JP2001195605A - Method for three-dimensional shape processing and storage medium stored with same shape processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional shape processing method which is enabled to receive three-dimensional shape data in standard format by making it easy to process three-dimensional shape data of a trimmed closed plane of rotation even when the data are received. SOLUTION: This three-dimensional shape processing method which can process a plane of rotation, finds a plane dividing the plane of rotation into two (S2), projects the generating line of the plane of rotation on the mentioned plane (S3), finds the curved line G2 obtained by rotating a projected curved line G1 by 180 deg. (S4), forms a loop by partially connecting border curved lines constituting trimming borders, etc., on one plane of rotation divided by the mentioned plane by using a part of the curved line G2 and regarding the loop as an external border (S5), finds a generating curved plane that the external border, etc., belongs to (S6), and represents one plane of rotation with information on plural planes such as planes surrounded with the external border and the other plane of rotation similarly (S7).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a curved surface of a closed closed rotary surface, which is carried out by a dedicated three-dimensional shape processing device or an information processing device such as a personal computer. Even if the 3D shape processing system cannot handle closed closed rotating surfaces,
The present invention relates to a curved surface processing method capable of handling three-dimensional shape data of a trimmed closed rotating surface obtained from a three-dimensional shape processing system.

[0002]

2. Description of the Related Art Conventionally, a three-dimensional shape processing system such as a CAD / CAM system using a graphics display device and a computer generates a three-dimensional shape, deforms the generated three-dimensional shape, A missing shape element is generated when a three-dimensional shape is generated using three-dimensional shape data acquired from another three-dimensional shape processing device or the like. Note that a three-dimensional shape (three-dimensional solid) refers to a shape generated as, for example, solid model data in a boundary representation format. A solid model in the boundary representation format is defined by an element such as a ridgeline, a vertex, or a surface. It defines a closed area in a three-dimensional space and expresses a solid body with a solid content. In recent years, in such a three-dimensional shape processing system, it has been widely performed to process three-dimensional shape data obtained from another three-dimensional shape processing system with the progress of collaboration and division of labor such as design work. I have. However, some three-dimensional shape processing systems cannot handle closed rotating surfaces such as the three-dimensional shape peripheral surface shown in FIG. Each point in the three-dimensional space at the position of the seam J of the closed rotating surface (the seam of the rotating surface, there is no actual seam or seam) is represented in the parameter space as shown in FIG. As shown in parentheses in FIG. 18, all positions on the curved surface are represented by two parameters u and v in two-dimensional coordinates, for example, both values from 0 to 1) as shown in FIG. Since it has two positions (the parameter values in FIG. 19 are an example), special handling is required when calculating the correspondence between the coordinate values in the real space (three-dimensional space) and the values in the parameter space. Because it becomes. As described above, the need for special treatment in the calculation means that the calculation cost is high. Therefore, depending on the three-dimensional shape processing system, the three-dimensional shape processing system does not support a closed rotating surface, and requires three When generating dimensional shape data, a closed rotating surface is not generated. However, IGES (Initial Graphics Exchange)
When taking in three-dimensional shape data from another three-dimensional shape processing system by an interface using a standard format such as a (Specification) format, a closed rotating surface is input, which causes a problem. Therefore, 3
If the three-dimensional shape processing system that receives the three-dimensional shape data cannot handle the closed rotating surface, it means that the three-dimensional shape data cannot be received via the standard format.

[0003]

As described above, in the prior art, if the three-dimensional shape processing system on the receiving side of the three-dimensional shape data cannot handle the trimmed closed rotating surface, the three-dimensional shape processing system uses the standard format. There is a problem that three-dimensional shape data cannot be received. SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and to receive three-dimensional shape data in a standard format so that the three-dimensional shape data of a trimmed closed rotating surface can be easily processed. An object of the present invention is to provide a three-dimensional shape processing method as described above.

[0004]

According to a first aspect of the present invention, there is provided a three-dimensional shape processing method capable of processing a rotating surface. The upper boundary curve is divided by a plane, and each of the divided boundary curves is formed into a closed loop to represent the rotation surface. According to a second aspect of the present invention, in the first aspect of the present invention, a plane on which a predetermined point on the generating line of the rotating surface and an axis of the rotating surface rides is a plane for dividing a boundary curve on the rotating surface. Was the way. According to a third aspect of the present invention, in the second aspect, the plane is determined such that one of the intersections of the plane dividing the rotation plane and the intersection of the rotation plane is the position of the seam of the rotation plane. . According to a fourth aspect of the present invention, in the third aspect of the present invention, a part of a curved line obtained by rotating a generating line projected at a position of a stitch on a plane by 180 degrees about an axis of a rotation surface is divided. The curve was made into a curve to make it a closed loop. According to a fifth aspect of the present invention, in the second or third aspect of the present invention, for a plurality of sample points on the generating line of the rotating surface, the distance between the sampling point and the axis of the rotating surface and the sample point are defined as the rotating surface. Find the projected point projected on the axis of
Having the same on-axis projection point as the sample point on the plane,
A sample projection point having a distance from the same axis is obtained, and an error distance between the sample projection point and a curve obtained by projecting the bus on a plane is obtained.The error distance is within a predetermined value for all of the plurality of sample points. Then, a method was adopted in which the projected curve was adopted as the projected bus. In the invention according to claim 6, in the invention according to claim 5, if all error distances are not within a predetermined value, a rotation plane is generated by rotating the generating line before projection as the axis of rotation. In this method, a line of intersection between the plane of rotation and the plane is determined, and the line of intersection is adopted as a projected bus. Also,
According to a seventh aspect of the present invention, a program programmed according to the three-dimensional shape processing method of the first to sixth aspects is stored in a storage medium storing the program.

[0005]

According to the first aspect of the present invention, the boundary curve on the trimmed rotation surface to be processed is divided by a plane, and the divided boundary curves are formed into closed loops. The rotation surface is represented by a plurality of curved surfaces obtained by the above. According to the second aspect of the present invention, in the first aspect of the present invention, a plane on which a predetermined point on the generatrix of the rotating surface and an axis of the rotating surface rides is a plane dividing the boundary curve on the rotating surface. According to a third aspect of the present invention, in the second aspect of the present invention, one of the intersections between the plane dividing the rotation surface and the rotation surface is the position of the seam of the rotation surface. According to a fourth aspect of the present invention, in the third aspect of the present invention, a boundary curve in which a part of a curve obtained by rotating a generating line projected at a position of a stitch on a plane by 180 degrees around an axis of a rotation plane is divided is formed. It becomes a curve for a closed loop. According to a fifth aspect of the present invention, in the second or third aspect of the present invention, for a plurality of sample points on the generatrix of the rotation surface, the distance between the sample point and the axis of the rotation surface and the sample point are defined as the axis of the rotation surface. A projection point projected on the plane is obtained, a sample projection point having the same on-plane projection point as the sample point on the plane and a distance from the same axis is obtained, and projecting the sample projection point and the generating line on the plane. An error distance from the calculated curve is obtained, and if the error distance is within a predetermined value for all of the plurality of sample points, the projected curve is adopted as a projected bus. In the invention according to claim 6, in the invention according to claim 5, if all error distances are not within a predetermined value, a rotation surface is generated by rotating the generating line before projection as the rotation axis as the rotation axis. A line of intersection between the plane of rotation and the plane is determined, and the line of intersection is adopted as the projected bus. According to a seventh aspect of the present invention, a program programmed according to the three-dimensional shape processing method according to the first to sixth aspects is stored in, for example, a removable storage medium.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a three-dimensional shape processing apparatus according to an embodiment of the present invention. As illustrated, the three-dimensional shape processing apparatus according to the present embodiment includes a memory (for example, a RAM) that stores a program and a CPU that operates according to the program to generate a three-dimensional shape model. A data processing unit 1 for performing related data processing, a mouse and a keyboard,
An input device 2 for inputting necessary instructions and information, a display device 3 for displaying a three-dimensional shape model and the like, a plotter 4 for outputting a three-dimensional shape model and the like on paper, a memory for temporarily storing various data (for example, , RAM) 5, a plurality of three-dimensional shape model data (hereinafter abbreviated as three-dimensional shape data)
An external storage device (for example, a hard disk device) 6 for storing programs and programs, etc., and a storage medium driving device 7 for driving a removable storage medium are provided. The three-dimensional shape data includes geometric shape data such as points, curves, and curved surfaces, and phase data indicating a correlation between the geometric shape data. The storage medium driving device 7 is for inputting three-dimensional shape data generated by another three-dimensional shape processing device or the like.
Alternatively, a data communication unit may be provided, and three-dimensional shape data may be input via the data communication unit. Such 3
In the three-dimensional shape processing apparatus, in this embodiment, the rotating surface is divided into two in the circumferential direction, so that even if there is a trim extending over 360 degrees, each curved surface constituting the rotating surface does not extend over 360 degrees. Thus, when each of the curved surfaces is expressed in the parameter coordinate system, one real coordinate (coordinate in a three-dimensional space) is prevented from having two values.

FIG. 2 shows an operation flow of an embodiment of the present invention. Hereinafter, the operation of this embodiment will be described with reference to FIG. First, the 3D shape generated by another three-dimensional shape processing device is used.
The three-dimensional shape data is inputted by the storage medium driving device 7 by the storage medium driving device 7 and the three-dimensional shape data is
(S1). It is assumed that the three-dimensional shape data includes data of a closed rotating surface trimmed over 360 degrees as shown in FIG. Also,
It is assumed that the rotation surface is represented by two parameters, u and v, as shown in FIG. 18 (this is called a parameter space expression. The parameter values shown in FIG. 18 are examples). Next, the data processing unit 1 reads out the three-dimensional shape data including the rotation surface to be processed from the external storage device 6, and obtains a plane that divides the rotation surface into two (S2). In addition,
The plane to be sought is a plane on which the midpoint of the generatrix of the rotating surface at the seam (joint) of the rotating surface and the axis of the rotating surface ride (see FIG. 4). Since the entire bus is not always on a plane, the point is defined as an intermediate point of the bus. However,
If the intermediate point of the bus is on the axis of the plane of rotation, another predetermined point is used instead of the intermediate point, for example, the start or end point of the bus. Subsequently, the data processing unit 1 projects the bus onto the obtained plane (S3). That is, a curve is obtained that connects points where straight lines drawn perpendicularly to the plane from all points on the bus line intersect the plane. For this purpose, for example, a control point on a plane at which a line drawn perpendicularly to the plane from each control point of the generatrix crosses the plane may be obtained, and a curve determined by the control point may be obtained. Note that the control points are shown in FIG.
Speaking of the example shown in FIG. 4, the coordinates are V1 to V4, and the coordinate values on the curve determined by these control points (the curve shown in bold in FIG. 16) are the coordinates of each control point depending on the position on the curve. The value is obtained by adding a value obtained by multiplying the coordinate value of each control point by a coefficient for changing the weight of the value. Next, whether the projected curve can be adopted as a generatrix on the plane from which the curve was obtained is determined based on the true values of a plurality of sample points (when the sample points on the generatrix before projection are rotated about the axis of the rotation plane). The inspection is performed by calculating an error from the coordinate value of a point that intersects with the plane. Therefore, some points on the bus before the projection are set as sample points, and the following processing is performed for each of them.

First, the distance between the sample point and the axis of the rotating surface,
Then, the position of the point where the sample point is projected on the axis is obtained (see FIG. 5). Further, a point having the same on-axis projected point as the sample point on the plane P and having a distance from the same axis is obtained (see FIG. 6), and a distance between the point and the projected curve, that is, an error is obtained. Then, it is determined whether or not this error is within the allowable value for all the sample points, and if it is within the allowable value, the projected curve is adopted as a generatrix on the obtained plane (S3). On the other hand, if the error exceeds the allowable value, the generating line before projection is rotated about the axis of the rotation surface, and the intersection of the rotation surface and the plane is obtained (see FIG. 7). It is adopted as a bus projected on a plane (S3). The generated bus projected on the plane P is defined as a curve G1.
A curve G2 obtained by rotating G1 by 180 degrees about the axis of the rotation surface is obtained (see FIG. 8) (S4). The curve G2 obtained in this way becomes an intersection line between the plane P and the rotation plane together with the curve G1. Since the curve G1 is located at the position of the seam, the curve G1
On the G1 side, the boundary curve (such as the boundary curve forming the boundary with the trim) is considered to be closed. On the curve G2 side, the intersection between the plane P and the boundary curve is an even number because the original boundary curve before division is closed (see FIG. 9).
However, when the boundary curve is in contact with the plane P, the contact point is not regarded as an intersection. Next, the following processing is performed on the boundary curve on one rotation surface side divided by the plane P. The boundary curves include boundary curves having no intersection with the plane P. First, the data processing unit 1 determines the intersection of the plane P and the boundary curve with the parameter value of the curve G2 (for example,
The start point of the curve G2 is aligned in the order of the parameter value 0 and the end point is 1.0), and a number is assigned to each intersection in the order of arrangement (see FIG. 10). Such an alignment is possible because the intersection is on curve G2. Subsequently, a boundary curve with an odd number, such as a boundary curve with a number 1 and a boundary curve with a number 2 at the intersection, a boundary curve with a number 3 and a boundary curve with a number 4 The curve and the even numbered boundary curve are connected using a part of the curve G2 to form a loop (see FIG. 11) (S5). In this way, the curve that connects
Since a part of G2 is used, by dividing the curve G2 by its parameter value, the shape data of the connected curve can be easily obtained. Since the curve G1 side is a seam, it is assumed that a plurality of boundary curves are already connected as shown in FIGS. Further, among the loops, those having no intersection are defined as internal boundaries, and others are defined as external boundaries (S5).
If there are a plurality of external boundaries and an internal boundary exists, it is geometrically determined which external boundary the internal boundary is inside. Also, an internal boundary inside a certain external boundary is an internal boundary belonging to the external boundary (FIG. 12).
reference).

[0009] Furthermore, the rotational surface on which the external boundary is placed is also divided by the same plane P, and the rotational surface on the same side as the external boundary of the two divided rotational surfaces is adopted as a base curved surface of the external boundary. . Then, the generating surfaces are copied by the number of the outer boundaries, and the boundaries of the respective generating surfaces are set as the obtained outer boundary and the inner boundary belonging to the outer boundary (S
6). Thus, a trimmed curved surface in one space divided by the plane P is represented by all of the obtained curved surfaces (see FIG. 13). In the above, the curve G1
The boundary curve on the side, that is, the seam side, may protrude from the rotation plane divided by the plane P as shown in FIG. In that case, extend the rotating surface as shown in FIG.
Make the generating surface fit the boundary curve in that range. Further, the same processing is performed on the other rotating surface divided by the plane P (S7), and the other side is represented by a curved surface as shown in FIG. Thus, according to this embodiment, even if the trim extends over 360 degrees of the rotating surface, the individual curved surfaces constituting the rotating surface do not extend over 360 degrees, and the individual curved surfaces are expressed in the parameter coordinate system. In this case, one real coordinate (coordinate in three-dimensional space) can be prevented from having two values, so that a closed revolved surface that has been trimmed can be processed, and thus the standard format 3 The dimensional shape data can be received. In the above description, one of the lines of intersection of the plane P dividing the plane of rotation and the plane of rotation is located at the seam of the plane of rotation, but this is not essential. However, if one of the intersection lines is not located at the seam, the boundary curve is connected not only on the curve G2 side but also on the curve G1 side. Although the above description has been made in the case where the three-dimensional shape processing apparatus shown in FIG. 1 is used, a program programmed according to the three-dimensional shape processing method according to the present invention is stored in, for example, a removable storage medium. By attaching the storage medium to an information processing device such as a personal computer which could not perform the three-dimensional shape processing according to the present invention, the three-dimensional shape processing according to the present invention is realized even in such an information processing device. can do.

[0010]

As described above, according to the present invention,
According to the first aspect of the present invention, the boundary curve on the trimmed rotation surface to be processed is divided into planes, and the divided boundary curves are formed into closed loops by a plurality of curved surfaces. Is represented, the same point on the three-dimensional coordinates does not have two positions on the parameter space even if the shape data of the rotation surface is represented in the parameter space, and therefore, the trimming is performed. Even if the three-dimensional shape data of the closed rotating surface is received, it can be easily processed. According to the second aspect of the present invention, in the first aspect of the present invention, the plane on which the predetermined point on the generating line of the rotating surface and the axis of the rotating surface ride is a plane dividing the boundary curve on the rotating surface. Can be placed on the plane to be divided, so that when the divided boundary curves are connected to form a loop, they can be connected using a part of the generated bus. According to the third aspect of the present invention, in the second aspect of the present invention, since one of the intersections of the plane that divides the rotation surface and the rotation surface is the position of the seam of the rotation surface, the seam of the divided boundary curve is stitched. The sides are closed in advance, so that one side of the divided boundary curve does not have to be connected. According to a fourth aspect of the present invention, in the third aspect of the present invention, the boundary obtained by rotating the generating line projected at the position of the stitch on the plane by 180 degrees about the axis of the rotation plane is divided. Since the curve is a curve for forming a closed loop, shape data for forming a closed loop can be easily obtained. According to a fifth aspect of the present invention, in the second or third aspect of the present invention, for a plurality of sample points on the generating line of the rotating surface, the distance between the sampling point and the axis of the rotating surface and the sample point are defined as the rotating surface. The projection point projected on the axis of the is obtained, the sample projection point having the same on-plane projection point as the sample point on the plane and the distance to the same axis is obtained, the sample projection point and the generating line on the plane An error distance from the projected curve is calculated, and if the error distance is within a predetermined value for all of the plurality of sample points, the projected curve is adopted as the projected bus. Can easily be obtained. In the invention according to claim 6, in the invention according to claim 5, if all error distances are not within a predetermined value, a rotation surface is generated by rotating the generating line before projection as the rotation axis. Since the intersection line between the rotation plane and the plane is obtained and the intersection line is adopted as the projected bus, the data of the shape of the projected bus cannot be obtained. Further, according to the invention described in claim 7, according to claim 1 to claim 6,
7. A program programmed according to the dimensional shape processing method can be stored in, for example, a removable storage medium, and the storage medium is stored in the storage medium.
By attaching to an information processing device such as a personal computer that could not perform the curved surface processing according to the described invention,
Even in such an information processing apparatus, the effects of the inventions of claims 1 to 6 can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a three-dimensional shape processing apparatus according to an embodiment of the present invention.

FIG. 2 is an operation flowchart of a three-dimensional shape processing method according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a three-dimensional shape processing method according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 5 is another explanatory diagram of the three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 6 is another explanatory diagram of the three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 7 is another explanatory diagram of the three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 8 is another explanatory diagram of the three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 9 is another explanatory diagram of the three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 10 is another explanatory diagram of the three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 11 is another explanatory diagram of the three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 12 is another explanatory diagram of the three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 13 is another explanatory diagram of the three-dimensional shape processing method according to the embodiment of the present invention.

FIG. 14 is another explanatory diagram of the three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 15 is another explanatory diagram of the three-dimensional shape processing method showing one embodiment of the present invention.

FIG. 16 is an explanatory diagram of a three-dimensional shape processing method according to the present invention and the prior art.

FIG. 17 is another explanatory diagram of the three-dimensional shape processing method according to the present invention and the prior art.

FIG. 18 is another explanatory diagram of the three-dimensional shape processing method according to the present invention and the prior art.

FIG. 19 is another explanatory diagram of the three-dimensional shape processing method according to the present invention and the prior art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 data processing unit 2 input device 3 display device 4 plotter 5 memory 6 external storage device 7 storage medium drive

Claims (7)

[Claims] In a three-dimensional shape processing method capable of processing a rotation surface, a boundary curve on a trimmed rotation surface to be processed is divided by a plane, and each of the divided boundary curves is formed into a closed loop. A three-dimensional shape processing method characterized by comprising: expressing the rotation surface. 2. The three-dimensional shape processing method according to claim 1, wherein a plane on which a predetermined point on a generating line of the rotating surface and an axis of the rotating surface ride is a plane for dividing a boundary curve on the rotating surface. A three-dimensional shape processing method characterized by the above-mentioned. 3. The three-dimensional shape processing method according to claim 2, wherein the plane is determined such that one of the intersections of the plane dividing the plane of rotation and the intersection of the plane of rotation is the position of the seam of the plane of rotation. Three-dimensional shape processing method. 4. A boundary curve obtained by dividing a part of a curve obtained by rotating a generating line projected at a position of a stitch on a plane by 180 degrees around an axis of a rotation plane in the three-dimensional shape processing method according to claim 3. A three-dimensional shape processing method, wherein a curve is used to form a closed loop. 5. The three-dimensional shape processing method according to claim 2, wherein, for a plurality of sample points on a generating line of the rotation surface, a distance between the sample point and an axis of the rotation surface, and a sample point are defined by the rotation of the rotation surface. The projection point projected on the axis was obtained, the sample projection point having the same on-axis projection point on the plane as the sample point was obtained, and the sample projection point having the same distance to the axis was obtained, and the sample projection point and the generating line were projected on the plane. A three-dimensional shape processing method, wherein an error distance from a curve is obtained, and if the error distance is within a predetermined value for all of the plurality of sample points, the projected curve is adopted as a projected bus. 6. The three-dimensional shape processing method according to claim 5, wherein, if all error distances are not within a predetermined value, a rotating surface is generated by rotating the generating line before projection as the axis of rotation. A three-dimensional shape processing method, wherein an intersection line between the rotation plane and the plane is obtained, and the intersection line is adopted as a projected bus. 7. A storage medium storing a program, the program being programmed according to the three-dimensional shape processing method according to claim 1. Description: