JP7333801B2 - DATA CONVERSION PROGRAM, DATA CONVERSION METHOD, AND DATA CONVERSION DEVICE - Google Patents

Description

The present disclosure relates to a data conversion program, a data conversion method, and a data conversion device.

Conventionally, a method for automatic conversion from a CAD model to a surface-based combinatorial geometry (SBCG) format is known (see, for example, US Pat.

Japanese Patent Publication No. 2006-528814

By the way, 3D models (three-dimensional models) are roughly classified into wireframe models, surface models, and solid models as a modeling system. Since Patent Document 1 is a surface-based combined geometric shape, it is represented by a surface model and conversion to a solid model is not considered. Solid model representation methods include, for example, boundary representation (B-rep: Boundary Representation) and CSG representation (CSG: Constructive Solid Geometry).

Here, when converting CAD data into CSG data expressing a solid model in CSG, if the conversion method of Patent Document 1 is used, information for converting to SBCG format, which is a surface model, can be obtained from the CAD data. Therefore, information for converting to CSG data is insufficient. Also, when converting from CAD data to CSG data, depending on the shape of the solid model, it may be necessary to set an ambiguous plane that serves as an auxiliary plane for enabling the conversion to CSG data. For this reason, when converting CAD data into CSG data, it is necessary to manually add missing information or set ambiguous planes, which requires labor.

Therefore, an object of the present disclosure is to provide a data conversion program, a data conversion method, and a data conversion device that can suitably and automatically convert data from CAD data to CSG data.

A data conversion program according to the present disclosure uses hardware to perform data conversion from CAD data including a solid model modeled in a three-dimensional space to CSG data, which is data expressing the solid model using a spatial domain construction method. a data conversion program executed on the above, comprising: generating B-rep data, which is data representing a boundary of the solid model, based on the CAD data; and based on the generated B-rep data, generating the CSG data of the solid model using a predetermined algorithm for converting from the boundary representation to the CSG representation; and generating the B-rep data, the CAD data a step of acquiring information on the shell that partitions the solid model from the CAD data; a step of acquiring information on the surface elements that make up the shell from the CAD data; A step of setting information about an ambiguous surface to be a surface and a step of defining a half-space for the surface element are executed.

The data conversion method of the present disclosure is a data conversion method for converting CAD data including a solid model modeled in a three-dimensional space into CSG data, which is data expressing the solid model in CSG, by a spatial domain construction method. generating B-rep data, which is data representing the boundary of the solid model, based on the CAD data; and converting the boundary representation into the CSG representation based on the generated B-rep data. and generating the CSG data of the solid model using a predetermined algorithm for, wherein the generating the B-rep data includes, from the CAD data, information about shells that partition the solid model. a step of obtaining from the CAD data information on surface elements that make up the shell; and a step of setting information on ambiguous surfaces that are auxiliary surfaces for enabling conversion to the CSG data. and defining a half-space for the surface element.

A data conversion device of the present disclosure includes a computing unit that converts CAD data including a solid model modeled in a three-dimensional space into CSG data representing the solid model using a spatial domain construction method. A data conversion device, wherein the computing unit generates B-rep data, which is data representing a boundary of the solid model, based on the CAD data; and based on the generated B-rep data, generating the CSG data of the solid model using a predetermined algorithm for converting from the boundary representation to the CSG representation; and generating the B-rep data, the CAD data a step of acquiring information on the shell that partitions the solid model from the CAD data; a step of acquiring information on the surface elements that make up the shell from the CAD data; The steps of setting information about an ambiguous surface, which is a surface, and defining a half-space for the surface element are performed.

According to the present disclosure, data conversion from CAD data to CSG data can be preferably automatically executed.

FIG. 1 is a block diagram of a data conversion device according to this embodiment. FIG. 2 is an explanatory diagram of a processing flow regarding data conversion. FIG. 3 is a flowchart of an example of forward conversion of the data conversion method according to this embodiment. FIG. 4 is a flowchart of an example of forward conversion of the data conversion method according to this embodiment. FIG. 5 is an explanatory diagram of an example of setting the ambiguity plane. FIG. 6 is an explanatory diagram of an example of logic operations. FIG. 7 is an explanatory diagram of an example of logic operations. FIG. 8 is an explanatory diagram of an example regarding the setting of the ambiguity plane. FIG. 9 is an explanatory diagram of an example of logic operations. FIG. 10 is an explanatory diagram of an example of logic operations. FIG. 11 is an explanatory diagram of an example of setting the ambiguity plane. FIG. 12 is an explanatory diagram of an example of setting the ambiguity plane. FIG. 13 is an explanatory diagram of an example of setting the ambiguity plane. FIG. 14 is an explanatory diagram of an example of setting the ambiguity plane. FIG. 15 is an explanatory diagram of an example of setting the ambiguity plane. FIG. 16 is an explanatory diagram relating to the classification of the external area, the spatial area, and the object area. FIG. 17 is a flowchart of an example of a data conversion method according to this embodiment. FIG. 18 is a flowchart of an example of inverse conversion of the data conversion method according to this embodiment.

Hereinafter, embodiments according to the present disclosure will be described in detail based on the drawings. In addition, this invention is not limited by this embodiment. In addition, components in the following embodiments include components that can be easily replaced by those skilled in the art, or components that are substantially the same. Furthermore, the components described below can be combined as appropriate, and when there are multiple embodiments, each embodiment can be combined.

[Embodiment]
The data conversion program P, the data conversion method, and the data conversion apparatus 1 according to this embodiment automatically execute data conversion from CAD data to CSG data, and from CSG data to CAD data. The data conversion device 1 is a so-called computer (hardware), and can perform data conversion by executing a data conversion program P (software) stored in the computer.

FIG. 1 is a block diagram of a data conversion device according to this embodiment. FIG. 2 is an explanatory diagram of a processing flow regarding data conversion. 3 and 4 are flowcharts of an example of forward conversion of the data conversion method according to this embodiment. 5, 8, and 11 to 15 are explanatory diagrams of an example of setting the ambiguity plane. 6, 7, 9, and 10 are explanatory diagrams of examples of logic operations. FIG. 16 is an explanatory diagram relating to the classification of the external area, the spatial area, and the object area. FIG. 17 is a flowchart of an example of a data conversion method according to this embodiment. FIG. 18 is a flowchart of an example of inverse conversion of the data conversion method according to this embodiment.

(data converter)
First, the data conversion device 1 will be described with reference to FIG. The data conversion device 1 has an arithmetic unit 11 and a storage unit 12 .

The calculation unit 11 includes an integrated circuit such as a CPU (Central Processing Unit) that performs calculations for executing various programs. By executing the data conversion program P stored in the storage unit 12, the calculation unit 11 can execute various types of processing.

The memory unit 12 includes, for example, any memory device such as a semiconductor memory device and a magnetic memory device. The storage unit 12 is used as a work area for temporarily storing processing results of the calculation unit 11, and stores various programs and various data. The storage unit 12 stores, for example, various programs such as a data conversion program P for performing data conversion. In addition, the storage unit 12 stores, as various data, CAD data D1 and CSG data D3 to be converted, B-rep data D2 generated when converting the CAD data D1 and CSG data D3, CAD data D1, A table T or the like for linking information included in the CSG data D3 is stored.

By executing the data conversion program P, the calculation unit 11 can forward-convert the CAD data D1 into the CSG data D3 and inversely convert the CSG data D3 into the CAD data D1. In addition, the calculation unit 11 executes the data conversion program P to change the file format of the CAD data into a different format, or converts the file format into a file format used in another program based on the CSG data D3. It is possible.

Here, with reference to FIG. 2, a processing flow regarding data conversion processed by executing the data conversion program P will be specifically described. This data conversion program P is a program called "McBit". The CAD data D1 is data generated by CAD software, and a model generated by the CAD software is a solid model. A solid model is a model that is generated as a solid object with a solid content. The CAD data D1 is solid model data generated in a finite closed space, and the solid model data includes vertex data, edge line data, surface data, and shell data. Then, a shape of a solid model is created by CAD software (step S101). This CAD data D1 is output as a file format, for example, in STEP (Standard for the Exchange of Product model data) format (step S102). Further, the CAD software can output the created solid model as mesh data whose file format is, for example, STL (Standard Triangulated Language) format (step S103). In this embodiment, the STEP format and the STL format are used as file formats, but the present invention is not particularly limited to the above, and any file format may be used.

The calculation unit 11 executing the data conversion program P reads the CAD data D1 (step S104). Then, the calculation unit 11 generates B-rep data D2 based on the read CAD data D1 (step S106). The B-rep data D2 is data representing the boundary of the solid model. Boundary expression is to express surface elements that constitute a solid model, ridges that are boundaries between surface elements, and vertices that are endpoints of the ridges using equations. Also, the B-rep data D2 is associated with substance information (step S107). The substance information is a table T stored in the storage unit 12 . Specifically, the table T associates the color information of the CAD data D1, the color information, and the material information. Based on this table T, the CSG data D3 is associated with the material information corresponding to the color information of the CAD data D1. Note that the substance information includes information about materials and information about densities. Further, the calculation unit 11 can write (generate) the CAD data D1 based on the B-rep data D2 (step S105). Based on the written CAD data D1, the calculation unit 11 can output the CAD data D1 in the STEP format, and can also output the mesh data in the STL format.

The calculation unit 11 forward-converts the generated B-rep data D2 to the CSG data D3 (step S110) to generate the CSG data D3 (step S112). The CSG data D3 is data expressing a solid model in CSG. CSG representation is to represent a solid model by combining basic solids (primitive solids) and performing logical operations (also called Boolean operations or set operations). The calculation unit 11 can also inversely transform the CSG data D3 into the B-rep data D2 (step S111) to generate the B-rep data D2 (step S106). This CSG data D3 is used, for example, for radiation transport analysis code, optical design, stray light analysis, thermal radiation transport analysis, visual scene depiction, ray tracing, and the like. Therefore, the computing unit 11 can output the CSG data D3 as an input file for PHITS, which is one of the radiation transport analysis codes (steps S114 and S115). It can be output as an input file of MCNP, which is one of the transport analysis codes (steps S117 and S118). Furthermore, the computing unit 11 can generate the CSG data D3 based on the PHITS input file (step S113), and similarly can generate the CSG data D3 based on the MCNP input file. (step S116).

(Data conversion method)
Next, a data conversion method by the data conversion device 1 will be described with reference to FIGS. 3 and 4. FIG. 3 and 4 are data conversion methods for forward conversion from CAD data D1 to CSG data D3. In the data conversion method, a step S1 of generating solid model B-rep data D2 based on CAD data D1, and a step S2 of generating solid model CSG data D3 based on the generated B-rep data D2. , is running. FIG. 3 illustrates step S1 for generating B-rep data D2, and FIG. 4 illustrates step S2 for generating CSG data D3.

First, as shown in FIG. 3, when the CAD data D1 is obtained, the computing unit 11 processes a group of solid models (one or more solid models) included in the CAD data D1 (step S11). At step S11, the computing unit 11 defines a half-space for each solid model included in the CAD data D1, and takes a set of half-spaces of the solid model group (H _solids = O: empty set). Defining a half-space for a solid model means, for example, if the solid model is a sphere, the inside of the sphere is defined as a solid object area, and the outside of the sphere is defined as an empty space area. and is defined based on CAD data. Although the details will be described later, when the process of step S1 is executed, the bounding box B is used to divide the area into an area that includes the solid model and an external area that does not include the solid model.

Next, the computing unit 11 processes one or more shells that form each solid model (step S12). A shell is a continuous surface that partitions a solid model. For example, if the solid model is a rectangular parallelepiped, six faces forming the surface are defined as one shell. Further, for example, when the solid model is a rectangular parallelepiped box having a space inside, the six faces forming the outer surface are defined as one shell, and the six faces forming the inner surface are defined as one shell. be. That is, in step S12, the computing unit 11 acquires information on shells that partition the solid model from the CAD data D1.

Next, the computing unit 11 collects a group of faces that form one shell (step S13). Collecting a group of faces means, for example, if the shell is six faces on the front side of a rectangular parallelepiped, the six face elements are collected as a set F _shell of the group of faces. In other words, in step S13, the calculation unit 11 acquires information on surface elements forming the shell from the CAD data D1.

Thereafter, the calculation unit 11 determines whether or not to set the ambiguous plane based on the setting conditions for setting the ambiguous plane, and if it determines to set the ambiguous plane, additionally sets the ambiguous plane as a surface element. (Step S14). Here, the ambiguous plane is an auxiliary plane for enabling conversion to CSG data. When logical operations are performed between surface elements expressed by equations, depending on the shape of the surface elements, it may be difficult to appropriately express the shape of the solid model at the time of conversion to CSG data. Ambiguous planes are auxiliary planes that are set to appropriately express the shape of the solid model. At step S14, the computing unit 11 sets an ambiguous plane when the solid model satisfies a predetermined setting condition.

Here, the setting of the ambiguous plane will be described with reference to FIGS. 5 to 15. FIG. 5 to 10, the second setting condition shown in FIG. 11, the third setting condition shown in FIG. 13, a fifth setting condition shown in FIG. 14, and a sixth setting condition shown in FIG.

The first setting condition is that when the solid model has a cylindrical surface (or conical surface), two boundary lines (edge lines) between other surfaces provided on both sides of the cylindrical surface (or conical surface) in the circumferential direction This is a condition for setting a plane including three end points O1 out of four end points O1 at both ends of L1 as the ambiguous plane 20a. As shown in FIG. 5, the solid model M1 has an outwardly convex cylindrical surface and two planes connected to both sides of the cylindrical surface in the circumferential direction. A boundary line L1 is formed between the cylindrical surface and the plane on the other side. In step S14, the calculation unit 11 sets a plane including arbitrary three end points O1 among the four end points O1 at both ends of the two boundary lines L1 as the ambiguous plane 20a.

FIGS. 6 and 7 are explanatory diagrams of logic operations in cross sections obtained by cutting the solid model M1 of FIG. 5 along a horizontal plane. FIG. 6 shows the logical operation when the ambiguity plane 20a is not set, and FIG. 7 shows the logical operation when the ambiguity plane 20a is set.

As shown in FIG. 6, when the ambiguous surface 20a is not set, the solid model M1 undergoes a logical operation using a cylindrical surface and two planes. Here, the cylindrical surface has a half space A2 set inside, and the two planes have half spaces A1 and A3 set in the directions of the arrows. The solid model M1 is erroneously expressed as a cylinder whose inside of the cylindrical surface is solid by taking the common part (A1∩A2∩A3) of the half spaces A1 to A3 as a logical operation.

On the other hand, as shown in FIG. 7, when setting the ambiguous surface 20a, the solid model M1 undergoes a logical operation using the cylindrical surface, two planes, and the ambiguous surface 20a. The ambiguous plane 20a has half space A4 set in the direction of the arrow, and negation of half space A4 set in the direction of the arrow on the opposite side of half space A4. The solid model M1 takes the intersection (A1∩A3∩A4) of the half-spaces A1, A3, and A4 as a logical operation, and the intersection (A2∩notA4) of the negation of the half-spaces A2 and A4. A proper expression is obtained by taking the union of these intersections ((A1∩A3∩A4)∪(A2∩notA4)).

The solid model M1a shown in FIG. 8 has an inwardly concave cylindrical surface and two planes connected to both sides of the cylindrical surface in the circumferential direction. L1 is formed, and boundary line L1 is formed between the cylindrical surface and the plane on the other side. The solid model M1a shown in FIG. 8 has the unevenness of the cylindrical surface opposite to that of the solid model M1 shown in FIG. In this case as well, in step S14, the calculation unit 11 sets a plane including arbitrary three end points O1 among the four end points O1 at both ends of the two boundary lines L1 as the ambiguous plane 20a.

FIGS. 9 and 10 are explanatory diagrams of logic operations in cross sections obtained by cutting the solid model M1a of FIG. 8 along a horizontal plane. FIG. 9 shows the logical operation when the ambiguity plane 20a is not set, and FIG. 10 shows the logical operation when the ambiguity plane 20a is set.

As shown in FIG. 9, when the ambiguous surface 20a is not set, the solid model M1a undergoes a logical operation using a cylindrical surface and two planes. Here, half space A2 is set on the outside of the cylindrical surface, and half spaces A1 and A3 are set on the two planes in the directions of the arrows. The solid model M1a is erroneously expressed as an object with a hollow inside of the cylindrical surface by taking the common part (A1∩A2∩A3) of the half spaces A1 to A3 as a logical operation.

On the other hand, as shown in FIG. 10, when setting the ambiguous surface 20a, the solid model M1a undergoes a logical operation using the cylindrical surface, two planes, and the ambiguous surface 20a. The ambiguous plane 20a has a half space A4 set in the direction of the arrow. The solid model M1a is appropriately expressed by taking the common part (A1∩A2∩A3∩A4) of the half spaces A1 to A4 as a logical operation.

In addition, in the second to sixth setting conditions described below, the description of the logical operation as in the first setting condition is omitted, but the shape of the solid model is appropriately set as in the first setting condition. An ambiguity plane is set to represent.

The second setting condition is that if the solid model has edges connecting non-planes and if the edges can be placed on a plane, the plane containing the edges is set as an ambiguous surface. As shown on the left side of FIG. 11, the solid model M2a is a model in which cylinders having the same diameter are orthogonally connected to each other, and the cylindrical surfaces are connected to each other. The ridgelines L2 connecting the cylindrical surfaces are formed one on the upper side of the cylinder whose axial direction is the vertical direction in FIG. 11, and one on the lower side of the cylinder. It is connected. Each edge line L2 can be placed on a plane, and the calculation unit 11 sets the plane including the edge line L2 as the ambiguous plane 20b in step S14. As shown on the right side of FIG. 11, the solid model M2b is a model in which cylinders are connected to both ends of a semicircular ring, and the torus surface and the cylindrical surface are connected. A ridge line L3 connecting the torus surface and the cylindrical surface is formed at one end of the semi-annular ring and the other end of the semi-annular ring, and has a circular shape. The two edges L3 can be arranged on a plane, and the calculation unit 11 sets the plane including the two edges L3 as the ambiguous plane 20c in step S14.

The third setting condition is to set a cylindrical surface coaxial with the rotation axis of the torus surface as the ambiguous surface when the solid model has a torus surface. As shown on the left side of FIG. 12, the solid model M3a is a model in which a cylinder having a predetermined radius and an annular ring having a semicircular cross section whose diameter is the length of the outer peripheral surface of the cylinder in the axial direction are connected. It has a torus surface. The ridge line L4 connecting the torus surface and the end surface of the cylinder in the axial direction has a circular shape that is the radius of the cylinder. Then, a cylindrical surface passing through the ridgeline L4 is set as the ambiguous surface 20d. As shown on the right side of FIG. 12, the solid model M3b is a model having a torus surface in which the periphery of the end face in the axial direction of a cylinder having a predetermined radius is chamfered. A ridge line L5 is formed on the inner side of the torus surface, and in step S14, the calculation unit 11 sets a cylindrical surface having a radius larger than the radius of the ridge line L5 and smaller than the radius of the outer peripheral surface of the cylinder as the ambiguous surface 20e. set.

A fourth setting condition is a condition that, if the solid model has a torus surface, a plane perpendicular to the rotation axis of the torus surface is set as an ambiguous surface. As shown in FIG. 13, the solid model M4 is a bolt, and the bolt head has a torus surface in which the periphery of the end face in the axial direction of the bolt is chamfered. In FIG. 13, the left side is a perspective view and the right side is a side view. A ridgeline L6 is formed between the outer peripheral surface of the head of the bolt and the torus surface, and the ridgeline L6 has a contact point O2 that is connected to the adjacent ridgeline L6 at its ends. The calculation unit 11 sets a plane orthogonal to the rotation axis of the torus surface and passing through the contact point O2 of the ridgeline L6 as the ambiguous plane 20f.

As shown in FIG. 14, the fifth setting condition is that when the solid model has a torus surface and the ambiguous surfaces 20b and 20c set in the second setting condition are perpendicular to the rotation axis of the torus surface, the edge line Since L2 draws a circle, it is a condition to set a cylindrical surface that passes on the ridge line L2 and is coaxial with the rotation axis of the torus surface as the ambiguous surface 20g.

The sixth setting condition is a condition for setting a plane including the end face on the connection side of the small diameter cylindrical surface as an ambiguous surface when the solid model is formed by connecting cylindrical surfaces with different diameters. As shown in FIG. 15, the solid model M5 is a model in which a small-diameter cylinder is orthogonally connected to a large-diameter cylinder, and the cylindrical surfaces are connected to each other. A ridge line L7 connecting the cylindrical surfaces is formed on the peripheral surface of the large-diameter cylinder. In step S14, the calculation unit 11 sets a plane including the end face on the connection side of the small-diameter cylinder as the ambiguous plane 20h.

Again referring to FIG. 3, after executing step S14, the computing unit 11 defines a half-space for a surface group (a plurality of surface elements) of one shell, and creates a half-space set H _shell (step S15). Defining a half-space for a plane element means, for example, when the plane element is a plane, one side of the plane is defined as a solid object area, and the other side of the plane is defined as an empty space area. is. An object region in each shell of the solid model is then defined by taking a set of half-spaces of faces.

Thereafter, the computing unit 11 associates a set of half-spaces of the solid group with a set of half-spaces of shells in each solid model (Step S16) (H _solids =Merge(H _solids , H _shell )). Thereby, one or more shells are associated with each of one or more solid models included in the CAD data D1, and one or more surface elements are associated with each shell. A half-space is associated with the surface element. By executing such processing, surface elements, shells, and solid models are grouped, and information is collected as a hierarchical structure. The calculation unit 11 stores the collected information in the storage unit 12 as B-rep data D2.

Then, the calculation unit 11 determines whether or not the collection of the shell face group has been completed (step S17), and if it is determined that the collection of the face group has not been completed (step S17: No), step S13 is performed again. proceed to On the other hand, if the calculation unit 11 determines that the collection of the plane group has ended (step S17: Yes), it determines whether or not the shell processing has ended (step S18), and determines whether the shell processing has ended. If it is determined that there is no (step S18: No), the process proceeds to step S12 again. On the other hand, if the calculation unit 11 determines that the shell processing has ended (step S18: Yes), the process proceeds to step S2 in FIG.

As shown in FIG. 4, when generating the CSG data D3 of the solid model, the computing unit 11 first based on the B-rep data D2 is a half-space set (H _solids ) is acquired (step S21). After that, the computing unit 11 processes one or more shells forming each solid model (step S22). That is, in step S22, the computing unit 11 acquires information on the shells that partition the solid model from the B-rep data D2. The calculation unit 11 acquires a set of face groups F _shell and a set of half-spaces of the face groups H _shell as information on shells (step S23). Then, the calculation unit 11 executes processing using a BHC (B-rep Half CSG) algorithm for converting from the boundary representation to the CSG representation (step S24). By executing step S24, the calculation unit 11 acquires the CSG data D3 representing one shell in CSG (step S25).

After that, the computing unit 11 determines whether or not the CSG expressions of all shells have ended (step S26). When it is determined that the CSG expressions of all shells have not ended (step S26: No), The process proceeds to step S23 again. On the other hand, if the calculation unit 11 determines that the CSG representations of all shells have been completed (step S26: Yes), the CSG representations of each shell are combined by the intersect operation, and one solid model is CSG represented by the CSG representation. Data D3 is obtained (step S27). Then, the computing unit 11 determines whether or not the CSG representation of all solid models has ended (step S28), and if it determines that the CSG representation of all solid models has not ended (step S28: No). , the process proceeds to step S22 again. On the other hand, when the calculation unit 11 determines that the CSG representation of all solid models has been completed (step S28: Yes), the process proceeds to the next step S29. By executing steps up to step S28, the calculation unit 11 acquires the CSG data D3 of the solid model, as shown in step S112 of FIG.

When generating an MCNP/PHITS input file based on the CSG data D3 of the solid model, the calculation unit 11 executes steps S29 and S30. Specifically, in step S29, the calculation unit 11 acquires the MCNP/PHITS cell representation (cell data) from the CSG representation for each solid model. After that, the calculation unit 11 acquires the surface representation (surface data) of MCNP/PHITS from the half-space set (H _solids ) of the solid model group (step S30). Here, based on the table T, the calculation unit 11 can acquire substance information associated with the CSG data D3. Therefore, the calculation unit 11 can acquire the cell (three-dimensional) representation, plane representation, and material information required as input files for MCNP/PHITS. After executing step S30, the calculation unit 11 ends the process for forward conversion from the CAD data D1 to the CSG data D3. In addition. In step S30, if the acquired surface data (surface elements) overlap in the solid model, a step of deleting the overlapping surface elements is executed.

Next, with reference to FIG. 16, regions classified at the time of data conversion will be described. The CAD data D1 represents a solid model in a finite three-dimensional area. On the other hand, the CSG data D3 represents a solid model in an infinite three-dimensional area. Therefore, when forward transforming the CAD data D1 into the CSG data D3, it is necessary to divide the solid model into finite three-dimensional regions.

The calculation unit 11 sets a bounding box B that can be partitioned as a finite three-dimensional area in the forward transform. The bounding box B is set so as to include all solid models included in the CAD data D1. An area outside the bounding box B is set as an external area E1, and the external area E1 is treated as an area not subject to computation. The area inside the bounding box B is divided into a spatial area E2 and an object area E3. The spatial region E2 and the object region E3 are divided based on the half-space defined by the surface elements. That is, by defining one side of the surface element within the bounding box B as the spatial area E2 and the other side of the surface element as the object area E3, the spatial area E2 and the object area E3 are classified.

Here, with reference to FIG. 17, the processing related to region classification in the data conversion method will be described. The calculation unit 11 performs the area classification process shown in FIG. 16 on the solid model of the CAD data D1, and determines whether or not there is interference between the object areas E3 and interference between the spatial areas E2 (step S41). When determining that there is no interference between the regions (step S41: Yes), the calculation unit 11 performs forward conversion data conversion from the CAD data D1 to the CSG data D3 (step S42), and ends the process. On the other hand, when determining that there is interference between the areas (step S41: No), the calculation unit 11 executes error notification (step S43), and terminates the process.

Next, referring to FIG. 18, a data conversion method for inverse conversion from CSG data D3 to CAD data D1 will be described. In the data conversion method, steps S51 and S52 are executed to generate CAD data D1 of a solid model based on CSG data D3.

In FIG. 18, inverse conversion is performed based on the MCNP/PHITS input file. Specifically, as shown in FIG. 18, the computing unit 11 sets a finite area including the solid model for the solid model of the CSG data D3 (step S51). In step S51, the calculation unit 11 expresses a spatial region E2 and an object region E3 defined on the front and back sides (both sides) of the surface element from the finite area and the definition of the half space in each surface element of the solid model represented by the CSG. CAD data D1 is generated. For example, if the solid model is a rectangular parallelepiped, 12 pieces of CAD data D1 are generated for the front and back sides of the six faces.

Subsequently, the calculation unit 11 replaces the set operation of the surface data of the solid (cell) included in the input file of MCNP/PHITS with the set operation using the CAD data D1, so that the solid corresponding to the cell data is calculated. CAD data D1 of the model is generated (step S52), and the process is terminated.

As described above, the data conversion program P, the data conversion method, and the data conversion apparatus 1 described in this embodiment are understood as follows, for example.

A data conversion device 1 according to a first aspect converts CAD data D1 including a solid model modeled in a three-dimensional space into CSG data D3, which is data expressing the solid model in CSG by a spatial domain construction method. Steps S1 and S106 for generating B-rep data D2, which is data representing the boundary of the solid model, based on the CAD data D1, in a data conversion program P executed on hardware to perform the , steps S2 and S110 of generating the CSG data D3 of the solid model using a predetermined algorithm for converting from the boundary representation to the CSG representation based on the generated B-rep data D2; In the step S1 of generating the B-rep data, step S12 of acquiring information on the shell that partitions the solid model from the CAD data D1, and the surface elements constituting the shell from the CAD data D1. a step S13 of acquiring information about the surface element, a step S14 of setting information about an ambiguous surface as an auxiliary surface for enabling conversion to the CSG data, and a step S15 of defining a half space for the surface element; , is executed.

According to this configuration, a set of half-spaces corresponding to the plane group can be obtained as information for converting the CAD data D1 into the CSG data D3. Since the shape of the solid model can be appropriately represented, the solid model can be appropriately converted into the CSG data D3.

As a second aspect, in the step S14 of setting information about the ambiguous plane, the ambiguous planes 20a to 20h are set when the solid models M1 to M5 satisfy predetermined setting conditions, and the predetermined setting conditions are set. , when the solid model M1 has a cylindrical surface or a conical surface, four end points O1 Among them, a first setting condition that sets a plane including the three end points O1 as the ambiguous surface 20a, and the solid models M2a and M2b have edges L2 and L3 that connect non-planes, A second setting condition of setting planes containing the edges L2 and L3 as the ambiguous surfaces 20b and 20c when the edges L2 and L3 can be placed on a plane, and the solid models M3a and M3b have torus surfaces. , a third setting condition that sets cylindrical surfaces coaxial with the rotation axis of the torus surface as the ambiguous surfaces 20d and 20e; A fourth setting condition for setting a plane to be the ambiguous surface 20f as the ambiguous surface 20f, the solid models M2a and M2b have torus surfaces, and the ambiguous surfaces 20b and 20c set in the second setting condition are the torus Since the ridgeline L2 draws a circle when perpendicular to the rotation axis of the surface, the fifth setting is to set a cylindrical surface that passes over the ridgeline L2 and is coaxial with the rotation axis of the torus surface as the ambiguous surface 20g. and a sixth setting condition for setting, as the ambiguous surface 20h, a plane including the end face on the connection side of the cylindrical surfaces having the smaller diameter when the solid model M5 is formed by connecting cylindrical surfaces having different diameters. , including at least one setting condition among the first to sixth setting conditions.

According to this configuration, since an appropriate ambiguity plane can be set based on the setting conditions, data conversion from the CAD data D1 to the CSG data D3 can be performed more appropriately.

As a third aspect, in the step S1 of generating the B-rep data, an area including the solid model and an external area E1 not including the solid model are divided, and half of the surface element is divided into an area E1 that does not include the solid model. In step S15 for defining the space, the half space is defined so as to divide the surface element into the object region E3 and the space region E2 in the region containing the solid model.

According to this configuration, even when the solid model of the CAD data D1 is expressed in CSG, it is possible to express the solid model in a finite three-dimensional area, so it is suitable for the CSG data D3 from the CAD data D1. data can be converted to

As a fourth aspect, in the step S2 of generating the CSG data D3, in step S41 of determining interference between the object areas E3 and interference between the spatial areas E2, if it is determined that there is interference, an error A step S43 of notifying is further executed.

According to this configuration, when converting the CAD data D1 into the CSG data D3, erroneous conversion of data due to area interference can be suppressed.

As a fifth mode, when the overlapping surface elements are defined in the solid model of the generated CSG data D3, the step of deleting the overlapping surface elements is further executed.

According to this configuration, for example, even when the CSG data D3 is used as an input file for MCNP or PHITS, an input file with appropriate surface data can be generated by deleting overlapping surface elements. can.

As a sixth aspect, the CAD data D1 further includes color information attached to the solid model, and the CSG data D3 generated based on a table T that associates the color information and material information. A step S107 of associating the material information with the solid model is further performed.

According to this configuration, the material information can be associated with the CSG data D3 using the table T based on the color information of the CAD data D1.

and generating the CAD data of the solid model based on the CSG data of the solid model.

According to this configuration, inverse transformation can be performed from the CSG data D3 to the CAD data D1.

A data conversion method according to an eighth aspect converts CAD data including a solid model modeled in a three-dimensional space into CSG data representing the solid model by a spatial domain construction method. A method comprising: generating B-rep data, which is data representing a boundary representation of the solid model, based on the CAD data; and generating the CSG representation from the boundary representation based on the generated B-rep data. and generating the CSG data of the solid model using a predetermined algorithm to convert the solid model into a step of obtaining information about a shell; a step of obtaining information about surface elements that make up the shell from the CAD data; and defining a half-space for the surface element.

According to this configuration, a set of half-spaces corresponding to the plane group can be obtained as information for converting the CAD data D1 into the CSG data D3. Since the shape of the solid model can be appropriately represented, the solid model can be appropriately converted into the CSG data D3.

A data conversion device 1 according to a ninth aspect performs data conversion from CAD data including a solid model modeled in a three-dimensional space to CSG data representing the solid model by a spatial domain construction method. a data conversion apparatus comprising: a step of generating B-rep data, which is data representing a boundary of the solid model, based on the CAD data; and the generated B-rep data. generating the CSG data of the solid model using a predetermined algorithm for converting from the boundary representation to the CSG representation based on , a step of obtaining from the CAD data information about the shells that partition the solid model, a step of obtaining from the CAD data about surface elements that constitute the shells, and a conversion into the CSG data. A step of setting information about an ambiguous surface, which is an auxiliary surface for estimating the surface element, and a step of defining a half-space for the surface element are executed.

According to this configuration, a set of half-spaces corresponding to the plane group can be obtained as information for converting the CAD data D1 into the CSG data D3. Since the shape of the solid model can be appropriately represented, the solid model can be appropriately converted into the CSG data D3.

1 data conversion device 11 calculation unit 12 storage unit 20a to 20h ambiguous surface P data conversion program D1 CAD data D2 B-rep data D3 CSG data T table B bounding box E1 external area E2 spatial area E3 object area M1 to M5 solid model

Claims (9)

A data conversion program executed on hardware to convert CAD data including a solid model modeled in a three-dimensional space into CSG data representing the solid model using the spatial domain construction method. and
a step of generating B-rep data, which is data representing a boundary of the solid model, based on the CAD data;
generating the CSG data of the solid model using a predetermined algorithm for converting from the boundary representation to the CSG representation based on the generated B-rep data;
In the step of generating the B-rep data,
obtaining information about shells that define the solid model from the CAD data;
a step of obtaining information about surface elements that constitute the shell from the CAD data;
setting information about an ambiguity plane that serves as an auxiliary plane for enabling conversion to the CSG data;
defining a half-space for the surface element. In the step of setting information about the ambiguity plane,
the ambiguity plane is set when the solid model satisfies a predetermined setting condition;
As the predetermined setting condition,
When the solid model has a cylindrical surface or a conical surface, three of the four end points at both ends of the two boundary lines between the cylindrical surface or the conical surface and other surfaces provided on both sides in the circumferential direction a first setting condition for setting a plane including the end point as the ambiguous plane;
a second setting condition for setting a plane including the edge line as the ambiguous surface if the solid model has an edge line connecting non-planes and the edge line can be placed on a plane;
a third setting condition for setting, when the solid model has a torus surface, a cylindrical surface coaxial with the rotation axis of the torus surface as the ambiguous surface;
a fourth setting condition for setting a plane orthogonal to the axis of rotation of the torus surface as the ambiguous surface when the solid model has a torus surface;
When the solid model has a torus surface, and the ambiguous surface set in the second setting condition is orthogonal to the rotation axis of the torus surface, the ridgeline draws a circle. , a fifth setting condition for setting a cylindrical surface coaxial with the rotation axis of the torus surface as the ambiguous surface;
a sixth setting condition for setting a plane including an end face on the connection side of the cylindrical surface with a smaller diameter as the ambiguous surface when the solid model is a model in which cylindrical surfaces with different diameters are connected to each other;
2. The data conversion program according to claim 1, including at least one setting condition among said first setting condition to said sixth setting condition. In the step of generating the B-rep data,
divided into an area containing the solid model and an external area not containing the solid model,
The step of defining a half-space for the surface element includes:
3. The data conversion program according to claim 1, wherein the half-space is defined so as to divide the plane element into an object area and a space area within the area containing the solid model. In the step of generating the CSG data,
determining interference between the object regions and interference between the spatial regions;
4. The data conversion program according to claim 3, further executing a step of announcing an error when it is determined that there is interference. 5. The data according to any one of claims 1 to 4, further comprising a step of deleting the overlapping surface elements if the overlapping surface elements are defined in the solid model of the generated CSG data. conversion program. the CAD data further includes color information attached to the solid model;
6. The method according to any one of claims 1 to 5, further comprising associating the material information with the solid model of the generated CSG data based on a table associating the color information with the material information. Data conversion program. and generating the CAD data of the solid model based on the CSG data of the solid model. Data conversion performed by a data conversion device having a computing unit that converts CAD data including a solid model modeled in a three-dimensional space into CSG data representing the solid model using a spatial domain construction method. a method,
The calculation unit is
a step of generating B-rep data, which is data representing a boundary of the solid model, based on the CAD data;
generating the CSG data of the solid model using a predetermined algorithm for converting from the boundary representation to the CSG representation based on the generated B-rep data;
In the step of generating the B-rep data,
obtaining information about shells that define the solid model from the CAD data;
a step of obtaining information about surface elements that constitute the shell from the CAD data;
setting information about an ambiguity plane, which is an auxiliary plane for enabling conversion to the CSG data;
defining a half-space for said surface element. A data conversion device comprising a computing unit that converts CAD data including a solid model modeled in a three-dimensional space into CSG data representing the solid model using a spatial domain construction method,
The calculation unit is
a step of generating B-rep data, which is data representing a boundary of the solid model, based on the CAD data;
generating the CSG data of the solid model using a predetermined algorithm for converting from the boundary representation to the CSG representation based on the generated B-rep data;
In the step of generating the B-rep data,
obtaining information about shells that define the solid model from the CAD data;
a step of obtaining information about surface elements that constitute the shell from the CAD data;
setting information about an ambiguity plane, which is an auxiliary plane for enabling conversion to the CSG data;
defining a half-space for said surface element.

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