JPH0219977A - Solid model processing system - Google Patents

Abstract

PURPOSE:To prevent the occurrence of an edge meaningless for a user and to solve the complexity of internal processing by recognizing the composition of a face from the plural sets of external boundary information based on either edges or vertexes when these plural sets of the external boundary information exist. CONSTITUTION:A boundary expressing model data creating processing part 14 composes and edits information related to the curved face of a solid model with the data structure of a winged edge having the plural sets of the external boundary information based on either the edges or the vertexes and stores the composed and edited information in a memory 15 when the solid model includes the curved face in creating/editing processing for the solid model. A face composition recognizing processing part 16 decides whether the plural sets of the external boundary information based on either the edges or the vertexes exist for the data of one face as a processing object or not and recognizes the composition of the face from the plural sets of the external boundary information when the plural sets of the external boundary information exist. Thus, the occurrence of the edge meaningless for the user can be prevented, and the complexity of the internal processing can be solved.

Description

[Detailed Description of the Invention] ((Renovation) A system that represents the two-dimensional shape of an object using a boundary representation model and performs processing including display processing of the object. , and an object of the present invention is to provide a means for preventing the generation of edges that are meaningless to the user and eliminating the complexity of internal processing in a solid model processing system improved to have a structure connected by edges.

Information regarding curved surfaces in a solid that includes curved surfaces is constructed using a winged-edge data structure that has multiple sets of external boundary information based on edges or vertices.

A boundary expression model data creation processing unit stored in a storage device determines whether or not multiple sets of external boundary information based on edges or vertices exist for data of one surface to be processed, and determines whether multiple sets of external boundary information exist. In this case, the present invention is configured to include a surface configuration recognition processing unit that recognizes the configuration of the surface from the plurality of sets of external boundary information.

[Industrial application field]

The present invention represents the three-dimensional shape of an object using a boundary representation model,
It is a system that performs processing including display processing of the object, and replaces the conventional winged structure connected only by ridgelines.
The present invention also relates to a solid model processing system improved to have a structure connected by edges.

[Prior Art] FIG. 6 is an explanatory diagram of boundary representation and winged edge structure used in a solid model processing system.

FIG. 7 shows an example of edge data in a winged edge structure, FIG. 8 shows an example of ghost edge occurrence in a conventional method, and FIG. 9 shows an example of a conventional internal data structure.

In systems such as CAD systems that handle solid models that can completely express the three-dimensional shape of an object, the solid model can be expressed using various methods such as the spatial grid method and the CSC model boundary expression model. is being carried out. In particular, in a system that employs the boundary representation model targeted by the present invention, the shape of an object is described by a boundary that separates the inside and outside of the object.

That is, in the boundary representation model, the three-dimensional shape of an object is represented as a set of boundary surfaces surrounding the solid, as shown in FIG. 6(a). Each boundary surface is.

It is represented by a set of ridgelines that make up the surface.

A winged edge structure is often used as a typical internal arc structure to realize a boundary expression model. (Reference: [1, G. Baumgart, 'A po
lyhedron representation f
or computer vision.

8 FIPS Conf, l”roc, 44.p.
p589-596) In the internal representation of a solid using this winged edge structure, by having an edge as the center, the connections between the edges, and the faces on both sides as data.

The relationship between edges and surfaces is defined to uniquely determine a solid.

For example, for the edge line E1 shown in FIG. 6(b), four edge line pointers 5R1Sl7 . Snake R,
EL, and a pointer R to the boundary information (hereinafter also referred to as a loop) of the surfaces on both sides of the edge line B1.
Has L and LL. Namely.

Winged i7 as topology data of one edge
In the data structure, a data structure as shown in FIG. 7 is generated. The geometric data pointed from this structure includes the coordinate information of the start point and end point, the arc, i
l! This is information regarding the L line, etc.

In this way, the internal representation of the solid is winged.

When attempting to express a solid body including a curved surface such as two cylinders and one cone in a system based on the geometric structure, according to the conventional method, it becomes necessary to set ridgelines on the curved surface, which are not necessarily present on the curved surface. This is called Ghost Edge.

In the case of a cylinder, ghost edges Gl and G2 as shown in FIG. 8(a) are required, and in the case of a two-cone.

Ghost work as shown in Figure 8 (b), JiG3゜G4
is required.

When a cylindrical object is expressed using a conventional winged geometry structure, its internal data structure will be as shown in FIG.

The data of the object OBJ cyclically points to the data of the first plane F1 to F4. In particular, the surface F3 constituting one cylindrical surface.
F4 is delimited by two ghosts, gi and gi.

The data for each side F1 to F4 is as follows.

Each has geometric data that defines the surface, and 1
Data of loops L1 to L1.4 are respectively pointed to as surface boundary information. Each loop L1 to L4 points to a set of edges that make up the loop.

Note that there are two types of loops: outer loops and inner loops9.
For example, in a perforated object as shown in Figure 6 (a), 5
The loop indicating the outer boundary is called the outer loop, and the loop indicating the inner boundary around the hole is called the inner loop. That is,
In the object shown in FIG. 6(a), a cylindrical hole is placed in a cube, and on the top and bottom surfaces of the object, the boundary of the square is the outer loop, and the boundary of the inner circle is the inner loop.

Whether a loop is an outer loop or an inner loop can be identified, for example, by a flag provided in a structure indicating the loop.

According to the conventional winged method structure, there is always one external loop on one surface, and there is never a plurality of external loops.

[Problem to be solved by the invention]

According to the conventional method, the structure of the surfaces constituting a solid is expressed only by the connection of edges, so the representation of a solid containing nine curved surfaces as shown in Figures 8 (a) and (b) is difficult. ,
Ghost Edge is required. However, if this ghost edge exists, its shape (for example, a cylindrical surface) will change as it is.

Since it cannot be treated as one page, complicated processing is required internally.

Processing also differs depending on whether the user is made aware of Ghost Edge or not.

If the user is made aware of ghost edges, the user must always consider lines that are originally unnecessary, which increases the burden on the user. In addition, when one cylindrical surface is to be shaded with two colors, it is necessary to carry out the veiling operation on two surfaces, which is not good in terms of operability.

On the other hand, if we do not make the user aware of ghost edges, the process of treating them externally as one surface becomes complicated. Various editing operations such as adding straddling protrusions and drilling holes require complicated processing that takes ghost edges into consideration.

The present invention aims to solve the above-mentioned problems, and aims to provide a means for preventing the generation of edges that are meaningless to the user and eliminating the complexity of internal processing.

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention.

In FIG. 1, 10 is a keyboard and a mouse.

Tablet and other input devices; 11 is a display device; 12 is a processing device including a CP tJ and memory; 13 is a user ink interface section that performs input control and display control; 14 is a boundary expression model data creation processing section; 15 is a A device 4g records data representing a solid by a boundary representation model, 16 represents a surface configuration recognition processing unit, and 17 represents model data.

The processing device 12 performs creation/El processing on a solid model representing the three-dimensional shape of the object using a boundary representation model, and performs processing for displaying the solid model on the display device 11.

In the solid model creation/editing process, the boundary expression model data creation processing unit 14 converts information regarding the curved surface into Winged Engine data having multiple sets of external boundary information based on edges or vertices, when the solid model includes a curved surface. The process of configuring and editing the data according to the structure and storing it in the storage device 15 is performed.

The surface configuration recognition processing unit 16 determines whether or not multiple sets of external boundary information based on ridge lines or vertices exist for the data of one surface that is the processing target, and if multiple sets exist, 2. This process recognizes the configuration of a surface from the external boundary information of a set.

For example, when creating/editing a single cylindrical object OBJ, the boundary expression model data creation processing unit 14 defines the shape of the object 013 J using data based on the winged geometry structure. without using.

Boundary information is represented by two outer loops Ll and L2,
From the topology data of the surface F2, the outer loop L1.
Point to the L2 topology data.

That is, whereas conventional data structures allow only one outer loop for one surface.

In the present invention, one curved surface can be described by a plurality of outer loops.

The surface configuration recognition processing unit 16 performs processing on one surface at each location where a solid model is processed.

It is determined whether there are a plurality of external loops pointed to from that surface, and if there are a plurality of external loops, the configuration of one surface is recognized based on information on the plurality of external loops.

[Effect]

FIG. 2 is an explanatory diagram of the operation of the present invention.

In the conventional boundary representation using the winged edge structure, the second
Temporary ridgelines such as ghost edges Gl and G2 shown in Figure (A) were provided on the cylindrical surface so that all the ridgelines could be traced.

The present invention eliminates the restriction that all ridgelines must be traced.・Abolish edges and instead introduce the concept of connecting not only by a ridgeline but also by two sides.

By recognizing that each processing unit is connected by surfaces, a consistent three-dimensional structure is ensured.

The present invention proposes a new expanded winged edge structure, which can be thought of as focusing on representing a solid model.This structure is similar to the conventional winged edge structure in terms of polyhedrons. The structure allows us to recognize that only objects with curved surfaces, such as cylindrical surfaces, are connected by those surfaces.

That is, in the conventional winged edge structure.

As a constraint that does not cause 3D contradiction, SR≠ for the ridgeline
There are constraints such as SL, IER≠EL, and RL≠LL.

On the other hand, in the expanded winged structure of the present invention,
As shown in FIG. 2(B), ghost edges are removed and data in the following state is allowed to exist.

・5Rf-3L and ER#IIZL and not itself.

・5R=SL and ER≠RL and not itself.

SR≠SI-and [', R=EI, and not itself.

・5R = SL power) 1 ER = EL power 1 Not yourself.

SRte5L=ER=IEL-Myself.

Here, "self" refers to the central ridgeline itself. The data for the ridgeline E1 shown in Figure 2 (b) is
As shown in Figure 2 (c).

It is expressed as rSR-3L-ER=EL-self (El)J (the same goes for the ridgeline E2 on the bottom surface), and in this case, the structure is based on the idea that they are connected by seven surfaces.

This makes it possible to eliminate ghost edges that existed only to make the structure consistent, and to simplify many of the internal processes involved.

〔Example〕

FIG. 3 is an example of a system to which the present invention is applied, FIG. 4 is an example of an internal data structure according to an embodiment of the present invention, and FIG. 5 is an example of an application system of the present invention.
- An example of calculation of intersection lines between surfaces in the example is shown.

The present invention represents the three-dimensional shape of an object using a boundary representation model,
It is applied to CAD systems etc. that handle the solid model. Figure 3 shows an example of this system.
Components with the same reference numerals as those in the figure correspond to those shown in FIG. A creation/editing processing section 23 performs editing such as drilling, protrusion addition, etc., a common processing section 24 performs various common processing such as coordinate transformation and intersection calculation, and a display control section 24 performs display control on the display device 11;
Reference numeral 25 represents an access control unit that accesses the model data, and 26 represents an external storage device such as a magnetic disk device in which the model data is stored.

The creation/editing processing unit 22 converts the data of the environment representation model into
Managed by an internal data structure based on winged edge structure. However, as mentioned above, the need to generate unnecessary ghost edges on one surface can be eliminated by introducing the concept of connections between two surfaces instead of expressing all five three-dimensional structures using only connections between edges. ing. Boundary expression model data creation processing unit 1 shown in Fig. 1
4 and the surface configuration recognition processing section 16 are the creation/editing processing section 2.
2 or the common processing unit 23.

Next, referring to FIG. 4, an internal data structure according to an embodiment of the present invention will be explained using a cylindrical object as an example.

As shown in FIG. 4(A), the object OBJ is composed of an upper surface F1, two cylindrical surfaces F2, and a lower surface F3. These data are pointed to cyclically from object 0I3J. Furthermore, between the object and the surface.

Other layers such as shells may be provided to represent cavities and the like. 2 loops each going around its boundaries to represent each face? [5 is pointed at from the one-sided structure.

Top surface F1. The relationship between the lower surface F3 and the loops L3 and L4 is similar to that of the conventional winged edge structure.

Regarding the cylindrical surface F2, in the present invention, its boundary information is expressed by two outer loops, the loop L1 and the loop L2, without using ghost edges.

If the boundary edge on the top surface is El and the boundary edge on the bottom surface is E2, loop 1.1. From L3, follow ridgeline E1.

Loop L2. From L4, point to ridgeline E2.

Specifically, the data shown in FIG. 4 (a) is as follows.

From the structure of surface 0 data that is generated and edited in the processing device and used as a hierarchical structure of two surfaces, loops, and edges of the object as shown in FIG. 4 (b).

Geometric data D1 to D3 such as equations of the surface are pointed, and geometric data D4. D5 is pointed.

The internal processing procedure for creating such a data structure can be realized by a simple application of conventional technology, so a description thereof will be omitted.

For example, for an object such as a 5-cone, the apex of the 2-cone is regarded as one outer loop, and the base is regarded as another outer loop, and the data structure shown in FIG. 4 is used.

It is possible to create an expression that removes ghost edges.

The semi-r end, etc. can be similarly expressed by providing an external loop of points on the two spheres.

The data structure shown in Figure 4 is created by the creation/data structure shown in Figure 3.
It is used in various parts of the editing processing section 22. For example, the differences from the process of 5 Conventional Technique 4Fi will be explained using as an example the process of finding the line of intersection between a cylindrical surface and a plane as shown in FIG. 5(A).

FIG. 5(b) shows a part of the processing in calculating the intersection line between the nine planes and the plane.

■ Read (RE A D) the data of the two surfaces in order to recognize the configuration of the surfaces that are subject to intersection line calculations.

Here, it is assumed that data for two cylindrical surfaces is read.

■ Read all loop data bound from surface data.

■ Determine whether there are multiple outer loops based on attribute information such as flags. If there is more than one, move on to process ■.

Here, since the two cylindrical surfaces have two external loops, we will move on to the fifth-order process (2).

■ Perform calculations using mathematical formulas using edge data pointed from two external loops. The expression format of the cylindrical surface is different from the conventional one.

Since it is possible to obtain all the information about the cylindrical surface, the calculations can be performed by normal processing. Since there are no ghost edges, internal processing such as boundary condition determination processing is simplified.

■ If there is no single outer loop, use the same winged edge structure data as before.

Perform the same processing as before.

Not limited to intersection line calculations, but also drilling, protruding, set operations, etc.
In various editing processes, it is possible to recognize the structure of a three-dimensional surface, including one curved surface, by simply adding processing that takes into account multiple external loops, and it is possible to discard all processing that takes into account ghost edges. becomes.

〔Effect of the invention〕

As explained above, according to the two aspects of the present invention, it is possible to prevent the occurrence of ridge lines that are boring to the user.

Improved man-machine interface. Further, regarding internal processing, it is possible to eliminate the complexity of processing for a solid including two curved surfaces, making it possible to shorten the development period and speed up the processing.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanation of the present invention. FIG. 2 is a diagram explaining the operation of the present invention. FIG. 3 shows an example of a system to which the present invention is applied. FIG. 4 is an example of an internal data structure according to an embodiment of the present invention. FIG. 5 is an example of calculation of intersection lines between surfaces in an embodiment of the present invention. FIG. 6 is an explanatory diagram of the boundary representation and winged geometry structure used in the solid model processing system. Figure 7 is an example of edge line data in a winged engine structure. Figure 8 shows an example of ghost edges generated using the conventional method. FIG. 9 shows an example of a conventional internal data structure. In the figure, IO is a human-powered device f, 11 is a display device, 1
2 is a processing device, 13 is a user ink face section, 15 is a storage device, and 16 is a surface configuration recognition processing section. 17 represents model data. Patent author: Fujitsu Ltd. Agent: Patent attorney: Yoshiyoshi Ogasawara (2 others) Figure 2: Example of applied system Figure 3: Illustration of the principles of the invention Figure 1: Internal data structure Example Figure 4 (a) A row of plane-to-plane intersection line calculations Figure 5 Conventional internal design Figure 9 Example of Yumaki

Claims (1)

[Claims] In a solid model processing system that represents the three-dimensional shape of an object using a boundary representation model and performs processing including display processing of the object, information regarding curved surfaces in a solid including curved surfaces is expressed by external boundaries by edges or vertices. A boundary expression model data creation processing unit (14) that is configured by a winged edge data structure having multiple sets of information and stored in a storage device, and A surface configuration recognition processing unit (1) that determines whether or not there are multiple sets of external boundary information based on
6) A solid model processing system comprising: