JP6651978B2 - Center determination program, center determination method, and center determination device - Google Patents

Description

  The present invention relates to a center determination program, a center determination method, and a center determination device.

  2. Description of the Related Art Conventionally, there is a technique for performing numerical analysis such as fluid analysis. In order to perform a numerical analysis, a model created by CAD (Computer Aided Design) is subjected to element division or the like, and a three-dimensional model for analysis is created.

  As prior art, two different tangent planes, their normal vectors, and bisecting planes are set from a plurality of points outside the cylinder, and the intersection of all the bisecting planes or the closest straight line to the center of the cylinder is set. There is a technique of calculating the position and orientation of an axis and calculating the diameter of a cylinder as the distance between the center axis of the cylinder and a tangent plane (for example, refer to Patent Document 1 below).

JP-A-11-051635

  However, conventionally, since the analysis model is represented by a plurality of elements, there is a problem that the analysis model does not have center information about the center. For example, when analyzing a fluid flowing through a pipe or the like, center information about the center of the pipe is used. If there is no central information, it takes time for the analyst to manually create the central information.

  In one aspect, an object of the present invention is to provide a center determination program, a center determination method, and a center determination device that can determine the center of a cross section of an analysis model having no center information.

  According to one aspect of the present invention, a cross-section of a three-dimensional model is specified in response to an input, and in a state where a center of a predetermined solid is located on each of the plurality of line segments included in the specified cross-section. The volume of the overlapping region between the predetermined solid and the three-dimensional model when the predetermined solid is moved is calculated, and the calculated volume of the overlapping region of the plurality of line segments is the largest. The line segment is specified according to a change in the volume of an overlapping area of the predetermined solid and the three-dimensional model when the predetermined solid is moved in the specified line segment. A center determination program, a center determination method, and a center determination device that determine and output the center point of the cross section from the points included in are provided.

  According to one embodiment of the present invention, the center of a cross section of an analysis model without center information can be determined.

FIG. 1 is an explanatory diagram illustrating an operation example of the center determination device. FIG. 2 is an explanatory diagram illustrating an example of a hardware configuration of the center determination device. FIG. 3 is a block diagram illustrating a functional configuration example of the center determination device. FIG. 4 is an explanatory diagram showing an example of a three-dimensional model based on CAD data and an analysis model based on analysis model data. FIG. 5 is an explanatory diagram illustrating a data configuration example of the analysis model data. FIG. 6 is an explanatory diagram showing an example of determining a normal line and a cross section of the three-dimensional model 401 by tetra selection. FIG. 7 is an explanatory diagram showing an example in which a cross section cannot be obtained. FIG. 8 is an explanatory diagram illustrating an example (part 1) of drawing a plurality of line segments. FIG. 9 is an explanatory diagram illustrating an example of calculating the diameter of a sphere. FIG. 10 is an explanatory diagram illustrating an example of movement of a sphere. FIG. 11 is an explanatory diagram illustrating an example of calculating a volume. FIG. 12 is an explanatory diagram illustrating an example of a change in volume in a line segment. FIG. 13 is an explanatory diagram illustrating an example of obtaining a center point of a cross section. FIG. 14 is an explanatory diagram illustrating an example (part 2) of drawing a plurality of line segments. FIG. 15 is an explanatory diagram illustrating an example of obtaining the center axis of the pipe. FIG. 16 is a flowchart illustrating an example of a procedure of a center determination process performed by the center determination apparatus. FIG. 17 is a flowchart illustrating an example of a cross-section identification processing procedure performed by the center determination device. FIG. 18 is a flowchart illustrating an example of a volume calculation processing procedure performed by the center determination device. FIG. 19 is a flowchart illustrating an example of a center point specifying process procedure.

  Hereinafter, with reference to the accompanying drawings, embodiments of a center determination program, a center determination method, and a center determination device according to the present invention will be described in detail.

  FIG. 1 is an explanatory diagram illustrating an operation example of the center determination device. The center determination device 100 is a computer that determines the center of a cross section 102 of a three-dimensional model 101 such as a pipe. The three-dimensional model 101 is in a state where numerical analysis can be performed by approximating an object or a human body to be analyzed, and is arranged in a simulation space.

  The simulation space is a space set to represent on a computer an analysis region including a physical object or a human body to be analyzed and a space outside the object or the human body. The analysis target model divides an object or a human body simulated in a simulation space into small small elements, and represents the shape of the entire analysis target object or human body as a set of elements. Examples of the shape of the element include a tetrahedron, a pentahedron, and a hexahedron. In the present embodiment, a tetrahedron is taken as an example of the shape of the element, and the element is also referred to as tetra. In the simulation space, for example, a three-dimensional orthogonal coordinate system having an x-axis, a y-axis, and a z-axis is defined.

  Conventionally, since an analysis model is represented by a plurality of elements, there is a problem that the analysis model has no center information about the center. For example, in order to analyze a fluid flowing through a pipe or the like, center information about the center of the pipe is used. However, if there is information on the center in the CAD data representing the three-dimensional shape, the CAD data may be diverted, but the CAD data may not have the center information on the center. Before analyzing the fluid, a user such as an analyst must manually determine the center of the pipe and create the center information, which is troublesome for the user.

  Therefore, in the present embodiment, the center determination device 100 determines the volume of the overlapping region between the solid and the model when the center of the solid is placed at each position on the line for each line on the cross section 102 of the analysis model. , The center point of the cross section 102 is specified from the respective positions. Thereby, the center of the cross section 102 of the analysis model having no center information can be determined. Then, since the central information can be easily obtained, the trouble of the user can be saved. In the example of FIG. 1, the three-dimensional model 101 is a model representing a pipe. Here, the three-dimensional model 101 is a cylinder, but the tube is not necessarily a cylinder, so it is difficult for the user to determine the center.

  First, the center determination device 100 specifies the cross section 102 of the three-dimensional model 101 according to the input. The center determination device 100 may receive, for example, a specification of which range is to be analyzed by a user operation. In addition, the center determination device 100 specifies, for example, a cross section 102 of the three-dimensional model 101 at a height designated by a user operation.

  Next, the center determination device 100 moves the predetermined solid in a state where the center of the predetermined solid is located on each of the plurality of line segments included in the specified cross section 102. In the example of FIG. 1, the predetermined solid is a sphere b. In the example of FIG. 1, the plurality of line segments included in the cross section 102 are line segments e1 to e5.

  Next, the center determination device 100 calculates the volume of the overlapping area of the sphere b and the three-dimensional model 101 when the sphere b is moved. The center determination device 100 may determine the movement interval for moving the sphere b by an input according to a user operation. In the example of FIG. 1, the center determination device 100 calculates the volume of the overlapping area of the sphere b and the three-dimensional model 101 when the sphere b is arranged at each of the points p21 to p25 of the line segment e2. Further, in the example of FIG. 1, the center determination device 100 calculates the volume of the overlapping area of the sphere b and the three-dimensional model 101 when the sphere b is arranged at each of the points p31 to p36 of the line segment e3.

  The center determination device 100 specifies a line segment having the largest volume of the calculated overlapping region among the plurality of line segments. In the example of FIG. 1, the line segment having the largest volume of the calculated overlapping area is the line segment e3.

  Then, the center determination device 100 calculates a cross-section from a point included in the line segment according to a change in the volume of the overlapping area between the sphere b and the three-dimensional model 101 when the sphere b is moved in the specified line segment. The center point of 102 is determined. The center determination device 100 sets the point p34 having the largest calculated volume among the points of the specified line segment e3 as the center point. Next, the center determination device 100 outputs the center point. The center determination device 100 displays, for example, a three-dimensional model 101, a cross section 102, and a center point on a display or the like. Thereby, the center of the cross section 102 of the analysis model having no center information can be determined.

(Example of hardware configuration of center determination device 100)
FIG. 2 is an explanatory diagram illustrating an example of a hardware configuration of the center determination device. The center determination device 100 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, a disk drive 204, and a disk 205. The center determination device 100 includes an I / F (Inter / Face) 206, a keyboard 207, a mouse 208, and a display 209. The CPU 201, the ROM 202, the RAM 203, the disk drive 204, the I / F 206, the keyboard 207, the mouse 208, and the display 209 are connected by the bus 200, respectively.

  Here, the CPU 201 governs overall control of the center determination device 100. The ROM 202 stores a program such as a boot program. The RAM 203 is used as a work area of the CPU 201. The disk drive 204 controls reading / writing of data from / to the disk 205 under the control of the CPU 201. The disk 205 stores data written under the control of the disk drive 204. Examples of the disk 205 include a magnetic disk and an optical disk.

  The I / F 206 is connected to a network 210 such as a LAN (Local Area Network), a WAN (Wide Area Network), or the Internet via a communication line, and is connected to another device via the network 210. The I / F 206 controls an internal interface with the network 210 and controls input and output of data from and to external devices. As the I / F 206, for example, a modem, a LAN adapter, or the like can be employed.

  The keyboard 207 and the mouse 208 are interfaces that receive input of various data by a user's operation. The display 209 is an interface that outputs data according to an instruction from the CPU 201.

  Although not shown, the center determination device 100 may be provided with an input device that captures an image or a moving image from a camera or an input device that captures sound from a microphone. Although not shown, the center determination device 100 may be provided with an output device such as a printer.

  In the present embodiment, a personal computer is used as an example of the hardware configuration of the center determination device 100. However, the hardware configuration is not limited thereto, and a server or the like may be used. When the center determination device 100 is a server, the center determination device 100 and a device operable by a user, a display 209, and the like may be connected via the network 210.

(Example of Functional Configuration of Center Determination Apparatus 100)
FIG. 3 is a block diagram illustrating a functional configuration example of the center determination device. The center determination device 100 includes a receiving unit 301, a cross section creating unit 302, a line segment creating unit 303, a diameter determining unit 304, a moving unit 305, a calculating unit 306, a first identifying unit 307, and a second identifying unit. It has a unit 308, a determination unit 309, a third specifying unit 310, and an output unit 311. The processing of the control unit from the reception unit 301 to the output unit 311 is coded in a program stored in a storage device such as the ROM 202, the RAM 203, and the disk 205 that can be accessed by the CPU 201 illustrated in FIG. Then, the CPU 201 reads out the program from the storage device and executes a process coded in the program. Thereby, the processing of the control unit is realized. The processing result of the control unit is stored in a storage device such as the RAM 203, the ROM 202, and the disk 205, for example.

  In each part, the process of creating a line segment, a plane, a cross section, a point, a sphere, a central axis, and the like is not created in an actual space but in a simulation space. Creating in the simulation space corresponds to generating information representing a line segment, a plane, a cross section, a point, a sphere, and a central axis in analysis model data and CAD data.

  FIG. 4 is an explanatory diagram showing an example of a three-dimensional model based on CAD data and an analysis model based on analysis model data. The three-dimensional model 400 is a three-dimensional model in which an object or a human body is represented by a polygon. The three-dimensional model 400 is represented by CAD data. CAD data is created using CAD.

  The three-dimensional model 401 is a three-dimensional model represented by dividing the shape of an object or a human body into a plurality of meshes. The three-dimensional model 401 is represented by analysis model data. The analysis model data is created by performing mesh division on the three-dimensional model 400 using CAE (Computer Aided Engineering). In the present embodiment, since the object to be analyzed is a tube, the three-dimensional model 401 is also called a tube.

  FIG. 5 is an explanatory diagram illustrating a data configuration example of the analysis model data. The analysis model data 500 has information indicating a tetra ID (Identification), a node ID, each coordinate, and the like. FIG. 5 shows one tetra. The ID of the tetra is "10000".

  The analysis model data 500 has tetra data 501 and node data 510. As shown in FIG. 5A, the tetra data 501 has a tetra ID field and four node ID fields. The tetra data 501 is stored as a record (such as 502-1) by setting information in each field. In the tetra ID field, a tetra ID, which is identification information of the tetra, is set.

  Taking the tetra ID "10000" as an example, the node IDs are "40000" to "40003".

  As shown in FIG. 5 (2), the node data 510 represents the position information of the node. The node data 510 has fields of node ID, x coordinate, y coordinate, and z coordinate. The information is set in each field and stored as a record (511-1 or the like). In the field of the node ID, a node ID which is identification information of the node is set. The x-coordinate value of the node is set in the x-coordinate field. The y-coordinate value of the node is set in the y-coordinate field. In the z coordinate field, the z coordinate value of the node is set.

  The reception unit 301 illustrated in FIG. 3 receives designation of an entrance and an exit of the three-dimensional model 401 by a user operation. The accepting unit 301 accepts the designation of the entrance and the exit of the three-dimensional model 401 in the three-dimensional model 401 displayed on the display 209 or the like by an operation input using the mouse 208 or the keyboard 207.

  FIG. 6 is an explanatory diagram showing an example of determining a normal line and a cross section of the three-dimensional model 401 by tetra selection. The cross section creation unit 302 selects any tetra from tetra included in the surface of the three-dimensional model 401. In the example of FIG. 6, the cross section creation unit 302 selects tetra ta.

  The cross section creation unit 302 generates a normal line from the bottom surface of the selected tetra ta in the direction toward the inside of the tube. Next, the cross section creation unit 302 selects any side of the bottom surface of the selected tetra ta. Then, the cross section creation unit 302 creates the plane 600 based on the selected one side and the normal line. Subsequently, the cross section creation unit 302 creates an overlapping portion of the created plane 600 and the three-dimensional model 401 as a section 601.

  FIG. 7 is an explanatory diagram showing an example in which a cross section cannot be obtained. As shown in FIG. 7, when the created plane 700 intersects with the end face that is the entrance 701 or the exit 702 of the three-dimensional model 401, a cross section of the three-dimensional model 401 cannot be obtained.

  Therefore, after creating the plane, the cross-section creating unit 302 determines whether or not the created plane intersects the end face of the three-dimensional model 401 that is the entrance 701 or the exit 702. Then, when the created plane does not intersect with the end face, the section creating unit 302 creates a section as described with reference to FIG.

  When determining that the created plane intersects the end face, the cross section creation unit 302 newly selects an unselected side of the bottom surface of the selected tetra ta. Next, as described with reference to FIG. 6, the cross section creation unit 302 creates a plane based on the selected side and the normal line. Then, the cross section creation unit 302 creates an overlapping portion between the created plane and the three-dimensional model 401 as a cross section.

  Next, the line segment creation unit 303 creates a plurality of line segments on the cross section based on either the starting point of the normal line or any point on the cross section on the created cross section. Here, an example is described in which the starting point of the normal is used as a reference. The reference indicates, for example, that the starting point of the normal line is the starting point of each line segment. By using the start point of the normal line when creating a plurality of line segments, the time for newly finding the start point of the line segment becomes unnecessary, so that the processing time can be shortened.

  The line segment creation unit 303 creates a plurality of line segments at random from the start point. Alternatively, the line segment creating unit 303 creates a plurality of line segments that form an angle with the normal on the cross section with reference to the start point of the normal. The line segment creating unit 303 creates, for example, a line segment that forms 25 degrees with the normal line. Then, the line segment creating unit 303 creates a line segment that forms 50 degrees with the normal line. Further, the line segment creating unit 303 creates a line segment that forms 75 degrees with the normal. As described above, the line segment creation unit 303 may create a plurality of line segments by sequentially increasing the angle.

  FIG. 8 is an explanatory diagram illustrating an example (part 1) of drawing a plurality of line segments. As shown in FIG. 8, the normal is not always perpendicular to the surface of the tube, which is the three-dimensional model 401. Therefore, by creating a line segment that forms an angle with the normal, the normal is closer to the center axis of the tube. Can be created.

  In the example of FIG. 8, the line segment creating unit 303 creates a plurality of line segments e1 to e5 on the created cross section, starting from the starting point of the normal. Line segment e2 is a normal line.

  Next, the moving unit 305 moves the predetermined solid in a state where the center of the predetermined solid is located on each of the plurality of line segments included in the specified cross section. Then, the calculation unit 306 calculates the volume of the overlapping area of the predetermined solid and the three-dimensional model 401 when the predetermined solid is moved. When the predetermined solid is a sphere, a polyhedron, or the like, the more uniform the distance between the center of the predetermined solid and the predetermined surface, the higher the possibility that the finally obtained center point is accurate. For example, in the case of a regular polyhedron, as the number of faces increases, the accuracy of the final center point can be improved. When the predetermined solid is a sphere, the moving unit 305 can easily generate a sphere in the simulation space based on information on the center and the radius. For this reason, the calculation time can be reduced.

  In the present embodiment, a predetermined solid is described as a sphere. FIG. 8 shows an example in which spheres are arranged for each line segment. Here, the diameter of the sphere moved by the moving unit 305 will be described. For example, the sphere must be at least larger than tetra alone. For this reason, the diameter determining unit 304 may set the diameter of the sphere to about 10 times the selected tetra.

  In addition, the diameter determining unit 304 determines the diameter of the sphere to be a value based on the maximum length of each of the plurality of line segments. The value based on the maximum length is the maximum length itself or a value obtained by adding or subtracting a margin from the maximum length. FIG. 9 shows an example of calculating the diameter of a sphere.

  FIG. 9 is an explanatory diagram illustrating an example of calculating the diameter of a sphere. The diameter determining unit 304 calculates the length of each of the plurality of line segments. The process of calculating the length of a line segment is the same as the process of calculating the length of a three-dimensional vector. For example, for each of the plurality of line segments, the diameter determining unit 304 calculates the distance between the start point of the line segment and the intersection between the line segment and the surface of the three-dimensional model 401. FIG. 9 shows a formula for calculating the length D3 of the line segment e3.

  Then, the diameter determining unit 304 determines the maximum length D3 of the calculated lengths D1 to D5 as the diameter of the sphere 900. For example, if the diameter of the sphere 900 is too small, the number of positions where the volume of the overlapping area between the sphere 900 and the three-dimensional model 401 becomes maximum when the sphere 900 is moved to each position of the line segment increases. . Further, if the diameter of the sphere 900 is larger than the cross section, the number of positions where the volume of the overlapping area of the sphere 900 and the three-dimensional model 401 becomes maximum when the sphere 900 is moved to each position of the line segment is large. turn into. Therefore, by setting the maximum length of the length of each line segment as the diameter of the sphere 900, the sphere 900 can include the whole in the direction of the line segment of the cross section, and the overlapping area of the sphere 900 and the tube Can be reduced in the number of positions where the volume becomes maximum. Therefore, the accuracy of obtaining the center point can be improved.

  Next, the moving unit 305 moves each of the plurality of line segments with the center of the sphere 900 positioned on the line segment. The movement interval may be, for example, about the length of a side included in the selected tetra included in the surface of the three-dimensional model 401.

  FIG. 10 is an explanatory diagram illustrating an example of movement of a sphere. Taking the line segment e3 as an example, the moving unit 305 moves the sphere 900 so that the center of the sphere 900 is located in order from the start point s1 to the end point sn of the line segment e3. The calculation unit 306 calculates the volume of the overlapping area between the sphere 900 and the three-dimensional model 401 when the sphere 900 is moved.

  FIG. 11 is an explanatory diagram illustrating an example of calculating a volume. The calculation unit 306 specifies an overlapping area between the sphere 900 and the three-dimensional model 401 in order to calculate the volume. For example, the calculation unit 306 specifies the tetra included in the sphere 900 among the tetra included in the three-dimensional model 401 as the overlapping area. In the example of FIG. 11, the calculation unit 306 specifies a tetra included in the sphere 900, such as “tetra t1, t2, t3, t4, t5. Then, the calculation unit 306 calculates the total value of the identified tetra volumes as the volume of the overlapping region. In the example of FIG. 11, the calculation unit 306 calculates the sum of the volumes of “tetra t1, t2, t3, t4, t5...” As the volume of the overlap region.

  Next, the first specifying unit 307 illustrated in FIG. 3 specifies, from among the plurality of line segments, the line segment having the largest volume of the calculated overlapping region. When there are a plurality of line segments having the same largest volume, the first specifying unit 307 specifies a line segment having the largest number of moving points for which the largest volume has been calculated among the line segments for which the largest volume has been calculated. I do. Since the volumes at a plurality of moving points are calculated for each line segment, the first specifying unit 307 improves the accuracy for obtaining the center point by specifying the line segment having the largest volume at more moving points. Can be achieved.

  FIG. 12 is an explanatory diagram illustrating an example of a change in volume in a line segment. FIG. 12 shows a graph of the volume at each moving point for two line segments. The graph 1200 and the graph 1201 show the sum of the volumes of tetra contained in the sphere 900 when the center of the sphere 900 is moved in each movement from the start point to the end point of the line segment. The maximum volume is the same between the volume at each moving point of the line segment represented by the graph 1200 and the volume at each moving point of the line segment represented by the graph 1201. In such a case, the first specifying unit 307 selects a line segment in which the volume has no peak and there are many moving points having the maximum volume.

  The second specifying unit 308 specifies the center point of the sphere 900 based on a change in volume of the line segment specified by the first specifying unit 307.

  When there is a volume peak as in the graph 1200, the second specifying unit 308 specifies the center point of the sphere 900 that is the volume peak. When there is no volume peak as in the graph 1201, the second specifying unit 308 specifies the center point located at the center among the center points of the spheres 900 having the maximum volume.

  The determination unit 309 determines the center point of the cross section based on the center point of the sphere 900 specified by the second specifying unit 308.

  FIG. 13 is an explanatory diagram illustrating an example of obtaining a center point of a cross section. The determination unit 309 determines, for example, the tetra node closest to the center point of the sphere 900 specified by the second specifying unit 308 as the center point of the cross section. In the example of FIG. 13, the center point of the specified sphere 900 coincides with the nearest tetra node.

  Then, the output unit 311 outputs the center point of the cross section. The output unit 311 displays the center point of the cross section on the display 209 or the like in accordance with the three-dimensional model 401, for example. The output unit 311 stores, for example, information indicating the central axis in a storage device such as the RAM 203 or the disk 205.

  In the above example, when creating a plurality of line segments, the line segment creation unit 303 shown in FIG. 3 sets the start point of the line segment as the start point of the normal line. That may be the point. In addition, when creating a plurality of line segments, the line segment creation unit 303 sets one start point of the line segment, but it may create a plurality of line segments from a plurality of start points.

  FIG. 14 is an explanatory diagram illustrating an example (part 2) of drawing a plurality of line segments. The line segment creation unit 303 includes a plurality of points included on the surface of the three-dimensional model 401 and connecting the specified points on the cross section and each of the plurality of points included on the surface of the three-dimensional model 401 and specified on the cross section. Specify the line segment of.

  A point included in the surface of the three-dimensional model 401 and on the cross section is, for example, a starting point of a line segment. The starting point may be randomly selected from the cross section. In addition, as shown in FIG. 14 (1-1) and FIG. 14 (2-1), the line segment creation unit 303 sets the start point st1 and the start point st2 so that line segments can be created from various directions. A plurality of starting points may be selected.

  In addition, a plurality of points on the identified cross section that are included in the surface of the three-dimensional model 401 are, for example, end points of a line segment. The plurality of end points may be randomly selected from the cross section. Further, as shown in FIG. 14 (1-1) and FIG. 14 (2-1), the line segment creating unit 303 may select a plurality of end points that are separated from each other in the cross section.

  In the example of FIG. 14A, the line segment creating unit 303 selects end points ed11 to ed16 for the start point st1. The line segment creating unit 303 specifies a plurality of line segments e11 to e16 connecting the start point st1 and the end points ed11 to ed16.

  In the example of FIG. 14 (2-1), the line segment creation unit 303 selects end points ed21 to ed25 for the start point st2. The line segment creating unit 303 specifies a plurality of line segments e21 to e25 connecting the start point st2 and the end points ed21 to ed25.

  Next, the moving unit 305 arranges the sphere 900 at a position where the center of the sphere 900 matches each of the plurality of points included in each of the plurality of line segments at the plurality of points included in each of the plurality of line segments. I do. In the example of FIG. 14 (1-2), the moving unit 305 arranges the sphere 900 at a position corresponding to each of the start point st1, the points p11 to p14, the end point ed14, and the like included in the line segment e14. In the example of FIG. 14 (2-2), the moving unit 305 arranges the sphere 900 at a position corresponding to each of the start point st2, the points p21 to p24, and the end point ed23 included in the line segment e23.

  Then, the calculation unit 306 calculates the volume of the overlapping region of the sphere 900 and the three-dimensional model 401 when the sphere 900 is arranged. Then, the first specifying unit 307 specifies the line segment having the largest sum of the volumes of the overlapping regions of the sphere 900 and the three-dimensional model 401 at a plurality of points included in each of the plurality of line segments. I do. Next, the determination unit 309 determines the center point of the cross section based on the volume of the overlapping area between the sphere 900 and the three-dimensional model 401 at a plurality of points included in the specified line segment.

  As described above, the example in which one cross section is specified from the three-dimensional model 401 representing the pipe and the center point of the cross section is obtained is described. The central axis of the model 401 may be obtained.

  FIG. 15 is an explanatory diagram illustrating an example of obtaining the center axis of the pipe. The cross-section creating unit 302 selects a plurality of tetras having different heights from tetras included on the surface of the three-dimensional model 401 representing the pipe. The number of sections to be obtained may be accepted by a user operation. For example, when accepting the designation of the entrance 701 and the exit 702 of the three-dimensional model 401 by the operation of the user, the accepting unit 301 accepts the designation of the number of cross sections. Further, the interval between the cross sections and the height of each cross section may be received by a user operation. For example, when accepting the designation of the entrance 701 and the exit 702 of the three-dimensional model 401 by the operation of the user, the accepting unit 301 accepts the specification of the interval between sections and the height of each section.

  For example, the cross section creation unit 302 selects a specified number of tetras having different heights from tetra included in the surface of the three-dimensional model 401. In the example of FIG. 15, the number of cross sections is four. Then, for each selected tetra, the cross-section creating unit 302 selects a side included in the tetra. Thus, as shown in FIG. 15, four sides are selected, and four cross sections 1501 to 1504 are specified. As shown in FIG. 15, since the tetrahedrons included in the surface of the tube are not connected smoothly, each cross section is not necessarily perpendicular to the surface of the tube, which is the three-dimensional model 401.

  Then, the center point of each section is specified by the processing of each section described above. A center point 1511 is specified for the cross section 1501. For the cross section 1502, a center point 1512 is specified. For the cross section 1503, a center point 1513 is specified. A center point 1514 is specified for the cross section 1504.

  Then, the determination unit 309 specifies, for example, the axis passing through the center point of each section as the center axis 1500 of the three-dimensional model 401. The output unit 311 outputs a central axis. The output unit 311 displays the central axis on the display 209 or the like in accordance with the three-dimensional model 401, for example. The output unit 311 stores, for example, information indicating the central axis in a storage device such as the RAM 203 or the disk 205.

(Example of center determination processing procedure by center determination apparatus 100)
FIG. 16 is a flowchart illustrating an example of a procedure of a center determination process performed by the center determination apparatus. The center determination device 100 acquires the analysis model data 500 (Step S1601). Next, the center determination device 100 receives the designation of the entrance 701 and the exit 02 of the pipe of the three-dimensional model, and sets the entrance and the exit of the analysis model (step S1602).

  Then, the center determination device 100 selects a plurality of tetras at different heights from the tetra included in the tube surface of the three-dimensional model 401 (step S1603). The center determination device 100 determines whether there is an untargeted tetra among the selected tetras (step S1604). When it is determined that there is an untargeted tetra (Step S1604: Yes), the center determination apparatus 100 selects one untargeted tetra as a target from the plurality of tetras (Step S1605). Then, the center determination device 100 performs a cross-section identification process (step S1606).

  Next, the center determination device 100 performs a volume calculation process (step S1607). Then, the center determination device 100 performs the process of specifying the center point (step S1608), and returns to step S1604. If it is determined in step S1604 that there is no untargeted tetra (step S1604: No), the center determination device 100 specifies the center axis of the three-dimensional model 401 connecting the determined passing points (step S1609). Then, center determination apparatus 100 outputs the specified center axis (step S1610), and ends a series of processing.

  FIG. 17 is a flowchart illustrating an example of a cross-section identification processing procedure performed by the center determination device. The center determination apparatus 100 specifies a normal in the pipe inner direction from the bottom surface of the selected tetra (Step S1701). Next, the center determination device 100 selects an unselected side of the bottom surface of the selected tetra (step S1702).

  Next, the center determination apparatus 100 generates a plane based on the selected side and the specified normal (step S1703). Then, the center determination device 100 determines whether the plane intersects the end face of the three-dimensional model 401 (step S1704). The end faces are an inlet 701 and an outlet 702. When it is determined that the plane intersects the end face of the three-dimensional model 401 (step S1704: Yes), the center determination device 100 returns to step S1702. When it is determined that the plane does not intersect with the end face of the three-dimensional model 401 (step S1704: No), the center determination device 100 determines a portion of the plane that overlaps the three-dimensional model 401 as a cross section of the tube of the three-dimensional model 401. The extraction is performed (step S1705), and a series of processing ends.

  FIG. 18 is a flowchart illustrating an example of a volume calculation processing procedure performed by the center determination device. The center determination device 100 creates a plurality of line segments on the cross section with reference to the start point of the normal on the cross section (step S1801). Then, for each of the intersections between the plurality of line segments and the tube surface, the center determination device 100 calculates the distance from the starting point of the normal (step S1802). Next, the center determination device 100 determines the longest distance as the diameter of the sphere 900 (step S1803).

  Then, the center determination device 100 selects an unselected line segment from the plurality of line segments (step S1804). Next, the center determination device 100 calculates the volume of the overlapping area of the sphere 900 and the three-dimensional model 401 in a state where the center of the sphere 900 having the determined diameter is arranged at the start point of the selected line segment (step S1805). . Subsequently, the center determination device 100 moves a predetermined length in the direction of the end point in a state where the center of the sphere 900 is located on the line segment (step S1806). Here, the end point is an end point of the line segment and is different from the start point. In step S1806, the center determination device 100 moves the center of the sphere 900 on the line segment toward the end point.

  Next, the center determination device 100 determines whether or not it has been able to move (step S1807). The case where movement is not possible is a case where the center of the current sphere 900 moves out of a line segment by moving a predetermined length in the direction of the end point. If it is determined that the movement is possible (Step S1807: Yes), the center determination device 100 calculates the volume of the overlap area between the moved sphere 900 and the three-dimensional model 401 (Step S1808), and returns to Step S1806.

  When it is determined that the user cannot move (Step S1807: No), the center determination device 100 determines whether there is an unselected line segment (Step S1809). When it is determined that there is an unselected line segment (step S1809: Yes), the center determination device 100 returns to step S1804. On the other hand, when it is determined that there is no unselected line segment (step S1809: No), the center determination device 100 ends a series of processing.

  FIG. 19 is a flowchart illustrating an example of a center point specifying process procedure. The center determination device 100 specifies the line segment having the largest volume (step S1901). Next, the center determination device 100 specifies the center point of the cross section based on the change in volume of the specified line segment (step S1902). Subsequently, the center determination device 100 determines a tetra node near the specified center point as a passing point of the pipe center axis (step S1903), and ends a series of processing.

  As described above, the center determination device 100 determines the line segment on the cross section of the analysis model based on the volume of the overlapping area of the solid and the model when the center of the solid is placed at each position on the line segment. Then, the center point of the cross section is specified from the respective positions. Thereby, the center of the cross section of the analysis model having no center information can be determined. Then, since the center point can be easily obtained, the user can save time and effort.

  In addition, the center determination device 100 specifies a normal line of a surface of any one of the tetrahedrons included in the surface of the three-dimensional model 401 among the plurality of tetrahedrons, and determines the normal line and the side included in the surface. A plane overlapping with the three-dimensional model 401 is specified as a cross section among the planes based on the three-dimensional model. Thereby, the cross section of the three-dimensional model 401 can be easily specified, and the calculation time can be reduced.

  In addition, the center determination device 100 calculates the sum of the volumes of the tetrahedrons included in the predetermined solid among the plurality of tetrahedrons included in the three-dimensional model 401 when the predetermined solid is moved, as the volume of the overlapping area. Is calculated as This makes it possible to easily calculate the volume of the overlapping area between the three-dimensional model 401 and the predetermined solid, and to reduce the calculation time.

  Further, the greater the overlap between the predetermined solid and the three-dimensional model 401, the higher the possibility that the position of the predetermined solid is the center of the cross section of the three-dimensional model 401. For this reason, the center determination device 100 determines, as the center point, a point at which the calculated volume of the overlapping region is the largest among the points included in the specified line segment. Thereby, it is possible to improve the accuracy of obtaining the center of the cross section of the analysis model having no center information.

  In addition, when moving a predetermined solid on a line segment, the center determination device 100 determines a maximum point when there are a plurality of line segment points where the volume of the overlapping region of the predetermined solid and the three-dimensional model 401 is the largest. The center point is determined as the center point of the cross section. Accordingly, it is possible to improve the accuracy of obtaining the center of the cross section of the analysis model having no center information.

  In addition, the center determination device 100 specifies, as a center point, a node closest to the position where the calculated volume of the overlapping region is maximum among the nodes included in the plurality of tetrahedrons. As a result, the center can be set at the node of the tetrahedron, so that it can be easily used for analysis.

  In addition, the center determination device 100 specifies a center axis based on the center point specified for each of the plurality of cross sections of the three-dimensional model 401. This makes it possible to specify the central axis of a pipe or the like, and can save the user time and effort.

  Also, the more uniform the distance of the predetermined surface from the center of the predetermined solid, the more the predetermined solid can cover the cross section evenly. For this reason, the center determination device 100 sets the predetermined solid as a sphere 900. Accordingly, if the sphere 900 has a uniform distance from the center of the predetermined solid to the predetermined surface, the possibility that the finally obtained center point is accurate is increased.

  Further, for example, if the diameter of the sphere 900 is too small, the number of positions where the volume of the overlapping region of the sphere 900 and the tube becomes maximum when the sphere 900 is moved to each position of the line segment increases. If the diameter of the sphere 900 is larger than the cross section, the number of positions where the volume of the overlapping area of the sphere 900 and the tube becomes maximum when the sphere 900 is moved to each position of the line segment increases. . Therefore, the center determination device 100 sets the diameter of the sphere 900 to a value based on the maximum length of each of the plurality of line segments. Accordingly, the sphere 900 can include the entirety in the direction of the line of the cross section, and the number of positions where the volume of the overlapping region of the sphere 900 and the tube becomes maximum can be reduced. Therefore, the accuracy of finding the center point can be improved.

  The center determination method described in the present embodiment can be realized by executing a prepared center determination program on a computer such as a personal computer or a workstation. The center determination program is recorded on a computer-readable recording medium such as a magnetic disk, an optical disk, and a USB (Universal Serial Bus) flash memory, and is executed by being read from the recording medium by the computer. The center determination program may be distributed via a network such as the Internet.

e1 to e5, e11 to e16, e21 to e25 Line segment 100 Center determining device 101, 401 3D model 102, 601, 1501, 1502, 1503, 1504 Cross section 301 Receiving unit 302 Cross section creating unit 303 Line segment creating unit 304 Diameter determination Unit 305 moving unit 306 calculating unit 307 first specifying unit 308 second specifying unit 309 determining unit 310 third specifying unit 311 output unit 500 analysis model data 600,700 plane 900 sphere 1500 center axis 1511,1512,1513,1514 center point ta, t1-t5 tetra

Claims (12)

According to the input, specify the cross section of the 3D model,
In each of the plurality of line segments included in the specified cross section, the predetermined solid and the three-dimensional model are moved when the predetermined solid is moved on the line segment in a state where the center of the predetermined solid is located. Calculate the volume of the overlapping area with
Of the plurality of line segments, the line segment in which the calculated volume of the overlapping region is the largest is specified,
In the specified line segment, when the predetermined solid is moved, a change in the volume of an overlapping area between the predetermined solid and the three-dimensional model causes a change in the volume of the cross section from a point included in the line segment. Determine the center point and output it,
A center determination program for causing a computer to execute processing.   The process of specifying the cross section includes, among a plurality of tetrahedrons included in the three-dimensional model, specifying a normal of a surface of any tetrahedron included in the surface of the three-dimensional model, and specifying the specified method A process that specifies a plane based on a line and a side included in a surface of any one of the tetrahedrons, and specifies, as the cross section, a surface overlapping the three-dimensional model among the specified planes. The center determination program according to claim 1, wherein:   The process of calculating the volume of the overlapping region is performed by, when the predetermined solid is moved, a sum of volumes of tetrahedrons included in the predetermined solid among a plurality of tetrahedrons included in the three-dimensional model. The center determination program according to claim 1, wherein the calculation is performed as a volume of the overlapping area.   The process of determining the center point of the cross section is a process of determining, as the center point, a point at which the calculated volume of the overlapping region is the largest among the points included in the specified line segment. The center determination program according to claim 1.   The center according to any one of claims 1 to 4, wherein a center axis connecting the center points determined for each of the plurality of cross sections of the three-dimensional model specified according to the input is specified. Judgment program.   The center determination program according to claim 1, wherein the predetermined solid is a sphere.   The computer-readable storage medium according to claim 6, wherein the diameter of the sphere is a value based on a maximum length of each of the plurality of line segments. According to the input, specify the cross section of the 3D model,
Identify a plurality of line segments that are included on the surface of the three-dimensional model and that specify the points on the cross section, and that are included on the surface of the three-dimensional model and that connect the plurality of points on the specified cross section, respectively. And
At a plurality of points included in each of the specified plurality of line segments, the predetermined solid is arranged at a position where the center of the predetermined solid corresponds to each of the plurality of points included in each of the plurality of line segments. Calculating the volume of the overlapping region between the predetermined solid and the three-dimensional model at the time,
Among the plurality of line segments, a line segment in which the sum of volumes of overlapping regions of the predetermined solid and the three-dimensional model at a plurality of points included in each of the plurality of line segments is specified,
Determining a center point of the cross section based on a volume of an overlapping area between the predetermined solid and the three-dimensional model at a plurality of points included in the specified line segment;
A center determination program for causing a computer to execute processing. According to the input, specify the cross section of the 3D model,
In each of the plurality of line segments included in the specified cross section, the predetermined solid and the three-dimensional model are moved when the predetermined solid is moved on the line segment in a state where the center of the predetermined solid is located. Calculate the volume of the overlapping area with
Of the plurality of line segments, the line segment in which the calculated volume of the overlapping region is the largest is specified,
In the specified line segment, when the predetermined solid is moved, a change in the volume of an overlapping area between the predetermined solid and the three-dimensional model causes a change in the volume of the cross section from a point included in the line segment. Determine the center point and output it,
A center determination method, wherein the processing is executed by a computer. According to the input, specify the cross section of the 3D model,
Identify a plurality of line segments that are included on the surface of the three-dimensional model and that specify the points on the cross section, and that are included on the surface of the three-dimensional model and that connect the plurality of points on the specified cross section, respectively. And
At a plurality of points included in each of the specified plurality of line segments, the predetermined solid is arranged at a position where the center of the predetermined solid corresponds to each of the plurality of points included in each of the plurality of line segments. Calculating the volume of the overlapping area of the predetermined solid and the three-dimensional model at the time of
Among the plurality of line segments, a line segment in which the sum of volumes of overlapping regions of the predetermined solid and the three-dimensional model at a plurality of points included in each of the plurality of line segments is specified,
Determining a center point of the cross section based on a volume of an overlapping area between the predetermined solid and the three-dimensional model at a plurality of points included in the specified line segment;
A center determination method, wherein the processing is executed by a computer. In response to the input, a cross section of the three-dimensional model is specified, and a plurality of line segments included in the specified cross section are moved in a state where the center of the predetermined solid is located on the line segment, and the predetermined solid is moved. At this time, the volume of the overlapping region between the predetermined solid and the three-dimensional model is calculated, and among the plurality of line segments, the line segment having the largest calculated volume of the overlapping region is specified and specified. The center of the cross section from a point included in the line segment according to a change in the volume of an overlapping area between the predetermined solid and the three-dimensional model when the predetermined solid is moved in the line segment A control unit that determines and outputs a point,
A center determination device comprising: In response to the input, a cross section of the three-dimensional model is specified, and a point on the cross section included and specified on the surface of the three-dimensional model and a point on the cross section included and specified on the surface of the three-dimensional model are specified. A plurality of line segments connecting each of the plurality of points are specified, and at a plurality of points included in each of the specified plurality of line segments, a plurality of points in which a center of a predetermined solid is included in each of the plurality of line segments Calculating a volume of an overlapping area of the predetermined solid and the three-dimensional model when the predetermined solid is arranged at a position corresponding to each of the points, and among the plurality of line segments, the plurality of line segments A line segment having the largest sum of the volumes of the overlapping regions of the predetermined solid and the three-dimensional model at a plurality of points included therein is specified, and the predetermined solid at a plurality of points included in the specified line segment is specified. And the 3D model Based on the volume of the band, it determines the center point of the cross section, the control unit,
A center determination device comprising:

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