JPH0385678A - Surface area recognizing system - Google Patents

Abstract

PURPOSE:To easily execute processing by adopting constitution to recognize a part sandwiched between open loops as a surface area. CONSTITUTION:A periodical ridgeline on a stereoscopic body is defined as an open loop 1 and on the stereoscopic body, the part sandwiched by a pair of open loops 1 is calculated as a surface area 2. Then, the calculated periodical surface area 2 is managed by one data structure. Thus, the surface area can be managed as one data structure and the recognition of a user can be made correspondent to the data structure in the internal part of a computer. Then, the periodical surface (surface area) on the stereoscopic body is exactly and easily recognized and the processing is made easy.

Description

[Detailed Description of the Invention] [Summary] Regarding a surface area recognition method that recognizes a surface 8N area sandwiched between ridge lines on a three-dimensional object, the part sandwiched between open loops is obtained and managed as a surface area, making it easier to process. For the purpose of It is managed by one data structure.

[Industrial application field]

The present invention relates to a surface area recognition method for recognizing a surface area sandwiched between ridgelines on a solid surface.

[Problems to be solved by conventional technology and invention] Figure 6 (
As shown in b), when a surface such as a cylindrical surface, conical surface, spherical surface, etc. is expanded into a two-dimensional parameter space u, v,
A surface that repeats the same shape at a certain period is called a periodic surface.

wing is a conventional method of expressing solid CAD data.
In the ed-edge structure, the contour of one surface defines a region from one external loop (loop representing the contour of the surface). Therefore, for a non-periodic surface, the area of the surface can be recognized from the loops that define its outline. However, surfaces with periodic properties cannot be recognized as a single surface, and are managed by dividing them into multiple surfaces. At this time, the surface that the user recognizes as one sheet is divided into a plurality of surfaces and managed inside the computer, so there is a problem that the user's recognition and the representation inside the computer do not match. For example, as shown in Figure 6 (a), regarding the side of the cylinder,
There was a difference between surface 1 and surface 2, which are managed as two surfaces within the computer and recognized by the user as one side. Also, as shown in Figure 6 (b), if there is a hole on the side of the cylinder, if the hole comes to the boundary (reference line) depending on the position of the ridge line, it is impossible to define a hole that spans two surfaces. , there was a problem that it could no longer be recognized as a hole.

An object of the present invention is to obtain and manage a portion sandwiched between open loops as a surface area, thereby facilitating processing.

[Means to solve problems]

Means for solving the problem will be explained with reference to FIG.

In FIG. 1, an open loop 1 defines periodic ridge lines on a solid surface.

The surface region 2 is a three-dimensional portion sandwiched between a pair of open loops 1.

[Effect]

As shown in FIG. 1, the present invention defines a periodic ridge line on a three-dimensional object as an open loop 1, and obtains a portion of the three-dimensional object sandwiched between a pair of open loops 1 as a surface area 2. The obtained periodic surface area 2 is managed using one data structure.

Therefore, by recognizing the part sandwiched between open loops 1 as surface area 2, periodic surface area 2 can be managed as one data structure, and the user's recognition corresponds to the data structure inside the computer. It becomes easier to accurately recognize periodic surfaces (surface areas) on a solid surface, and processing becomes easier.

〔Example〕

Next, the configuration and operation of one embodiment of the present invention will be explained in detail using FIGS. 1 to 5.

In FIG. 1, open loop 1 defines periodic ridge lines on a solid surface. For example, in the case of a cylinder shown in FIG.

The surface region 2B is a three-dimensional portion sandwiched between a pair of open loops 1. For example, in the case of the cylinder shown in FIG. 1(a), this is the portion on the cylinder sandwiched between the open loop (top) and the open loop (bottom).The shape of the surface area can be defined by the following equation (1).

Shape of surface area = part sandwiched between a pair of open loops -
Σ Inner loop・・・・・・・・・・・・(1) Here, Σ
As will be described later, the inner loop is a loop that exists inside a portion sandwiched between l pairs of open loops.

FIG. 1(a) shows the surface area of the cylinder. The surface region 2 of the cylinder schematically shown on the left side is a portion on the cylinder sandwiched between an open loop (top) and an open loop (bottom). The data structure is shown on the right side, and the (1) surface is a cylinder (radius R1
Consists of height H), f21 open loop (upper), and (31 open loop (lower).This is different from the conventional 6th
According to the winged-edge method shown in Figure (a), surface 1
, surface 2, compared to the case where there are two data structures, according to this embodiment, it can be expressed by one data structure as shown in the figure.

FIG. 1(b) shows the surface area of a cone. The surface region 2 of the cone schematically shown on the left is the part on the cone sandwiched between the apex O (regarded as an open loop) and the open loop (bottom).The data structure is shown on the right, and (1) surface is composed of a cone (radius R1 height H) and (2) an open loop (bottom).

FIG. 1(c) shows the surface area of the sphere. The surface region 2 of the sphere schematically shown on the left side is a portion sandwiched between the pole (top) and the pole (bottom), each of which is regarded as an open loop 1. The data structure is shown on the right, and (1) the surface is a sphere (radius R
It is composed of one central position W).

FIG. 1(d) shows the surface area of the sphere. The surface area 2 of the sphere schematically shown on the left is the part sandwiched between the pole (top) and the open loop (bottom).

The data structure is shown on the right side, and the (L) surface is composed of a sphere (radius R1 center position) and (2) an open loop (bottom).

FIG. 2 shows a definition explanatory diagram of a periodic surface according to the present invention.

A three-dimensional (solid) surface can generally be expressed by two-dimensional parameters.

For example, in the case of a plane in Fig. 2 (a), in the case of a cylindrical surface in Fig. 2 (b), and in the case of a torus surface in Fig. 2 (C), define OlZ, X, u, v, etc. as shown. .

According to these definitions, when U is periodic, a point P on the surface area can be expressed as shown in FIG.

Here, n is an integer and CI is a periodic constant. Similarly, when ■ is periodic, the point P on the surface area can be expressed as shown in (b) in FIG. Here, m is an integer, and C2 is a periodic constant.

FIG. 3 shows an example of expression in a two-dimensional parameter space.

FIG. 3(A) shows an open loop (U direction) of the cylindrical surface. This is a case where the open loop (bottom) schematically shown on the left continues from points P, P2, . . . P9 as shown. As shown on the right, (u+, Vl)≠(ul,■,)−・・・(2)
Therefore, it is an open loop.

On the other hand, FIG. 3(b) shows the inner loop of the cylindrical surface. This is the case when the inner loop schematically shown on the left continues with points P, , P, . As shown on the right, (u3, ■,) - (u7, ■,)...
- Since (3) is, it is an internal loop.

FIG. 4 shows an example of expression of a surface area in Duv.

FIG. 4(a) shows the case of type (plane). This is the case for a surface area such as a plane that is not periodic in both the u and v directions, and as shown in the figure, the EDI
This is the case where the surface area is sandwiched by J.

FIG. 4 (b) shows the case of type 2 (cylindrical surface, etc.). This is a cylindrical surface, etc., and one of u1■
This is the case for a surface region that is periodic in only one direction, for example for a surface region sandwiched by an open loop (top) and an open loop (bottom) as shown.

FIG. 4(c) shows the case of type 3 ()--rath surface. This is the case when both u and v are periodic surface areas such as a torus surface. For example, as shown in the figure, an open loop in the direction of U and This is the case for sandwiched surface areas.

FIG. 5 shows an example of expression of a surface area in Duv.

This describes cases where the inner loop does not straddle the reference line and cases where it straddles the reference line.

FIG. 5(A) shows the case where the inner loop does not straddle the reference line. In this case, as shown in the face area on the right,
The internal loop forms a hole in the surface area.

Figure 5 (mouth) shows the case where the internal loop straddles the reference line. In this case, as shown in the surface area on the right,
The inner loop is divided into two parts by a reference line, and these are treated as the contours of the surface area instead of the reference line.

Figure 5 (c) shows the case where the internal loop straddles the reference line. In this case, as shown in the surface area on the right,
Since the surface area is divided into two by the inner loop, these two are processed separately, and if a point is included in either area, that point is determined to be inside the surface area and processed. . Although the description has been made regarding a surface area having an open loop, the same processing is performed for an inner loop having no open loop.

0 [Effects of the Invention] As explained above, according to the present invention, since a configuration is adopted in which the portion sandwiched between the open loops 1 is recognized as a surface (surface area), a periodic surface area can be The data structure can be managed as one data structure, and the user's recognition corresponds to the data structure inside the computer, making it easy to recognize periodic surface areas on a solid surface.

[Brief explanation of drawings]

Fig. 1 is a composition diagram of one embodiment of the present invention, Fig. 2 is an explanatory diagram of the definition of a periodic surface according to the present invention, Fig. 3 is an example of expression in a two-dimensional parameter space, Figs. The figure shows an example of representation of a surface area in Duν, and FIG. 6 shows an explanatory diagram of the prior art. In the figure, 1 represents an open loop, and 2 represents a surface area (surface).

Claims (1)

[Claims] In a surface area recognition method that recognizes a surface area sandwiched between ridgelines on a solid, periodic ridgelines on a solid are defined as an open loop (1), and one of the open loops (1) is defined as an open loop (1). A plane area recognition method characterized in that the part on the solid between the pairs is determined as a plane area (2), and the determined periodic plane area (2) is managed by one data structure. .