Implicit expression and rendering method and device of reinforcement model and storage medium

Abstract

The invention discloses a steel bar model implicit expression and rendering method and device and a storage medium, and belongs to the field of BIM. The method comprises the steps that an IFC file of a reinforcement model is analyzed, and global coordinate information and combination information of each single reinforcement in the reinforcement model are obtained according to relative coordinates and combination information between hierarchies; setting an object space coordinate system of the cubic grid as an implicit expression coordinate system of the reinforcement model; a ray equation is defined as follows: a scanning path of a single steel bar and the ray equation are combined, an intersection test of the ray and the single steel bar is executed in a shader, fragment coloring is changed according to an intersection result, and after pipeline mixing, a visualization result of implicit expression of a steel bar model is obtained; wherein the parameters are the starting point of the ray, the advancing direction of the ray and the parameters of the ray. The working efficiency of BIM software is improved, and the requirement of a user for visual expression of the steel bar model is met.

Description

Technical Field

[0001] This invention belongs to the field of BIM, and more specifically, relates to an implicit representation and rendering method, device and storage medium for a steel reinforcement model. Background Technology

[0002] In traditional BIM visualization, surface subdivision of pipelines is typically used to generate triangular meshes for parametric models. For example, the open-source BIM framework xBIM provides the GetGeometryData method to obtain the geometric information of components in the BIM. For reinforced concrete models, this process generates a large number of triangles to fit their cylindrical surface properties. Common methods include reducing the level of surface subdivision and using the Level of Depth (LOD) method to reduce the number of triangles in the scene.

[0003] Expressing rebar models explicitly using triangular meshes requires minimizing the number of triangles in the scene to achieve a reasonable frame rate. Current techniques, such as controlling the subdivision level, effectively reduce the number of triangles, but at the cost of significantly reduced visualization accuracy. Balancing accuracy and efficiency is a very difficult choice. The LOD method introduces several models with both high and low precision, further increasing the video memory overhead of the rendering scene and requiring developers to manually adjust appropriate model switching strategies. For example, when the number of rebars reaches 100,000, existing subdivision methods generate approximately 10 million triangles, consuming over 4GB of video memory and resulting in a rendering frame rate below 30fps. Using the LOD method requires storing 3-5 additional models with different precision levels, increasing video memory overhead by 40%, and visual distortions are prone to occur during model switching.

[0004] In existing technologies, implicit expressions are mostly used for free-form surface modeling (such as car shells), but have never been applied to BIM reinforcement models. This is because reinforcement models have the characteristics of large quantity, regular arrangement, and need to be linked with BIM parameters. Directly applying conventional implicit functions will lead to parameter incompatibility and low intersection efficiency. Summary of the Invention

[0005] In view of the shortcomings of related technologies, the purpose of this invention is to provide an implicit expression and rendering method, device and storage medium for steel reinforcement models, aiming to solve the problem of the adaptability of implicit expression in BIM steel reinforcement scenarios.

[0006] To achieve the above objectives, in a first aspect, the present invention provides an implicit representation and rendering method for a steel reinforcement model, comprising: Obtain and parse the IFC file of the rebar model to get the spatial coordinate system hierarchy corresponding to the rebar model; according to the combination information, the relative coordinates between the hierarchy are superimposed sequentially to obtain the global coordinates of each individual rebar in the rebar model; The object space coordinate system of the cube mesh is set as the implicit expression coordinate system of the steel reinforcement model. In this coordinate system, the global coordinates of a single steel reinforcement are represented as the spatial coordinates of the two endpoints of the cylinder. Based on the classification and combination information of the steel reinforcement model, the corresponding implicit expression equation is constructed within the space of the cube mesh. Specifically, in the steel reinforcement model, a single steel reinforcement uses the two endpoints of the cylinder as vectors, and the radius of the cylinder... As a scalar, it is implicitly expressed; the composite reinforcement is based on the single reinforcement and is implicitly expressed by combining the composite information; the radius parameter of the implicit expression corresponds to 1 / 2 of the diameter of the reinforcement in the reinforcement model, and the sweep path parameter corresponds to the axis trajectory of the reinforcement. Define the ray equation as The sweep path and ray equations of a single rebar are combined, and an intersection test between the ray and the single rebar is performed in the shader. This process is repeated for all single rebars in the rebar model. The intersection test results for each single rebar are used to determine whether an implicit primitive is hit. Multiple results are then combined to obtain a visualization of the implicit representation of the rebar model. The starting point of the ray. The direction in which the ray travels. These are the parameters of the ray.

[0007] Optionally, the spatial coordinate system hierarchy includes: a hierarchical division based on the building coordinate system, floor coordinate system, and entity coordinate system in sequence.

[0008] Optionally, the classification of the reinforcement model includes: The steel reinforcement model is divided into single steel bars and composite steel bars according to the number of individual steel bars in the model, and the composite steel bars are further classified into mesh steel bars and column steel bars.

[0009] Optionally, the implicit representation within the space of the cubic mesh further includes: Based on the implicit representation of a single steel bar in the steel bar model, and the combination information of single steel bars in the mesh steel bar and column steel bar, the mesh steel bar and column steel bar are implicitly represented.

[0010] Optionally, the sweep path is:

[0011] in, Let be the coordinates of the starting point of the cylinder's axis. The coordinates of the endpoint of the cylinder axis, parameters satisfy The effective range corresponding to the axis of the reinforcing bar.

[0012] Optionally, the intersection test includes: In the intersection test calculation of the composite reinforcement, a set of parallel reinforcement bars are extracted from the composite reinforcement as candidate reinforcement bars; the candidate reinforcement bars have the characteristics of equal length, equal spacing and perpendicular arrangement direction; The upper and lower boundaries of the candidate steel bars are obtained based on the intersection of the projection of the ray and the upper and lower offset planes; several target steel bars for which the intersection test needs to be performed are selected from the candidate steel bars based on the upper and lower boundaries; wherein, the upper and lower offset planes are two planes formed by offsetting the axis along the normal line by a distance of radius r of the cylinder; The intersection calculation is performed on all target reinforcing bars separately, replacing the intersection calculation of the combined reinforcing bars.

[0013] Secondly, the present invention also provides an implicit representation and rendering device for a steel reinforcement model, comprising: The parameter calculation module is used to acquire and parse the IFC file of the steel reinforcement model to obtain the spatial coordinate system level corresponding to the steel reinforcement model; and to obtain the global coordinates of each individual steel reinforcement in the steel reinforcement model by sequentially superimposing the relative coordinates between the levels according to the combination information. An implicit expression module is used to set the object space coordinate system of the cube mesh as the implicit expression coordinate system of the steel reinforcement model. In this coordinate system, the global coordinates of a single steel reinforcement are represented as the spatial coordinates of the two endpoints of the cylinder. Based on the classification and combination information of the steel reinforcement model, a corresponding implicit expression equation is constructed within the space of the cube mesh. Specifically, in the steel reinforcement model, a single steel reinforcement uses the two endpoints of the cylinder as vectors, and the radius of the cylinder... As a scalar, it is implicitly expressed; the composite reinforcement is based on the single reinforcement and is implicitly expressed by combining the composite information; the radius parameter of the implicit expression corresponds to 1 / 2 of the diameter of the reinforcement in the reinforcement model, and the sweep path parameter corresponds to the axis trajectory of the reinforcement. The rendering module is used to define the ray equation as follows: The sweep path and ray equations of a single rebar are combined, and an intersection test between the ray and the single rebar is performed in the shader. This process is repeated for all single rebars in the rebar model. The intersection test results for each single rebar are used to determine whether an implicit primitive is hit. Multiple results are then combined to obtain a visualization of the implicit representation of the rebar model. The starting point of the ray. The direction in which the ray travels. These are the parameters of the ray.

[0014] Thirdly, the present invention also provides a storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the implicit representation and rendering method of the steel reinforcement model as described in any one of the first aspects.

[0015] Compared with the prior art, the above-described technical solutions conceived in this invention can achieve the following beneficial effects: 1. This invention provides an implicit representation and rendering method for rebar models. Based on the modeling parameters of the rebar model, the parameters required for the implicit representation of a single rebar are designed, and the process of solving for the intersection of rays (light rays) and implicit surfaces is implemented in the fragment shader. During the intersection calculation, an analytical solution intersection formula is designed for the cylindrical characteristics of the rebar, avoiding the iterative calculations of conventional implicit intersection calculations and improving efficiency. This implicit representation method effectively utilizes the modeling parameters of the rebar, avoids the additional overhead of explicit representation, improves the representation efficiency of the rebar network model in the BIM software platform, reduces the number of triangles in the scene, and alleviates the memory bottleneck problem. This improves the working efficiency of BIM software and meets users' needs for the visual representation of rebar models.

[0016] 2. This invention provides an implicit representation and rendering method for rebar models. It incorporates rebar arrangement rules (such as parallel arrangement and quadrilateral stirrups) to design an accelerated strategy for candidate range filtering and encoding intersection, solving the intersection redundancy problem in scenarios with a large number of rebars, as well as the adaptability problem of implicit representation in BIM rebar scenarios. This can improve the efficiency of BIM software in scenarios such as teaching visualization, project progress visualization, and user design. Furthermore, this invention's implicit representation method for rebar models can also provide a new way of representing commonly used rebar models in engineering, offering new solutions in applications such as rebar recognition and rebar collision detection. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating an implicit representation and rendering method for a steel reinforcement model provided by the present invention. Figure 2 This is a schematic diagram illustrating the classification of reinforcing bars according to the present invention. The diagram shows that the reinforcing bars are divided into single reinforcing bars, mesh reinforcing bars, and columnar reinforcing bars. Figure 3 This is a schematic diagram illustrating how the parameters of columnar reinforcing bars function. Figure 4 This is a schematic diagram illustrating the accelerated intersection finding of a set of parallel reinforcing bars; Figure 5 This is a schematic diagram that categorizes and discusses the intersections of the quadrilaterals formed by columnar steel bars and light rays; Figure 6 This is the encoding table for the intersection results of quadrilaterals and rays in this invention, with a total of 16 intersection results in four-digit encoding; Figure 7 This is a schematic diagram illustrating the classification of intersections between the stirrups of a columnar steel bar and light rays; Figure 8 This invention provides a visualization result of the steel reinforcement structure of a building. Figure 9 This is the visualization result of the present invention on the reinforced concrete structure of a tunnel. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0019] The following description, in conjunction with a preferred embodiment, illustrates the content involved in the above embodiments.

[0020] Example 1 This invention provides an implicit representation and rendering method for a steel reinforcement model, comprising: Obtain and parse the IFC file of the rebar model to get the spatial coordinate system hierarchy corresponding to the rebar model; according to the combination information, the relative coordinates between the hierarchy are superimposed sequentially to obtain the global coordinates of each individual rebar in the rebar model; The spatial coordinate system of the cube mesh is set as the implicit coordinate system for the steel reinforcement model. In this coordinate system, the global coordinates of a single steel reinforcement are represented as the spatial coordinates of the two endpoints of the cylinder. Based on the classification and combination information of the steel reinforcement model, corresponding implicit expression equations are constructed within the space of the cube mesh. Specifically, in the steel reinforcement model, a single steel reinforcement uses the two endpoints of the cylinder as vectors, and the radius of the cylinder... As a scalar, it is implicitly expressed; the composite reinforcement is based on the single reinforcement and is implicitly expressed by combining the composite information; the radius parameter of the implicit expression corresponds to 1 / 2 of the diameter of the reinforcement in the reinforcement model, and the sweep path parameter corresponds to the axis trajectory of the reinforcement. Define the ray equation as The sweep path and ray equations of a single rebar are combined, and an intersection test between the ray and the single rebar is performed in the shader. This process is repeated for all single rebars in the rebar model. The intersection test results for each single rebar are used to determine whether an implicit primitive is hit. Multiple results are then combined to obtain a visualization of the implicit representation of the rebar model. The starting point of the ray. The direction in which the ray travels. These are the parameters of the ray.

[0021] The implicit representation and rendering method for steel reinforcement models provided by this invention realizes the parametric representation and corresponding visualization of steel reinforcement components in BIM software. This invention is applicable to BIM models with ≥10,000 steel reinforcement bars, such as large floor slabs, high-rise building columns, and bridge main structures. It is not applicable to scenarios such as non-cylindrical steel reinforcement bars (e.g., curved sweep paths) and irregularly arranged irregularly shaped steel reinforcement bars. These scenarios require additional intersection testing and are considered extended applications of this invention.

[0022] In the specific solution of this invention, implicit expression parameters for the cylinder are designed based on the modeling parameters of the rebar model, and the process of solving the intersection point of the ray and the implicit surface is implemented in the fragment shader. By combining the scheme of 'rebar type classification → parameter mapping → targeted acceleration algorithm', the adaptability problem of implicit expression in BIM rebar scenarios is solved.

[0023] In designing the implicit parameter representation, the parameters used during the modeling of the cylindrical rebar model are fully utilized for visualization. By transferring only parameters between the CPU and GPU instead of the explicit model, communication bandwidth is significantly reduced, improving rendering efficiency. During rendering, ray casting intersection is performed based on the implicit parameters. A specific intersection algorithm for cylindrical rebar models enables real-time rendering of the implicit rebar model. In this embodiment, with a scene containing 30,000 rebars, the number of triangles is reduced to below 10,000, memory usage is controlled within 1GB, the rendering frame rate remains above 60fps, and there are no model switching drop-off issues, greatly improving the rendering efficiency of large-scale cylindrical rebar models.

[0024] Specifically, it includes the following: (1) Obtain the parameters of the reinforcement model Parametric modeling of reinforcement includes: spatial coordinate system layering, reinforcement placement rules within concrete entities, and reinforcement instances.

[0025] By parsing the IFC file of the rebar model, the spatial coordinate system hierarchy corresponding to the rebar model is obtained. In the IFC standard, the spatial information of an entity is represented by relative coordinates, divided into levels such as architectural coordinate system, floor coordinate system, and entity coordinate system. Based on the relative coordinates (local coordinates) of each level, the global coordinates of the rebar model are obtained by sequentially superimposing them; each local coordinate is the coordinate of the current level relative to the previous level, representing the offset of each level.

[0026] Concrete is the solid that encloses reinforcing bars. The parameters input for bar placement act within the solid coordinate system, thus obtaining the global coordinates of a single reinforcing bar. Information about reinforcing bar instances is recorded in a reinforcing bar cluster library. During bar placement, the modeling software sets the instance ID of the current reinforcing bar and searches the cluster library to generate the corresponding reinforcing bar. This allows for the assignment of attributes with the same geometry to multiple reinforcing bar instances, thereby improving modeling efficiency. The coordinate system and bar placement rules provide precise spatial information about the reinforcing bars, and reinforcing bar instances can be matched with a preset reinforcing bar in the cluster library, allowing the type of reinforcing bar model to be defined. This invention classifies common reinforcing bar types in Building Information Modeling scenarios as follows, distinguishing between single reinforcing bars and composite reinforcing bars based on quantity. Figure 2 This demonstrates how categorized reinforcing bars are represented in a scene, along with their appearance. Different individual reinforcing bars are distinguished by different sweep paths, the most common being a straight line segment representing a single straight bar. Composite reinforcing bars are formed by combining a number of individual reinforcing bars in a specific way, defined by reinforcement rules. The most common type of composite reinforcing bar is mesh reinforcement, which defines two groups of mutually perpendicular reinforcing bars, each group arranged parallel to each other at a certain interval, commonly used in floor slab concrete. Columnar reinforcement arrangements in floor column concrete are also very common, defining several main bars and several stirrups bent into rectangles perpendicular to the main bars. Both of these common types of reinforcing bars can be automatically generated using the intervals and quantities specified in the reinforcement rules. Floor slabs and floor column concrete can constitute most of the reinforcing bars in a building, and this invention primarily uses these two types of composite reinforcing bars for representation and implementation.

[0027] Based on the properties of the rebar model, determine how the rebars are distributed within that model; retrieve the diameter, length, and material properties of the rebar instances from the rebar cluster library; classify the rebar model into single rebars and composite rebars according to the number of individual rebars in the model, and further categorize composite rebars into mesh rebars and column rebars. If it is a single rebar, its global coordinates can be directly obtained; if it is multiple rebars, the coordinates of each individual rebar need to be calculated based on the definition of the rebar placement rules in the properties; finally, obtain the coordinate information of one or more individual rebars, as well as the combination information (combination method).

[0028] (2) Implicit expression Implicit representations require a suitable medium to visualize these parameters. In this embodiment, a cubic mesh is used as the medium. On one hand, it serves as the object for data storage; on the other hand, in the rendering pipeline, it can obtain rays emanating from the viewpoint, perform intersection calculations between the rays and the implicit equations, and modify the rendering result on the cubic mesh based on the calculation results, thereby completing the visualization. This invention specifies the coordinate system of the implicit representation as the local coordinate system of the cubic mesh. Subsequent 3D spatial information will be defined in object space, while the intersection result will be output in world space coordinates.

[0029] To render implicitly represented data, rays can be emitted from the camera's position to intersect these implicit surfaces. In the rasterization pipeline, a planar mesh can be defined to generate sampling rays emanating from the camera. The observation results of the reinforcing bars have two distinct characteristics: one is observation from a perspective perpendicular to the cylinder's radial direction, where the radial specular highlight and sweep path are the primary observation results; the other is observation from a perspective parallel to the cylinder's radial direction, where the cylinder's cross-section circle and gradually decreasing radius are the observation results. Since reinforcing bars are usually arranged vertically, both observation results will occupy a certain proportion of the image from a single viewing angle. If sampling rays are generated using only a single plane, it is difficult to achieve a consistent and effective representation across different viewing angles, especially when the viewing angle is almost perpendicular to the plane's normal, significantly amplifying visual errors. Since reinforcing bars are usually encased within a cubic concrete frame, which is a natural bounding box, and the six faces of the cube provide omnidirectional input for the sampling rays, this invention chooses to generate and render the implicitly represented data within a cubic mesh.

[0030] Once the implicit representation carrier is available, the method for defining the implicit representation can be determined based on the carrier's properties. First, the carrier (cube mesh) will have scaling properties for its length, width, and height. These properties should not affect the implicit representation; otherwise, unexpected scaling will occur, leading to deviations in the results. This is because the size of the reinforcement should only be related to the sweep radius and the sweep line length. The cube mesh will also have translation and rotation properties, which can affect the implicit representation. That is, the translation and rotation of the cube will simultaneously affect the implicit representation. This allows for quick movement and rotation of implicit primitives defined within the cube mesh through manipulation.

[0031] Based on the classification of the reinforcement model, the required implicit expression equations are defined in the object space coordinate system of the cubic mesh.

[0032] The representation of a single reinforcing bar uses the two endpoints of the cylinder as vectors, along with the radius of the cylinder. As scalars, three variables are used to represent the parameters. The implicitly expressed radius parameter corresponds to half the diameter of the rebar in the BIM model, and the sweep path parameter corresponds to the axis trajectory of the rebar, ensuring consistency between the implicit expression and the BIM modeling parameters. The sweep path is defined as:

[0033] in, Let be the coordinates of the starting point of the cylinder's axis. The coordinates of the endpoint of the cylinder axis, parameters satisfy The effective range corresponding to the axis of the reinforcing bar.

[0034] Composite reinforcement is based on the implicit expression of single reinforcement bars, combined with composite information for implicit expression; mesh reinforcement defines two sets of mutually perpendicular and spaced... The reinforcing bars are arranged in parallel at certain intervals in each group.

[0035] In Revit, the most commonly used BIM software, users can automatically arrange rebar by configuring the spacing and quantity of rebar. To correspond with the settings in the modeling stage, this invention also defines the combined rebar based on these two user-configured parameters. Specifically, it uses distance (total length of rebar arrangement) and the number of segments (number of rebars) as scalar parameters to obtain the precise distribution interval and location during calculation. For mesh rebar, implicit parameters record the two-dimensional length and width, as well as the number of segments in these two directions. Columnar rebar, on the other hand, has three-dimensional length, width, and height, as well as the corresponding number of segments. The results of the parameter interaction are as follows: Figure 3 As shown. Figure 3 As shown, main reinforcement bars will be generated along the length and width sides of the quadrilateral in the length and width directions, respectively, while quadrilateral stirrups will be generated in the height direction on a plane perpendicular to the main reinforcement bars. Note that the radius of the stirrups is usually smaller than the radius of the main reinforcement bars, and a scalar is also required. To record this radius.

[0036] (3) The fragment shader performs an intersection test. This invention realizes the process of finding the intersection of a ray and a single steel bar in the shader through analytical solution. The analytical solution can be obtained by simultaneously solving the cylinder sweep path equation and the ray equation. The calculation needs to consider the root formula and boundary judgment.

[0037] The solution process can be carried out in the following way: The equation of a ray is defined as follows: ,in, The starting point of the ray. These are the directions in which the rays travel; they are all three-dimensional vectors. These are the parameters of the ray. Simultaneously, the axis of a single reinforcing bar is defined as... , Let be the coordinates of the starting point of the cylinder's axis. The coordinates of the endpoint of the cylinder axis, parameters satisfy It can be defined. For vectors This facilitates the next step of calculation. A point in computation space To the axis Distance:

[0038] Let this distance be equal to the radius of the cylinder. We can obtain:

[0039] Will Using ray equations After making the substitution, we get:

[0040] This is about parameters. The equation, when expanded on the left side, is as follows:

[0041]

[0042] Put the right side of the equation By merging the constant terms, we obtain the final result regarding... The quadratic equation:

[0043] Therefore, the coefficients of each term in the quadratic equation are as follows:

[0044]

[0045]

[0046] Using the quadratic formula Quickly discard rays that will not intersect with the side of the cylinder. Since the cylinder is truncated, the result in the axial direction also needs to be considered. Projection on:

[0047] The value needs to be Within the range of values, i.e. .

[0048] During the calculation process, first calculate the circle intersecting the cylinder. The value can be obtained by calculating the distance from the intersection point of the ray and the plane to the center of the circle, comparing it with the radius of the circle, and then discarding the result of hitting the back side based on the plane normal. Following the above process, the intersection points of the ray and the cylinder are calculated by simultaneously solving the equations, retaining the smallest value. value.

[0049] The intersection of individual steel bars in composite steel bars is based on the above calculation process. In the calculation process of intersection test of composite steel bars, this invention designs an algorithm that can exit quickly, thereby reducing the number of intersection tests for individual steel bars and improving test efficiency.

[0050] In the intersection test of composite reinforcement, the conventional method is to perform an intersection test on each reinforcement bar with the observation ray and retain the first hit along the emission direction of the observation ray (corresponding to the result with the smallest ray parameter). However, this results in a large number of invalid calculations. Specifically, in the intersection test calculation process of composite reinforcement, a group of parallel reinforcement bars are extracted from the composite reinforcement as candidate reinforcement bars. These candidate reinforcement bars have the characteristics of equal length, equal spacing, and perpendicular arrangement direction. The upper and lower boundaries of the candidate reinforcement bars are obtained based on the intersection points of the ray projection and the upper and lower offset planes. Based on the upper and lower boundaries, several target reinforcement bars are selected from the candidate reinforcement bars to perform intersection tests. Intersection calculations are performed on all target reinforcement bars separately, replacing the intersection calculation of the composite reinforcement. Here, the upper and lower offset planes are the two planes formed by offsetting the axis along the normal line by a distance of radius r of the cylinder.

[0051] To quickly perform intersection tests within a set of arrangements, it's necessary to minimize the number of times a single rebar is intersected with the observed ray. This means identifying a set of candidate rebars; if a rebar might be a match, it must be within the candidate set. Minimizing the number of candidate rebars improves efficiency. Since the arrangement is a continuous set of rebars, and the candidate rebars are also a continuous subset, defining the upper and lower boundaries of the arrangement determines the range of candidate rebars.

[0052] like Figure 4 As shown, the observation ray is projected onto a set of arranged forward directions. Along the direction perpendicular to the arrangement, the plane containing the axis of the arranged single cylindrical steel bar is offset vertically by the radius of the cylinder. By measuring the distance, we can obtain the incident and exit points of the observed ray in this projection direction. The positions of the incident and exit points can quickly define the upper and lower boundaries of the candidate reinforcement bars, thereby filtering out several target reinforcement bars. In the figure, Line 1 and Line 2 represent the projection of a certain observed ray in the arrangement direction, anchored by the incident and exit points on the projection. The plane containing the arranged axes is offset upwards. The upper boundary, Similarly; and This is the intersection of the projected light rays on the upper and lower planes; This refers to the index position of the reinforcing bars in the arrangement. Line1 is... The point of incidence is generated at the location Starting from the incident direction, its nearest index is ;exist The point of origin is generated. Along the opposite direction of the incident direction, its nearest index is Therefore, the upper and lower boundaries of Line1 can be determined as follows: and Along the incident direction, that is, from arrive The target steel bars are traversed in the direction of intersection, and the first intersection test result is the hit result, which is the final result.

[0053] Line 2 provides a more efficient elimination method, using the same upper and lower boundary determination method as Line 1, with its upper and lower boundaries being respectively... and When defining the ray along the incident direction, since the index of the upper boundary is less than that of the lower boundary, an empty interval is created. At this point, it can be quickly defined that the ray will not hit any cylindrical reinforcement bars, thus avoiding intersection with any bars. However, in the shader implementation, considering that there are some visible reinforcement bars between index values, the case of Line2 cannot be quickly discarded in these areas. To reduce the extensive use of if branches in the shader, this invention adopts a conservative method, namely, offsetting the upper and lower boundaries. The upper and lower boundaries of Line2 are each widened by one index, at which point the upper and lower boundaries become... and If the interval is valid, an intersection test will be performed on the two cylindrical steel bars.

[0054] The columnar reinforcement can be considered as four mesh reinforcements arranged on each of the four sides of a quadrilateral, retaining the smaller one among the eight results. We can directly perform intersection calculations using the values. However, this is costly, and when viewed along the direction perpendicular to the quadrilateral, any ray actually only passes through two sides of the quadrilateral. Therefore, reducing the number of times the quadrilateral's edges are traversed can reduce the computational cost by up to half, thus improving efficiency.

[0055] For example, by analyzing the quadrilateral stirrups in a columnar steel structure, after determining the candidate reinforcement bars where the required intersections of the stirrups are located, the arrangement of the main reinforcement bars required to intersect in length and width can also be determined. For example... Figure 5As shown, the observation ray is first projected onto a fixed plane parallel to the stirrup, specifically the XOZ plane used in this implementation. The Y direction represents the height of the column. Line 2 in the diagram represents the central axis of the stirrup, and the four sides represent four individual steel bars. Their endpoints are closed by a sphere to create a connected appearance, and their endpoints are adjacent and coincident. The four endpoints are defined as Index 0-3, and the four sides of the stirrup are defined as Side 0-3. Figure 5 As shown, Side is the index of the four sides of the quadrilateral, Index is the index of the endpoints of the quadrilateral, and their endnotes represent the positive and negative values. The positional relationship between the observation ray and the quadrilateral can be determined in constant time by determining the sign of the four endpoints on the line equation. Using the bottom left corner as the origin and right and top as positive directions, substituting the four endpoints into the line containing the projection of the observation ray yields four positive and negative results, indicated by endnotes in the endpoint labels. In practice, zero values ​​from the endpoints in the line equation can be ignored and included in the positive values, as strictly zero values ​​are almost nonexistent in shaders; the sign determination function provided in the shader code library can be used.

[0056] By encoding positive endpoints as 1 and negative endpoints as 0, the edges that need to be intersected can be obtained in constant time using a fixed encoding table. Figure 5 The observation ray represented by Line 1 on the left does not intersect the quadrilateral, and its four endpoints are 0101 from Index 3-0; Line 2 on the right intersects with Side 2 and Side 3, and its encoding result is 0100. Figure 6 The encoding table summarized in this invention is shown, which can efficiently obtain the intersection of a quadrilateral with its edges by encoding the results of the four endpoints.

[0057] The two sides represent the case where only the central axis of a single steel bar is considered. In reality, a steel bar cylinder has volume, and when the volume is taken into account, three sides will be used to find the intersection queue; otherwise, the result will be biased. Figure 7 This illustrates the case when considering the region of the cylinder's radius, where the endpoints are no longer defined by the cylinder's central axis, but rather by offsetting the endpoints from the cylinder's radius along their length and width directions. After determining the distance, the inner and outer endpoints are obtained, using the same definition order as the Index, and are respectively used... and .like Figure 7 As shown, Side is the side containing the axis of the stirrup cylinder. and After considering the radius of the stirrups, the three line segments represent different intersection scenarios for the four endpoints of the inner and outer quadrilaterals.

[0058] The observation rays are classified into three categories, represented by Line1, Line2, and Line3. Line2 represents the most likely observation scenario (considering the cylinder's length is much greater than its radius). Its characteristic is that the encoding results of the inner and outer endpoints are consistent. In this case, it can be determined that only the two sets of edges corresponding to the encoding results need to be entered into the intersection queue. The observation ray represented by Line1 is characterized by inconsistent encoding results of the inner and outer endpoints. In this case, the two sets of edges corresponding to the inner and outer endpoint encodings need to be merged, as they will always have an intersection. Therefore, three edges need to be intersected. For example, if the inner endpoint encoding result of Line1 is 0111, corresponding to edge 03, and the outer endpoint encoding result is 0011, corresponding to edge 02, their union is edge 023. The final result will also be generated from the arrangement of these three edges. Line3 is the most special. Its outer endpoints are encoded with results, while its inner endpoints correspond to the case where it does not intersect with the four edges. This only occurs when the observed ray almost overlaps with the rebar axis. Similarly, considering the reduction of if conditional branches in the shader, all four edges will be included in the intersection queue, instead of merging the two edges adjacent to the current edge (a total of three edges). The arrangement of the set of edges far from the current edge will also exit quickly due to a large number of cases where the root formula in a single rebar is less than 0.

[0059] After the intersection test is completed, the results of the intersection test for a single rebar determine whether an implicit primitive is matched. If an implicit primitive is matched, it is shading based on the normal and material. If no implicit primitive is matched, the primitive is discarded and made completely transparent. Each fragment will be rendered as transparent or opaque based on the test results. Transparent fragments will display fragments with greater depth, while opaque fragments will display the visible result of the rebar model. Each pixel will output the visual image of the rebar model through a transparency blending process based on the fragment shading results within the current pixel.

[0060] In one specific embodiment, the software platform used is Unity 2022.3.52f1c1, and the hardware platform is an Intel i7-11700KF CPU, 16GB of memory, and an Nvidia GeForce RTX 3060 GPU. Figure 8This paper demonstrates the visualization results of the steel reinforcement structure of a four-story building based on the present invention. Through the aforementioned implementation method, a mesh of steel reinforcement representing the floor slabs and columnar steel reinforcement representing the columns and beams were generated, resulting in a scene containing a total of 32,471 cylindrical steel bars. In the original explicit representation, based on a surface subdivision method that divides the cross-section of a cylinder into 16 segments and 64 triangles, the explicit representation in this embodiment has 2 million triangles, and the scene's single-frame rendering time is 0.91ms. In this implementation, a cubic mesh can contain 22-40 cylindrical steel bars, the specific number determined by parameters. In this case, the scene only requires 6,000 triangles to represent, and the appearance is consistent with the explicit representation, with no obvious flaws. The scene's single-frame rendering time is 2.43ms, meeting the requirements of real-time rendering.

[0061] Figure 9 The invention demonstrates the visualization results of reinforcing steel bars in tunnel engineering, constructed using several sets of parallel-arranged implicit reinforcing steel bar models. The scene contained 145,000 reinforcing steel bars; in this case, the explicit representation of a 16-segment cylinder required 9 million triangles to represent the scene, with a single-frame rendering time of 2.08ms. The implementation of this invention requires only 30,000 triangles to represent the scene, with a single-frame rendering time of 6.78ms.

[0062] In this embodiment of the invention, parameters required for the implicit representation of a single rebar are designed based on the modeling parameters of the rebar model. The process of finding the intersection points of rays (fibers) and implicit surfaces is implemented in the fragment shader. During the intersection process, an analytical solution for the intersection is designed to address the cylindrical characteristics of the rebar, avoiding the iterative calculations of conventional implicit intersection and improving efficiency. An acceleration strategy for candidate range filtering and encoding intersection is designed based on rebar arrangement rules (such as parallel arrangement and quadrilateral stirrups), solving the redundancy problem in intersection calculations for scenarios with a large number of rebars, as well as the adaptability problem of implicit representation in BIM rebar scenarios. This improves the representation efficiency of the rebar network model in the BIM software platform, reduces the number of triangles in the scene, and enhances the working efficiency of the BIM software, meeting users' needs for the visual representation of the rebar model.

[0063] Example 2 The present invention also provides an implicit representation and rendering device for a steel reinforcement model, comprising: The parameter calculation module is used to acquire and parse the IFC file of the steel reinforcement model to obtain the spatial coordinate system level corresponding to the steel reinforcement model; and to obtain the global coordinates of each individual steel reinforcement in the steel reinforcement model by sequentially superimposing the relative coordinates between the levels according to the combination information. An implicit expression module is used to set the object space coordinate system of the cube mesh as the implicit expression coordinate system of the steel reinforcement model. In this coordinate system, the global coordinates of a single steel reinforcement are represented as the spatial coordinates of the two endpoints of the cylinder. Based on the classification and combination information of the steel reinforcement model, a corresponding implicit expression equation is constructed within the space of the cube mesh. Specifically, in the steel reinforcement model, a single steel reinforcement uses the two endpoints of the cylinder as vectors, and the radius of the cylinder... As a scalar, it is implicitly expressed; the composite reinforcement is based on the single reinforcement and is implicitly expressed by combining the composite information; the radius parameter of the implicit expression corresponds to 1 / 2 of the diameter of the reinforcement in the reinforcement model, and the sweep path parameter corresponds to the axis trajectory of the reinforcement. The rendering module is used to define the ray equation as follows: The sweep path and ray equations of a single rebar are combined, and an intersection test between the ray and the single rebar is performed in the shader. This process is repeated for all single rebars in the rebar model. The intersection test results for each single rebar are used to determine whether an implicit primitive is hit. Multiple results are then combined to obtain a visualization of the implicit representation of the rebar model. The starting point of the ray. The direction in which the ray travels. These are the parameters of the ray.

[0064] The implicit expression and rendering device for a steel reinforcement model provided in this embodiment of the invention is used to execute the implicit expression and rendering method for a steel reinforcement model in Embodiment 1, and has the same beneficial effects.

[0065] Example 3 The present invention also provides a storage medium storing a computer program thereon, which, when executed by a processor, implements the implicit representation and rendering method of the steel reinforcement model as described in any one of Embodiment 1.

[0066] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An implicit representation and rendering method for a steel reinforcement model, characterized in that, include: Obtain and parse the IFC file of the reinforcement model to obtain the spatial coordinate system level corresponding to the reinforcement model; The global coordinates of each individual steel bar in the steel bar model are obtained by sequentially superimposing the relative coordinates between the layers based on the combination information. The object space coordinate system of the cube mesh is set as the implicit coordinate system of the steel reinforcement model; in this coordinate system, the global coordinates of a single steel reinforcement are represented as the spatial coordinates of the two endpoints of the cylinder; based on the classification and combination information of the steel reinforcement model, the corresponding implicit expression equation is constructed in the space of the cube mesh; wherein, in the steel reinforcement model, the two endpoints of the cylinder are used as vectors for a single steel reinforcement, and the radius of the cylinder is... As a scalar, it is implicitly expressed; the composite reinforcement is based on a single reinforcement bar and is implicitly expressed by combining the composite information; the radius parameter of the implicit expression corresponds to 1 / 2 of the diameter of the reinforcement bar in the reinforcement bar model, and the sweep path parameter corresponds to the axis trajectory of the reinforcement bar. Define the ray equation as The sweep path and ray equations of a single rebar are combined, and an intersection test between the ray and the single rebar is performed in the shader. This process is repeated for all single rebars in the rebar model. The intersection test results for each single rebar are used to determine whether an implicit primitive is hit. Multiple results are then combined to obtain a visualization of the implicit representation of the rebar model. The starting point of the ray. The direction in which the ray travels. These are the parameters of the ray.

2. The method as described in claim 1, characterized in that, The spatial coordinate system hierarchy includes: a hierarchical division based on the building coordinate system, floor coordinate system, and entity coordinate system in sequence.

3. The method as described in claim 1, characterized in that, The classification of the reinforcement models includes: The steel reinforcement model is divided into single steel bars and composite steel bars according to the number of individual steel bars in the model, and the composite steel bars are further classified into mesh steel bars and column steel bars.

4. The method as described in claim 3, characterized in that, The implicit representation within the space of the cubic mesh also includes: Based on the implicit representation of a single steel bar in the steel bar model, and the combination information of single steel bars in the mesh steel bar and column steel bar, the mesh steel bar and column steel bar are implicitly represented.

5. The method as described in claim 1, characterized in that, The sweep path is: in, Let be the coordinates of the starting point of the cylinder's axis. The coordinates of the endpoint of the cylinder axis, parameters satisfy The effective range corresponding to the axis of the reinforcing bar.

6. The method as described in claim 3, characterized in that, The intersection test includes: In the intersection test calculation of the composite reinforcement, a set of parallel reinforcement bars are extracted from the composite reinforcement as candidate reinforcement bars; the candidate reinforcement bars have the characteristics of equal length, equal spacing and perpendicular arrangement direction; The upper and lower boundaries of the candidate steel bars are obtained based on the intersection of the projection of the ray and the upper and lower offset planes; several target steel bars for which the intersection test needs to be performed are selected from the candidate steel bars based on the upper and lower boundaries; wherein, the upper and lower offset planes are two planes formed by offsetting the axis along the normal line by a distance of radius r of the cylinder; The intersection calculation is performed on all target reinforcing bars separately, replacing the intersection calculation of the combined reinforcing bars.

7. An implicit representation and rendering device for a steel reinforcement model, characterized in that, include: The parameter calculation module is used to acquire and parse the IFC file of the reinforcement model to obtain the spatial coordinate system level corresponding to the reinforcement model; The global coordinates of each individual steel bar in the steel bar model are obtained by sequentially superimposing the relative coordinates between the layers based on the combination information. An implicit expression module is used to set the object space coordinate system of the cube mesh as the implicit expression coordinate system of the steel reinforcement model. In this coordinate system, the global coordinates of a single steel reinforcement are represented as the spatial coordinates of the two endpoints of the cylinder. Based on the classification and combination information of the steel reinforcement model, a corresponding implicit expression equation is constructed within the space of the cube mesh. Specifically, in the steel reinforcement model, a single steel reinforcement uses the two endpoints of the cylinder as vectors, and the radius of the cylinder... As a scalar, it is implicitly expressed; the composite reinforcement is based on a single reinforcement bar and is implicitly expressed by combining the composite information; the radius parameter of the implicit expression corresponds to 1 / 2 of the diameter of the reinforcement bar in the reinforcement bar model, and the sweep path parameter corresponds to the axis trajectory of the reinforcement bar. The rendering module is used to define the ray equation as follows: The sweep path and ray equations of a single rebar are combined, and an intersection test between the ray and the single rebar is performed in the shader. This process is repeated for all single rebars in the rebar model. The intersection test results for each single rebar are used to determine whether an implicit primitive is hit. Multiple results are then combined to obtain a visualization of the implicit representation of the rebar model. The starting point of the ray. The direction in which the ray travels. These are the parameters of the ray.

8. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the implicit representation and rendering method of the steel reinforcement model as described in any one of claims 1 to 6.

Images