JPH06309417A - Sweep solid generating device - Google Patents

Abstract

PURPOSE:To provide a device capable of generating a sweep solid in which a feature included in a track curve is reflected without being influenced by torsion due to a change in curvature and expressing a synthesized sweep solid by a general curve format. CONSTITUTION:This sweep solid generating device is provided with a feature curve calculating part 8 for calculating a feature curve on an optional point on a track curve, a feature curve arranging part 7 for arraging the feature curve on both the end point of the track curve, a solid generating method judging part 9 for judging whether an approximating method is to be used for the generation of a sweep solid based upon the track curve and the feature curves arranged on both the end points of the track curve or not, a section sweep solid generating part 10 for generating a sweep solid at the time of judging that the approximating method is not used, an approximate section sweep solid generating part 11 for properly adding the feature curve to the track curve and approximately generating a solid at the time of judging its use, an inter-curved surface matching part 12 for matching continuation between adjacent solids in a section sweep solid obtained by respective sweep solid generating parts 10, 11, and a solid synthesizing part 13 for synthesizing one sweep solid from respective solids.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to shape processing such as computer-aided design (CAD) and computer-aided production (CAM), and more particularly to a sweep solid generator for generating a swept curved surface.

[0002]

2. Description of the Related Art As a conventional technique, when a CAD system has a plurality of orbital curves, the orbital curves are converted into one free curve, and the orbital curve is made into one, and then a sweep solid is generated. Was there.

Further, as another conventional technique, Japanese Patent Laid-Open No. Hei 4
In the "three-dimensional solid shape generating device" described in Japanese Patent Publication No. 117572, coordinate conversion is performed based on a tangent vector and a curvature vector at a point on the trajectory curve,
An interpolation curve is generated, and a sweep solid is generated by interpolating the characteristic curve and the interpolation curve with a Gregory Patch.

[0004]

However, in the method of converting a plurality of trajectory curves used in the above-mentioned conventional CAD system into one free curve, since the number of characteristic curves is one, the sweep solid generation is performed. Although there is an advantage that one time algorithm can be achieved,
Since a section such as a straight line or an arc that can generate a sweep solid clearly from the type of orbit curve is also treated as a free curve, the amount of data that defines the sweep solid increases and the processing load increases, resulting in unstable processing. There was a problem.

In the above-described "three-dimensional solid shape generating device",
The sweep curved surface obtained in a portion where the curvature changes drastically has a problem that it is extremely twisted, or the generated sweep solid is divided into fine patches due to the nature of the curved surface used. In addition, the curved surface expression described in the "3rd-dimensional solid shape generation device" is a new curved surface expression that solves the problem that has occurred when a curved surface that is smoothly connected to an adjacent curved surface has been solved. There was a problem that compatibility of was required.

An object of the present invention is to generate a swept solid reflecting the characteristics of an orbit curve without being affected by the twist caused by a drastic change in curvature, and express the synthesized swept solid in a general curved surface format. Provided is a sweep stereoscopic generation device.

[0007]

An object of the present invention is to provide a characteristic curve calculating means for calculating a characteristic curve at an arbitrary point of a trajectory curve, and a characteristic for arranging the calculated characteristic curve at both end points of the trajectory curve. A curve placement means, a solid generation method determination means for determining whether or not to use an approximation method for generating a sweep solid based on the trajectory curve and the characteristic curves placed at both ends of the trajectory curve, and a solid generation method determination means. In the generation of the sweep solid, when it is determined that the approximation method is not used, the interval sweep solid generating unit that generates the sweep solid based on the trajectory curve and the feature curve, and the solid generating method determination unit generate the sweep solid. When it is determined that the approximation method is used, the characteristic curve calculation means is used to appropriately add a characteristic curve to the trajectory curve to approximately generate a solid, and an approximate interval sweep solid generation means and an interval sweep The three-dimensional generation means and the approximate section sweep three-dimensional generation means are provided with inter-curved surface matching means for adjusting connectivity between adjacent three-dimensional sections in the three-dimensional sweep solid, and three-dimensional composition means for synthesizing the three-dimensional section sweep solid into one swept solid. Is achieved by a sweeping stereoscopic generator.

[0008]

The sweep volume generating apparatus of the present invention sweeps by moving or rotating one or a plurality of trajectory curves arranged in space and one or a plurality of characteristic curves along the trajectory curve. To generate a curved surface,
Using a characteristic curve calculating means for calculating a characteristic curve at an arbitrary point of the trajectory curve, the characteristic curves are arranged at both end points and inflection points of each trajectory curve, and at each trajectory curve section, arranged at both ends of the section. On the basis of the feature curve and the trajectory curve, it is determined whether or not the approximation method is necessary for the sweep solid generation means, and if it is determined that the approximation method is not necessary, the interval sweep solid generation means Generate a swept solid based on the trajectory curve. When it is determined that the approximation method is necessary, the approximate sweep solid generation unit appropriately adds the characteristic curve to the trajectory curve using the characteristic curve calculation unit to approximately generate the solid. The generated interval sweep solid arranges connectivity between adjacent solids and combines them into one sweep solid. Further, in the characteristic curve calculating means, the characteristic curve is calculated according to the type of the trajectory curve,
If the coordinate transformation matrix used for calculation cannot be specified uniquely, specify an appropriate plane and set the coordinate transformation matrix at the parameter points based on the normal vector of the plane and the tangent vector at any parameter point of the trajectory curve. Define. In the section sweep solid generation means,
An interval sweep solid corresponding to the type of trajectory curve is generated.
Then, in the approximate section sweep solid generation means, the section curve at an arbitrary parameter point of the section sweep solid is compared with the curve calculated at the parameter point using the characteristic curve calculation means.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sweep solid generator of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the sweep solid generator of the present invention.

The sweep stereoscopic generator shown in FIG. 1 includes a control unit 1, a display unit 2 connected to the control unit 1, a keyboard unit 3 connected to the control unit 1, a tablet unit 4 connected to the control unit 1, and a control unit. File unit 5 connected to the unit 1, modeling unit 6 connected to the control unit 1, characteristic curve arrangement unit 7 connected to the control unit 1, characteristic curve calculation unit 8 connected to the characteristic curve arrangement unit 7, control A stereoscopic generation method discrimination unit 9 connected to the unit 1,
Section Sweep 3D Generation Section 10 Connected to 3D Generation Method Discrimination Section 9, Approximate Section Sweep Generation Section 11 Connected to 3D Generation Method Discrimination Section 9 and Feature Curve Calculation Section 8, Matching between Curved Surfaces Connected to Control Section 1 It is configured by the unit 12 and the three-dimensional synthesis unit 13 connected to the control unit 1.

Next, referring to the flowchart of FIG.
The operation of each of the above components will be described.

First, as shown in FIG. 3, the modeling unit 6 inputs one or a plurality of trajectory curves and one or a plurality of characteristic curves (step S1). Next, the characteristic curve arranging unit 7 arranges the characteristic curves input using the characteristic curve calculating unit 8 at both end points and inflection points of the trajectory curve, as shown in FIG. 4 (step S2). At that time, the characteristic curve calculation unit 8 uses a sweeping method of the characteristic curve or a calculation method according to the type of the trajectory curve. For example, when the characteristic curve is calculated while maintaining the angle between the characteristic curve and the trajectory curve, the parallel movement method is used when the trajectory curve is a straight line, and the rotation movement method is used when the trajectory curve is an arc. Calculate using. When the trajectory curve is a free curve, after dividing at the inflection point, a plane is designated in the divided section, a coordinate conversion matrix is generated based on the designated plane, and a characteristic curve is calculated.

The plane designation method is a method of uniformly designating a plane in any section as shown in FIG. 5 or three points of the section end points and the middle points in each divided section as shown in FIG. There is a way to determine the plane. In that case, when the plane cannot be determined at three points, the section is determined to be a straight line, and the parallel movement method is used to calculate the characteristic curve.

Once the plane has been determined, then, at the points on the characteristic curve on the trajectory curve and the characteristic curve calculation destination points, the outer product is calculated by the tangent vector at each point and the normal vector of the plane, Let it be the main normal vector. Then, the cross product is taken from the main normal vector and the tangent vector, and the result is taken as the binormal vector.

As shown in FIG. 7, a coordinate conversion matrix between two points is calculated by using the tangent vector, the main normal vector and the subnormal vector thus obtained as a coordinate system, and the coordinate conversion is performed, as shown in FIG. The characteristic curve is calculated as follows.

When sweeping the characteristic curves in parallel, the parallel movement method is used for calculation regardless of the type of the trajectory curve. Therefore, the arrangement is as shown in FIG.

Further, as shown in FIG. 10, in the case of sweeping with characteristic curves of different shapes, at the calculation destination point for calculating the characteristic curve, as shown in FIG. Each characteristic curve is calculated at the calculation destination point based on the characteristic curve, and then linear interpolation is performed based on the ratio of the lengths from the respective points where the original characteristic curve is arranged to the calculated two points to the calculation destination point. Do.

As shown in FIG. 12, the curve obtained by the linear interpolation is used as the characteristic curve of the calculation destination point.

After the characteristic curves are arranged at the end points and the inflection points of the trajectory curve, a section sweep solid is generated in each trajectory curve section based on the trajectory curve and the characteristic curve (step S3). The solid generation method determination unit 9 determines whether or not the section sweep solid can be generated based on the characteristic curve and the trajectory curve, and when it is determined that the section sweep solid can be generated, the section sweep solid generation unit 10 generates the section sweep solid.

For example, as shown in FIG. 13, when the trajectory curve is a straight line, the section sweep solid can be generated by using the ruled surface generation method. In addition, as shown in FIG. 14, when a circular arc is used as a trajectory curve and the shapes of the characteristic curves at both ends of the circular arc match each other, it is possible to perform section sweep stereoscopic generation using a stereoscopic generation method around the arc.

When the stereoscopic method determining unit 9 determines that it is impossible to generate the interval sweep solids, the approximate interval sweep solids generation unit 11 generates the interval sweep solids. For example, as shown in FIG. 15, when the trajectory curve is a free curve, a section sweep solid is generated using the approximate section sweep generation method.

The operation of the approximate interval sweep solid generation unit 11 will be described below with reference to the flowchart of FIG.

The approximate section sweep solid generator 11 first generates a solid using a skinning method based on the arranged characteristic curves (step T1). For skinning, a rational B-spline (N
URBS (Non-Uniform Rational)
B-Spline)) curve is used, for example, "On Nervus: Survey, Les Piegres,
Institute of Electronics and Electrical Engineers, Computer Graphics and Applications, January 1991 ("OnNUR
BS: A Survey "(Les Piegl, IE
EE Computer Graphics & Ap
The method of skinning described in the publication, January 1991)) is used.

Next, at the intermediate point between the characteristic curves on the trajectory curve, the characteristic curve calculating section 8 calculates the characteristic curve (step T2), and at the same time, calculates the three-dimensional sectional curve at the parameter point ( Step T3). Then, as shown in FIG. 17, the characteristic curve and the section curve at the parameter point are compared (step T).
4).

As means for comparing the characteristic curve and the section curve, it is possible to compare the curves themselves or, in the case of a NURBS curve, compare each control vertex. If the comparison is not determined to be within the allowable range, the calculated characteristic curve is stored as the characteristic curve for the next reproduction of the solid (step T5).
The operations after the three-dimensional generation (step T1) are performed for all characteristic curves (step T6). When the processing is completed for all the characteristic curves, it is judged whether or not the calculated characteristic curve stored in the above step T5 exists (step T7), and if there is, the stored calculated characteristic curve is newly characterized. Add as a curve (step T8).
Based on the added feature curve, the skinning method is used to regenerate the solid body, and the operations after step T2 are repeated. It is determined whether or not the stored calculated characteristic curve no longer exists (step T7), and the above step T
When it is determined that the calculated characteristic curve stored in 7 does not exist, the processing is terminated, and the solid body generated at that time is set as the approximate interval sweep solid body.

After generating the section sweep solid on each trajectory curve, the inter-curved surface matching unit 12 orbits both ends of the solid in order to adjust the connectivity between adjacent solids in the section sweep solid as shown in FIG. Correction is made in the direction of the tangent vector of the corresponding end points of the curve (step S4 in FIG. 2).

For modification of both end portions of a solid, for example, "Visual Continuity", Wolfgang Baume, CAD, Vol. 20, number 6,1988
("Visual continuity", Wolf
gang Boehm, CAD Volume 20
number 6, 1988) Tangent plain continuous patchwork (TANGENT)
PLANE CONTINUOUS PATCH W
The method described in the section (ORK) is used.

Then, the three-dimensional synthesizing unit 13 synthesizes each section sweep solid generated on the trajectory curve into one sweep solid as shown in FIG. 19 (step S in FIG. 2).
5). Here, in the case of generating a curved surface by a NURBS curve for synthesis, for example, "On Nervus: Survey, Les.
Piegr, Institute of Electronics and Electrical Engineers, Computer Graphics and Applications, January 1991 ("On NURBS: A Survey" (Les P
IEGL, IEEE Computer Graphi
cs & Application, January
1991)), the NURBS curved surface Oslo algorithm and the order increasing algorithm
The orders of the URBS curved surfaces are made uniform, and one NURBS curved surface is generated.

As is clear from the above description, the sweep solid generation device of the present invention has the following effects.

1) When a characteristic curve at an arbitrary position of a trajectory curve is calculated, a characteristic curve corresponding to the type of the trajectory curve is calculated, and when the coordinate conversion matrix used for the calculation cannot be uniquely defined, an appropriate plane is obtained. Is specified and the coordinate transformation matrix at the parameter points is defined based on the normal vector of the plane and the tangent vector at the arbitrary parameter points of the trajectory curve, so that it is not affected by the twist due to the drastic change in curvature. Curved surface generation is possible.

2) Since the section sweep solid corresponding to the type of the trajectory curve is generated, it is possible to generate the sweep solid reflecting the characteristics of the trajectory curve.

3) Since both end portions of the section sweep solid are corrected in the directions of the tangent vectors at both ends of the trajectory curve, if the trajectory curves are smoothly connected, the generated section sweep solids are also smoothly connected. To be done. Therefore, the combined sweep solid can be a smooth curved surface. Also, it can be expressed in a curved surface format having generality such as a NURBS curved surface.

[0034]

The sweep volume generating apparatus of the present invention is characterized by a characteristic curve calculating means for calculating a characteristic curve at an arbitrary point of a trajectory curve and a characteristic curve for arranging the calculated characteristic curve at both end points of the trajectory curve. A placement means, a solid generation method determination means for determining whether or not to use an approximate method for generation of a sweep solid based on a trajectory curve and a characteristic curve disposed at both end points of the trajectory curve, and a solid generation method determination means. Approximately by a section sweep solid generation means for generating a sweep solid based on a trajectory curve and a feature curve when it is determined that the method of approximation is not used in generation of a sweep solid, and generation of a sweep solid by a solid generation method determination means When it is determined that the method of (3) is used, the feature curve calculation means is used to appropriately add the feature curve to the trajectory curve to approximately generate a solid, and the approximate interval sweep solid generation means, A curved surface matching means for adjusting the connectivity between adjacent solids in the interval sweep solid obtained by the approximate solid sweep generation means and the approximated sweep solid generation means, and a stereoscopic synthesis means for synthesizing the sweep sweep solid into one sweep solid. Since it is provided, since the sweep solid corresponding to the type of the trajectory curve is generated in the trajectory curve section, the sweep solid reflecting the characteristics of the trajectory curve can be generated. Further, since the connectivity between adjacent solids is taken into consideration in the sweep solid generated in the section, if the trajectory curves are smoothly connected, the generated sweep solid will also be a smooth curved surface.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a sweep solid generation apparatus of the present invention.

FIG. 2 is a flow chart for explaining the operation of the sweep volume generating apparatus of FIG.

FIG. 3 is an explanatory diagram of an input trajectory curve and a characteristic curve.

FIG. 4 is an explanatory diagram when characteristic curves are arranged at both ends and inflection points of a trajectory curve.

FIG. 5 is an explanatory diagram of a characteristic curve and a designated plane in a section.

FIG. 6 is an explanatory diagram of a characteristic curve and a designated plane in a section.

FIG. 7 is an explanatory diagram of a conversion coordinate system.

FIG. 8 is an explanatory diagram of arrangement of characteristic curves.

FIG. 9 is an explanatory diagram of arrangement of characteristic curves.

FIG. 10 is an explanatory diagram of an arrangement when feature curves have different shapes.

FIG. 11 is an explanatory diagram for calculating a characteristic curve at a calculation destination point.

FIG. 12 is an explanatory diagram of a characteristic curve linearly interpolated at a calculation destination point.

FIG. 13 is an explanatory diagram of section sweep solid generation when a straight line is used as a trajectory curve.

FIG. 14 is an explanatory diagram of section sweep solid generation when an arc is used as a trajectory curve.

FIG. 15 is an explanatory diagram of section sweep solid generation when a free curve is a trajectory curve.

16 is a flowchart for explaining the operation of the approximate interval sweep solid generation unit in FIG.

FIG. 17 is an explanatory diagram of comparison between a sectional curve and a trajectory curve.

FIG. 18 is a diagram for explaining the operation of the stereoscopic matching unit in FIG. 1.

FIG. 19 is a diagram showing an example of a result obtained by the sweep stereoscopic apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 control part 2 display part 3 keyboard part 4 tablet part 5 file part 6 modeling part 7 characteristic curve arrangement part 8 characteristic curve calculation part 9 three-dimensional generation method determination part 10 interval sweep three-dimensional generation part 11 approximate interval sweep generation part 12 matching between curved surfaces Division 13 Stereoscopic Synthesis Division

Claims (1)

[Claims] 1. A characteristic curve calculating means for calculating a characteristic curve at an arbitrary point of a trajectory curve, a characteristic curve arranging means for arranging the calculated characteristic curve at both end points of the trajectory curve, and the trajectory curve and Based on the characteristic curves arranged at both end points of the trajectory curve, a stereoscopic generation method discriminating means for discriminating whether or not to use an approximate method for generating a swept stereoscopic body, and the stereoscopic production method discriminating means for discriminating the sweep solid body. Section sweep solid generation means for generating the sweep solid based on the trajectory curve and the characteristic curve when it is determined that the approximation method is not used in generation, and generation of the sweep solid by the solid generation method determination means In the case where it is determined that the approximation method is to be used, the approximation section sweep solid generation unit that appropriately adds the feature curve to the trajectory curve using the feature curve calculation unit to approximately generate a solid, Section switch Curved surface matching means for adjusting connectivity between adjacent solids in the interval sweep solid obtained by the approximated sweep solid generation means and the approximated sweep solid generation means,
A sweep solid generation device comprising: a solid synthesizing unit that synthesizes the section sweep solid into one sweep solid.