An Automatic Recognition and Application Method for the Axis Network of Architectural and Structural CAD Drawings

Abstract

The present invention discloses an automatic recognition method for the axis network of building and structural CAD drawings. The automatic recognition method for the axis network of building and structural CAD drawings comprises the following steps: S1, drawing initialization; S2, drawing element reading; S3, drawing element analysis to preliminarily extract axis network objects; S4, finding missing axis network objects. The present invention also discloses an application method for the axis network of building and structural CAD drawings. Compared with the prior art, by using the automatic recognition method for the axis network of building and structural CAD drawings of the present invention, axis network information can be accurately extracted, and the extracted axis network information can be applied to BIM modeling to assist in solving the problem of automatic global positioning of individual modeling objects during the BIM modeling process, and improve the automation degree and efficiency of BIM modeling.

Description

Technical Field

[0001] The present invention belongs to the technical field of building information modeling, and particularly relates to a method for automatically identifying and applying the axis network of building and structural CAD drawings. Background Art

[0002] In the construction field, building information modeling and management (BIM) is widely regarded as a new type of tool that can improve production efficiency and delivery quality. BIM can provide a visual building model for a building project. In the prior art, the method of manually modeling based on the content of two-dimensional CAD drawings to form a BIM model takes a long time and requires a large amount of financial and material resources. Therefore, it is of great significance to develop a technology that can automatically convert CAD building drawings into BIM models.

[0003] In the development of a technology that can automatically convert CAD building drawings into BIM models, the problem of automatic axis network recognition needs to be solved. The axis network is a network composed of building axes. It is artificially set in the building drawings to mark the detailed dimensions of components according to general customary standards. It is usually marked on the center lines of symmetric interfaces or cross-sectional components. The axis network is the main framework of architectural drawing. The main supporting components of a building are arranged according to the axis network positioning, achieving orderliness.

[0004] In the prior art, a technical solution for extracting axis network objects by finding the axis network layer is disclosed.

[0005] The deficiencies of the prior art are that, due to the complex sources of current building and structural CAD drawings and the inconsistent drawing specifications of each drawing, in actual situations, there are a large number of cases where the axis networks in building and structural CAD drawings are not all placed in the same axis network layer, or other features are mixed into the axis network layer. In such cases, using the method in the prior art will result in the situation of missing extraction of axis network information or extracting non-axis network objects more. Therefore, the axis network extraction method in the prior art has poor applicability and inaccurate extracted information. Summary of the Invention

[0006] (1) Technical Problems to be Solved

[0007] Based on this, the present invention proposes a method for automatically identifying and applying the axis network of building and structural CAD drawings, aiming to solve the technical problems of poor applicability and inaccurate extracted information of the axis network extraction method in the prior art.

[0008] (2) Technical Solutions

[0009] To solve the above technical problems, the present invention proposes an automatic axis network recognition method for building and structural CAD drawings, including the following steps:

[0010] S1, drawing initialization

[0011] S11. Determine the range where the axis network needs to be extracted according to the architectural and structural CAD drawings;

[0012] S12. Explode all the blocks within the range where the axis network needs to be extracted into basic objects;

[0013] S2. Drawing element reading

[0014] Read the basic objects within the range where the axis network needs to be extracted;

[0015] S3. Drawing element analysis, initially extract the axis network objects

[0016] Analyze the scale objects within the range where the axis network needs to be extracted, and find all the scale objects that are connected end to end and jointly form a largest enclosed area; find the line segments that coincide with the dimension lines forming the largest enclosed area, then find all the circle objects within the range where the axis network needs to be extracted that are connected to this line segment, and analyze this circle object. If the circle object simultaneously meets the following three conditions:

[0017] Condition 1: The circle object contains text objects;

[0018] Condition 2: There are line segments connected to the side of the circle object;

[0019] Condition 3: According to the line segment connected to the circle object, find the line segment that coincides with it horizontally or vertically. This line segment is set as the axis network auxiliary line, and this auxiliary line is the longest horizontal or vertical line within the range where the axis network needs to be extracted;

[0020] Then this circle object and the line segments connected to the side of this circle object are the initially extracted axis network objects; S4. Find the missing axis network objects

[0021] According to the initially extracted axis network objects obtained from the analysis in step S3, the following information can be obtained: the size of the axis network circles, the layer of the axis network circles, the layer of the axis network text, the layer of the axis network line segments, the layer of the axis network auxiliary lines;

[0022] Then use the above information to search in reverse to find the missing axis network objects. The missing axis network objects and the initially extracted axis network objects obtained in step S4 jointly form all the axis network objects.

[0023] Preferably, the architectural and structural CAD drawings in step S11 are specifically the floor plan of the standard floor of the project building, and the floor plan of the standard floor of the project building is a file in.dwg format.

[0024] Preferably, in step S11, determining the range where the axis network needs to be extracted includes two methods:

[0025] Method 1: Cut the standard floor plan into files containing only a single drawing frame according to the range determined by each drawing frame in the standard floor plan;

[0026] Method 2: Manually select a single drawing frame in the standard floor plan to determine the range where the axis network needs to be extracted.

[0027] Preferably, the basic objects in step S12 include: circles, straight lines, polylines, polygons, text, and dimension lines.

[0028] Preferably, when the range where the axis network needs to be extracted in step S12 includes a block definition with attributes, the attribute text needs to be restored; before step S2 after step S12, there also includes:

[0029] S13, set the Z coordinates of all objects in the range where the axis network needs to be extracted to zero.

[0030] Preferably, before step S1, there are also the following steps: check whether the floor plan of the standard floor of the project building can be normally opened and displayed by AutoCAD software; when the floor plan of the standard floor of the project building is a file in.dwg format drawn by a non-original CAD software, the file needs to be converted into a native file.

[0031] Preferably, the automatic recognition method for the axis network of the building and structure CAD drawings also includes: S5, according to all the axis network objects obtained in step S4, extract the intersections of all axis networks in different directions within the area enclosed by all the axis network objects. The intersections contain their own coordinate information and the information of the two axis networks forming the intersections; select the intersection closest to the lower left corner of the largest enclosed area among all the intersections as the reference point; calculate the relative coordinate information of all the intersections to the reference point to complete the extraction of the axis network information, and the extracted axis network information is used as the main axis network of the project building.

[0032] Preferably, the automatic recognition method for the axis network of the building and structure CAD drawings also includes: S6, storage of the axis network information

[0033] Save the axis network information extracted in S5 as a.txt file and save it to the cloud database to complete the storage of the axis network information.

[0034] Preferably, the relative coordinate information in step S5 refers to: the distance and angle information from the intersection to the reference point, and the angle information refers to the included angle information between the line connecting each intersection and the reference point and the positive direction of the X coordinate axis.

[0035] The present invention also discloses an application method for the axis network of building and structural CAD drawings, which includes the following steps: During the BIM modeling process, after completing the modeling according to the building drawings or structural drawings, according to the axis network data of each modeling object in the building drawings or structural drawings, perform offset conversion to the main axis network of the project building obtained by the above method, and then combine with the elevation data to automatically realize the spatial positioning of each building model.

[0036] (III) Beneficial effects

[0037] Compared with the prior art, the beneficial effects of the automatic recognition and application method for the axis network of building and structural CAD drawings of the present invention mainly include:

[0038] By using the automatic recognition method for the axis network of building and structural CAD drawings of the present invention, it can assist in the rapid filtering of axis network information during the process of reading building drawings and structural drawings; it can accurately extract the axis network information, and the extracted axis network information can be applied to BIM modeling to assist in solving the problem of automatic global positioning of a single modeling object in the project building during the BIM modeling process, improving the automation degree and efficiency of BIM modeling. Moreover, the extracted axis network information can be used for unified coordinate positioning of all building drawings and structural drawings; through the axis network information and the elevation view, the projection relationship of the elevation view can be established. Description of the drawings

[0039] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings. The drawings are schematic and should not be construed as any limitation to the present invention. In the drawings:

[0040] Figure 1 It is the floor plan of the standard floor of the project building in the automatic recognition method for the axis network of building and structural CAD drawings according to the embodiment of the present invention;

[0041] Figure 2 It is for using the automatic recognition method for the axis network of building and structural CAD drawings of the present invention to Figure 1 perform analysis to obtain the initially extracted axis network objects;

[0042] Figure 3 It is for using the automatic recognition method for the axis network of building and structural CAD drawings of the present invention to Figure 1 perform analysis to find the missing axis network objects;

[0043] Figure 4 It is for using the automatic recognition method for the axis network of building and structural CAD drawings of the present invention to Figure 1 perform analysis to obtain all the axis network objects;

[0044] Figure 5 It is the effect diagram after excluding the already analyzed objects such as the axis network and scale in Figure 1 ;

[0045] Figure 6 This is a schematic flow chart of an automatic recognition method for the axis network of architectural and structural CAD drawings of the present invention. Detailed implementation manners

[0046] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following detailed description of the specific implementation manners of the present invention will be given in conjunction with the accompanying drawings. Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific implementations disclosed below.

[0047] The following will further describe Figure 1-6 an automatic recognition method for the axis network of architectural and structural CAD drawings of the present invention.

[0048] Please refer specifically to Figure 6 , the present invention discloses an automatic recognition method for the axis network of architectural and structural CAD drawings, including the following steps:

[0049] S1. Drawing initialization

[0050] S11. Determine the range of the axis network to be extracted according to the architectural and structural CAD drawing.

[0051] S12. Explode all the blocks within the range of the axis network to be extracted into basic objects.

[0052] S13. Set the Z coordinate of all the objects within the range of the axis network to be extracted to zero.

[0053] S2. Drawing element reading

[0054] Read the basic objects within the range of the axis network to be extracted.

[0055] S3. Drawing element analysis, and initially extract the axis network objects

[0056] Analyze the scale objects within the range of the axis network to be extracted, and find all the scale objects that are connected end to end and jointly form a largest enclosed area. Find the line segments that coincide with the dimension lines forming the largest enclosed area, then find all the circle objects within the range of the axis network to be extracted that are connected to this line segment, and analyze this circle object. If the circle object simultaneously meets the following three conditions:

[0057] Condition 1: The circle object contains a text object.

[0058] Condition 2: There is a line segment connected to the side line of the circle object.

[0059] Condition 3: Find the horizontal or vertical overlapping line segment according to the line segment connected to the circle object, and set this line segment as the grid auxiliary line, which is the longest horizontal or vertical line within the range where the grid needs to be extracted.

[0060] Then the circle object and the line segments connected to the edges of the circle object are the initially extracted grid objects.

[0061] S4. Find the missing grid objects

[0062] According to the initially extracted grid objects obtained from the analysis in step S3, the following information can be obtained: the size of the grid circles, the layer of the grid circles, the layer of the grid text, the layer of the grid line segments, and the layer of the grid auxiliary line.

[0063] Then use the above information to search in reverse to find the missing grid objects, and the missing grid objects and the initially extracted grid objects obtained in step S4 together form all the grid objects.

[0064] According to the specific implementation manner of the present invention, the building and structure CAD drawing in step S11 is specifically the floor plan of the standard floor of the project building, and the floor plan of the standard floor of the project building is a file in.dwg format.

[0065] It should be noted that in the above implementation manner, the floor plan of the standard floor of the project building as shown in Figure 1 is selected.

[0066] Figure 2 is the initially extracted grid object obtained by parsing using the automatic recognition method of the grid in the building and structure CAD drawing of the present invention for Figure 1 .

[0067] Figure 3 is to find the missing grid objects by parsing using the automatic recognition method of the grid in the building and structure CAD drawing of the present invention for Figure 1 .

[0068] Figure 4 is the all grid objects obtained by parsing using the automatic recognition method of the grid in the building and structure CAD drawing of the present invention for Figure 1 .

[0069] Figure 5 is the effect diagram after excluding the parsed objects such as the grid and scale in Figure 1 . This diagram excludes information such as the grid and scale, and can be used as the basic drawing for the recognition of other components. It excludes the interference factors in the recognition process of other components, which is conducive to improving the recognition accuracy and reducing the recognition difficulty of other components.

[0070] According to the specific implementation manner of the present invention, in step S11, there are two ways to determine the range where the grid needs to be extracted:

[0071] Method 1: Cut the standard floor plan into files containing only a single drawing frame according to the range determined by each drawing frame in the standard floor plan.

[0072] Method 2: Manually select a single drawing frame in the standard floor plan to determine the range where the grid needs to be extracted.

[0073] It should be noted that:

[0074] (1) In step S12, exploding all the drawing blocks within the range where the grid needs to be extracted into basic objects means decomposing the drawing blocks using the decomposition command of Auto-CAD. The basic objects include: circle objects, line objects, polyline objects, polygon objects, text objects, ruler objects, etc.

[0075] (2) In step S2, all the objects within the range where the grid needs to be extracted are classified by type, including: circle objects, line objects, polyline objects, polygon objects, text objects, ruler objects. The ruler object is a dimension, which consists of dimension lines, dimension lines, dimension starting and ending symbols, and dimension numbers.

[0076] (3) In step S4, reverse search means: according to the information such as the size of the grid circles, the layer of the grid circles, the layer of the grid text, the layer of the grid line segments, and the layer of the grid auxiliary lines in the initially extracted grid objects, then search for other grid objects within the range where the grid needs to be extracted, and find the missing grid objects in this way. For example: by searching for other circles with the same size as the grid circles in the layer of the grid circles, this circle is the missing grid object. Of course, the missing grid objects can be found separately by searching in the layer of the grid auxiliary lines, the layer of the grid line segments, and the layer of the grid text.

[0077] In specific implementation, when the provided architectural and structural CAD drawings are relatively standard (the standard means that the grid text is on the same layer. The grid circles, grid auxiliary lines, grid line segments, etc. are on the same layer respectively, or the three are on the same layer together), through the above method, the missing grid features can be quickly and accurately found. If the quality of the provided architectural and structural CAD drawings is low, after the reverse search step, it is necessary to manually verify the results of the reverse search, and ensure the accuracy of the objects by manually excluding misselected items or manually adding missing items. However, regardless of whether the manual verification step is added, the efficiency of the automatic recognition method of the grid of an architectural and structural CAD drawing according to the present invention is still greatly improved compared with the existing manual model conversion operation method.

[0078] According to the specific implementation manner of the present invention, the basic objects in step S12 include: circles, lines, polylines, polygons, text, and dimension lines.

[0079] According to the specific embodiments of the present invention, when the range where grid lines need to be extracted in step S12 includes block definitions with attributes, the attribute text needs to be restored.

[0080] According to the specific embodiments of the present invention, before step S1, the following steps are further included: checking whether the floor plan of the standard floor of the project building can be normally opened and displayed by AutoCAD software. When the floor plan of the standard floor of the project building is a file in.dwg format drawn by a non-original CAD software, the file needs to be converted into a native file.

[0081] According to the specific embodiments of the present invention, the automatic recognition method for grid lines of the building and structure CAD drawings further includes: S5, based on all the grid line objects obtained in step S4, extracting the intersection points of all grid lines in different directions within the area enclosed by all the grid line objects. The intersection points include their own coordinate information and the information of the two grid lines forming the intersection points. Take the intersection point closest to the lower left corner of the largest enclosed area among all the intersection points as the reference point. Calculate the relative coordinate information of all the intersection points to the reference point to complete the extraction of grid line information, and the extracted grid line information is used as the main grid lines of the project building.

[0082] In specific implementation, if there are supplementary grid lines in other drawings, they can be added to the main grid lines in step S5.

[0083] According to the specific embodiments of the present invention, the automatic recognition method for grid lines of the building and structure CAD drawings further includes:

[0084] S6, storage of grid line information

[0085] Save the grid line information extracted in S5 as a.txt file and save it to the cloud database to complete the storage of grid line information.

[0086] In this embodiment, by determining the range where grid lines need to be extracted in the floor plan of the standard floor of the project building, it is used to extract the main grid line information of the building. Since the standard floor corresponding to the floor plan of the standard floor of the project building is conducive to extracting the main grid line information and improving the accuracy of grid line extraction.

[0087] According to the specific embodiments of the present invention, the relative coordinate information in step S5 refers to: the distance and angle information from the intersection point to the reference point, and the angle information refers to the included angle information between the line connecting each intersection point and the reference point and the positive direction of the X coordinate axis. Among them, the expression method of relative coordinates is the conventional expression method in Auto-CAD software drawing, that is, by the parameters of the distance and angle of the grid line intersection point relative to the reference point, the position of the grid line intersection point is accurately determined.

[0088] Of course, in specific implementation, other expression methods of relative coordinates can also be adopted, and the positions of the intersection points of the axis network can also be accurately determined. For example, by means of the incremental parameters of the X-axis and Y-axis of the intersection points of the axis network relative to the reference point.

[0089] The present invention also discloses an application method for the axis network of architectural and structural CAD drawings, including the following steps: during the BIM modeling process, after completing the modeling according to the architectural drawings or structural drawings, according to the axis network data of each modeling object in the architectural drawings or structural drawings, perform offset conversion towards the main axis network of the project building obtained in the above implementation manner, and then combine with the elevation data to automatically realize the spatial positioning of each building model.

[0090] In summary, it can be seen that by using the automatic recognition method for the axis network of architectural and structural CAD drawings of the present invention, it is possible to assist in the rapid filtering of axis network information during the process of reading architectural and structural drawings; the axis network information can be accurately extracted.

[0091] Apply the axis network information extracted by the automatic recognition method for the axis network of architectural and structural CAD drawings of the present invention to BIM modeling to assist in solving the problem of automatic global positioning of a single modeling object in a project building during the BIM modeling process, and improve the automation degree and efficiency of BIM modeling.

[0092] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An automatic recognition method for the axis network of architectural and structural CAD drawings, characterized in that, It includes the following steps: S1, Drawing initialization S11, Determine the range where the grid needs to be extracted according to the architectural and structural CAD drawings; There are two ways to determine the range where the grid needs to be extracted: Method 1: Cut the standard floor plan into files containing only a single drawing frame according to the range determined by each drawing frame in the standard floor plan; Method 2: Manually select a single drawing frame in the standard floor plan to determine the range where the grid needs to be extracted; S12, Explode all the blocks within the range where the grid needs to be extracted into basic objects. When the range where the grid needs to be extracted includes block definitions with attributes, the attribute text needs to be restored. The basic objects include: circles, lines, polylines, polygons, text, dimension lines; S13, Set the Z coordinates of all objects within the range where the grid needs to be extracted to zero; S2, Drawing element reading Read the basic objects within the range where the grid needs to be extracted; S3, Drawing element analysis, initially extract grid objects Analyze the scale objects within the range where the grid needs to be extracted, and find all the scale objects that are connected end to end and jointly form a largest enclosed area; Find the line segments that coincide with the extension lines of the dimensions that make up the largest enclosed area, and then find all the circle objects within the range where the grid needs to be extracted that are connected to this line segment, and analyze the circle objects. If the circle objects simultaneously meet the following three conditions: Condition 1: The circle object contains a text object; Condition 2: There is a line segment connected to the side of the circle object; Condition 3: According to the line segment connected to the circle object, find the line segment that coincides with it horizontally or vertically. This line segment is set as the grid auxiliary line, and this auxiliary line is the longest horizontal or vertical line within the range where the grid needs to be extracted; Then the circle object and the line segment connected to the side of the circle object are the initially extracted grid objects; S4, Find the missing grid objects Based on the initially extracted grid objects obtained from the analysis in step S3, the following information can be obtained: the size of the grid circles, the layers of the grid circles, the layers of the grid text, the layers of the grid line segments, the layers of the grid auxiliary lines; Then use the above information to search in reverse to find the missing grid objects. The missing grid objects and the initially extracted grid objects obtained in step S4 together form all the grid objects; S5, According to all the grid objects obtained in step S4, extract the intersections of all the grids in different directions within the area enclosed by all the grid objects. The intersections contain their own coordinate information and the information of the two grids that form the intersections; Take the intersection closest to the lower left corner of the largest enclosed area among all the intersections as the reference point; Calculate the relative coordinate information of all the intersections to the reference point to complete the extraction of the grid information. The extracted grid information is used as the main grid of the project building; The relative coordinate information refers to: the distance and angle information from the intersection to the reference point. The angle information refers to the included angle information between the line connecting each intersection to the reference point and the positive direction of the X coordinate axis.

2. The automatic recognition method of the axis network of the building and structure CAD drawings according to claim 1, characterized in that, The architectural and structural CAD drawings in step S11 are specifically the floor plan of the standard floor of the project building, and the floor plan of the standard floor of the project building is a file in.dwg format.

3. The automatic recognition method of the axis network of the building and structure CAD drawings according to claim 1, characterized in that, Before step S1, the following steps are further included: Check whether the floor plan of the standard floor of the project building can be normally opened and displayed using AutoCAD software; when the floor plan of the standard floor of the project building is a file in.dwg format drawn by a non-original CAD software, the file needs to be converted into a native file.

4. The automatic recognition method of the axis network of the building and structure CAD drawing according to claim 1, characterized in that, The automatic recognition method for the axis network of the architectural and structural CAD drawings further includes: S6, storage of axis network information Save the axis network information extracted in S5 as a.txt file and save it to the cloud database to complete the storage of the axis network information.

5. A method for applying the axis network of architectural and structural CAD drawings, characterized in that, It includes the following steps: During the BIM modeling process, after completing the modeling according to the architectural drawings or structural drawings, according to the axis network data of each modeling object in the architectural drawings or structural drawings, perform an offset conversion to the main axis network of the project building obtained in any one of claims 1-4, and then combine with the elevation data to automatically realize the spatial positioning of each building model.

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