Middle plane extraction method and device for three-dimensional model of extraction part, equipment and medium

Abstract

The invention relates to the field of computer-aided engineering. The method comprises the following steps: firstly, identifying a cross section of a three-dimensional model of an extraction piece; secondly, grouping all edges in the cross section of the three-dimensional model of the extracted part according to a parallel or approximately parallel standard of the edges, so as to obtain a plurality of paired edge groups corresponding to all the edges in the cross section of the three-dimensional model of the extracted part; searching a matching surface of each edge in the plurality of matching edge groups; and finally, based on the plurality of pairing edge groups and the pairing surface of each edge in the plurality of pairing edge groups, obtaining the middle surface of the three-dimensional model of the extraction piece. According to the method, the edges in the cross section of the three-dimensional model of the extraction piece are grouped based on parallelism, and the non-manifold structure of the three-dimensional model of the extraction piece can be systematically analyzed and reconstructed, so that the non-manifold structure becomes a manifold structure which is easier to process. According to the process, the mid-plane quality of the three-dimensional model of the extraction piece is improved, and the accuracy and reliability of product design and simulation based on the mid-planes are further improved.

Description

Technical Field

[0001] This application relates to the field of computer-aided engineering, and in particular, to a method, device, equipment, and medium for extracting the mid-surface of a three-dimensional model of an extractive part. Background Art

[0002] In the field of modern engineering design and manufacturing, especially for thin-walled structures or shell structures with complex shapes (such as automobile bodies, aircraft fuselages, etc.), accurately generating the geometric mid-surface of an extractive part based on the three-dimensional model of the extractive part is crucial for computer-aided engineering (CAE) simulation analysis. These geometric mid-surfaces are idealized two-dimensional surfaces extracted from the original three-dimensional model of the extractive part, located inside the solid and equidistant from the two side surfaces, used to simplify complex three-dimensional models, reduce the amount of calculation and improve the simulation efficiency, while maintaining the necessary accuracy.

[0003] However, the inventors found that in practical engineering applications, the three-dimensional model of an extractive part in a complex engineering structure often contains non-manifold structures, that is, there are topological anomalies, such as multiple faces sharing an edge or a vertex connecting too many faces. These non-manifold structures will lead to poor quality of the generated mid-surface, and further affect the accuracy and reliability of product design and simulation based on these mid-surfaces. Therefore, solving the non-manifold problem to ensure high-quality mid-surface generation is crucial for improving the effectiveness of CAE simulation analysis and the performance of the final product. Summary of the Invention

[0004] This application provides a method, device, equipment, and medium for extracting the mid-surface of a three-dimensional model of an extractive part to solve the problem that the non-manifold structure in the three-dimensional model of the extractive part leads to poor quality of the generated mid-surface.

[0005] The first aspect of this application provides a method for extracting the mid-surface of a three-dimensional model of an extractive part, the method comprising:

[0006] Obtain the faces of the three-dimensional model of the extractive part, and identify the cross-sections of the three-dimensional model of the extractive part based on the concavity and convexity of the faces;

[0007] Group the edges of the cross-section according to the parallel or approximately parallel criterion of the edges to obtain a plurality of paired edge groups, wherein the approximately parallel criterion of the edges indicates that when the included angle formed by two edges is less than the first preset angle threshold, the two edges are determined to be approximately parallel;

[0008] Find the paired faces of each edge in the plurality of paired edge groups;

[0009] Obtain the mid-surface of the three-dimensional model of the extractive part based on the plurality of paired edge groups and the paired faces of each edge in the plurality of paired edge groups.

[0010] In some embodiments of the present application, the three-dimensional model of the extraction part includes multiple faces, and the steps of identifying the cross-section of the three-dimensional model of the extraction part based on the concavity and convexity of the faces include:

[0011] Find all the faces adjacent to each face in the three-dimensional model of the extraction part, and call all the faces adjacent to each face the adjacent faces of that face. Among them, there is a common edge between each face and its adjacent faces;

[0012] Identify all the thickness faces based on the concavity and convexity of all the common edges;

[0013] Use the inner ring feature to find all the thickness faces containing inner rings, and take all the thickness faces containing inner rings as the cross-section of the three-dimensional model of the extraction part.

[0014] In some embodiments of the present application, the steps of identifying all the thickness faces based on the concavity and convexity of all the common edges include:

[0015] Take each face in the three-dimensional model of the extraction part as the target face, calculate the angle between the target face and each of its adjacent faces at the common edge, and when the angle is greater than the first preset angle threshold, determine that the common edge between the target face and each adjacent face is a convex edge;

[0016] Check whether there are two parallel or approximately parallel adjacent faces among the adjacent faces corresponding to all the convex edges. If so, determine that the target face is a convex face. Among them, the two parallel or approximately parallel adjacent faces of the target face cannot be directly connected. When the angle formed by two adjacent faces is less than the second preset angle threshold, it is determined that the two adjacent faces are approximately parallel;

[0017] When the target face is determined to be a convex face, calculate the distance between the two adjacent faces, and when the lengths of the two common edges between the target face and the two adjacent faces are both greater than the distance between the two adjacent faces, determine the target face as a thickness face.

[0018] In some embodiments of the present application, the steps of grouping the edges of the cross-section to obtain multiple paired edge groups include:

[0019] Form a parallel edge group with the parallel or approximately parallel edges in the cross-section, and obtain multiple parallel edge groups based on all the edges of the cross-section;

[0020] Take the longest edge in each parallel edge group as the main edge and the other edges as the secondary edges;

[0021] Project each secondary edge in each parallel edge group onto the main edge, and calculate whether the projection line of each secondary edge on the main edge intersects with other secondary edges. Among them, when the projection line of the secondary edge does not intersect with other secondary edges, form a paired edge with the main edge for this secondary edge;

[0022] Form a paired edge group from all paired edges in each group of parallel edges, and obtain multiple paired edge groups corresponding to all edges in the cross-section of the three-dimensional model of the extraction part based on multiple groups of parallel edges.

[0023] In some embodiments of the present application, the step of finding the mating surface of each edge in multiple paired edge groups includes:

[0024] According to the preset geometric property method, find the circular arc edges in multiple paired edge groups, and find the fillet surface corresponding to each circular arc edge in multiple paired edge groups along the preset extraction direction of the extraction part;

[0025] Find the mating surface of each edge in multiple paired edge groups without circular arc edges;

[0026] According to the positional relationship between each fillet surface and other fillet surfaces in the three-dimensional model of the extraction part, obtain the mating surface of each fillet surface and use it as the mating surface of the corresponding circular arc edge in multiple paired edge groups.

[0027] In some embodiments of the present application, the step of obtaining the mid-surface of the three-dimensional model of the extraction part based on multiple paired edge groups and the mating surface of each edge in multiple paired edge groups includes:

[0028] Calculate the midline of each paired edge group;

[0029] Find the sweep line of each paired edge group, where the sweep line connects the mating surfaces of each edge in each paired edge group into a straight line;

[0030] Sweep the sweep line of each paired edge group with the midline of each paired edge group as the baseline to obtain the mid-surface of each paired edge group;

[0031] Classify the mid-surfaces of each paired edge group based on the mating surface of each edge in each paired edge group, and splice all the mid-surfaces into the mid-surface of the three-dimensional model of the extraction part based on the classification results.

[0032] In some embodiments of the present application, taking the mating surface corresponding to the main edge in each paired edge group as the top surface, the mating surface corresponding to the secondary edge as the bottom surface, and the step of classifying the mid-surface of each paired edge group includes:

[0033] Take the mating surfaces of all edges in each paired edge group as a group of mating surfaces, and according to the first preset determination method, obtain the connection relationship between each top surface in each group of mating surfaces and each top surface and each bottom surface in other groups of mating surfaces;

[0034] According to the second preset determination method, obtain the connection relationship between each bottom surface in each group of mating surfaces and each top surface and each bottom surface in other groups of mating surfaces;

[0035] Based on the connection relationships between each top surface in each pair of mating surfaces and each top surface and each bottom surface in each other pair of mating surfaces, and the connection relationships between each bottom surface in each pair of mating surfaces and each top surface and each bottom surface in each other pair of mating surfaces, obtain the connection relationships between each surface in each pair of mating surfaces and each surface in other pairs of mating surfaces;

[0036] Based on the connection relationships between each surface in each pair of mating surfaces and each surface in other pairs of mating surfaces, determine whether there is a T-shaped connection relationship or an L-shaped connection relationship between every two pairs of mating surfaces;

[0037] Stitch the middle surfaces of each pair of edges corresponding to all pairs of mating surfaces with T-shaped connection relationships and L-shaped connection relationships into the middle surface of the three-dimensional model of the extraction part.

[0038] The second aspect of the present application provides a middle surface extraction device for a three-dimensional model of an extraction part. The device includes:

[0039] A cross-section recognition module, configured to obtain the surfaces of the three-dimensional model of the extraction part, and recognize the cross-section of the three-dimensional model of the extraction part based on the concavity and convexity of the surfaces;

[0040] An edge grouping module, configured to group the edges of the cross-section according to the parallel or approximately parallel criterion of the edges to obtain a plurality of pairs of edges, where the approximately parallel criterion of the edges indicates that when the included angle formed by two edges is less than the first preset angle threshold, it is determined that the two edges are approximately parallel;

[0041] A mating surface search module, configured to search for the mating surfaces of each edge in a plurality of pairs of edges;

[0042] A middle surface generation module, configured to obtain the middle surface of the three-dimensional model of the extraction part based on a plurality of pairs of edges and the mating surfaces of each edge in the plurality of pairs of edges.

[0043] The third aspect of the present application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method described in any one of the first aspects in the above embodiments are implemented.

[0044] The fourth aspect of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps of the method described in any one of claims 1-7 are implemented.

[0045] The present application has the following beneficial effects:

[0046] This application first identifies the cross-section of the three-dimensional model of the extraction part; secondly, according to the parallel or approximately parallel standard of the edges, all the edges in the cross-section of the three-dimensional model of the extraction part are grouped to obtain multiple paired edge groups corresponding to all the edges in the cross-section of the three-dimensional model of the extraction part; then, the mating faces of each edge in the multiple paired edge groups are searched; finally, based on the multiple paired edge groups and the mating faces of each edge in the multiple paired edge groups, the mid-plane of the three-dimensional model of the extraction part is obtained. By grouping the edges in the cross-section of the three-dimensional model of the extraction part based on parallelism, this application can systematically analyze and reconstruct the non-manifold structure of the three-dimensional model of the extraction part, making it into a more easily processed manifold structure. This process not only improves the quality of the mid-plane of the three-dimensional model of the extraction part, but also further improves the accuracy and reliability of product design and simulation based on these mid-planes. Description of the Drawings

[0047] The drawings herein are incorporated into the specification and form a part of this specification. These drawings illustrate embodiments consistent with this application and, together with the specification, are used to explain the technical solutions of this application.

[0048] Figure 1 It is an exemplary schematic diagram of a convex surface provided by this application;

[0049] Figure 2 It is an exemplary schematic diagram of a convex edge provided by this application;

[0050] Figure 3 It is an exemplary schematic diagram of a thickness plane provided by this application;

[0051] Figure 4 It is a schematic flowchart of an embodiment of the method for extracting the mid-plane of the three-dimensional model of the extraction part provided by this application;

[0052] Figure 5 It is a schematic flowchart of an embodiment of the method for identifying the cross-section of the three-dimensional model of the extraction part based on the concavity and convexity of the surface provided by this application;

[0053] Figure 6 It is an exemplary schematic diagram of a thickness plane including an inner ring provided by this application;

[0054] Figure 7 It is a schematic flowchart of an embodiment of the method for identifying all thickness planes based on the concavity and convexity of all common edges provided by this application;

[0055] Figure 8 It is a schematic flowchart of an embodiment of the method for obtaining multiple paired edge groups corresponding to all the edges in the cross-section of the three-dimensional model of the extraction part provided by this application;

[0056] Figure 9 It is an exemplary schematic diagram of a main edge and multiple secondary edges parallel to it provided by this application;

[0057] Figure 10 It is an exemplary schematic diagram of multiple secondary edges provided by this application projecting onto a main edge respectively;

[0058] Figure 11 It is an exemplary schematic diagram of multiple paired edge groups provided by this application;

[0059] Figure 12 It is a schematic flowchart of an embodiment of a method for removing edge matching redundancy from multiple paired edge groups provided by this application;

[0060] Figure 13 It is an exemplary schematic diagram of a method for removing edge matching redundancy from multiple paired edge groups provided by this application;

[0061] Figure 14 It is a schematic flowchart of an embodiment of a method for obtaining the mating surface of each edge in multiple paired edge groups provided by this application;

[0062] Figure 15 It is an exemplary schematic diagram of the process of finding the mating surface of a pair of parallel edges provided by this application;

[0063] Figure 16 It is a flowchart of another embodiment of a method for obtaining the mid - surface of the three - dimensional model of the extracted part provided by this application;

[0064] Figure 17 It is an exemplary schematic diagram of sweeping the sweep lines of each paired edge group provided by this application;

[0065] Figure 18 It is an exemplary schematic diagram of the existence of cutting positions in the three - dimensional model of the extracted part provided by this application;

[0066] Figure 19 It is a schematic flowchart of an embodiment of a method for classifying the mid - surfaces of each paired edge group provided by this application;

[0067] Figure 20 It is an exemplary schematic diagram of the T - type connection relationship of surfaces provided by this application;

[0068] Figure 21 It is an exemplary schematic diagram of the L - type connection relationship of surfaces provided by this application;

[0069] Figure 22 It is a schematic framework diagram of an embodiment of a mid - surface extraction device for the three - dimensional model of the extracted part provided by this application;

[0070] Figure 23 It is a schematic framework diagram of an embodiment of an electronic device provided by this application;

[0071] Figure 24 It is a schematic framework diagram of an embodiment of a computer - readable storage medium provided by this application. Detailed Implementation Modes

[0072] The following will combine with the accompanying drawings of the specification to elaborate on the solutions of the embodiments of the present application in detail.

[0073] In the following description, specific details such as specific system structures, interfaces, and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the present application.

[0074] The term "and / or" in this article is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after. In addition, "multiple" in this article means two or more than two. In addition, the term "at least one" in this article represents any one of multiple types or any combination of at least two of multiple types. For example, including at least one of A, B, and C can represent including any one or more elements selected from the set composed of A, B, and C.

[0075] As described in the background art, the inventor found that in actual engineering applications, the three-dimensional model of the extractable part in complex engineering structures often contains non-manifold structures, that is, there are topological anomalies, such as multiple faces sharing an edge or a vertex connecting too many faces, etc. These non-manifold structures will result in poor quality of the generated mid-surfaces, and further affect the accuracy and reliability of product design and simulation based on these mid-surfaces.

[0076] To solve the above problems, the present application proposes a mid-surface extraction scheme for the three-dimensional model of the extractable part. In the solution of the present application, by grouping the edges in the cross-section of the three-dimensional model of the extractable part based on parallelism, the non-manifold structure of the three-dimensional model of the extractable part can be systematically analyzed and reconstructed to make it a more easily processable manifold structure. This process not only improves the quality of the mid-surfaces of the three-dimensional model of the extractable part, but also further improves the accuracy and reliability of product design and simulation based on these mid-surfaces.

[0077] To more clearly understand the technical solution of the present application, before introducing the specific embodiments of the present application, the related concepts involved in the present application will be introduced first.

[0078] An extractable part refers to a part that needs to be extracted or demolded from a mold. Among them, the extractable part has the following common geometric features: (1) The cross-section is consistent, there are inner rings on the cross-section, the normal direction is parallel to the extraction direction and the transition is sharp; (2) There is a non-manifold structure in the three-dimensional model of the extractable part; (3) There is a fillet transition on the edges of the cross-section of the extractable part; (4) There are cutting features in the direction perpendicular to the extraction direction, etc.

[0079] The mid - surface refers to an idealized two - dimensional or quasi - two - dimensional surface located inside a solid object, and the distances from this surface to all points on the solid boundary are equal. The mid - surface is very important for understanding the geometric characteristics of the extracted part and has wide applications in fields such as finite element analysis (FEA), computational fluid dynamics (CFD), rapid prototyping, etc.

[0080] The convex surface refers to a situation where there is an adjacent surface between two parallel or approximately parallel surfaces, and both connecting edges between the adjacent surface and the parallel surfaces are convex edges, then this surface is called a convex surface. For example, as Figure 1 shown, where surface ① and surface ② are two parallel surfaces, surface ③ is the adjacent surface of surface ① and surface ②, and when both of the two common edges between surface ③ and surface ① and surface ② are convex edges, surface ③ is a convex surface.

[0081] The convex edge refers to calculating the angle at the common edge of two adjacent surfaces. If the angle is greater than PI, it is called a convex edge, otherwise it is a concave edge. For example, as Figure 2 shown, where calculating the angle at the common edge between surface ③ and surface ①, if this angle is greater than PI, then this common edge is a convex edge.

[0082] The thickness surface refers to two parallel adjacent surfaces of a surface, the distance in the direction perpendicular to the surface is less than the distance in the longitudinal direction of the surface, and it is the adjacent convex surface of two parallel or approximately parallel surfaces, then this surface is called a thickness surface. For example, as Figure 3 shown, the two parallel adjacent surfaces of surface ① are surface ③ and another surface parallel to surface ③ and adjacent to surface ①. Calculate the distance in the direction perpendicular to surface ① and the longitudinal distance between surface ③ and another surface parallel to surface ③ and adjacent to surface ①. If the perpendicular distance is less than the longitudinal distance along the surface, and surface ① is a convex surface, then surface ① is a thickness surface. Similarly, according to the above definition of the thickness surface, surface ② is also a thickness surface.

[0083] The following will detail this application in combination with the attached drawings and specific embodiments.

[0084] According to an embodiment of the present application, the present application provides a method for extracting the mid - surface of a three - dimensional model of an extracted part. As Figure 4 shown, this method includes: S1. Obtain the surfaces of the three - dimensional model of the extracted part, and identify the cross - section of the three - dimensional model of the extracted part based on the convexity and concavity of the surfaces; S2. Group the edges of the cross - section of the three - dimensional model of the extracted part according to the parallel or approximately parallel standard of the edges, so as to obtain multiple paired - edge groups corresponding to all the edges in the cross - section of the three - dimensional model of the extracted part, where the approximately parallel standard of the edges indicates that when the included angle formed by two edges is less than the first preset angle threshold, it is determined that the two edges are approximately parallel; S3. Find the paired surfaces of each edge in the multiple paired - edge groups; S4. Based on the multiple paired - edge groups and the paired surfaces of each edge in the multiple paired - edge groups, obtain the mid - surface of the three - dimensional model of the extracted part. The solutions of steps S1 - S4 will be elaborated below.

[0085] I. Step S1

[0086] In step S1, obtain the faces of the three - dimensional model of the extraction part, and identify the cross - section of the three - dimensional model of the extraction part based on the concavity and convexity of the faces.

[0087] Among them, according to an embodiment of the present application, the three - dimensional model of the extraction part includes multiple faces. As Figure 5 shown, step S1 of identifying the cross - section of the three - dimensional model of the extraction part based on the concavity and convexity of the faces in the above - mentioned embodiment of the present application includes: S11. Find all the faces adjacent to each face in the three - dimensional model of the extraction part, and call all the faces adjacent to each face the adjacent faces of this face. Among them, there is a common edge between each face and its adjacent faces; S12. Identify all the thickness faces based on the concavity and convexity of all the common edges; S13. Use the inner - ring feature to find all the thickness faces containing inner rings, and take all the thickness faces containing inner rings as the cross - section of the three - dimensional model of the extraction part.

[0088] For example, as Figure 6 shown, it can be seen from Figure 6 that the black arrow is a thickness face containing an inner ring.

[0089] As can be seen from the above description, in the above - mentioned embodiment of the present application, by finding the thickness face with an inner ring in the three - dimensional model of the extraction part as the cross - section, the finally obtained cross - section can accurately reflect the internal structure and thickness distribution of the three - dimensional model of the extraction part, avoiding information loss that may be caused by only relying on the external contour, ensuring that every important geometric detail is considered in the mid - surface extraction process of the three - dimensional model of the extraction part, thereby improving the quality of the mid - surface of the extracted three - dimensional model of the extraction part; at the same time, by identifying the cross - section of the three - dimensional model of the extraction part, the extraction of the mid - surface is simplified to two - dimensional, reducing the identification difficulty and improving the identification efficiency.

[0090] Among them, according to an embodiment of the present application, as Figure 7 shown, step S12 of identifying all the thickness faces based on the concavity and convexity of all the common edges in the above - mentioned embodiment of the present application includes: S121. Take each face in the three - dimensional model of the extraction part as the target face, calculate the angle between the target face and each adjacent face at the common edge, and when the angle is greater than the first preset angle threshold, determine that the common edge between the target face and each adjacent face is a convex edge; S122. Check whether there are two parallel or approximately parallel adjacent faces among the adjacent faces corresponding to all the convex edges. If so, determine that the target face is a convex face. Among them, the two parallel or approximately parallel adjacent faces of the target face cannot be directly connected. When the angle formed by two adjacent faces is less than the second preset angle threshold, it is determined that the two adjacent faces are approximately parallel; S123. When the target face is determined to be a convex face, calculate the distance between the two adjacent faces, and when the lengths of the two common edges between the target face and the two adjacent faces are both greater than the distance between the two adjacent faces, determine the target face as a thickness face.

[0091] As can be seen from the above description, in the above embodiments of the present application, by judging the concavity and convexity of each surface in the three-dimensional model of the extraction part, all convex surfaces in the three-dimensional model of the extraction part are screened out, and the true thickness surface of the three-dimensional model of the extraction part is found based on all convex surfaces to facilitate the extraction of the middle surface. This can avoid the complexity and discontinuity brought by concave surfaces, ensure that the middle surface is smoother and more continuous, thereby improving the quality of the middle surface extraction, making the subsequent design, analysis, or manufacturing process based on the middle surface more accurate and efficient. At the same time, by selecting two non-directly connected adjacent surfaces that are parallel or approximately parallel to judge whether the target surface is convex, the true geometric features can be effectively identified, rather than just local changes on the model surface, which can avoid misjudgment caused by the edges or sharp corners of the three-dimensional model of the extraction part, ensure that the concavity and convexity judgment is more accurate, thereby improving the accuracy and reliability of subsequent processing such as middle surface extraction, and ensuring the quality of the analysis results.

[0092] II. Step S2

[0093] In step S2, according to the parallel or approximately parallel standard of the edges, the edges of the cross-section are grouped to obtain a plurality of paired edge groups. Among them, the approximately parallel standard of the edges indicates that when the included angle formed by two edges is less than the first preset angle threshold, the two edges are determined to be approximately parallel.

[0094] The inventor has found through research that after finding the cross-section of the three-dimensional model of the extraction part in step S1, based on the characteristic that the cross-section of the extraction part is consistent in the extraction direction, the paired information of the surfaces can be equivalently identified only by using the paired information of the edges on the cross-section of the three-dimensional model of the extraction part, that is, the edges on the cross-section of two paired surfaces are also paired edges, and the distance between these two paired edges is the closest in the projection direction.

[0095] Therefore, according to an embodiment of the present application, as Figure 8 shown, step S2 of grouping the edges of the cross-section to obtain a plurality of paired edge groups in the above embodiments of the present application includes: S21, forming a parallel edge group from the edges that are parallel or approximately parallel in the cross-section, and obtaining a plurality of parallel edge groups based on all the edges of the cross-section; S22, taking the longest edge in each parallel edge group as the main edge and the other edges as the secondary edges; S23, projecting each secondary edge in each parallel edge group onto the main edge, and calculating whether the projection line of each secondary edge on the main edge intersects with other secondary edges. Among them, when the projection line of the secondary edge does not intersect with other secondary edges, the secondary edge and the main edge form a paired edge; S24, forming a paired edge group from all the paired edges in each parallel edge group, and obtaining a plurality of paired edge groups corresponding to all the edges in the cross-section of the three-dimensional model of the extraction part based on the plurality of parallel edge groups.

[0096] Among them, in order to better understand the concepts of the main edge, secondary edge, projection of the secondary edge onto the main edge, and paired edge group, in combination with Figure 9 、 Figure 10 andFigure 11 is described as follows. For example, Figure 9 as shown, it shows a schematic diagram of a main edge and multiple secondary edges parallel to it; for example, Figure 10 as shown, it shows a schematic diagram of multiple secondary edges projecting onto a main edge respectively; for example, Figure 11 as shown, it shows a schematic diagram of multiple paired edge groups. It can be seen from the figure that it shows the edge pairing situation of 9 paired edge groups.

[0097] As can be known from the above description, in the above embodiments of the present application, by the direction and distance of the edges, the non-manifold surface group of the three-dimensional model of the extraction part is cut into a manifold surface group, making it a more easily processable manifold structure. This process not only improves the mid-surface quality of the three-dimensional model of the extraction part.

[0098] The inventor has found through research that there may be a situation where a main edge or a secondary edge is matched in multiple groups among the multiple paired edge groups obtained through the above embodiments (also known as edge matching redundancy). Therefore, according to an embodiment of the present application, as Figure 12 shown, the embodiments of the present application perform edge matching redundancy removal processing on multiple paired edge groups corresponding to all edges in the cross-section of the three-dimensional model of the extraction part by executing steps S25 - S28 to obtain multiple new paired edge groups corresponding to all edges in the cross-section of the three-dimensional model of the extraction part: S25, obtain any paired edge group, and take any main edge in the paired edge group as the first initial edge, and mark the first initial edge as positive, and mark all secondary edges that form paired edges with the first initial edge in all paired edge groups as negative; S26, take each secondary edge that forms a paired edge with the first initial edge in all paired edge groups as the second initial edge, and find all main edges that form paired edges with each second initial edge in the paired edge group, and mark each unmarked main edge that forms a paired edge with each second initial edge as positive; S27, take each unmarked main edge that forms a paired edge with each second initial edge as the third initial edge, and find all secondary edges that form paired edges with each third initial edge in the paired edge group, and mark each unmarked secondary edge that forms a paired edge with each third initial edge as negative; S28, after completing the marking of each edge in all paired edge groups by iterating the above steps S25 - S27, set the edges marked as positive in each paired edge group as the main edges and the edges marked as negative as the secondary edges to obtain multiple new paired edge groups corresponding to all edges in the cross-section of the three-dimensional model of the extraction part.

[0099] To better understand the process of the above embodiments, in combination with Figure 13 a detailed description of the solution for removing edge matching redundancy in all paired edge groups is given.

[0100] For example, Figure 13As shown in the figure, the process of removing redundant edge matching for multiple paired edge groups corresponding to all edges in the cross-section of the extracted part three-dimensional model is as follows: First, initialization: that is, select any main edge in any paired edge group and mark it as A; Second, mark all secondary edges that form a matching relationship with A as B; Third, determine whether all edges in all paired groups have been marked. If the marking is completed, end the iterative algorithm. If the marking is not completed, execute the following steps; Fourth, mark all secondary edges marked as B in the second step as A; Fifth, and mark all unmarked secondary edges corresponding to the main edge marked as A in the fourth step as B, and continue to determine whether all edges in all paired edge groups have been marked. If not, continue to execute according to the methods of the first to third steps until all edges in all paired edge groups are marked and then stop the above iterative algorithm.

[0101] As can be seen from the above description, in the above embodiments of the present application, by selecting any main edge in any paired edge group as the starting point, and performing positive and negative marking on the main edges and secondary edges in all paired edge groups through continuous iterative marking, the situation where a main edge or a secondary edge has paired edges in two or more paired edge groups can be removed, thereby removing the redundant paired edges in the paired edge groups, so as to achieve that each edge in multiple paired edge groups is only paired once. This processing method reduces the possible distortion or incorrect connection (that is, ensures the topological correctness and geometric consistency of the mid-surface), makes the finally generated mid-surface more accurate and smooth, and helps to obtain a high-quality mid-surface of the extracted part three-dimensional model.

[0102] III. Step S3

[0103] In step S3, find the paired surfaces of each edge in multiple paired edge groups.

[0104] The inventor has found through research that there are fillet transitions at the edges of the cross-section of the extracted part three-dimensional model. When there are fillet transitions at the edges of the cross-section of the extracted part three-dimensional model, the curvature change at the fillet will cause discontinuity or deviation in the mid-surface algorithm when determining the boundary and calculating the normal direction, and further cause problems such as distortion, self-intersection or uneven thickness in this area of the mid-surface, affecting the geometric accuracy and topological structure correctness of the model, and making the extracted mid-surface unable to accurately reflect the key structure of the extracted part three-dimensional model. At the same time, the difference between the grouping of edges and the grouping of surfaces is that the shape of the surface does not completely match the shape of the edge. Therefore, it is necessary to screen the correct surface with the shape information of the edge while identifying the surface grouping.

[0105] Among them, according to an embodiment of the present application, as Figure 14As shown in the figure, step S3 of finding the mating surface of each edge in multiple mating edge groups in the above embodiments of the present application includes: S31. According to a preset geometric property method, find the circular arc edges of multiple mating edge groups, and find the fillet surfaces corresponding to each circular arc edge in multiple mating edge groups along the preset extraction direction of the extraction part; S32. Find the mating surfaces of each edge in multiple mating edge groups without circular arc edges; S33. According to the positional relationship between each fillet surface and other fillet surfaces in the three-dimensional model of the extraction part, obtain the mating surface of each fillet surface and use it as the mating surface of the corresponding circular arc edge in multiple mating edge groups.

[0106] As can be seen from the above description, in the above embodiments of the present application, the circular arc edges and parallel edges in multiple mating edge groups are separated, and the mating surfaces of the parallel edges (i.e., straight lines) and circular arc edges (i.e., curves) in the cross-section of the three-dimensional model of the extraction part are found separately, avoiding the influence of local discontinuity and calculation errors caused by fillet surfaces on the overall mid-surface, that is, improving the geometric accuracy and continuity of the mid-surface in each area, and ensuring that the mid-surface can correctly reflect the true shape of the three-dimensional model of the extraction part.

[0107] The following expands and explains steps S32 and S33.

[0108] (1) Step S32

[0109] In step S32, find the mating surface of each edge in multiple mating edge groups without circular arc edges.

[0110] Among them, according to an embodiment of the present application, step S32 includes: taking the preset internal direction of the three-dimensional model of the extraction part as the search direction, finding the surfaces formed by each edge in all mating edge groups without circular arc edges, and calculating the angle between the adjacent surfaces adjacent to this surface at the common edge. When this angle is less than the third preset angle threshold, the surface along the internal direction of the extraction part of each edge is used as the mating surface of this edge, and the breadth-first search method is used to find other mating surfaces of this edge along the mating surface of each edge. When the fillet surface obtained through step S31 is found, the search for the mating surface of each edge stops.

[0111] For example, as Figure 15 shown, it shows a schematic diagram of the search process for the mating surface of a parallel mating edge. From Figure 15As can be seen, the preset internal direction along the three-dimensional model of the extraction part is the search direction. Search for the mating surface of the edge marked by the black dashed line in the figure, find the first surface, and calculate the angle between the first surface and its adjacent surface at the common edge. When the angle between the two surfaces is 90 degrees and the third preset angle threshold is 30 degrees, since this angle is greater than the third preset angle threshold, it indicates that the first surface is not the mating surface of the edge at the black dashed line. Continue to use the breadth-first search method to find the mating surface. It should be noted that the above third preset angle threshold is only an example threshold given to better illustrate how the present application finds the mating surface of the edge. The specific value of the third preset angle threshold needs to be determined according to the geometric characteristics of the specific three-dimensional model of the extraction part, and no specific limitation is made here.

[0112] As can be seen from the above description, in the above embodiment of the present application, the breadth-first search method is used to find the mating surface of the parallel edges, which can systematically traverse the adjacent surfaces of the edges, ensure efficient and comprehensive exploration of possible matching options, and at the same time avoid repeated calculations through hierarchical search, improve the search speed and accuracy, and can stop in time when encountering non-conforming surfaces (such as rounded surfaces), thereby simplifying the logic, reducing mis-matching, and improving the accuracy of the found mating surface.

[0113] (2) Step S33

[0114] In step S33, according to the positional relationship between each rounded surface and other rounded surfaces in the three-dimensional model of the extraction part, the mating surface of each rounded surface is obtained and used as the mating surface of the circular arc edge corresponding to the rounded surface in the multiple paired edge groups.

[0115] Among them, according to an embodiment of the present application, step S33 includes: regarding the rounded surface corresponding to each circular arc edge in the multiple paired edge groups as the target rounded surface, and calculating whether there is a parallel relationship between the target rounded surface and each other rounded surface according to the preset geometric determination method, and regarding the rounded surface having a parallel relationship with the target rounded surface as the mating surface of the target rounded surface.

[0116] As can be seen from the above description, in the above embodiment of the present application, by calculating the parallel relationship between the rounded surface (target rounded surface) corresponding to each circular arc edge and other rounded surfaces, the search process is simplified and the mating surface of the target rounded surface is accurately determined.

[0117] IV. Step S4

[0118] In step S4, based on the multiple paired edge groups and the mating surfaces of each edge in the multiple paired edge groups, the middle surface of the three-dimensional model of the extraction part is obtained.

[0119] The inventor has found through research that since the surfaces may not be completely parallel, and there are variable thicknesses in the fillets and different mating surfaces, the quality of the three-dimensional model of the extracted part finally obtained is not high. Therefore, it is necessary to generate the mid-surface by calculating the geometric center line based on the pairing information of the edges and sweeping along the extraction direction.

[0120] Among them, according to an embodiment of the present application, as Figure 16 shown, the steps S4 for obtaining the mid-surface of the three-dimensional model of the extracted part based on multiple paired edge groups and the mating surfaces of each edge in the multiple paired edge groups include: S41, calculating the center line of each paired edge group; S42, finding the sweeping line of each paired edge group, where the sweeping line connects the mating surfaces of each edge in each paired edge group into a straight line; S43, sweeping the sweeping line of each paired edge group with the center line of each paired edge group as the baseline to obtain the mid-surface of each paired edge group; S44, classifying the mid-surfaces of each paired edge group based on the mating surfaces of each edge in each paired edge group, and splicing all the mid-surfaces into the mid-surface of the three-dimensional model of the extracted part based on the classified results.

[0121] Among them, in order to better understand the concept of sweeping, it is demonstrated and explained in combination with Figure 17 this.

[0122] For example, as Figure 17 shown, the dotted line in the figure is the center line of a paired edge group, and this center line sweeps the sweeping line of each paired edge group along the preset sweeping direction.

[0123] It can be seen from the above description that the above embodiment of the present application accurately constructs the center line based on the paired edges, ensuring that the center line geometrically accurately reflects the central path of the original three-dimensional model of the extracted part, and the sweeping along the extraction direction is dynamically adjusted to adapt to the thickness change and non-parallel surfaces, thereby generating a continuous and smooth mid-surface, significantly improving the quality and accuracy of the mid-surface of the three-dimensional model of the extracted part.

[0124] The inventor has found through research that since there may be cutting positions in the three-dimensional model of the extracted part (that is, there are cutting features in the direction perpendicular to the extraction direction of the extracted part), this may lead to inconsistent mid-surface generation results on both sides of the cutting position. For example, as Figure 18 shown, the place circled by the black circle in the figure represents the cutting position in the three-dimensional model of the extracted part.

[0125] In order to, according to an embodiment of the present application, when there is a cutting position in the three-dimensional model of the extracted part, step S42 includes: generating a complete sweeping line by bridging the lines on both sides of the cutting position.

[0126] As described above, in the above embodiments of the present application, the mating surfaces of each edge in each paired edge group are connected into a straight line as the sweeping line, and when there is a cutting position, a complete sweeping line is generated by bridging the lines on both sides. This method helps to eliminate irregularities caused by non-parallel surfaces or thickness changes, especially near the cutting features. By precisely connecting the mating surfaces and bridging the two sides of the cutting position, a mid-plane that smoothly and accurately reflects the original model structure can be created, significantly improving the quality and reliability of the mid-plane.

[0127] To this end, according to an embodiment of the present application, step S43 includes: performing a Boolean operation on the mid-plane of each paired edge group and the three-dimensional model of the extract, finding the cutting positions in the three-dimensional model of the extract, and cutting the mid-plane of each paired edge group based on the cutting positions to obtain the mid-plane of each paired edge group after cutting.

[0128] As described above, in the above embodiments of the present application, through the Boolean operation, the mid-plane can be precisely adjusted according to the actual geometry of the extract, so that the mid-plane strictly follows the boundaries and internal structures of the model, and the mid-plane is cut to ensure the consistency and continuity of the mid-plane on both sides of the cutting position.

[0129] Among them, according to an embodiment of the present application, the mating surface corresponding to the main edge in each paired edge group is used as the top surface, and the mating surface corresponding to the secondary edge is used as the bottom surface. As Figure 19 shown, step S44 for classifying the mid-plane of each paired edge group in the above embodiments of the present application includes steps S441-S445 to complete the classification of the mid-plane of each paired edge group. Each step is introduced in detail below.

[0130] (1) Step S441

[0131] In step S441, the mating surfaces of all edges in each paired edge group are used as a mating surface group, and according to the first preset determination method, the connection relationship between each top surface in each mating surface group and each top surface and each bottom surface in each other mating surface group is obtained.

[0132] Among them, according to an embodiment of the present application, the first preset determination method is: if there is at least one top surface in each mating surface group that is connected to one or more top surfaces in each other mating surface group, it is determined that there is a top surface connection relationship between the two mating surface groups; if there is at least one top surface in each mating surface group that is connected to one or more bottom surfaces in each other mating surface group, it is determined that there is a top-bottom surface connection relationship between the two mating surface groups.

[0133] (2) Step S442

[0134] In step S442, according to the second preset determination method, the connection relationship between each bottom surface in each mating surface group and each top surface and each bottom surface in each other mating surface group is obtained.

[0135] Among them, according to an embodiment of the present application, the second preset determination method is as follows: if there is at least one bottom surface in each pair of mating surface groups that is connected to one or more top surfaces in each of the other pairs of mating surface groups, it is determined that there is a bottom-top connection relationship between the two pairs of mating surface groups; if there is at least one bottom surface in each pair of mating surface groups that is connected to one or more bottom surfaces in each of the other pairs of mating surface groups, it is determined that there is a bottom surface connection relationship between the two pairs of mating surface groups.

[0136] As can be seen from the descriptions of the above steps S441 and S442, in the above embodiment of the present application, the connection type between the pairs of mating surface groups is determined by determining the connection relationship between the top surfaces in each pair of mating surface groups and the top surfaces or between the top surfaces in the other pairs of mating surface groups, and the connection type between the pairs of mating surface groups is determined by determining the connection relationship between the bottom surfaces in each pair of mating surface groups and the top surfaces or between the top surfaces in the other pairs of mating surface groups. It can accurately identify and classify the interaction methods between different pairs of mating surface groups, ensuring the accurate capture of the relationships between the pairs of mating surface groups during the mid-surface generation process, thereby improving the accuracy and reliability of the mid-surface construction.

[0137] (3) Step S443

[0138] In step S443, based on the connection relationship between each top surface in each pair of mating surface groups and each top surface and each bottom surface in each of the other pairs of mating surface groups, and the connection relationship between each bottom surface in each pair of mating surface groups and each top surface and each bottom surface in each of the other pairs of mating surface groups, the connection relationship between each surface in each pair of mating surface groups and each surface in the other pairs of mating surface groups is obtained.

[0139] (4) Step S444

[0140] In step S444, based on the connection relationship between each surface in each pair of mating surface groups and each surface in the other pairs of mating surface groups, it is determined whether there is a T-shaped connection relationship or an L-shaped connection relationship between every two pairs of mating surface groups.

[0141] Among them, according to an embodiment of the present application, the following method is used to determine whether there is a T-shaped connection relationship or an L-shaped connection relationship between every two pairs of mating surface groups:

[0142] The connection relationship between every two pairs of mating surface groups =

[0143]

[0144] i = 1, 2, 3..., N, j = 1, 2, 3..., N, j ≠ i

[0145] where N is the number of pairs of mating surface groups, FP ijIndicates the connection relationship between the i-th paired surface group and the j-th paired surface group. (Not AA and not BA) means that there is neither a top surface connection relationship nor a bottom-top surface connection relationship between the i-th paired surface group and the j-th paired surface group. (Not BB and not AB) means that there is neither a bottom surface connection relationship nor a top-bottom surface connection relationship between the i-th paired surface group and the j-th paired surface group. (Not AA and not AB) means that there is neither a top surface connection relationship nor a top-bottom surface connection relationship between the i-th paired surface group and the j-th paired surface group. (Not BB and not BA) means that there is neither a bottom surface connection relationship nor a bottom-top surface connection relationship between the i-th paired surface group and the j-th paired surface group. (Not AB and not BA) means that there is neither a top-bottom surface connection relationship nor a bottom-top surface connection relationship between the i-th paired surface group and the j-th paired surface group. (Not AA and not BB) means that there is neither a top surface connection relationship nor a bottom surface connection relationship between the i-th paired surface group and the j-th paired surface group.

[0146] To more clearly understand the concepts of the T-shaped connection relationship and the L-shaped connection relationship of surfaces, the following will be described in conjunction with Figure 20 and Figure 21 for illustration.

[0147] For example, as Figure 20 shown, it shows a schematic diagram of the T-shaped connection relationship of surfaces. The dashed line in Figure 20 indicates that the two surfaces are in a T-shaped connection relationship. As Figure 21 shown, it shows a schematic diagram of the L-shaped connection relationship of surfaces. The dashed line in Figure 21 indicates that the two surfaces are in an L-shaped connection relationship.

[0148] From the above description, it can be seen that in the above embodiments of the present application, the connection relationships of surfaces are comprehensively classified through different determination conditions, ensuring the accurate and comprehensive identification of the connection relationships between paired surface groups, thereby improving the accuracy and consistency of the generation of the middle surface.

[0149] (5) Step S445

[0150] In step S445, the middle surfaces of each paired edge group corresponding to all paired surface groups with T-shaped connection relationships and L-shaped connection relationships are spliced into the middle surface of the extracted part three-dimensional model. It should be noted that splicing the middle surfaces corresponding to the paired surface groups based on whether there are T-shaped connection relationships or L-shaped connection relationships in the paired surface groups is only one embodiment of the present application. With the continuous research on technology, the middle surface can also be spliced based on other types of connection relationships, which will not be specifically limited here.

[0151] As can be seen from the above description, in the above embodiments of the present application, the mid-planes of each paired-edge group corresponding to all mating-face groups with T-shaped connection relationships and L-shaped connection relationships are spliced into the mid-plane of the extracted part three-dimensional model. By accurately capturing the connection relationships between different mating-face groups, the smooth transition and geometric consistency of the mid-plane in the transition region are ensured (that is, the continuity and accuracy of the mid-plane at complex geometric structures such as T-shaped and L-shaped connections can be ensured), avoiding possible fault or discontinuity problems, and thus significantly improving the overall quality and reliability of the mid-plane.

[0152] The following describes the mid-plane extraction scheme of the extracted part three-dimensional model of the present application from the system side.

[0153] According to an embodiment of the present application, the present application provides a mid-plane extraction device for the extracted part three-dimensional model based on the mid-plane extraction method of the extracted part three-dimensional model according to any of the above embodiments, as Figure 22 shown. The device includes: a cross-section recognition module, configured to obtain the faces of the extracted part three-dimensional model and recognize the cross-sections of the extracted part three-dimensional model based on the concavity and convexity of the faces; an edge grouping module, configured to group the edges of the cross-section according to the parallel or approximately parallel criterion of the edges to obtain a plurality of paired-edge groups, where the approximately parallel criterion of the edges indicates that when the included angle formed by two edges is less than the first preset angle threshold, the two edges are determined to be approximately parallel; a mating-face search module, configured to search for the mating faces of each edge in the plurality of paired-edge groups; and a mid-plane generation module, configured to obtain the mid-plane of the extracted part three-dimensional model based on the plurality of paired-edge groups and the mating faces of each edge in the plurality of paired-edge groups.

[0154] In summary, the inventors have found through research that characteristics such as the non-manifold structure of the three-dimensional model of the extracted part, the rounded transition of the edges of the cross-section of the extracted part, and the cutting features in the direction perpendicular to the extraction direction will affect the quality of the mid-plane of the extracted part three-dimensional model. Therefore, in the above embodiments of the present application, by grouping the edges in the cross-section of the extracted part three-dimensional model based on parallelism, the non-manifold structure of the extracted part three-dimensional model can be systematically analyzed and reconstructed into a more easily processed manifold structure. By separating the circular arcs and parallel edges in the plurality of paired-edge groups and separately searching for the mating faces of the parallel edges (i.e., straight lines) and circular arc edges (i.e., curves) in the cross-section of the extracted part three-dimensional model, the influence of local discontinuity and calculation errors caused by rounded faces on the overall mid-plane is avoided. And through Boolean operations, the mid-plane can be accurately adjusted according to the actual geometric shape of the extracted part, so that the mid-plane strictly follows the boundaries and internal structures of the model, and the mid-plane is cut to ensure the consistency and continuity of both sides of the cutting position, and finally a mid-plane of a high-quality extracted part three-dimensional model is obtained.

[0155] It should be noted that the mid-surface extraction method of the extracted part three-dimensional model in this application can accurately extract the mid-surfaces of various extracted part models in CAE simulations, and the extracted mid-surfaces have a high degree of matching with the original models.

[0156] Based on the inventive concept of the above embodiments, this application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method described in the above embodiments are implemented. The following is a detailed description in conjunction with Figure 23 for detailed description.

[0157] As Figure 23 shown, it shows the electronic device of this application, which may specifically include a processor 110 and a memory 120. The memory 120 is coupled to the processor 110.

[0158] The processor 110 is used to control the operation of the electronic device. The processor 110 may also be referred to as a CPU (Central Processing Unit, central processing unit). The processor 110 may be an integrated circuit chip with signal processing capabilities. The processor 110 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 devices, discrete gate or transistor logic devices, discrete hardware components. The general-purpose processor may be a microprocessor, or the processor 110 may also be any conventional processor, etc.

[0159] The memory 120 is used to store computer programs, which may be RAM, ROM, or other types of storage terminals. Specifically, the memory 120 may include one or more computer-readable storage media, which may be non-transitory or transitory. The memory 120 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage terminals and flash storage terminals. In some embodiments, the non-transitory computer-readable storage medium in the memory 120 is used to store at least one program code.

[0160] The processor 110 is used to execute the computer program stored in the memory 120 to implement the methods described in the method embodiments of this application.

[0161] In some embodiments, the electronic device may further include: a peripheral terminal interface 130 and at least one peripheral terminal. The processor 110, the memory 120, and the peripheral terminal interface 130 may be connected through a bus or signal lines. Each peripheral terminal may be connected to the peripheral terminal interface 130 through a bus, signal lines, or a circuit board. Specifically, the peripheral terminal includes at least one of a radio frequency circuit 140, a display screen 150, an audio circuit 160, and a power supply 170.

[0162] The peripheral terminal interface 130 can be used to connect at least one peripheral terminal related to I / O (Input / Output) to the processor 110 and the memory 120. In some embodiments, the processor 110, the memory 120, and the peripheral terminal interface 130 are integrated on the same chip or circuit board; in some other embodiments, any one or two of the processor 110, the memory 120, and the peripheral terminal interface 130 can be implemented on a separate chip or circuit board, and this embodiment does not limit this.

[0163] The radio frequency circuit 140 is used to receive and transmit RF (Radio Frequency) signals, also known as electromagnetic signals. The radio frequency circuit 140 communicates with a communication network and other Internet of Things devices through electromagnetic signals, and the radio frequency circuit 140 is the communication circuit of the electronic device. The radio frequency circuit 140 converts an electrical signal into an electromagnetic signal for transmission, or converts the received electromagnetic signal into an electrical signal. Optionally, the radio frequency circuit 140 includes: an antenna system, an RF transceiver, one or more amplifiers, a tuner, an oscillator, a digital signal processor, a codec chipset, an operator identity module card, and so on. The radio frequency circuit 140 can communicate with other terminals through at least one wireless communication protocol. The wireless communication protocol includes but is not limited to: the World Wide Web, a metropolitan area network, an intranet, various generations of mobile communication networks (2G, 3G, 4G, and 5G), a wireless local area network, and / or a WiFi (Wireless Fidelity) network. In some embodiments, the radio frequency circuit 140 may further include a circuit related to NFC (Near Field Communication), and this application does not limit this.

[0164] The display screen 150 is used to display the UI (User Interface, the operator interface). The UI may include graphics, text, icons, videos, and any combination thereof. When the display screen 150 is a touch display screen, the display screen 150 also has the ability to collect touch signals on or above the surface of the display screen 150. The touch signals can be input to the processor 110 as control signals for processing. At this time, the display screen 150 can also be used to provide virtual buttons and / or a virtual keyboard, also known as soft buttons and / or a soft keyboard. In some embodiments, there can be one display screen 150, which is provided on the front panel of the electronic device; in other embodiments, there can be at least two display screens 150, which are respectively provided on different surfaces of the electronic device or are in a foldable design; in other embodiments, the display screen 150 can be a flexible display screen, which is provided on the curved surface or the folding surface of the electronic device. Even further, the display screen 150 can be set to an irregular non-rectangular shape, that is, a special-shaped screen. The display screen 150 can be prepared using materials such as LCD (Liquid Crystal Display) or OLED (Organic Light-Emitting Diode).

[0165] The audio circuit 160 can include a microphone and a speaker. The microphone is used to collect sound waves of the operator and the environment, and convert the sound waves into electrical signals and input them to the processor 110 for processing, or input them to the radio frequency circuit 140 to achieve voice communication. For the purpose of stereo collection or noise reduction, there can be multiple microphones, which are respectively provided at different parts of the electronic device. The microphone can also be an array microphone or an omnidirectional collection microphone. The speaker is used to convert the electrical signals from the processor 110 or the radio frequency circuit 140 into sound waves. The speaker can be a traditional thin film speaker or a piezoelectric ceramic speaker. When the speaker is a piezoelectric ceramic speaker, it can not only convert electrical signals into sound waves audible to humans, but also convert electrical signals into sound waves inaudible to humans for uses such as ranging. In some embodiments, the audio circuit 160 can also include a headphone jack.

[0166] The power supply 170 is used to supply power to each component in the electronic device. The power supply 170 can be alternating current, direct current, a disposable battery, or a rechargeable battery. When the power supply 170 includes a rechargeable battery, the rechargeable battery can be a wired rechargeable battery or a wireless rechargeable battery. A wired rechargeable battery is a battery charged through a wired line, and a wireless rechargeable battery is a battery charged through a wireless coil. The rechargeable battery can also be used to support fast charging technology.

[0167] For the detailed description of the functions and execution processes of each functional module or component in the embodiment of the electronic device of the present application, reference can be made to the description in the above method embodiments of the present application, and details are not described herein again.

[0168] In several embodiments provided by the present application, it should be understood that the disclosed electronic devices and methods can be implemented in other ways. For example, the various embodiments of the electronic devices described above are merely illustrative. For example, the division of modules or units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be an indirect coupling or communication connection through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0169] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0170] In addition, in each embodiment of the present application, the various functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0171] Based on the inventive concept of the above embodiments, the present application also provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the steps of the method described in any of the above embodiments are performed. The following combines Figure 24 to illustrate the execution process of the above embodiments in the computer-readable storage medium.

[0172] Such as Figure 24As shown, it shows the computer-readable storage medium of the present application. If the above integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in the computer-readable storage medium 200. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions / computer programs to enable an Internet of Things device (which can be a personal computer, a server, or a network terminal, etc.) or a processor to execute all or part of the steps of the methods in various embodiments of the present application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs, as well as electronic terminals such as computers, mobile phones, laptop computers, tablet computers, cameras, etc. having the above storage media.

[0173] The description of the execution process of the computer program stored in the computer-readable storage medium can be referred to the description in the above method embodiments of the present application, and will not be elaborated here.

[0174] The above are only the embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present application by the same token.

[0175] Those skilled in the art can understand that in the above methods of the specific embodiments, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

Claims

1. A method for extracting the mid-surface of a three-dimensional model of an extraction part, characterized in that: The method comprises: Acquire a surface of the three-dimensional model of the extraction part, and identify a cross section of the three-dimensional model of the extraction part based on the concavity and convexity of the surface; According to the parallel or approximately parallel standard of the edges, the edges of the cross section are grouped to obtain a plurality of paired edge groups, wherein the approximately parallel standard of the edges indicates that when the angle formed by the two edges is less than a first preset angle threshold, the two edges are determined to be approximately parallel; Finding a paired face for each edge in the plurality of paired edge groups; Based on the multiple paired edge groups and the paired faces of each edge in the multiple paired edge groups, the mid-face of the three-dimensional model of the pull-out part is obtained.

2. The method for extracting the mid-surface of the three-dimensional model of the extracted part according to claim 1, characterized in that: The three-dimensional model of the extraction part includes a plurality of surfaces, and the step of identifying a cross section of the three-dimensional model of the extraction part based on the concavity and convexity of the surfaces includes: Find all faces adjacent to each face in the three-dimensional model of the extraction part, and refer to all faces adjacent to each face as adjacent faces of the face, wherein each face has a common edge with the adjacent face; identifying all thickness faces based on the concavity and convexity of all said common edges; The inner ring feature is used to find all thickness surfaces including the inner ring, and all thickness surfaces including the inner ring are used as cross sections of the three-dimensional model of the extraction part.

3. The method for extracting the mid-surface of the three-dimensional model of the extracted part according to claim 2, characterized in that: The step of identifying all thickness surfaces based on the concavity and convexity of all the common edges comprises: Taking each face in the three-dimensional model of the extracted part as a target face, calculating the angle between the target face and each adjacent face at the common edge, and determining that the common edge between the target face and each adjacent face is a convex edge when the angle is greater than a first preset angle threshold; Find out whether there are two parallel or approximately parallel adjacent faces among the adjacent faces corresponding to all convex edges. If so, the target face is determined to be a convex face, wherein the two parallel or approximately parallel adjacent faces of the target face cannot be directly connected, and approximately parallel indicates that when the angle formed by the two adjacent faces is less than a second preset angle threshold, the two adjacent faces are determined to be approximately parallel; When the target surface is determined to be a convex surface, the distance between the two adjacent surfaces is calculated, and when the lengths of the two common edges between the target surface and the two adjacent surfaces are both greater than the distance between the two adjacent surfaces, the target surface is determined to be a thickness surface.

4. The method for extracting the mid-surface of the three-dimensional model of the extracted part according to claim 1, characterized in that: The step of grouping the edges of the cross section to obtain a plurality of paired edge groups comprises: The parallel or approximately parallel edges in the cross section are formed into a parallel edge group, and a plurality of parallel edge groups are obtained based on all edges of the cross section; The longest side in each of the parallel side groups is used as the main side, and the other sides are used as the secondary sides; Projecting each of the secondary edges in each of the parallel edge groups onto the primary edge, and calculating whether the projection line of each secondary edge on the primary edge intersects with other secondary edges, wherein when the projection line of the secondary edge does not intersect with other secondary edges, the secondary edge and the primary edge form a paired edge; All paired edges in each of the parallel edge groups constitute a paired edge group, and based on the multiple parallel edge groups, multiple paired edge groups corresponding to all edges in the cross section of the three-dimensional model of the pull-out part are obtained.

5. The method for extracting the mid-surface of the three-dimensional model of the extracted part according to claim 1, characterized in that: The step of finding the paired face of each edge in the plurality of paired edge groups comprises: According to a preset geometric property method, searching for arc edges in the plurality of paired edge groups, and searching for a fillet surface corresponding to each arc edge in the plurality of paired edge groups along a preset extraction direction of the three-dimensional model of the extraction part; Find the paired face of each edge in the plurality of paired edge groups that do not contain arc edges; According to the positional relationship between each rounded corner surface and other rounded corner surfaces in the three-dimensional model of the extraction part, the matching surface of each rounded corner surface is obtained and used as the matching surface of the arc edge corresponding to the rounded corner surface in the plurality of matching edge groups.

6. The method for extracting the mid-surface of the three-dimensional model of the extracted part according to claim 1, characterized in that: The step of obtaining the middle surface of the three-dimensional model of the extraction part based on the plurality of paired edge groups and the paired surface of each edge in the plurality of paired edge groups comprises: calculating the median line of each of said paired edge groups; Finding a sweep line of each of the paired edge groups, wherein the sweep line connects the paired faces of each edge in each of the paired edge groups into a straight line; Taking the midline of each of the paired edge groups as a baseline, sweeping the sweep line of each of the paired edge groups to obtain the mid-surface of each of the paired edge groups; Based on the paired faces of each edge in each paired edge group, the mid-faces of each paired edge group are classified, and based on the classification results, all the mid-faces are spliced ​​into the mid-faces of the three-dimensional model of the extraction part.

7. The method for extracting the mid-surface of the three-dimensional model of the extraction part according to claim 6, characterized in that: The paired surface corresponding to the primary edge in each paired edge group is used as the top surface, and the paired surface corresponding to the secondary edge is used as the bottom surface, and the step of classifying the middle surface of each paired edge group includes: Taking the paired faces of all the edges in each paired edge group as a paired face group, and obtaining the connection relationship between each top face in each paired face group and each top face and each bottom face in each other paired face group according to a first preset determination method; According to the second preset determination method, the connection relationship between each bottom surface in each paired surface group and each top surface and each bottom surface in each other paired surface group is obtained; Based on the connection relationship between each top surface in each paired surface group and each top surface and each bottom surface in each other paired surface group, and the connection relationship between each bottom surface in each paired surface group and each top surface and each bottom surface in each other paired surface group, the connection relationship between each surface in each paired surface group and each surface in each other paired surface group is obtained; Based on the connection relationship between each face in each paired face group and each face in other paired face groups, it is determined whether there is a T-type connection relationship or an L-type connection relationship between each two paired face groups; The middle surfaces of each of the paired edge groups corresponding to all the paired face groups having T-type connection relationships and L-type connection relationships are spliced ​​into the middle surface of the three-dimensional model of the pull-out part.

8. A mid-surface extraction device for a three-dimensional model of a pull-out part, characterized in that: The device comprises: A cross-section recognition module, used to obtain a surface of the three-dimensional model of the extraction part, and to recognize a cross-section of the three-dimensional model of the extraction part based on the concavity and convexity of the surface; an edge grouping module, configured to group the edges of the cross section according to a parallel or approximately parallel standard of the edges to obtain a plurality of paired edge groups, wherein the approximately parallel standard of the edges indicates that when an angle formed by two edges is less than a first preset angle threshold, the two edges are determined to be approximately parallel; A paired face search module, used to search for a paired face of each edge in the plurality of paired edge groups; A mid-surface generation module is used to obtain the mid-surface of the three-dimensional model of the extraction part based on the multiple paired edge groups and the paired faces of each edge in the multiple paired edge groups.

9. An electronic device, characterized in that: The method comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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