JPH04111173A - Graphic expressing system - Google Patents

Abstract

PURPOSE:To faithfully express real things on a computer by discriminating whether a dividing processing of a line segment is for the front side or the rear side, and expressing a graphic by using the line segment whose front side and rear side can be independently divided based on dividing state information. CONSTITUTION:A line segment two side discriminating part 14 discriminates the front side and rear side of the line segment according to a constant refer ence. A two side line segment graphic model managing part 15 controls an operation to constitute a graphic model while referring to the discriminated result of the line segmesnt two side discriminating part 14. A graphic data storing area 17 stores graphic data being a final aim. An overlap (interruption) between graphic data stored in a data inputting area 16 and graphic data stored in the graphic data storing area 17 is processed, and then, the data of the data inputting area 16 are added to the graphic data storing area 17.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention uses so-called boundary representation, in which a figure is expressed by an arrangement of boundary line segments, and the boundary line segments are expressed by the start and end points of the line segments.
This relates to the graphic representation method according to n).

[Conventional technology]

Boundary representation has been widely used as a means to faithfully represent a design object that exists in reality [for example, fl) M,
An 1ntroductin to by Mantyla
5solid modeling, Computer
5science Press 1988, (2) Patent Application Publication, 1983-279983. graphics processing system,
(3) Patent application publication, 1982-105271. Interactive Shape Modeling System]. In boundary representation, based on the idea that a boundary line segment is created by the intersection of two surfaces, a surface is represented by an ordered arrangement (ring) of adjacent line segments, and a boundary line segment is created by the start and end points of the line segment. expressing. Boundary expressions have the advantage that it is easy to directly understand the correspondence between real objects and the basic elements of boundary expressions.

For example, when a floor plan of a building is expressed using a boundary representation, rooms correspond to planes, walls correspond to lines, and columns correspond to points. 1st
FIG. 2 is a boundary representation of the figure shown in FIG. 11.

FIG. 13 shows the operation of boundary expression, which is a conventional technique. Operation 1 described here uses a figure data storage area for storing figures and a data input area for temporarily storing figures to be added.

First, in step 4.01, the graphic data storage area is initialized. Next, step 4.02 determines whether the end symbol of data input is input and it is one column. If it is not the end of data input, the data input area is initialized in step 403, and the name of the surface to be input and boundary line segment data are stored in the pig input area in step 404. Step 405 is a step for all line segments in the graphic data recording area and all line segments Ln in the data manual area.
406.407, 408.409. In step 406, the line segment LF and the line segment. It is determined whether or not they overlap. If they do not overlap, the process returns to step 405 for processing the next line segment. If they overlap, in step 407, the overlapping portion (line segment Lc) of line segment L and line segment is extracted and stored in the graphic data storage area as an independent line segment. Next, in step 408, line segment LF is separated. The drawn part is stored as a new line segment in the graphic data storage area. Step 409 is line segmentation. Line segment from.

The drawn part is a new line segment, which is closed and stored in the graphic data storage area. After performing the above processing for all line segments LP in the figure data storage area and all line segments 1-D in the data manual area, all data in the data input area is processed in step 410. Add to graphic data storage area.

For example, when defining the figure in Figure 14, first
The name of the line segments Ll, L2 . that are the boundaries of this surface. L
3. Enter L4. At this time, the graphic data storage area is initialized and nothing is stored, so step 40
No processing is performed in steps 5, 406, 407, 408, and 409, and data regarding plane AI is moved to the graphic data storage area in step 410. Next, the name of surface A2 and the line segment L5. which is the boundary of this surface. L6. L7L8. L
9 manually. This time, since there is data regarding surface A1 in the graphic data storage area, steps 40, 406, and 4 are performed.
07.408.409 processing is performed. In the case of the figure in FIG. 14, line segments L2 and Ll overlap. The overlapping portion is added to the graphic pig storage area as an independent line segment in step 407 (named Lzb in FIG. 14). The original line segments L2 and Ll are obtained by removing the overlapping parts of line segment L2b, respectively, and
Redefined as 2a+L 7b. Thereafter, the process of step 410 is performed, and the data shown in FIG. 15 is stored in the graphic data storage area.

[Problem to be solved by the invention]

Conventional boundary expression methods have a problem in that the additional definition of a region also affects adjacent regions. For example, in the floor plan shown in FIG. 11, if a room A2 is additionally defined as shown in FIG. 14, the already defined room A1 will be affected as follows.

(1) Wall L2, which was originally one wall, is divided into two (14th
In the figure, L2□ and L2. ).

(2) As a result, room A1, which was originally surrounded by four walls,
, divided walls Lea and Lzb, L3. L4. I have no choice but to express that it is surrounded by the five walls of Ll.

Similarly, room A2, which is originally surrounded by five walls, is divided into walls L7b, Lzb, L8. L9, L5.
I have no choice but to express that it is surrounded by six walls of L6.

A situation where an existing wall is divided because a new room is added behind a certain wall is inconvenient when interpreted in relation to the actual floor plan. The above effect occurs because the line segment in the boundary representation is a line segment in a mathematical sense, and there is no distinction between a front side and a back side like a wall in a building.

If the conventional boundary expression is used as is, processing is required to convert the data structure so that when viewed from the room AI, the wall L2m is taken and the walls zb are combined to form one wall. Similarly, when viewed from room A2, walls L7b and I-zb
It is necessary to convert the data structure so that the data structures are combined to form a single wall. Such processing causes problems in maintaining data consistency and making further processing complicated and inefficient.

The present invention was made in order to solve the above-mentioned problems, and it introduces a means for distinguishing between the front side and the back side of a line segment in boundary expression, so that the front side and the back side of the line segment can be independently divided. The purpose is to obtain a boundary representation method that allows for faithful representation of real objects, such as walls in a building floor plan, on a computer.

[Means to solve the problem]

The graphic representation method according to the present invention includes a discriminating means (line segment front/back discriminating unit 14) for discriminating between the front side and the back side of a line segment and for discriminating whether the dividing process for a line segment is for the front side or the back side; A storage means (figure data storage area 17) for separately storing division state information of the front side and back side of the line segment determined by the determination means, and a line segment that can independently divide the front side and the back side based on the division state information. It is equipped with a graphic modeling means (front and back line segment graphic model management unit 15) that expresses a graphic using the graphic model management unit 15.

:Operation: The discriminating means (line segment front/back discriminating unit 14) discriminates between the front side and the back side of a line segment, and also discriminates whether the dividing process for the line segment is for the front side or the back side.

Storage means (graphic data storage area 17)! , :J- Separately stores the division state information of the front side and the back side of the line segment discriminated by the record discriminating means. The graphic modeling means (front and back line segment graphic model management unit 15) uses the above division state information? [Represent the figure using line segments that can independently divide the front and back sides based on 5.

〔Example〕

FIG. 1 is a block diagram showing the configuration of a graphic representation system according to an embodiment of the present invention. In FIG. 1, 11 is an input/output device that inputs and outputs data, 12 is a CPU (central processing unit) that performs graphic processing, etc., 13 is a main memory that stores data necessary for graphic processing, and 14 is an internal memory in CPU 2. A line segment front/back discriminating unit 15 is provided as a discriminating means for discriminating between the front side and the back side of a line segment and for discriminating whether the dividing process for a line segment is for the front side or the back side.
A front and back line segment graphic model management unit provided in the PU 12 and serving as a graphic modeling means for expressing a graphic using line segments that can independently divide the front side and the back side based on the following division state information;
Reference numeral 16 is a data input area provided in the main storage device 13 for temporarily storing a figure input manually from the input/output device 11, and 17 is provided in the main storage device 13 and is discriminated by the line segment front/back discrimination unit 14. This is a graphic data storage area that serves as a storage means for separately storing division state information for the front side and back side of a line segment. The line segment front/back discrimination unit 14 discriminates between the front side and the back side of a line segment according to a certain standard. Front and back line segment figure model management section 1
5 defines the operation of constructing a graphic model while referring to the discrimination result of the line segment front/back discrimination section 14. The graphic data storage area 17 stores graphic data that is the final target. After processing (overlapping interference between the graphic data stored in the data input area 16 and the graphic data stored in the graphic data storage area 17), the data in the data input area 16 is added to the isomorphic data storage area 17. Go. In this way, the final target graphic data is successively constructed.

FIG. 2 is a flowchart showing the processing of the line segment front/back discriminating unit 14 in FIG. This line segment front/back discrimination unit 14 determines the coordinates (x+, y+) (xz, yz) of the end points of the line segment,
The point you want to determine whether it is on the front side or the back side of this line segment (
Xll, y3) as input, and when it is on the front side, 1. When it is on the back side, the output value is -1. Step 701 is a process of determining whether the line segment is the front side or the back side. The criteria for judgment are
When the point (X3.y3) is in the positive area of the line segment, the point (X
3. The side visible from y3) is the front side (or the point (X: +
, y3) is on the front side of the line segment. on the other hand,
When the point (x:+, y:+) is in the negative area of the line segment, the side visible from the point (X:+, y3) is the back side (or the point (
x3. yz) is on the back side of the line segment. Step 702 is executed when the point (X:l, y3) is on the front side of the line segment, and returns a value of 1. Step 703 is executed when the point (X:++y3) is on the back side of the line segment, and returns the value -1.

FIG. 3 shows a data structure for storing line segments. There are two types of line segments in this embodiment. In other words, there are line segments that can independently divide the front side and back side, and line segments that represent the divided front side or back side. Line segments in the former sense will be simply referred to as ``line segments,'' and line segments in the latter sense will be referred to as ``element line segments.'' Figure 3 (A) shows a diagram for storing line segments. It shows the data structure.In order to divide the front and back sides of a line segment into element line segments of arbitrary value, two types of links, "front link" and "back link", can be stored. If there is no division, a nil value is entered.Third
Figure (B) shows a data structure for storing element line segments. Since an element line segment is an element obtained by dividing a line segment, links (element links) to other element line segments were prepared.

Both line segments and element line segments can be components of a surface, so
Links to trace the ring structure that represents the surface (ring/
link). On the other hand, identification names and definition parameters are required for both line segments and element line segments.

Figure 4 shows a line segment that divides the front side of an edge into three parts and has no division on the back side. FIG. 5 shows a data structure representing the line segments in FIG.

FIG. 6 is a flowchart showing the operation of expressing the boundary of a figure using line segments that can independently divide the front side and the back side. The use of the graphic data storage area and data input area for data input, and the process of determining the end of data input, are the same as the conventional boundary expression process shown in FIG. 13, but step 405 The controlled line segment division processing is different.

FIGS. 7 and 8 show classifications of line segment division patterns. In the figure, L is a line segment defined within the graphic data storage area, and L is a line segment defined within the data input area. Figure 7 shows the front side of line segment Lp' as line segment L.
The case is shown in which the line segment is divided into Fa and LFb, and the back side of the line segment is divided into line segments LDa and LDb. On the other hand, conceptually, to express that the two line segments LFb and LDa are the same line segment, the following is done. First, only one of the element line segment storage areas is left (LFb is left in the data structure of FIG. 9). Next, line segment, take.

Connect this element line segment storage area with a link. By facilitating only one data structure for the same line segment, data consistency management is facilitated. FIG. 9 shows a data structure corresponding to FIG. FIG. 8 shows a case where the back side of line segment LF is divided by the front side of line segment LF, and FIG. 10 shows an example of the data structure created by this division.

Step 1101 in FIG. 6 is for determining the division pattern shown in FIG. 7, and step 1103 is for processing this division pattern.

Step 1102 in FIG. 6 is for determining the division pattern shown in FIG. 8, and step 1104 is for processing this division pattern.

In addition, in the above example, a straight line equation was used to distinguish between the front side and the back side of the line segment, but any method that can uniquely distinguish between the front side and the back side of the line segment will suffice. It is not limited to such processing. Further, the data structure for storing the line segment is not limited to the data structure shown in FIG. 3, as long as it can independently store the front side and back side divisions of the line segment. Further, in this embodiment, only straight lines are treated as line segments, but circular arcs, elliptical arcs, free curves, etc. may be used as long as the front side and the back side can be distinguished.

〔Effect of the invention〕

As described above, according to the present invention, division processing for a line segment in boundary expression is performed while determining whether it is for the front side or the back side, and division state information for the front side and the back side of the line segment is divided separately. Since the figure is expressed using line segments that can be memorized and divided into the front and back sides independently based on the division status information, it is now possible to divide the front and back sides of the line segment independently. The effect is that it becomes possible to faithfully represent a real object such as a wall in a floor plan on a computer. In other words, in the conventional method, when a line segment or surface is additionally defined, it is necessary to change the data structure, which does not correspond to the actual object, and special processing is required to maintain data consistency. However, according to the present invention, for additional definitions of line segments or surfaces, the correspondence with actual objects is clear, and there is no need to prepare special processing to maintain data consistency. Effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a graphic representation system according to an embodiment of the present invention, FIG. FIG. 4 is a diagram showing the figures explained in this embodiment. FIG. 5 is a diagram expressing the figures shown in FIG. 4 using a data structure.
FIG. 6 is a flowchart showing the processing of the front and back line segment figure model management section in FIG. 1, FIGS. 7 and 8 are diagrams showing line segment division patterns in this embodiment, and FIG. A diagram showing a data structure corresponding to a dividing pattern of line segments,
FIG. 10 is a diagram showing a data structure corresponding to the line segment division pattern in FIG. Figure 13 depicting a figure expressed using the conventional figure expression method.
14 is a diagram showing figures for explaining the conventional method, and FIG. 15 is a diagram showing the figures shown in FIG. 14 in the conventional method. 14...Line segment front/back discrimination unit (discrimination means), 15.
. . . Front and back line segment graphic model management unit (graphic modeling means), 17 . . . Graphic data storage area (storage means). Agent Patent Attorney Jun Miyazono - (A7 Line (3) Haya I Kojike Diagram 13 Teno) C Sode Seisho (self-motivated) July 1991 Kuchimochi J' ``Director-General 1, Case Indication Special Ganpei 2 230945 No. 1?q 2222" 3. Name of the person making the amendment (601) Mitsubishi Electric Corporation Representative Moriya Shiki 4゜ Column for detailed explanation of the invention in the specification subject to amendment by agent . Contents of the amendment (1) In the 6th line of page 13 of the specification, the word "easy" is amended to read "prepared." 12

Claims (1)

[Claims] A graphical representation method in which a two-dimensional figure is represented by a line of line segments that are the boundaries of the figure arranged in adjacent order, and each line segment is expressed as connecting the starting point and ending point of the line segment. Discrimination means for discriminating between the front side and the back side of a line segment, and determining whether the dividing process for the line segment is for the front side or the back side, and division state information of the front side and the back side of the line segment determined by this discriminating means. A graphic representation method comprising: storage means for storing data separately; and graphic modeling means for representing a graphic using line segments that can independently divide the front side and the back side based on the division state information.