JPH0325823B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for connecting disconnected parts of a line figure in a line figure recognition device.

[Technical background of the invention and its problems]

In recent years, research and development of automatic input devices for various design drawings has been conducted.
Development has begun. In such drawing processing, structural features and geometric features of line figures are used to recognize line figures. For this reason, the performance of drawing processing greatly depends on the neatness and image quality of the input drawing. For example, if a break such as a blurred line occurs, one connected figure will structurally become multiple connected figures as shown in Figure 10. As a result, a closed figure becomes an open figure, which deteriorates the recognition rate of connecting lines and symbols, and also causes connection information of symbol connecting lines that are originally connected to each other to be lost. That is, in the conventional technology, there was a problem in that performance deteriorated when a randomly drawn drawing or a drawing with poor image quality was input.

[Object of the Invention] An object of the present invention is to provide a disconnection connection method for automatically repairing a disconnected portion of a line figure in a line figure recognition device.

[Summary of the invention]

The present invention analyzes the vicinity of the end points of a line segment having a certain length or more, and prioritizes connection from a certain end point to end points on the extension of the line and within a predetermined range.
Broken lines due to pen pressure fluctuations shown in Figure 11a, which tend to occur when drawing long line segments by connecting broken parts as endpoints within a predetermined range or intermediate points within a predetermined range on the extension of the line, as shown in Figure 11b. This is a method that automatically connects three types of disconnections at locations where the line is often drawn in two parts, such as the inflection point and the T-junction shown in c.

Moreover, this process can be performed with high accuracy by performing the disconnection/connection process in the order of . In other words, when processing disconnections in line figures, first perform processing in order of ease of processing and the number of target parts, then process related to refraction points on the line figure that has been linearly repaired by this process, and finally, By providing a processing procedure (priority order) in which the target portion is subjected to less T-shaped processing () compared to a straight line or L-shaped portion, an effect is obtained in that erroneous connection processing is less likely to be performed.

〔Effect of the invention〕

According to the present invention, disconnected portions of inputted line figures are automatically connected, so drawings can be reliably automatically input without deteriorating performance even in drawings that are randomly drawn or drawings with poor image quality.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an embodiment of the present invention. First, the overall operation will be outlined using FIG. 1. The design drawing 1 is stored as a black and white binary image in an image memory 3 via an input unit 2 configured by an imaging device such as a facsimile.
In order to facilitate subsequent processing, the input line figure image is subjected to processing such as thinning and removal of coarse image components (removal of isolated points, hair removal) by the image preprocessing unit 4. In the image memory 3 in which the thinned image from which the miscellaneous image components have been removed is stored, the connection processing unit 5 sets a "black" value to the connection disconnection portion of the disconnection, and the image is restored. It is stored in memory 3. By referring to the thinned image that has undergone this disconnection/connection processing, the recognition processing unit 6 recognizes the line figure as a character connection line/symbol, and the resulting code data is stored in the recognition data memory 7. Ru. In this way, drawings are automatically input and converted into code data.

Next, the disconnection/connection processing section according to the present invention will be described. When a wire break occurs, at least two endpoints occur. Therefore, the disconnection process is performed by analyzing the vicinity of the end points in the line figure. This algorithm will be explained below. The length of the line segment to which it belongs is
These processes are performed sequentially for endpoints with TL ₁ or higher.

Connecting end points on the extension of a line segment First, connect the end points on the extension of the line segment. In Fig. 2, the points extending lengths TL _1/2 and TL ₁ from a certain end point E ₁ are L ₁ , respectively.
Let it be L ₂ . The angle θ ₁ between E ₁ −L ₂ and E ₁ −L ₁ is
When θ ₁ ≦Tθ ₁ , the width TD ₁ is an extension of L ₂ −E ₁
(TD ₁ <line spacing), a rectangle with length TD ₂ is searched from E ₁ (Figure 3). If end tightening E ₂ is detected,
Connect E ₁ and E ₂ . Line segment to which E ₂ belongs
When the length of E ₂ −E ₃ is less than TL ₃ and is isolated, the extension of L ₂ −E ₁ is further traced from E ₃ .

Connection of end points within a certain range Next, as shown in Figure 4, if there is one end point within a length TL ₄ of which θ ₂ ≦Tθ ₂ from one of the unconnected end points, then Connect the end points of If there are two or more endpoints that meet this condition, the ones with the shortest distance are connected.

Connection between an end point and a point in the middle of a line segment If there is no end point to be connected near a certain end point E ₁ , search the extension of the line segment to which that end point belongs, and find a point in the middle of the line segment within TL ₄ from E ₁ . When point L ₃ exists (Fig. 5), connect E ₁ and L ₃ .

Figure 6 shows the flow chart of the algorithm. First, calculate the length from the thinned image in image memory 3.
Extract all endpoints of line segments with TL ₁ or higher and register them in the endpoint table 8. An example of the endpoint table is shown in FIG. By referring to the endpoint table, connections are made according to the priority order of conditions . When the disconnection process in the drawing shown in Fig. 8 is performed using this method,
First, the part in Figure 8a is connected by connecting the end points on the extension of the line segment, and the part in Figure 8b is connected by connecting the end points within a predetermined range.
The portion c in FIG. 8 is connected by the connection between the end point and the midpoint of the line segment, resulting in the result as shown in FIG. 9.

In FIG. 8, an internal counter i specifies an algorithm for determining conditions for end point connections. The disconnection connection processing unit 5 reads the end point data specified by the pointer P from the end point table 8, and if the flag indicating whether or not it has been processed is not set, determines whether the end point is on an extension of the line segment. If there are endpoints E ₁ and E ₂ that satisfy the above conditions, these endpoints are
Write a black pixel between E ₁ and E ₂ to repair. After examining the above processing for each point in the end point table, the internal counter i is incremented and the end point connection condition determination algorithm is sequentially selected and the same processing is executed for each point.

[Other embodiments of the invention]

Although one embodiment of the present invention has been described above, the present invention is not limited to this. For example, in the embodiment, each processing section is written to be executed by dedicated hardware, but it is of course also possible to execute all the processing sections 4, 5, and 6 in FIG. 1 as a program on the same computer. It is. Furthermore, the processed image may, of course, be processed by extracting end points and the like by tracing the contour line, for example, without performing line thinning. Also, the search area when connecting to the end point on the extension of the line segment does not have to be the rectangle shown in Figure 3.
For example, as shown in FIG. 12, search regions having an angle θ from E ₁ may be set on both sides of the extension line of L ₂ −E ₁ . Further, the search area in FIG. 4 does not have to be square, but may be circular, for example. That is, it is sufficient to set an appropriate search area.

In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an example of a drawing processing device according to the present invention, FIG. 2 is a diagram for explaining a method for estimating the direction of a line segment to which an end point belongs, and FIG. 3 is a diagram for explaining the direction of a line segment to which an end point belongs. Figure 4 is a diagram to explain how to search for a certain end point. Figure 4 is a diagram to explain how to search for an end point within a predetermined range. Figure 5 is a diagram to explain how to search for an end point within a predetermined range. Figure 5 is a diagram to explain how to search for an end point within a predetermined range. Figure 5 is a diagram to explain how to search for an end point within a predetermined range. A diagram for explaining the method, FIG. 6 is a flowchart showing an example of disconnection connection processing according to this method, FIG. 7 is a diagram showing an example of an end point table, and FIGS. 8 and 9 are examples of input drawings. A diagram showing the processing results, FIG. 10 is a diagram for explaining the problem when a disconnection occurs,
FIG. 11 is a diagram showing a disconnection to be connected by this method, and FIG. 12 is a diagram showing a modification of the setting area when searching for an end point on an extension of a line segment. 1...Design drawing, 2...Input section, 3...Image memory, 4...Image preprocessing section, 5...Disconnection connection section,
6... Recognition processing unit, 7... Recognition data memory.

Claims (1)

[Claims] 1 Line figures separated by end points or branch points of the input line figure are defined as segments, and end points of segments of a certain length or more are extracted, and the segment to which the extracted first end point belongs is extracted. A second line on the extension line and within a specified range from the extension line.
a first process of connecting the first end point and the second end point when the end point is extracted, and a fourth end point is extracted within a predetermined range from the extracted third end point. a second process of connecting the third end point and this fourth end point, and when a midway point of the line is extracted within a predetermined range on the extension of the segment to which the extracted fifth end point belongs; A third point connecting the fifth end point and this halfway point
A method for disconnecting and connecting line figures, characterized in that the first process, the second process, and the third process are performed on input line figures in this order. 2 The first process is when a second end point is extracted on the extension of the segment to which the extracted first end point belongs and within a predetermined range from the extension line, and the segment to which the second end point belongs is isolated. and the length is within a predetermined range, the first
and the second end point, and further connect another end point to be connected to the sixth end point opposite to the second end point on the extension of the segment to which the first end point belongs. Claim 1, characterized in that the search is performed in an area within a predetermined range from the end point.
Disconnection connection method of line diagram described in section.