JPH07325852A - Cad system - Google Patents

Abstract

PURPOSE:To eliminate a manual elimination operation for a useless dimension line and to improve the efficiency of drawing the dimension line of a graphic by providing a symmetrical line segment extraction part and a dimension line decision part and drawing the dimension line only for a line segment decided in the dimension line decision part. CONSTITUTION:For a rectangular graphic 4, the outside lines are extracted as the line segments by a line segment extraction part 5. Then, the attributes of the extracted respective line segments are discriminated by a line segment attribute discrimination part 9. It is performed by obtaining the maximum value and the minimum value of the coordinate and the length of the extracted outside line and recognizing the parallel, vertical and orthogonal relation of the respective line segments by judgement by a production rule 10. Thereafter, by the symmetrical line segment extraction part 6, the symmetry of the graphic is judged based on the attribute information of the respective line segments. Then, the line segments of the outside line for drawing the dimension line and the outside line for not drawing the dimension line are decided by the dimension line decision part 7 for the outside lines judged as symmetrical and the drawing processing of the dimension line is performed by a dimension line drawing part 8 for the outside line for which it is decided to draw the dimension line.

Description

Detailed Description of the Invention

[0001]

The present invention relates to CAD (Comput).
er Aided Drawing, a computer-aided drafting system, and in particular, C suitable for reducing the human work load and mistakes required for drawing dimension lines.
It relates to an AD system.

[0002]

2. Description of the Related Art Conventionally, when drawing a dimension line in a CAD system, as shown in FIG. 4, all dimension lines for a figure are automatically drawn, and thereafter unnecessary portions are manually deleted. ing. However, in this way, in the technique of automatically drawing all dimension lines for a figure and then manually deleting unnecessary parts, the unnecessary dimension lines are manually deleted, which is troublesome. Mistakes also occur.

As a conventional technique for dealing with such a problem, for example, there is one disclosed in Japanese Patent Laid-Open No. 62-187975. In the technique disclosed in this publication, by using the maximum coordinate value and the minimum coordinate value of the XY coordinates of the circumscribing rectangle, the dimension display can be automatically determined so as to properly match the outer shape of the graphic element. In particular, for parallel lines that are equidistant from the center line of the figure, the dimensions are displayed in the form of center distribution. In this case, center distribution is performed by finding a symmetric parallel line across the center line passing through the origin and calculating the dimension therebetween. But with this technology,
In order to find a symmetric parallel line across the center line that passes through the origin and display the dimension lines in a manner that the center lines are distributed, for example, as in the case of a columnar shape as shown in FIG. However, it cannot be applied to the rectangular figure 4 as shown in FIG.

[0004]

The problem to be solved by the prior art is that in the prior art, unnecessary dimension lines cannot be automatically deleted when the figure is not the object of the center line. Is. An object of the present invention is to solve these problems of the prior art, and to provide a CAD system capable of increasing the efficiency of drawing a dimension line of a figure by eliminating the need for manual deletion work for a dimension line. Is.

[0005]

In order to achieve the above object, the CAD system of the present invention comprises: (1) symmetry line segment extraction for determining the symmetry of each line segment of a figure and extracting each symmetric line segment. And a dimension line determination unit 7 that determines, based on a predetermined rule, a dimension line to be drawn from the plurality of symmetrical line segments extracted by the symmetrical line segment extraction unit 6. The feature is that the dimension line is drawn only for the line segment determined by the dimension line determination unit 7. (2) In the CAD system described in (1) above, the symmetric line segment extraction unit 6 determines the positional relationship between the extracted line segments and the intersections, and the positional relationship between the line segments as the attributes of each line segment. The line segment attribute determining unit 9 for determining
It is characterized in that the symmetry of each line segment is judged based on the attribute discrimination result of each line segment. (3) In the CAD system described in (1) or (2) above, the dimension line determination unit 7 has a production rule 10 that gives priority to the left and lower line segments. Based on the production rule 10, one line segment from which a dimension line is drawn is selected from a plurality of symmetrical line segments.

[0006]

In the present invention, when there are a plurality of line segments judged to be symmetrical, a dimension line is drawn for one of the line segments. That is, first, according to the conventional technique, the contour line is identified with respect to the graphic data of which the dimension line is to be drawn, and is extracted as a line segment. Next, as the attributes of each line segment, the relationship between the intersections of the outlines, the position relationship between the line segments, and the length of the line segment are determined. Then, based on these determination results, the symmetry of each line segment is identified, and the line segment of the outline that does not draw a dimension line,
The line segment of the contour line from which the dimension line is drawn is selected, and the dimension line drawing processing is performed only on the line segment of the contour line from which the dimension line is drawn. Here, the selection as to whether or not to draw the dimension line is performed based on, for example, a production rule constructed by the user. By doing so, it is possible to draw the dimension line without waste.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the configuration of the CAD system of the present invention according to the present invention. In the figure, 1 is an input device such as a mouse and 2 is a CRT (Cath).
display device such as ode ray tube, cathode ray tube,
3 is C on the screen of the display device 2 based on the operation of the input device 1.
A drawing creation unit for drawing the graphic 4 by AD, 5 is a line segment extraction unit for extracting the outline of the graphic 4 in line segment units, and 6 is a symmetry of each line segment extracted by the line segment extraction unit 5, A symmetry line segment extraction unit according to the present invention for extracting each symmetric line segment, and 7 is a predetermined number of symmetric line segments extracted by the symmetry line segment extraction unit 6, which are dimension lines. A dimension line determination unit 8 according to the present invention, which is determined based on a rule, is a dimension line drawing unit that draws a dimension line only for the line segment determined by the dimension line determination unit 7.

The symmetry line segment extraction unit 6 discriminates the length of each line segment extracted by the line segment extraction unit 5 and the positional relationship between the intersections and the positional relationship between the line segments as the attribute of each line segment. The section 9 is provided, and the symmetry of each line segment is determined based on the attribute determination result of each line segment by the line segment attribute determination section 9. In addition, the dimension line determining unit 7 has a production rule 10 that gives priority to the left and lower line segments, and based on this production rule 10, one line segment from which a dimension line is drawn is drawn from a plurality of symmetrical line segments. select. The processing operation according to the present invention of the CAD system having such a configuration will be described below with reference to FIG.

FIG. 2 is a flow chart showing an embodiment of the dimension line drawing processing according to the present invention of the CAD system shown in FIG. First, the line segment extraction unit 5 in FIG. 1 extracts the outline of the rectangular graphic 4 as shown in FIG. 6 as a line segment (step 101). here,
The outline forming the rectangular figure 4 is a line connecting ABCFHGED. Also, to recognize the line segment of the outline,
A production rule (IF-T) obtained from the relationship between orthogonal points and the maximum and minimum values of coordinates in the entire figure.
HEN rule) is used.

Next, the line segment attribute discriminating unit 9 in FIG. 1 discriminates the attribute of each extracted line segment. This is performed by obtaining the maximum value, the minimum value, and the length of the coordinates of the extracted outline, and recognizing the parallel, vertical, or orthogonal relationship between the line segments by the determination according to the production rule.
That is, to determine the attributes of each line segment, first of all,
The relationship of each intersection is identified (step 102). this is,
For example, in the rectangular figure 4 of FIG. 6, “intersection points A, B,
"C is collinear in the vertical direction" and "intersection points C, F, and H are collinear in the horizontal direction". Secondly, the positional relationship of each line segment is identified (step 103). For example, in the rectangular figure 4 in FIG. 6, “AB and DE
Are parallel, AB and EF are parallel, AB and GH are parallel "," A
B and AD are vertical, BC and CF are vertical, and AD and DE are vertical. " Thirdly, the lengths of the respective line segments are compared (step 104). For example, in the rectangular figure 4 in FIG. 6, “AB = DE, BC = G”
H, AD = CF, EG = FH ”.

In this way, after the line segment attribute determination unit 9 in FIG. 1 determines the attributes of each line segment, the symmetry line segment extraction unit 9 in FIG. 1 determines the symmetry of the figure (step 105). ). The determination of the symmetry is made based on the attribute information of each line segment described above.
If “AB and DE are parallel and AB = DE, and A and D have the same vertical coordinates”, “AB and DE are symmetric”.
That is. For each contour line (line segment) that is determined to be symmetrical, the dimension line determination unit 7 in FIG. 1 determines a contour line that does not draw a dimension according to a rule that a dimension is not drawn (step 106). Here, as a rule that does not draw the dimension line, for example, there is a production rule such as "when the symmetrical line segments have the same length, the outer shape line on the left side (or the lower side in the case of the top and bottom) is prioritized". The data is stored as a database in the dimension line determining unit 7 in FIG. In this way, the dimension line drawing unit 8 in FIG. 1 performs the dimension line drawing process on the outline determined to be drawn (step 107). The dimension line thus drawn is shown in FIG. The drawing processing of this dimension line is a known technique and will not be described here.

As described above with reference to FIGS. 1 to 3, in the CAD system of the present embodiment, unnecessary dimension lines are automatically selected even when the figure is not symmetrical with respect to the center line. Since it can be deleted, it is possible to reduce the human work load and mistakes required for drawing the dimension line. The present invention is not limited to the embodiment described with reference to FIGS. 1 to 3, and various modifications can be made without departing from the scope of the invention.

[0013]

According to the present invention, unnecessary dimension lines can be automatically deleted even when a figure is not symmetrical with respect to the center line, and unnecessary work for deleting dimension lines is unnecessary. Therefore, it is possible to reduce the human work load and mistakes required for drawing the dimension line, and it is possible to improve the efficiency and reliability of the drawing process of the dimension line of the figure by CAD.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a configuration according to the present invention of a CAD system of the present invention.

FIG. 2 is a flow chart showing one embodiment of the dimension line drawing processing according to the present invention of the CAD system in FIG.

FIG. 3 is an explanatory diagram showing a rectangular figure drawn by the CAD system in FIG. 1 and its dimension line.

FIG. 4 is an explanatory diagram showing a rectangular figure drawn by a conventional CAD system and its dimension line.

FIG. 5 is an explanatory diagram showing a columnar figure drawn by a conventional CAD system and its dimension line.

FIG. 6 is an explanatory diagram showing an example of a rectangular figure which is a target of dimension line drawing by the CAD system in FIG.

[Explanation of symbols]

 1 Input device 2 Display device 3 Drawing creation part 4 Rectangular figure 5 Line segment extraction part 6 Symmetric line segment extraction part 7 Dimension line determination part 8 Dimension line drawing part 9 Line segment attribute determination part 10 Production rules

Claims (3)

[Claims] 1. A symmetry of each line segment in a CAD system for extracting an outline line of a figure drawn based on an interactive operation with an operator in line segment units and drawing dimension lines for all the extracted line segments. Symmetry line segment extraction means for extracting each symmetric line segment, and a plurality of symmetric line segments extracted by the symmetry line segment extraction means for drawing a dimension line,
A CAD system, comprising: a dimension line determining unit that determines the dimension line based on a predetermined rule, and drawing a dimension line only for the line segment determined by the dimension line determining unit. 2. The CAD system according to claim 1, wherein the symmetry line segment extraction means defines the positional relationship between the extracted line segments and the intersections, and the positional relationship between the line segments as an attribute of each line segment. A CAD system comprising: a line segment attribute determining unit that determines the line segment attribute determination unit, and determines the symmetry of each line segment based on the attribute determination result of each line segment by the line segment attribute determining unit. 3. The CAD system according to claim 1 or 2, wherein the dimension line determining means has a production rule that gives priority to the left and lower line segments, and the production rule. A CAD system which selects one line segment from which a dimension line is drawn from a plurality of symmetrical line segments.