Topological adaptive modeling method and system for building stair riser extension plate

Abstract

The application discloses a kind of topological adaptive modeling method and system of building stair segment extension plate, belong to CAD / BIM three-dimensional geometric modeling field.For the problem that existing tool generates geometric interference collapse under limit parameter and lacks topological adaptive ability, the application generates single inclined surface entity by automatically switching to oblique cutting branch when the length of extension plate is compared with critical cutoff eigenvalue;When it is, a transition entity containing a horizontal section is generated using a double-fold line branch.For multi-layer heterogeneous structures, the critical value is calculated independently for the plaster layer to determine the linkage, and the special case of "structural layer with horizontal section and plaster layer without horizontal section" is handled.Meanwhile, a gap compensation entity is automatically generated at the intersection of the stair segment and the platform based on the height difference ΔY.The application completely eliminates geometric collapse under limit parameters, ensuring that a correct topological three-dimensional model is generated under any input.

Description

Technical Field

[0001] This invention pertains to three-dimensional geometric modeling technology in the fields of computer-aided design (CAD) and building information modeling (BIM). Specifically, it relates to a method and system for automatically calculating critical truncation characteristic values ​​and realizing adaptive branch judgment of three-dimensional topology under the limit parameter constraints of the end extension plate (horizontal transition section) of the stair flight during parametric stair modeling. Background Technology

[0002] (I) Current Status of the Industry In real-world building construction, staircases on the same floor often feature stair flights of unequal length. The bottom and top of these flights typically require horizontal extensions (starting and ending extensions) to connect the landings on each floor. Most mainstream CAD / BIM tools do not offer automatic parametric modeling of these stair flight extensions, requiring users to manually process the model of such special staircases. This reduces modeling efficiency and is prone to errors.

[0003] (II) Existing technology defect 1: Geometric interference and collapse of staircase model under limiting parameters When designers use general-purpose modeling tools to reduce the length parameter of the stair extension slab below a certain critical value, interference occurs between the bottom surface of the straight section and the bottom surface of the sloping main stair section in space—the horizontal extension line of the straight section intersects the sloping line of the main stair section within the target length of the extension slab. At this point, existing software typically exhibits the following problems: Generating self-intersecting entities: The software still generates geometry according to the standard topology ("sloping surface + horizontal segment" double polyline), which causes the bottom contour lines to self-intersect, resulting in incorrect overlapping meshes; Errors and crashes: Some software's Boolean operation engine cannot handle self-intersecting inputs, directly throwing an exception or crashing; Silent errors: Some software does not report errors but generates visually incorrect models, which designers can only discover in the 2D cross-sectional view.

[0004] (iii) Existing technology defect 2: lack of topology adaptation capability of the model Existing modeling tools lack a "topology adaptation under limiting parameters" mechanism—that is, they cannot automatically determine whether the current extension plate length is sufficient to form a valid horizontal segment and intelligently switch between "polyline transition entities (double polylines)" and "diagonally truncated entities (single slopes)." Designers must manually determine critical conditions and adjust parameters; otherwise, the model will inevitably malfunction.

[0005] (iv) Existing technology defect three: Lack of linkage modeling judgment in multi-story structures of staircase models In actual engineering projects, staircases are composed of three layers: a concrete structural layer, a decorative surface layer, and a plaster leveling layer. When the extension slab is at its limit parameters, the thickness difference between the different layers causes the critical cutoff positions of each layer to be inconsistent—a special case may occur where "the structural layer has a horizontal section but the plaster layer does not." Existing tools, because they do not distinguish between layers, are simply unable to handle this multi-layer linkage judgment problem.

[0006] (v) Existing technical defect four: Lack of gap compensation at the junction of the stair section and the platform At the junction of the sloping staircase surface and the horizontal platform surface, a height difference ΔY inevitably occurs due to the difference in slope, forming a geometric gap (Z-fighting). Existing tools usually ignore this gap or require designers to manually repair it, and cannot automatically generate accurate compensation entities. Summary of the Invention

[0007] (a) The technical problem solved by the present invention: The present invention aims to overcome the shortcomings of the prior art and provide a method capable of: 1) Automatically calculate the critical cutoff characteristic value of the extended stair section, transforming architectural construction experience into mathematical branch judgment conditions; 2) Select the topology branch in real time based on the input parameters—adaptively switch between "oblique cut (single slope)" and "double polyline transition (slope + horizontal segment)" to ensure that the correct geometric contour is generated under any parameters; 3) Independent linkage judgment under multi-layer heterogeneous structure - Each layer (structural layer, surface layer, plaster layer) independently calculates its own critical characteristic value and judges the topological branch, and handles special sub-cases caused by the difference in thickness between layers; 4) Automatically detect and compensate for gaps at the junction of stair sections and platforms – automatically generate compensation geometry with a cross-section of ft × ΔY based on the height difference ΔY.

[0008] (II) Technical Solution - This invention achieves topology adaptive modeling of the extended slab of a building staircase through the following technical steps: Step S1: Obtain extension plate parameters and stair flight foundation parameters - Obtain the user-input multi-dimensional parameter set of the staircase, which includes at least the following parameters: 1) Basic dimensional parameters: - Step width run, step height rise, staircase width sw. 2). Structural layer parameters: - Ladder slab thickness h (concrete structural layer), surface layer thickness ft (decorative finish), plaster layer switch mark, plaster layer thickness. 3) Extension plate parameters: - The independent existence and length of the extension plates at both ends of each stair section. Step S2: Calculate the critical cutoff eigenvalues 1) Calculate the basic geometric characteristic values: - Slope of the staircase k = rise / run; Vertical projection thickness of the stair slab . 2). Derivation of the critical truncation characteristic value: - The intersection point of the bottom surface of the straight extended section and the inclined bottom surface of the main ladder section satisfies the following system of equations: - Equation for the inclined base: - Equation for a flat base: Solving the simultaneous equations for the X-coordinate offset of the intersection point yields the "critical truncation eigenvalue": The physical meaning of this characteristic value is: from the end of the last step of the staircase The distance along the horizontal direction to the intersection of the bottom surface of the straight extension section and the bottom surface of the inclined main stair section. When the length of the extension slab... At this time, it means that the end of the extension plate falls before the intersection point—the straight section cannot form a valid entity. Step S3: Topology Adaptive Branch Decision - Input the target length of the extension board from the user. With critical cutoff eigenvalues Perform real-time comparison: - Branch A (oblique truncation branch): If The system determines that the current parameters are in the extreme short range. It automatically switches the 3D solid topology to a sloping truncation boundary—locating a truncation plane on the extension line of the original sloping bottom surface, generating a single-sloping solid structure that extends directly along the slope and is truncated, removing the horizontal transition polylines. Specific control point calculation: Y coordinate of the end cutoff point: - Generate a sequence of control points for closed polygons with obliquely truncated contours. Branch B (standard polyline branch): If The system determines that there is sufficient length space. It generates a standard bi-linear topological boundary containing a flat bottom surface and an inclined transition surface, and locates the coordinates of the inflection points. Construct a polygonal envelope control surface formed by the intersection of the horizontal bottom surface and the main inclined surface. Step S4: Calculation and linkage judgment of independent critical values ​​of plaster layer When the structural layer adopts branch A (oblique cut-off), the plaster layer simultaneously adopts the oblique cut-off mode; when the structural layer adopts branch B (double-broken line), the plaster layer independently calculates its own critical cut-off characteristic value and determines whether a horizontal segment is formed based on this value. , in pt represents the vertical projection thickness of the plaster layer. A special sub-case may occur where "the structural layer has horizontal sections but the plaster layer does not" (i.e.) At this point, the plaster layer still adopts the cut-off mode to ensure the correct thickness relationship between the two layers. Step S5: Generate entity to compensate for gaps at the junction of stair section and platform (Principle: First, automatically detect the spatial height difference at the junction of the stair section surface and the platform surface; when the difference meets the threshold requirement, draw a closed polygon). S5a. Extract upper limit height: - Upper limit height of platform surface layer - Maximum height of the stepped surface layer at the junction . S5b. Solve for the height difference: S5c. Compensation Entity Generation: When When the value exceeds the preset tolerance threshold, an area with a cross-sectional dimension of [value missing] is automatically constructed in space, using the boundary point as a reference. The compensated boundary closed polygon. Step S6: Generate the final solid of the 3D components (generate the corresponding 3D component solids based on the contour data of each layer to obtain the complete staircase model.)

[0009] (III) Beneficial Effects: 1. Completely eliminate geometric collapse under limiting parameters. This is achieved through the critical truncation eigenvalue formula. The system can generate the correct geometric profile under any input parameters—without requiring manual intervention to determine whether the extension plate is too short. This is a capability that existing CAD / BIM tools completely lack. 2. Precise linkage judgment of multi-layered heterogeneous structures. Plaster layers are calculated independently. The mechanism ensures that the thickness relationship of the three-layer structure (concrete / surface layer / plaster) remains correct under limiting parameters. In particular, the special sub-case of "the structural layer has horizontal sections but the plaster layer does not" is simply beyond the capabilities of existing tools. 3. Automatic gap compensation eliminates Z-fighting. Based on The automatic generation mechanism of the compensation entity eliminates the geometric gaps at the junction of the stair section and the platform, eliminating the need for manual repair by the designer. (iv) Specific implementation methods The method described in this invention can be implemented in any CAD / BIM platform that supports parametric modeling through the following algorithmic flow: 1) After receiving the multi-dimensional parameter set of the staircase input by the user, first calculate the slope k of the stair flight and the vertical projection thickness of the stair slab. . 2) Based on the critical cutoff characteristic value Determine whether the length L of the extension plate is sufficient to form a horizontal segment: - like Select the obliquely truncated branch to generate a sequence of two-dimensional contour control points for a single-slope surface; - like Select the bilinear branch and locate the inflection point coordinates. Construct a closed polygon containing a flat bottom and an inclined transition surface. 3) When the structural layer uses a bi-linear branch, independently calculate the critical cutoff characteristic value of the plaster layer. And simultaneously determine its topological branch. If If the plaster layer still adopts the oblique cut-off mode, it will ensure the correct thickness relationship between the two layers. 4) Inspect the height difference at the junction of the staircase surface and the platform surface. When the preset tolerance threshold is exceeded, a cross-section is automatically generated. The compensation polygon. 5) Generate corresponding 3D component entities based on the contour data of each layer, and output a complete staircase model for all sub-components within the same layer. Figure 1 The bottom of the stair flight has no plaster layer and In this model, the upper structural layer of the stair section is directly connected to the extension plate; Figure 2 The bottom of the stair flight has no plaster layer and At that time, the upper structural layer of the stair section in the model was truncated; Figure 3 The bottom of the stair flight has a plaster layer and In the model, the upper structural layer of the stair section is directly connected to the extension plate structural layer, and the bottom plaster layer of the stair section is directly connected to the bottom plaster layer of the extension plate. Figure 4 The bottom of the stair flight has a plaster layer and In this case, the upper structural layer and the bottom plaster layer of the stair section in the model are directly cut off; Figure 5 The bottom of the stair flight has a plaster layer and At that time, the upper structural layer and the bottom plaster layer of the stair section in the model were directly cut off.

Claims

1. A topology adaptive modeling method and system for the extension slab of a building staircase, characterized in that... Includes the following steps: Step S1: Receive the user-input set of stair parameters and the length of the extension slab. The parameter set includes at least the step width, step height, and stair tread thickness; Step S2: Calculate the critical cutoff characteristic value based on the stair parameters. ,in The horizontal offset of the intersection point of the extended bottom surface of the stair section and the inclined bottom surface of the main stair section relative to the end of the stair section; Step S3: Extend the length of the plate The topological branch is selected based on the comparison result by comparing the critical truncation eigenvalue with the eigenvalue. - when When the current parameter is determined to be in the extreme short range, a staircase segment obliquely truncated boundary entity is generated—a single-sloping structure that extends directly along the slope and is truncated. - when If sufficient length space is available, a double-polyline boundary entity containing the bottom surface of the extended stair section plate and the inclined transition surface of the stair section is generated.

2. The method according to claim 1, characterized in that: The critical cutoff eigenvalue is calculated using the following formula: in The slope of the ladder segment ( Step height (step width) The vertical projection thickness of the ladder slab ( (To extend the plate thickness).

3. The method according to claim 1 or 2, characterized in that: When the staircase construction includes a plaster leveling layer, the critical cutoff characteristic value of the plaster layer should be calculated independently. ; When the structural layer adopts a double-polyline boundary entity (i.e. When this is done, the length of the extended plate will be further increased. and Compare: - like The plaster layer still adopts the oblique cut-off mode; - like The plaster layer still adopts the oblique cut-off mode.

4. The method according to claim 3, characterized in that: The critical cutoff characteristic value of the plaster layer is calculated using the following formula: , in This represents the vertical projection thickness of the plaster layer. This refers to the thickness of the plaster layer; when In some cases, a special sub-case occurs where "the structural layer has horizontal segments but the plaster layer does not." In this case, the plaster layer adopts a diagonal truncation mode while the structural layer adopts a double-broken-line boundary entity.

5. The method according to claim 1 or 2, characterized in that: The staircase construction is decomposed into three independently driven parameter sets: a concrete structural layer, a decorative surface layer, and a plastering leveling layer (on the bottom surface of the stair flight and the extension slab). Each layer calculates its own critical cutoff eigenvalue and independently determines the topological branch, but they share the same extension slab length. As a benchmark for comparison.

6. The method according to claim 1 or 2, characterized in that: For the extended slab at the bottom of the stair section, the same critical cutoff characteristic value calculation and branch judgment mechanism is used; whereby The horizontal coordinate is... The coordinates are vertical (with the top surface of the platform as the origin). Let be the length of the bottom extension plate; the equation of the inclined bottom surface of the bottom extension plate is: The equation of the flat bottom is: The corresponding critical truncation offset is: .

7. The method according to claim 1 or 2, characterized in that: When generating the surface layer entity, the spatial height difference at the junction of the stair section surface layer and the platform surface layer is automatically detected. ;when When the preset tolerance threshold is exceeded, a cross section is automatically generated at the junction. The compensation geometry (where (This refers to the surface layer thickness).

8. A topology adaptive modeling system for the extension slab of a building staircase, implementing the method as described in any one of claims 1-5, characterized in that... include: The parameter receiving module is used to receive the multi-dimensional parameter set of the staircase input by the user; The critical value calculation module is used to calculate the critical cutoff characteristic value based on the tread width, tread height, and slab thickness. ; The branch decision module is used to compare the length of the extension plate with the critical truncation feature value and select the topological branch. The geometry generation module is used to generate a sequence of corresponding 3D solid control points based on the selected topology branch. The compensation generation module is used to detect the height difference at the junction of the stair section and the platform and automatically generate compensation geometry.

9. The system according to claim 8, characterized in that: The critical value calculation module further includes an independent critical value calculation unit for the plaster layer, used to calculate... The branch judgment module further includes a plaster layer linkage judgment unit, which is used to handle the special sub-case of "the structural layer has horizontal segments but the plaster layer does not have horizontal segments".

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by the processor, it implements the method as described in any one of claims 1-7.

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