a further improvement of the present invention, the process of creating four side surfaces that enclose and generate a non-uniform rational B-spline three-dimensional terrain entity includes the following steps: Extract the maximum elevation value in the control point dataset, combine it with the minimum elevation value and minimum thickness, and obtain the side extrusion height; Use the defined bottom plane boundary line as the extrusion reference; abandon traditional normal extrusion and establish an absolute vertical vector; generate a unit direction vector perpendicular to the XY plane based on the bottom plane coordinate system; use line1 as the reference line, extend the extrusion height along the unit direction vector to generate the side surface; iteratively generate four side surfaces in sequence; The top, bottom, and side surfaces of the following elements are topologically integrated; through spatial position constraints, the six surfaces form a continuous closed area at the boundary, forming a non-uniform rational B-spline three-dimensional terrain entity.

[0012] As a further improvement of the present invention, the process of forming a continuous closed area at the boundaries of the six curved surfaces includes the following steps: Extract the four generated side surface boundary lines and simultaneously obtain the top and bottom surface boundaries; Bind each control line of the bottom plane surfaced to the bottom boundary of the corresponding side surface to form a seamless connection; align the four boundary lines of the surface surfacet with the top boundaries of the four side surfaces respectively; and collinearly couple the lateral boundaries of adjacent side surfaces to eliminate gaps. Generate a closed solid structure. The bottom plane surfaced provides the reference coordinate system, and its four control lines become the starting points of all geometric connections. The four side surfaces extend in the absolute vertical direction, mapping the bottom surface boundary to the top surface boundary. The surface surfacet forms a closed interface with the top of the side surface through the preset boundary position. The final output is a closed non-uniform rational B-spline terrain entity directly constructed by six surfaces through spatial constraints.

[0013] As a further improvement of the present invention, the top surface boundary is the four edge lines of the three-dimensional surface surfacet; and the bottom surface boundary is the four control lines of the bottom plane surfaced.

[0014] As a further improvement of the present invention, the process of forming a seamless connection includes the following steps: Extract the bottom plane control line as the reference geometric element; synchronously obtain the bottom boundary lines of the four side surfaces generated and record them as geometric elements; Set the local coordinate system of the bottom plane surfaced as the global reference system; match the coordinates of each control point of the bottom boundary line of the side surface with the coordinates of the corresponding control line point by point; After the coordinates are reset, the control line completely coincides with the side and bottom boundaries, forming a rigid geometric connection.

[0015] As a further improvement of the present invention, it also includes establishing a triangulated surface of the original terrain of the target area according to the terrain contour lines through the surface function of the civil engineering three-dimensional design software; according to the actual needs of the project, determining the rectangular plane boundary to be fitted into the non-uniform rational B-spline terrain entity.

[0016] As a further improvement of the present invention, it also includes converting terrain contour data into digital elevation model data; loading the digital elevation model with specified control point spacing into civil engineering three-dimensional design software to generate a grid surface; adjusting the display model of the grid surface to control points, extracting all control points of the grid surface, and obtaining a control point data set.

[0017] To achieve the above object, the present invention also provides the following technical solutions: A smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation system, comprising: The module "Fitting Rectangular Plane Boundary" is used to create a triangulated surface of the original terrain of the target area based on the terrain contours using the surface function of Civil 3D. It also determines the rectangular plane boundary to be fitted into the non-uniform rational B-spline terrain entity according to the actual needs of the project: The control point dataset module is used to convert terrain contour data into DEM data; load the DEM with specified control point spacing into Civil 3D to generate a raster surface; adjust the display model of the raster surface to control points, extract all control points of the raster surface, and obtain a control point dataset; The NURBS 3D terrain entity model module is used to create a bottom plane that encloses and generates a non-uniform rational B-spline 3D terrain entity; create four side surfaces that enclose and generate a non-uniform rational B-spline 3D terrain entity: use the 3D surface surface, the bottom plane and the four side surfaces to enclose a non-uniform rational B-spline 3D terrain entity.

[0018] The present invention establishes a triangulated surface, specifies the boundary to be fitted into a non-uniform rational B-spline terrain entity, converts it into DEM data, creates a grid surface, extracts grid points, fits a non-uniform rational B-spline curve in the UV direction, and fits it into a non-uniform rational B-spline terrain entity; it can quickly and efficiently achieve smooth non-uniform rational B-spline three-dimensional terrain entity fitting; it can customize the control point grid spacing to achieve on-demand adjustment of the surface fitting accuracy; the generated non-uniform rational B-spline three-dimensional terrain entity can be applied to CAE simulation calculations; it is suitable for combination with a panel dam partition quantity calculation algorithm, and by inputting the maximum contour of the panel dam, it can achieve three-dimensional refined and rapid solution of the panel dam partition engineering quantity; and it solves the problem of non-smooth traditional triangulated surface modeling. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1A schematic flow chart of the steps of an embodiment of a method for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting according to the present invention; Figure 2 This is a specific flow chart of the method for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting according to the present invention; Figure 3 This is a three-dimensional schematic diagram of the smooth non-uniform rational B-spline three-dimensional terrain entity fitting results based on Civil 3D of the present invention; Figure 4 This is a flow chart of the steps of determining the rectangular plane boundary to be fitted into the non-uniform rational B-spline terrain entity according to one embodiment of the smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method of the present invention; Figure 5 It is a triangulated surface graph of the original terrain in the smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method of the present invention; Figure 6 A flow chart showing the steps of obtaining a control point data set in one embodiment of a method for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting according to the present invention; Figure 7 A grid control point spacing diagram in the smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method of the present invention; Figure 8 The grid surface image in the smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method of the present invention; Figure 9 This is a control point data set diagram in the smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method of the present invention; Figure 10 A group of non-uniform rational B-spline curves in the smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method of the present invention; Figure 11 The present invention provides a method for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting and a non-uniform rational B-spline three-dimensional surface surface map; Figure 12 A flowchart of the steps for creating and enclosing a bottom plane of a non-uniform rational B-spline three-dimensional terrain entity according to one embodiment of the smooth non-uniform rational B-spline three-dimensional terrain entity creation method of the present invention; Figure 13 This is a functional module diagram of an embodiment of a smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation system of the present invention; Figure 14 This is a schematic structural diagram of an embodiment of an electronic device of the present invention; Figure 15 This is a schematic structural diagram of an embodiment of a storage medium of the present invention. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0021] The terms "first," "second," and "third" in this disclosure are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Therefore, features specified as "first," "second," or "third" may explicitly or implicitly include at least one of such features. In the description of this disclosure, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this disclosure are intended only to illustrate the relative positional relationships and movement of components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly. Furthermore, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements and may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to such process, method, product, or apparatus.

[0022] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] like Figure 1 As shown, this embodiment provides an embodiment of a method for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting. In this embodiment, the method for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting specifically includes the following steps: Step S1: Based on the terrain contours, use the surface function of Civil 3D to create a triangulated surface of the original terrain of the target area; according to the actual needs of the project, determine the rectangular plane boundary to be fitted into the non-uniform rational B-spline terrain entity: Step S2: Convert the terrain contour data into DEM data; load the DEM with the specified control point spacing in Civil 3D to generate a grid surface; adjust the display model of the grid surface to the control points, extract all the control points of the grid surface, and obtain a control point dataset; Step S3: creating a bottom plane to enclose and generate a non-uniform rational B-spline three-dimensional terrain entity; creating four side surfaces to enclose and generate the non-uniform rational B-spline three-dimensional terrain entity: using the three-dimensional surface surface, the bottom plane and the four side surfaces to enclose the non-uniform rational B-spline three-dimensional terrain entity.

[0024] Preferably, this embodiment uses the surface function of Civil 3D to establish a triangulated surface of the original terrain of the target area based on the terrain contour lines; according to the actual needs of the project, determine the rectangular plane boundary to be fitted into the non-uniform rational B-spline terrain entity: including the minimum X coordinate x min , the maximum X coordinate x max , minimum Y coordinate y min , maximum Y coordinate y max etc.; convert the contour data into digital elevation model (DEM) data; use the rectangular plane boundary as the outer boundary of the terrain triangulation surface; export the terrain triangulation surface as a DEM, and specify the grid control point spacing based on the required fitting accuracy of the surface. Load a DEM with specified control point spacing in Civil 3D to generate a raster surface. Adjust the display model of the raster surface to control points, extract all control points of the raster surface, and obtain a control point dataset Pts. Group points with the same Y value in the control point dataset and arrange them in ascending order of X value. Fit each group of arranged data to a non-uniform rational B-spline curve in the U direction to obtain a non-uniform rational B-spline curve group in the U direction. Group points with the same X value in the control point dataset and arrange them in ascending order of X value. Fit each group of arranged data to a non-uniform rational B-spline curve in the V direction to obtain a non-uniform rational B-spline curve group in the V direction. Fit the generated non-uniform rational B-spline curve groups in the U and V directions to form a smooth non-uniform rational B-spline three-dimensional surface surface_t. Create the bottom plane surface_d that encloses the non-uniform rational B-spline 3D terrain entity: Create four control points P1(x min ,y min ), P2(x min ,y max ), P3(x max ,y max ), P4(x max ,y min ); Get the minimum elevation value Z in the control point dataset Pts min, define the minimum thickness h of a non-uniform rational B-spline three-dimensional terrain entity, then the elevation of the bottom plane is Z min-h ; Create four control lines of the bottom plane: line1(P1, P2), line2(P2, P3), line3(P3, P4), line4(P4, P1), and the elevation value of the four lines is Z min-h ; Use four control lines to create the bottom plane surfaced; Create four side surfaces that enclose the non-uniform rational B-spline three-dimensional terrain entity; Get the maximum elevation value Z in the control point dataset Pts max , then the stretching height h of the four side surfaces cm Z max -Z min+h ; Use line1 as the stretching object, the normal of surface2 as the stretching direction, and h cm Create an extruded surface surface1 for line1 for the extruded height; using the same method, create extruded surfaces surface2, surface3, and surface4 for line2, line3, and line4 respectively; use the three-dimensional surface surface surfacet, the bottom plane surfaced, and the four side surfaces (surface1, surface2, surface3, and surface4) to enclose a non-uniform rational B-spline three-dimensional terrain entity. That is, create a triangulated surface, specify the boundary to be fitted into the non-uniform rational B-spline terrain entity, convert it into DEM data, create a grid surface, extract grid points, fit the non-uniform rational B-spline curve in the UV direction, and fit it into a non-uniform rational B-spline terrain entity (for the specific principle, please refer to the attached Figure 2 And attached Figure 3 ).

[0025] Furthermore, if Figure 4 As shown, the process of determining the rectangular plane boundary to be fitted into the non-uniform rational B-spline terrain entity in step S1 specifically includes the following steps: Step S11: Acquire project data such as contour lines and elevation points; add the contour data to the surface definition to generate a triangulated mesh surface; check and adjust the surface smoothness, delete triangles, and eliminate artifacts through local smoothing; divide the area according to project requirements, rebuild the surface boundary, and regenerate the optimized triangulated mesh surface; Step S12: Obtain the closed curve of the target area and extract the outer contour line in the topographic map as the boundary line; after generating the triangulated surface, hide other contour data and retain the outer closed curve; select the optimized triangulated surface and convert it into a 3D solid model; Step S13: Unify the generated triangulated surface and 3D solid model into a unified format, select the terrain range, and generate an initial non-uniform rational B-spline surface; discretize the initial non-uniform rational B-spline surface, uniformly extract the contour line, fit the initial non-uniform rational B-spline surface after discretization, and adjust the flexibility parameter to control the smoothness.

[0026] Preferably, this embodiment obtains project data such as contour lines and elevation points, and adds these data to the surface definition to generate a triangulated mesh surface; by constructing scattered elevation point data into a triangulated mesh, the irregularities of the terrain data can be effectively handled, and a continuous surface model can be generated. After the triangulated mesh surface is generated, it is necessary to check and adjust the surface smoothness, delete unnecessary triangles, and eliminate artifacts through local smoothing functions; ensure the smoothness and continuity of the final surface to avoid visual or functional defects caused by data noise or model irregularities. The generated triangulated mesh surface and entity are exported to a unified format, and the terrain range is selected to generate an initial non-uniform rational B-spline surface. After the initial non-uniform rational B-spline surface is generated, it is discretized, the contour lines are uniformly extracted, and the initial non-uniform rational B-spline surface is fitted. The external contour lines in the topographic map are extracted as boundary lines, and other contour data are hidden after the triangulated mesh surface is generated, retaining the external closed curves. Subsequently, the optimized triangulated mesh surface is converted into a three-dimensional solid model. By generating elevation data and triangulated networks, combined with the fitting of non-uniform rational B-spline surfaces, a high-precision three-dimensional terrain model can be generated, which is suitable for fields such as engineering design, terrain analysis, and landscape planning. The generation and optimization process of non-uniform rational B-spline surfaces is efficient, and can quickly process complex terrain data, reducing computing time and resource consumption. Non-uniform rational B-spline surfaces have good flexibility and modifiability, allowing users to adjust the shape and parameters of the surface according to engineering requirements to meet the needs of different application scenarios. The resulting non-uniform rational B-spline surfaces can be used for terrain analysis, landscape design, water conservancy projects, etc., providing intuitive three-dimensional visualization effects to facilitate decision-making and planning (for specific principles, please refer to the attached Figure 5 ).

[0027] Furthermore, if Figure 6 As shown, the process of obtaining the control point dataset in step S2 specifically includes the following steps: Step S21: converting the terrain contour data into DEM data; using the rectangular plane boundary as the outer boundary of the terrain triangulation surface; exporting the terrain triangulation surface as a DEM, and specifying the grid control point spacing according to the required surface fitting accuracy; Step S22: Load the DEM with the specified control point spacing in Civil 3D to generate a grid surface; adjust the display model of the grid surface to the control points, extract all the control points of the grid surface, and obtain a control point dataset; Step S23: Analyze the control point data set to obtain a U-direction non-uniform rational B-spline curve group and a V-direction non-uniform rational B-spline curve group; fit the generated U-direction non-uniform rational B-spline curve group and the V-direction non-uniform rational B-spline curve group into a smooth non-uniform rational B-spline three-dimensional surface.

[0028] Preferably, this embodiment can realize digital simulation of terrain by converting contour data into regular two-dimensional grid data (DEM). After generating the DEM, the spacing of the grid control points is specified according to the fitting accuracy requirements; the setting of the control point spacing directly affects the smoothness and accuracy of the final non-uniform rational B-spline surface; the display model of the DEM grid surface is adjusted to the control points, and after extracting all the control points, the non-uniform rational B-spline curve group in the U direction and the V direction is fitted, and finally a smooth non-uniform rational B-spline three-dimensional surface surface is constructed. Through the generation of DEM and the precise setting of control points, high-precision modeling of the terrain can be achieved to meet the application requirements of engineering design, terrain analysis and other fields. The generation of non-uniform rational B-spline surfaces makes the terrain model smoother and continuous, which is convenient for visual display and interactive operation in a three-dimensional environment. The mathematical expression of non-uniform rational B-spline surfaces makes the processing and rendering of terrain data more efficient, and is particularly suitable for the processing of large-scale terrain data (for specific principles, refer to the attached). Figure 7 , Attachment Figure 8 , Attachment Figure 9 And attached Figure 10 ).

[0029] Furthermore, the process of specifying the grid control point spacing in step S21 specifically includes the following steps: Step S211: converting the terrain contour data into DEM data; using the rectangular plane boundary as the outer boundary of the terrain triangulation surface; exporting the terrain triangulation surface as a DEM; loading the contour data and selecting all contour lines; Step S212: Group all selected contour lines, call the surface generation tool, and generate a triangulated surface using the contour line group as a data source; select an external closed curve and set the rectangular plane boundary line predefined in the graphical interface as the external boundary; Step S213: Set the boundary type parameters, execute the regeneration surface, make the rectangular boundary effective and clip the triangulated network to the boundary range, adjust the surface display style, and verify whether the external boundary accurately limits the surface range.

[0030] Preferably, this embodiment can realize the numerical expression of terrain by converting contour data into DEM data, which is convenient for subsequent terrain analysis and modeling. When generating a terrain triangulated network surface, the rectangular plane boundary is used as the external boundary to ensure that the generated surface is clipped within the specified area to avoid exceeding the set range. By calling the surface generation tool and generating a terrain triangulated network surface with the contour group as the data source, three-dimensional modeling of the terrain can be achieved. By setting the boundary type parameters and performing the regeneration surface operation, it can be ensured that the rectangular boundary is effective and the triangulated network is clipped within the boundary range; after the surface is generated, adjusting its display style can optimize the visual effect, making it easier for users to intuitively view and analyze terrain data.

[0031] Furthermore, the process of extracting all control points of the grid surface in step 22 specifically includes the following steps: Step S221: Load the DEM data with the specified control point spacing in Civil 3D to generate a grid surface; right-click the surface node in the tool space to create a new surface, enter a name, and add the DEM data to the surface definition; Step S222: Adjust the display model of the grid surface from the default triangulated network or contour lines to control points; use the extraction tool of Civil 3D to select all control points of the grid surface; and generate a control point dataset containing coordinates from the extraction results.

[0032] Preferably, this embodiment generates a raster surface by loading DEM data with specified control point spacing. This surface is used to represent the three-dimensional geometric model of the terrain. Create a new surface object in Toolspace and add the DEM data to the surface definition to incorporate terrain information into the surface. Adjust the display model of the raster surface from the default triangulated mesh or contour lines to control points. Using Civil 3D's Extract tool, select all control points of the raster surface and generate a control point dataset containing coordinates. This functionality is crucial for subsequent tasks such as terrain analysis and earthwork calculations.

[0033] Furthermore, the process of analyzing the control point dataset in step S23 specifically includes the following steps: Step S231: Grouping points with the same Y value in the control point data set into a group, then arranging them in ascending order of X value, fitting each group of arranged data into a non-uniform rational B-spline curve in the U direction to obtain a U-direction non-uniform rational B-spline curve group; Step S232: Grouping points with the same X value in the control point data set into a group, then arranging them in ascending order of X value, and fitting each group of arranged data into a non-uniform rational B-spline curve in the V direction to obtain a V-direction non-uniform rational B-spline curve group; Step S233: fitting the generated U-direction non-uniform rational B-spline curve group and V-direction non-uniform rational B-spline curve group into a smooth non-uniform rational B-spline three-dimensional surface surfacet.

[0034] Preferably, points with the same Y value in the control point data set are grouped together and arranged in ascending order of X value; points with the same X value are grouped together and arranged in ascending order of Y value; non-uniform rational B-spline curve fitting is performed on the grouped data in the U and V directions respectively; the generated non-uniform rational B-spline curve groups in the U and V directions are combined to fit a smooth three-dimensional non-uniform rational B-spline surface. Non-uniform rational B-spline technology can accurately represent complex surfaces such as terrain, reduce data redundancy, and improve modeling accuracy; non-uniform rational B-spline surfaces can be easily modified in shape by adjusting control points, facilitating subsequent optimization and adjustment; through grouping and sorting, the data processing process is simplified and modeling efficiency is improved; the generated non-uniform rational B-spline surfaces can be used for three-dimensional visualization and geological analysis, providing support for engineering design and decision-making (for specific principles, please refer to the attached figure). Figure 11 ).

[0035] Furthermore, if Figure 12 As shown, the process of creating the bottom plane of the non-uniform rational B-spline three-dimensional terrain entity in step S3 specifically includes the following steps: Step S31: creating a bottom plane surfaced that encloses and generates a non-uniform rational B-spline three-dimensional terrain entity; creating four control points P1 of the bottom plane; Among them, the four control points P1(x min ,y min ), P2(x min ,y max ), P3(x max ,y max ), P4(x max ,y min ); Step S32: Obtain control point dataset P ts The minimum elevation value Z in min , define the minimum thickness h of a non-uniform rational B-spline three-dimensional terrain entity, then the elevation of the bottom plane is Z min-h ; Create four control lines of the bottom plane, the elevation values ​​of the four lines are min-h ; Create the bottom plane using four control lines; Among them, the four control lines of the bottom plane are line1(P1, P2), line2(P2, P3), line3(P3, P4) and line4(P4, P1); Step S33: creating four side surfaces that enclose a non-uniform rational B-spline three-dimensional terrain entity; using the three-dimensional surface surfacet, the bottom plane surfaced and the four side surfaces to enclose the non-uniform rational B-spline three-dimensional terrain entity.

[0036] Preferably, this embodiment creates a bottom plane by defining four control points (P1, P2, P3, P4), and calculates the bottom plane based on the minimum elevation value Z in the control point dataset. min and a predefined minimum thickness h to determine the elevation of the bottom plane (Z min-h ); Create four control lines based on the four control points. The elevation values ​​of these lines are all Z min-h , and then use these four control lines to create the bottom plane; use the three-dimensional surface surfacet, the bottom plane surfaced and the four side surfaces to enclose the non-uniform rational B-spline three-dimensional terrain entity; by precisely controlling the elevation and shape of the bottom plane, the accuracy of the non-uniform rational B-spline three-dimensional terrain entity is ensured; using the non-uniform rational B-spline surface modeling method, the details of the terrain model can be flexibly adjusted to adapt to complex geological structures; by defining control points and control lines, the terrain model construction process is simplified and the modeling efficiency is improved.

[0037] Furthermore, the process of creating four side surfaces that enclose and generate the non-uniform rational B-spline three-dimensional terrain entity in step S33 specifically includes the following steps: Step S331: Create four side surfaces that enclose the non-uniform rational B-spline three-dimensional terrain entity; obtain the maximum elevation value Z in the control point data set Pts max , then the stretching height h of the four side surfaces cm Z max -Z min+h ; Step S332: Use line1 as the stretching object, the normal of surface2 as the stretching direction, and h cm Create an extruded surface surface1 for line1 for the extrusion height; in the same way, create extruded surfaces surface2, surface3, and surface4 for line2, line3, and line4 respectively; Step S333: Use the three-dimensional surface surfacet, the bottom plane surfaced and the four side surfaces to enclose a non-uniform rational B-spline three-dimensional terrain entity.

[0038] Preferably, this embodiment creates four side surfaces and stretches them to generate a three-dimensional entity, which reflects the advantages of non-uniform rational B-splines in complex surface modeling; the maximum elevation value Z is obtained through the control point data set Pts max, and calculate the stretching height h accordingly cm , which demonstrates the ability to accurately model terrain data. Using line1 as the stretching object, it is stretched along the normal direction of surface2 to form surface1. Similar methods are then used to generate other side surfaces. Finally, the three-dimensional ground surface, the bottom plane, and the four side surfaces are used to enclose a non-uniform rational B-spline three-dimensional terrain entity. The entire process, from contour line import, TIN model generation, data conversion, control point extraction, and non-uniform rational B-spline surface fitting, simplifies and improves terrain modeling. Non-uniform rational B-spline modeling not only accurately represents terrain, but also maintains geometric consistency in subsequent analysis, avoiding computational deviations caused by geometric errors in traditional FEA.

[0039] Furthermore, the process of creating four side surfaces that enclose and generate the non-uniform rational B-spline three-dimensional terrain entity in step S331 specifically includes the following steps: Step S33311: extract the maximum elevation value in the control point data set, combine it with the minimum elevation value and minimum thickness, and obtain the side stretching height; Step S33312: Use the defined bottom plane boundary line as the stretching reference; abandon the traditional normal stretching and establish an absolute vertical vector; generate a unit direction vector perpendicular to the XY plane based on the bottom plane coordinate system; use line1 as the reference line, extend the stretch height along the unit direction vector to generate the side surface; iteratively generate four side surfaces in sequence; Step S33313: Topologically integrate the top, bottom, and side surfaces of the following elements; through spatial position constraints, make the six surfaces form a continuous closed area at the boundary to form a non-uniform rational B-spline three-dimensional terrain entity.

[0040] This embodiment preferably provides a complete technical process for integrating and enclosing the four side surfaces of a non-uniform rational B-spline three-dimensional terrain entity. Based on a dynamic calculation model of maximum / minimum elevation values ​​and minimum thickness, a highly adaptive side extrusion parameter system is constructed to ensure precise geometric tolerances along the Z-axis of the terrain entity. Standardization of the absolute vertical vector eliminates surface distortion caused by traditional normal extrusion, ensuring that the side surfaces strictly follow the Z-axis of the world coordinate system. Using the bottom plane boundary as a reference geometric element, a parameterized surface generation process is established through the mathematical definition of a unit direction vector. Strict geometric consistency is ensured for the four side surfaces, with the UV parameterized direction of each surface maintaining a topological correspondence with the bottom boundary, providing a standardized geometric foundation for subsequent Boolean operations. Boundary continuity control for the six surfaces (top / bottom / four side surfaces) is achieved through a spatial position constraint algorithm, and the G1 continuity condition of the non-uniform rational B-spline surface is applied to ensure parametric connectivity between adjacent surfaces. The topological integration process utilizes a BREP data structure, ensuring that the resulting closed entity meets strict manifold geometry requirements and possesses complete boundary representation characteristics. The entire process forms a complete parametric construction chain from 2D boundaries to 3D entities. All geometric elements maintain the mathematical properties of non-uniform rational B-splines, supporting subsequent precision adjustments and parametric modifications. The generated entities possess precise geometric definitions and can be directly used in professional engineering applications such as finite element analysis and terrain visualization. Ultimately, the automated generation of parametric 3D terrain entities from discrete elevation data is achieved. Its core value lies in integrating the geometric constraints, topological relationships, and parametric control in the terrain modeling process into a unified mathematical expression system.

[0041] Furthermore, the process of forming a continuous closed area at the boundary of the six curved surfaces in step S33313 specifically includes the following steps: Step S333131: extract the four generated side surface boundary lines, and simultaneously obtain the top surface boundary and the bottom surface boundary; The top boundary is the four edge lines of the three-dimensional surface surfacet; the bottom boundary is the four control lines of the bottom plane surfaced; Step S333132: Bind each control line of the bottom plane surfaced to the bottom boundary of the corresponding side surface to form a seamless connection; align the four boundary lines of the surface surfacet with the top boundaries of the four side surfaces; and collinearly couple the lateral boundaries of adjacent side surfaces to eliminate gaps. Step S333133: Generate a closed solid structure. The bottom plane surfaced provides the reference coordinate system, and its four control lines become the starting points of all geometric connections; the four side surfaces extend in the absolute vertical direction, mapping the bottom surface boundary to the top surface boundary; the surface surface surfacet forms a closed interface with the top of the side surface through the preset boundary position; the final output is a closed non-uniform rational B-spline terrain entity directly composed of six surfaces through spatial constraints.

[0042] Preferably, the technical process of the embodiment of the present invention is to fuse the six surface boundaries to form a closed non-uniform rational B-spline terrain entity; based on the reference coordinate system of the bottom plane control line, a vertical mapping relationship is established from the bottom surface to the top surface to achieve parametric alignment of the side surface with the top / bottom surface; by binding the boundary line position and synchronizing the coordinates, the geometric discontinuity between the surfaces is eliminated, ensuring that the edges of each surface are strictly matched to form a seamless closed loop structure. The hierarchical constraint logic of the bottom control line, side boundary, and top surface boundary is used to integrate the discrete surfaces into a unified topological entity; the bottom surface control line serves as a geometric reference to drive the vertical extension of the side surface; the top surface boundary is coupled with the top of the side surface through a preset position to form a bidirectional constraint network, so that the six surfaces meet the G1 continuity condition in three-dimensional space. Through boundary mapping in the vertical direction, the parametric characteristics of the bottom plane are transferred to the top surface, maintaining the mathematical consistency of the non-uniform rational B-spline surface; the collinear coupling processing of adjacent side surfaces ensures the parametric connection of the lateral boundaries, and finally generates a closed BREP structure with a complete parameter chain.

[0043] In summary, this embodiment achieves automated construction from discrete boundaries to closed entities. All surfaces are directly linked through spatial constraints, eliminating the need for intermediate geometric repair. The output non-uniform rational B-spline terrain entity meets strict manifold requirements and can directly support downstream applications such as engineering analysis and numerical simulation. Its boundary topological integrity provides a structural foundation for subsequent Boolean operations or LOD simplification. Unifying multiple source surfaces into a parametric closed entity solves the problems of precision loss and topological errors caused by manual stitching in traditional methods.

[0044] Furthermore, the process of forming a seamless connection in step S3331321 specifically includes the following steps: Step S33313211: extract the bottom plane control line as a reference geometric element; simultaneously obtain the generated four side surface bottom boundary lines and record them as geometric elements; Step S33313212: Set the local coordinate system of the bottom plane surfaced as the global reference system; match the coordinates of each control point of the bottom boundary line of the side surface with the coordinates of the corresponding control line point by point; Step S33313213: After the coordinates are reset, the control line completely coincides with the side bottom boundary to form a rigid geometric connector.

[0045] Preferably, this embodiment uses the bottom plane control line as the reference geometric element to establish a precise matching framework in the global coordinate system; by aligning the control points of the bottom boundary line of the side surface with the bottom control line point by point, strict spatial synchronization of the parameterized geometric elements is achieved to ensure the mathematical continuity of the connection parts. By uniformly converting the local coordinate system to the global reference system, the coordinate system differences of the multi-source geometric bodies are eliminated; the point-by-point matching process of the control points is essentially the synchronous optimization of the non-uniform rational B-spline parameter space, so that the bottom control line and the side boundary are completely overlapped at the topological and geometric levels, forming a rigid connection without redundant errors. The connector generated after the coordinates are reset has structural immutability, and its mathematical expression meets the continuity and differentiability requirements in differential geometry; this mechanism provides a high-precision benchmark for subsequent top surface fusion and lateral coupling through underlying parameter synchronization, ensuring that the final entity meets the strict closure conditions of the BREP model.

[0046] like Figure 13 As shown, this embodiment further provides a smooth non-uniform rational B-spline 3D terrain entity fitting creation system. In this embodiment, the smooth non-uniform rational B-spline 3D terrain entity fitting creation system is applied to the smooth non-uniform rational B-spline 3D terrain entity fitting creation method in the above embodiment. The smooth non-uniform rational B-spline 3D terrain entity fitting creation system includes: Fitting Rectangular Plane Boundary Module 1 is used to create a triangulated surface of the original terrain of the target area based on the terrain contours using the surface function of Civil 3D. Based on the actual needs of the project, the rectangular plane boundary to be fitted into the non-uniform rational B-spline terrain entity is determined: Control point dataset module 2 is used to convert terrain contour data into DEM data; load the DEM with specified control point spacing into Civil 3D to generate a raster surface; adjust the display model of the raster surface to control points, extract all control points of the raster surface, and obtain a control point dataset; NURBS three-dimensional terrain entity model module 3 is used to create a bottom plane that encloses and generates a non-uniform rational B-spline three-dimensional terrain entity; create four side surfaces that enclose and generate a non-uniform rational B-spline three-dimensional terrain entity: use the three-dimensional surface surface, the bottom plane and the four side surfaces to enclose the non-uniform rational B-spline three-dimensional terrain entity.

[0047] Preferably, this embodiment utilizes Civil 3D's surface functionality to convert terrain contour data into a triangulated mesh surface, and determines the rectangular boundary of a non-uniform rational B-spline terrain entity based on engineering requirements. The contour data is converted into a DEM (digital elevation model), and a raster surface is generated, extracting a control point dataset. By setting the control point spacing, the terrain data is refined, thereby improving the accuracy and continuity of the non-uniform rational B-spline surface fitting. A non-uniform rational B-spline three-dimensional terrain entity is generated by enclosing the bottom plane and four side surfaces. Leveraging the mathematical advantages of non-uniform rational B-spline surfaces, high-precision terrain modeling and visualization is achieved. Non-uniform rational B-spline surfaces offer significant advantages in reverse engineering and CAD modeling, enabling high-quality surface fitting and reconstruction.

[0048] like Figure 14 As shown, this embodiment provides an embodiment of an electronic device. In this embodiment, the electronic device 4 includes a processor 41 and a memory 42 coupled to the processor 41.

[0049] The memory 42 stores program instructions for implementing the layout method of the smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method of any of the above embodiments.

[0050] The processor 41 is configured to execute program instructions stored in the memory 42 to perform the layout of the smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method.

[0051] The processor 41 may also be referred to as a CPU (Central Processing Unit). The processor 41 may be an integrated circuit chip with signal processing capabilities. The processor 41 may also 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 device, a discrete gate or transistor logic device, or a discrete hardware component. The general-purpose processor may be a microprocessor or any conventional processor.

[0052] Furthermore, Figure 15This is a schematic diagram of the structure of a storage medium in an embodiment of the present application. The storage medium 5 in the embodiment of the present application stores program instructions 51 that can implement all of the above methods. The program instructions 51 can be stored in the above storage medium in the form of a software product, including a number of instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, or terminal devices such as a computer, server, mobile phone, and tablet.

[0053] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0054] In addition, the functional units in the various embodiments of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated units may be implemented in the form of hardware or in the form of software functional units. The above is only an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

[0055] The above detailed description of the specific embodiments of the invention is intended to be illustrative only, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications or substitutions to the invention are also within the scope of the present invention. Therefore, equivalent changes, modifications, and improvements made without departing from the spirit and scope of the present invention are also encompassed within the scope of the present invention.

Claims

1. A smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method, characterized in that: The process of the smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method includes the following steps: Construct a triangulated surface in civil engineering 3D design software based on terrain contours and determine the rectangular plane boundary required for non-uniform rational B-spline terrain solid fitting. Convert the contours into digital elevation model data, generate and extract control point datasets through raster surfaces, and provide basic geometric parameters for non-uniform rational B-spline surface fitting. Create a bottom plane to enclose a non-uniform rational B-spline 3D terrain entity; create four side surfaces to enclose a non-uniform rational B-spline 3D terrain entity: use the 3D surface surface, the bottom plane and the four side surfaces to enclose a non-uniform rational B-spline 3D terrain entity.

2. The smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method according to claim 1, characterized in that: The process of creating a bottom plane for enclosing and generating a non-uniform rational B-spline 3D terrain entity includes the following steps: Create a bottom plane surfaced that encloses and generates a non-uniform rational B-spline three-dimensional terrain entity; create four control points of the bottom plane; Obtain the minimum elevation value in the control point dataset, define the minimum thickness of a non-uniform rational B-spline 3D terrain entity, and the elevation of the bottom plane; create four control lines of the bottom plane and the elevation values ​​of the four lines; create the bottom plane using the four control lines; Create four side surfaces that enclose a non-uniform rational B-spline three-dimensional terrain entity; use the three-dimensional surface surfacet, the bottom plane surfaced and the four side surfaces to enclose the non-uniform rational B-spline three-dimensional terrain entity.

3. The smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method according to claim 2, characterized in that: The process of creating four side surfaces that enclose and generate a non-uniform rational B-spline three-dimensional terrain entity includes the following steps: Create four side surfaces that enclose a non-uniform rational B-spline three-dimensional terrain entity; obtain the maximum elevation value in the control point data set; Use line1 as the stretching object, the normal of surface2 as the stretching direction, and the stretching height to create the stretching surface surface1 of line1; using the same method, create the stretching surfaces surface2, surface3, and surface4 of line2, line3, and line4 respectively; A non-uniform rational B-spline three-dimensional terrain entity is enclosed by a three-dimensional surface surfacet, a bottom plane surfaced and four side surfaces.

4. The smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method according to claim 3, characterized in that: The process of creating four side surfaces that enclose and generate a non-uniform rational B-spline three-dimensional terrain entity includes the following steps: Extract the maximum elevation value in the control point dataset, combine it with the minimum elevation value and minimum thickness, and obtain the side extrusion height; Use the defined bottom plane boundary line as the extrusion reference; abandon traditional normal extrusion and establish an absolute vertical vector; generate a unit direction vector perpendicular to the XY plane based on the bottom plane coordinate system; use line1 as the reference line, extend the extrusion height along the unit direction vector to generate the side surface; iteratively generate four side surfaces in sequence; The top, bottom, and side surfaces of the following elements are topologically integrated; through spatial position constraints, the six surfaces form a continuous closed area at the boundary, forming a non-uniform rational B-spline three-dimensional terrain entity.

5. The smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method according to claim 4, characterized in that: The process of making the six surfaces form a continuous closed region at the boundary includes the following steps: Extract the four generated side surface boundary lines and simultaneously obtain the top and bottom surface boundaries; Bind each control line of the bottom plane surfaced to the bottom boundary of the corresponding side surface to form a seamless connection; align the four boundary lines of the surface surfacet with the top boundaries of the four side surfaces respectively; and collinearly couple the lateral boundaries of adjacent side surfaces to eliminate gaps. Generate a closed solid structure. The bottom plane surfaced provides the reference coordinate system, and its four control lines become the starting points of all geometric connections. The four side surfaces extend in the absolute vertical direction, mapping the bottom surface boundary to the top surface boundary. The surface surfacet forms a closed interface with the top of the side surface through the preset boundary position. The final output is a closed non-uniform rational B-spline terrain entity directly constructed by six surfaces through spatial constraints.

6. The method for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting according to claim 5, characterized in that: The top boundary is the four edge lines of the three-dimensional surface surfacet; the bottom boundary is the four control lines of the bottom plane surfaced.

7. The method for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting according to claim 5, characterized in that: The process of forming a seamless connection includes the following steps: Extract the bottom plane control line as the reference geometric element; synchronously obtain the bottom boundary lines of the four side surfaces generated and record them as geometric elements; Set the local coordinate system of the bottom plane surfaced as the global reference system; match the coordinates of each control point of the bottom boundary line of the side surface with the coordinates of the corresponding control line point by point; After the coordinates are reset, the control line completely coincides with the side and bottom boundaries, forming a rigid geometric connection.

8. The method for creating a smooth non-uniform rational B-spline three-dimensional terrain entity fitting according to claim 1, characterized in that: It also includes establishing a triangulated surface of the original terrain of the target area based on the terrain contour lines through the surface function of the civil engineering 3D design software; and determining the rectangular plane boundary to be fitted into the non-uniform rational B-spline terrain entity according to the actual needs of the project.

9. The smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method according to claim 1, characterized in that: It also includes converting terrain contour data into digital elevation model data; loading the digital elevation model with specified control point spacing into civil engineering 3D design software to generate a grid surface; adjusting the display model of the grid surface to control points, extracting all control points of the grid surface, and obtaining a control point data set.

10. A smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation system, which is applied to the smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation method according to any one of claims 1 to 9, characterized in that: The smooth non-uniform rational B-spline three-dimensional terrain entity fitting creation system includes: The module for fitting rectangular plane boundaries is used to establish a triangulated surface of the original terrain of the target area based on the terrain contours using the surface function of the civil engineering 3D design software. The module also determines the rectangular plane boundary to be fitted into the non-uniform rational B-spline terrain entity according to the actual needs of the project: The control point dataset module is used to convert terrain contour data into digital elevation model data; load the digital elevation model with specified control point spacing into the civil engineering 3D design software to generate a grid surface; adjust the display model of the grid surface to the control points, extract all the control points of the grid surface, and obtain the control point dataset; The NURBS 3D terrain entity model module is used to create a bottom plane that encloses and generates a non-uniform rational B-spline 3D terrain entity; create four side surfaces that enclose and generate a non-uniform rational B-spline 3D terrain entity: use the 3D surface surface, the bottom plane and the four side surfaces to enclose a non-uniform rational B-spline 3D terrain entity.

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