JP2002342395A - Device and method for processing three-dimensional form - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a processing accompanied with interference calculation with a free-form surface expressed by a higher-order curved surface expression or three-dimensional(3D) form composed of a large number of free-form surfaces by utilizing a polyhedron corresponding to simplified convex closure. SOLUTION: In a convex polyhedron calculating part 2, a convex polyhedron roughly expressing the size and position of a curved surface is found for each of a plurality of curved surfaces configuring a plurality of 3D forms and in a convex polyhedron interference deciding part 3, on the basis of each of found convex polyhedrons, the presence/absence of interference on the curved surface between the 3D forms is roughly decided. Concerning the curved surface, with which the possibility of interference is decided by that decision, in a convex closure calculating part 4, the convex closure including that curved surface is found and on the basis of each convex closure found in a convex closure interference deciding part 5, the presence/absence of interference on the curved surface between the 3D forms is more exactly decided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a three-dimensional CAD /
The present invention relates to a three-dimensional shape processing device and a three-dimensional shape processing device that involve interference calculation of a three-dimensional shape such as CAM / CAE / CG.

[0002]

2. Description of the Related Art A three-dimensional shape processing system capable of handling various processes for a three-dimensional shape composed of a free-form surface represented by a parameter represented by a Bezier surface or a B-spline surface. In the above, the calculation of the interference for a curved surface has a high calculation cost, and when executing the processing involving the calculation of the interference, the interference calculation processing is not suddenly applied. Conventionally, as a pre-process, a convex hull including a curved surface is used to check the possibility that the curved surfaces interfere with each other, and then, only when there is such a possibility, the interference calculation process is applied. For example, in the case of interference calculation for a plurality of curved surfaces having a three-dimensional shape, it is checked whether or not convex hulls including the respective curved surfaces interfere with each other. Only when there is a possibility that they interfere with each other, an interference line is obtained by using a technique such as a recursive division method or a tracking method.

[0003] As described above, by performing a check using a convex hull as a pre-process and suppressing the interference calculation to a necessary minimum, it is possible to reduce the costly interference calculation as much as possible and to speed up the entire processing for the three-dimensional shape. This is effective in realizing a high-speed operation as compared with a case where direct interference calculation is applied. Conventional techniques for obtaining a convex hull for the three-dimensionally shaped free-form surface and for performing high-speed interference calculation using the convex hull include the following techniques.
R. E. FIG. Barnhill, S .; N. Kersey. :
"A Marching Method for Pa
rametic surface / surface
intersection "(Computer Ai
ded Geometric Design, 199
0)

[0004]

However, according to the above-mentioned prior art, when the order of a surface expression representing a free-form surface is higher or when the target shape is composed of a very large number of free-form surfaces, a convex hull is formed. There is a problem that the processing itself for the three-dimensional shape is reduced because the calculation itself becomes a heavy processing load. The present invention has been made to solve the above-mentioned problem, and simplifies processing involving interference calculation for a free-form surface represented by a higher-order surface equation or a three-dimensional shape composed of a large number of free-form surfaces. It is an object of the present invention to perform high-speed processing by using a polyhedron corresponding to a typical convex hull.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is a three-dimensional shape processing apparatus for executing a process involving interference calculation for a three-dimensional shape, comprising a plurality of three-dimensional shapes. Convex polyhedron calculation means for obtaining a convex polyhedron roughly representing the size and position of each of the plurality of curved surfaces, and interference of the curved surfaces of the three-dimensional shapes with each other based on each convex polyhedron obtained by the convex polyhedron calculation means Convex polyhedron interference determination means for roughly determining the presence or absence of
A convex hull calculating means for obtaining a convex hull including the curved surface for a curved surface determined to possibly interfere by the determination by the convex polyhedron interference determining means, and a convex hull calculated by the convex hull calculating means. Provided is a three-dimensional shape processing device including a convex hull interference determination unit that more accurately determines whether or not there is interference between curved surfaces of three-dimensional shapes.

Further, it is preferable to provide a judgment result management means for collectively managing the judgment result by the convex polyhedron interference judgment means and the judgment result by the convex hull interference judgment means with the same data structure. Further, when a correct determination result is not obtained by the convex polyhedron interference determining means, the convex hull calculating means obtains a convex hull including each of the curved surfaces constituting each of the three-dimensional shapes, and calculates the convex hull. It is preferable to provide means for controlling the interference determining means to more accurately determine the presence or absence of interference between the curved surfaces of the three-dimensional shapes based on each convex hull obtained by the convex hull calculating means.

Also, there is provided a three-dimensional shape processing method for executing processing involving interference calculation with respect to a three-dimensional shape, wherein the size and position of each of a plurality of curved surfaces constituting a plurality of three-dimensional shapes are roughly determined. A convex polyhedron calculation step of obtaining a convex polyhedron represented by: and a convex polyhedron interference determination step of roughly determining whether or not there is interference between curved surfaces of the three-dimensional shapes based on each convex polyhedron obtained by the convex polyhedron calculation step, A convex hull calculation step for obtaining a convex hull including the curved surface for the curved surface determined to have a possibility of interfering by the determination by the convex polyhedron interference determination step; Also provided is a three-dimensional shape processing method including a convex hull interference determining step of more accurately determining the presence or absence of a curved surface between two-dimensional shapes.

It is preferable that the result of the judgment in the convex polyhedral interference judging step and the result of the judgment in the convex hull interference judging step are managed collectively in the same data structure. Further, when a correct determination result is not obtained in the convex polyhedron interference determining step, a convex hull including each of the curved surfaces constituting each of the three-dimensional shapes is obtained in the convex hull calculating step, and the convex hull is obtained. It is preferable that the interference judging step more accurately judge the presence or absence of interference between the curved surfaces of the three-dimensional shapes based on each convex hull obtained in the convex hull calculating step.

[0009]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 2 is a block diagram showing a system configuration of a three-dimensional shape correction processing device according to an embodiment of the present invention. The three-dimensional shape correction processing device is a microcomputer CP that controls the input device 10 such as a keyboard and a mouse, and controls the whole of the three-dimensional shape correction processing device and realizes each functional unit according to the present invention.
U11, a memory 12 for storing a control program operated by the CPU 11 on this computer system, and used as a work area when executing various processes and for temporarily storing information such as a three-dimensional shape, which will be described later. An external storage device 13 such as a hard disk device that stores information such as a surface table and a three-dimensional shape, an output device 14 that is a display device such as a CRT and an LCD, and a bus 15 through which various units 10 to 14 exchange data. Become.

FIG. 1 is a block diagram showing a functional configuration according to the present invention of the CPU 11 of the three-dimensional shape processing apparatus shown in FIG. Here, as an operation involving interference calculation for a three-dimensional shape, an operation of displaying interference lines between target shapes will be described. The CPU 11 calculates an input unit 1, a convex polyhedron calculating unit 2 for calculating and calculating a convex polyhedron representing the size and position of the surface, a convex polyhedron interference determining unit 3 for performing interference determination by the convex polyhedron, and calculating a convex hull including the surface. Hull calculation unit 4, convex hull interference determination unit 5 that performs interference determination by convex hull, and interference calculation unit 6.

That is, the three-dimensional shape correction device is a three-dimensional shape processing device that executes a process involving an interference calculation with respect to the three-dimensional shape, and the convex polyhedron calculation unit 2 includes a plurality of three-dimensional shapes. The function of a convex polyhedron calculation means for obtaining a convex polyhedron roughly representing the size and position of each of the curved surfaces. The convex polyhedron interference judging section 3 functions as a convex polyhedron interference judging means for roughly judging the presence or absence of interference between curved surfaces of the three-dimensional shapes based on each convex polyhedron obtained by the convex polyhedron calculating means.
The convex hull calculation unit 4 functions as a convex hull calculation unit that obtains a convex hull including the curved surface for a curved surface determined to have a possibility of interference by the determination by the convex polyhedron interference determination unit. The convex hull interference determining unit 5 functions as a convex hull interference determining unit that more accurately determines the presence or absence of interference between curved surfaces of the three-dimensional shapes based on each convex hull obtained by the convex hull calculating unit.

Further, the external storage device 13 functions as a judgment result management means for collectively managing the judgment result by the convex polyhedron interference judgment means and the judgment result by the convex hull interference judgment means with the same data structure. . Further, the CP
When U11 cannot obtain a correct determination result by the convex polyhedron interference determining means, the convex hull calculating means obtains a convex hull including each of the curved surfaces constituting each of the three-dimensional shapes, and obtains the convex hull. The interference determining means functions as a means for controlling so as to more accurately determine the presence or absence of interference between the curved surfaces of the three-dimensional shapes based on the convex hulls calculated by the convex hull calculating means.

The CPU 11 calculates a convex polyhedron for each of a plurality of curved surfaces forming a plurality of three-dimensional shapes, and calculates a convex polyhedron roughly representing the size and position of the curved surface. It is determined that there is a possibility of interference by a convex polyhedron interference determining step of roughly determining whether or not there is interference between curved surfaces of the three-dimensional shapes based on each convex polyhedron obtained by the above, and a determination by the convex polyhedral interference determining step. A convex hull calculating step of obtaining a convex hull including the curved surface with respect to the curved surface, and a convex hull for more accurately determining the presence or absence of interference between the curved surfaces of the three-dimensional shapes based on each convex hull obtained by the convex hull calculating step The process of the interference determination step is performed.

Further, under the control of the CPU 11, the judgment result in the convex polyhedron interference judgment step and the judgment result in the convex hull interference judgment step are collectively managed in the external storage device 13 with the same data structure. Further, when a correct determination result is not obtained in the convex polyhedron interference determining step, the CPU 11 obtains a convex hull including each curved surface constituting each of the three-dimensional shapes by the convex hull calculating step. The presence / absence of interference between curved surfaces of the three-dimensional shapes is more accurately determined based on the convex hulls determined in the convex hull calculation step in the convex hull interference determination step.

Next, an interference processing operation in the three-dimensional shape correction processing device will be described. FIG. 3 is a flowchart of the interference processing in the three-dimensional shape correction processing device.
In this process, the presence or absence of interference is checked for three-dimensional shapes that may have an interference portion, and if so, an interference line is obtained and displayed.

In step (indicated by "S" in the figure) 1, two three-dimensional shapes B1 and B2 composed of a plurality of surfaces are stored and prepared in an external storage device. These three-dimensional shapes B1, B2
Are respectively set to n and m, and are registered and managed in the curved surface table T01 for the three-dimensional shapes B1 and B2 in step 2. This curved surface table T01
Is an identifier for identifying each of the curved surfaces of the three-dimensional shapes B1 and B2 (the curved surface of the three-dimensional shape B1 is 1
To n, the curved surface of the three-dimensional shape B2 is 1 to m), and holds geometric information of the curved surface, information of a polyhedron roughly indicating the size and position of the curved surface, and information of a convex hull including the curved surface. However, at the time of this step 2, only the identifier and the geometric information are registered, and the other values are initialized. In step 3, it is determined whether or not to perform processing using a convex polyhedron. If so, in step 4, a convex polyhedron roughly representing the size and position of each curved surface is obtained and registered in the corresponding location of the curved surface table T01.

The convex polyhedron is obtained, for example, as follows. By examining the coordinate values at both ends of all the curves constituting the curve sequence that forms the boundary of the curved surface, the minimum values Xmin, Ymin, Zmin and the maximum values Xmax, Ym are obtained for the X, Y, and Z components.
ax and Zmax are obtained. Then, the convex polyhedron is configured to be a rectangular parallelepiped which is composed of a total of six sheets, two in each of the XY plane, the YZ plane, and the ZX plane, and whose eight corners have the following coordinate values. (Xmin, Ymin,
Zmin), (Xmin, Ymax, Zmin), (X
max, Ymin, Zmin), (Xmax, Yma
x, Zmin), (Xmin, Ymin, Zmax),
(Xmin, Ymax, Zmax), (Xmax, Ym
in, Zmax), (Xmax, Ymax, Zmax)
However, as it is, the closed space surrounded by the convex polyhedron is too small, the curved surface often does not include the boundary curve, and the accuracy is too poor to express the size and position of the curved surface, although roughly. The polyhedron is made larger with a value based on the distance between the adjacent coordinate values which is the maximum among the coordinate values of the eight corners.

In step 5, for each of the three-dimensional shapes B1 and B2, the size and position of the entire shape are roughly calculated by summing convex polyhedrons that roughly represent the size and position of the curved surface to be formed with reference to the curved surface table T01. Is obtained. In step 6, for each curved surface F1i (1 ≦ i ≦ n) constituting the three-dimensional shape B1, the convex polyhedron corresponding to the curved surface registered in the curved surface table T01 interferes with the convex polyhedron corresponding to the whole of the opponent three-dimensional shape B2. It is determined whether or not this is the case, and the result of the determination is registered in the relevant portion of the curved surface table T01. Furthermore, the three-dimensional shape B2
Is determined for each curved surface F2j (1 ≦ j ≦ m) constituting the curved surface T2, whether or not the convex polyhedron for the curved surface registered in the curved surface table T01 interferes with the convex polyhedron for the entire three-dimensional shape B1 of the partner. Then, the determination result is registered in the corresponding portion of the curved surface table T01.

In step 7, by referring to the curved surface table T01 for each curved surface, it is determined whether or not the result of determination that there is a possibility of interference in step 6 is registered or has been initialized by using a known technique. A convex hull including the curved surface is obtained and registered in the corresponding portion of the curved surface table T01. In step 8, for each of the three-dimensional shapes B1 and B2, the convex hulls of the respective curved surfaces formed with reference to the curved surface table T01 are summed to obtain the three-dimensional shapes B1 and B2.
Find the overall convex hull of B2. 3D shape B in step 9
1 for each curved surface F1i (1 ≦ i ≦ n), it is determined whether or not the convex hull of the curved surface registered in the curved surface table T01 interferes with the convex hull of the other three-dimensional shape B2. Then, the determination result is registered in the corresponding portion of the curved surface table T01. Further, for each of the curved surfaces F2j (1 ≦ j ≦ m) constituting the three-dimensional shape B2, whether or not the convex hull for the curved surface registered in the curved surface table T01 interferes with the convex hull for the entire other three-dimensional shape B1 Is determined, and the result of the determination is registered in the corresponding location of the curved surface table T01.

In step 10, the following processes (1) to (4) are executed. (1) Each curved surface F1i (1 ≦ i) constituting the three-dimensional shape B1
For ≦ n), it is determined whether or not the convex hull of the curved surface interferes with the convex hull of the entire other three-dimensional shape B2 with reference to the curved surface table T01. If there is no interference, the process is terminated because the curved surface does not exist in the interference portion. If there is interference, proceed to the next process (2). (2) Each curved surface F2j (1 ≦ j) constituting the three-dimensional shape B2
For ≦ m), it is determined whether or not the convex hull of the curved surface interferes with the convex hull of the entire other three-dimensional shape B1 with reference to the curved surface table T01. If there is no interference, the process is terminated because the curved surface does not exist in the interference portion. If there is interference, the process proceeds to the next process (3). (3) Referring to the curved surface table T01, it is determined whether or not the convex hulls of the curved surface F1i and the curved surface F2j interfere with each other. If there is no interference, the process is terminated because the curved surface does not exist at the interference portion. If there is interference, go to the next process (4). (4) Referring to the geometric information of the curved surface F1i and the curved surface F2j,
The interference line between the curved surfaces is calculated using a known technique, and when the interference line is found, the interference line is displayed on the output device.

The method of obtaining a convex polyhedron described above as an example often includes a curved surface. However, when the curve forming the boundary of the curved surface is complicated or when the curved surface shape is significantly different from the boundary curve sequence, the convex polyhedron may not include the curved surface. If the convex polyhedron obtained in step 4 does not include the curved surface, the displayed result may be incorrect. Therefore, if it is determined that the result is not correct based on the result, the above steps 4 to 6 are skipped and an input is made explicitly from the input device to start the process from step 7. That is, it is determined in Step 3 that the result of the interference determination by the convex polyhedron cannot be correctly obtained. If the processing by the convex polyhedron is not performed, the process proceeds to Step 7 to obtain a convex hull including the curved surface using a known technique. Is registered in the corresponding portion of the curved surface table T01.

In step 8, for each of the three-dimensional shapes B1 and B2, the convex hulls of the respective curved surfaces formed with reference to the curved surface table T01 are summed to obtain the three-dimensional shapes B1 and B2.
The overall convex hull of 1 and B2 is obtained. In step 9, for each curved surface F1i (1 ≦ i ≦ n) constituting the three-dimensional shape B1, whether the convex hull for the curved surface registered in the curved surface table T01 interferes with the convex hull for the entire other three-dimensional shape B2 Is determined, and the determination result is stored in the curved surface table T.
01 is registered in the corresponding location. Further, for each of the curved surfaces F2j (1 ≦ j ≦ m) constituting the three-dimensional shape B2, whether or not the convex hull for the curved surface registered in the curved surface table T01 interferes with the convex hull for the entire other three-dimensional shape B1 Is determined, and the result of the determination is registered in the corresponding location of the curved surface table T01.

In step 10, the following processes (1) to (4) are executed. (1) Each curved surface F1i (1 ≦ i) constituting the three-dimensional shape B1
For ≦ n), it is determined whether or not the convex hull of the curved surface interferes with the convex hull of the entire other three-dimensional shape B2 with reference to the curved surface table T01. If there is no interference, the process is terminated because the curved surface does not exist in the interference portion. If there is interference, proceed to the next process (2). (2) Each curved surface F2j (1 ≦ j) constituting the three-dimensional shape B2
For ≦ m), it is determined whether or not the convex hull of the curved surface interferes with the convex hull of the entire other three-dimensional shape B1 with reference to the curved surface table T01. If there is no interference, the process is terminated because the curved surface does not exist in the interference portion. If there is interference, the process proceeds to the next process (3). (3) Referring to the curved surface table T01, it is determined whether or not the convex hulls of the curved surface F1i and the curved surface F2j interfere with each other. If there is no interference, the process is terminated because the curved surface does not exist at the interference portion. If there is interference, go to the next process (4). (4) Referring to the geometric information of the curved surface F1i and the curved surface F2j,
The interference line between the curved surfaces is calculated using a known technique, and when the interference line is found, the interference line is displayed on the output device.

In this way, processing involving interference calculation for a three-dimensional shape can be executed at high speed. Also,
The process involving the calculation of interference with the three-dimensional shape can be executed using the memory area efficiently. Further, regarding processing involving interference calculation for a three-dimensional shape,
When accurate results cannot be obtained when execution speed is prioritized, accurate results can also be obtained by prioritizing accuracy.

[0025]

As described above, according to the present invention,
According to the three-dimensional shape processing apparatus and the three-dimensional shape processing method, a process involving interference calculation for a free-form surface represented by a high-order surface equation or a three-dimensional shape composed of a large number of free-form surfaces can be simply performed by a convex method. It can be performed at high speed by using a polyhedron corresponding to a parcel.

[Brief description of the drawings]

FIG. 1 shows a CPU 11 of the three-dimensional shape processing apparatus shown in FIG.
1 is a block diagram showing a functional configuration according to the present invention.

FIG. 2 is a block diagram illustrating a system configuration of a three-dimensional shape correction processing apparatus according to an embodiment of the present invention.

FIG. 3 is a flowchart of an interference process in the three-dimensional shape correction processing device.

[Explanation of symbols]

 1: Input unit 2: Convex polyhedron calculation unit 3: Convex polyhedron interference judgment unit 4: Convex hull calculation unit 5: Convex hull interference judgment unit 6: Interference calculation unit 10: Input device 11: CPU 12: Memory 13: External storage device 14: Output device 15: Bus

Claims (6)

[Claims] 1. A three-dimensional shape processing apparatus for executing a process involving an interference calculation with respect to a three-dimensional shape, wherein a size and a position of each of the plurality of curved surfaces constituting the plurality of three-dimensional shapes are roughly determined. A convex polyhedron calculating means for obtaining a convex polyhedron represented by: Convex hull calculation means for obtaining a convex hull containing the curved surface for the curved surface determined to have a possibility of interference by the determination by the convex polyhedron interference determination means; A three-dimensional shape processing apparatus comprising: a convex hull interference determining unit that more accurately determines the presence or absence of a curved surface between two-dimensional shapes. 2. A judgment result managing means for managing the judgment result by said convex polyhedron interference judging means and the judgment result by said convex hull interference judging means collectively with the same data structure. 3. The three-dimensional shape processing apparatus according to 1. 3. When a correct judgment result is not obtained by the convex polyhedron interference judging means, the convex hull calculating means obtains a convex hull containing each curved surface constituting each of the three-dimensional shapes, Means for controlling so as to more accurately determine the presence or absence of interference between the curved surfaces of the three-dimensional shapes based on each convex hull obtained by the convex hull calculating means by the convex hull interference determining means. 3D shape processing device. 4. A three-dimensional shape processing method for executing a process involving interference calculation with respect to a three-dimensional shape, wherein a size and a position of each of the plurality of curved surfaces constituting the plurality of three-dimensional shapes are roughly determined. A convex polyhedron calculation step of obtaining a convex polyhedron represented by: a convex polyhedron interference determining step of roughly determining whether or not there is interference between curved surfaces of the three-dimensional shapes based on each convex polyhedron obtained in the convex polyhedron calculation step; A convex hull calculating step of obtaining a convex hull containing the curved surface for the curved surface determined to possibly interfere by the determination by the convex polyhedron interference determining step; A convex hull interference determining step of more accurately determining the presence or absence of interference between the curved surfaces of the two-dimensional shapes.
Dimensional shape processing method. 5. The three-dimensional shape processing according to claim 4, wherein the judgment result in said convex polyhedron interference judging step and the judgment result in said convex hull interference judging step are collectively managed in the same data structure. Method. 6. When a correct determination result is not obtained in the convex polyhedral interference determining step, a convex hull including the curved surface is obtained for each of the curved surfaces constituting each of the three-dimensional shapes by the convex hull calculating step. A three-dimensional shape processing method, wherein the presence or absence of interference between curved surfaces of the three-dimensional shapes is more accurately determined based on each convex hull obtained in the convex hull calculation step in the convex hull interference determining step.