JP3113217B2 - Dashed line recognition method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recognizing a dashed line described in a handwritten or printed drawing input through an image scanner or the like, and more particularly, to a target dashed line. Is assumed to be limited to several types of drawn angles, so that the lines constituting the dashed line can be recognized even if there is distortion, noise, contact with other line segments, etc. due to handwriting, etc., and vector data The present invention relates to a method for recognizing a dashed line that is automatically converted to a dashed line.

[0002]

2. Description of the Related Art Conventionally, as a method of recognizing a broken line drawn in a drawing, a method of detecting a short line segment from a drawing and associating a nearby short line segment has been used. However, this method has a problem that a short line segment cannot be properly associated with a drawing having a distortion due to handwriting or the like, and a short line segment in contact with another line segment cannot be detected.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the conventional method for recognizing a broken line, and is applicable not only to a correctly printed drawing but also to a handwritten drawing in which line distortion or contact exists. It is an object of the present invention to provide a method for recognizing broken lines.

[0004]

A dashed line recognizing method according to the present invention detects a line segment having a length within a predetermined value, which does not contact or cross another line segment, as a short line segment constituting the dashed line. ,
Obtain local projection information for a broken line portion that touches or intersects another line segment, and based on the projection information ,
, The process of recognizing the type of the detected dashed line from the arrangement of the short line, and the process of recognizing the start and end points of the dashed line by approximating the auxiliary line position in the drawing. It is characterized by the following.

As described above, according to the present invention, a method for approximating an extracted short line segment to a fixed position from its position and orientation, and a method for extracting a short line segment that could not be detected due to contact or intersection with vertical pixel row data. Use a detection method.
By approximating the obtained short line segment or end point to a predetermined position, it is possible to reduce the influence of handwritten line segment distortion or positional deviation. Further, by using a pixel row in the vertical direction for a line segment, the problem that a short line segment cannot be extracted due to contact with another line segment is solved. In the dashed line recognition process, the type of dashed line is recognized after the acquired dashed line candidate data is converted into a numerical pattern using a threshold value with a wide range that allows handwriting fluctuation.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing the overall processing flow of the broken line recognition method of the present invention. The processing is roughly divided into a dashed line map creation processing 10 and a dashed line recognition processing 20 . A broken line map creation process 10 is a process 1 for tracing the outline of a line segment on drawing data obtained via an image scanner or the like.
1. A process 12 for extracting a dashed line candidate based on the result of contour tracing and registering a dashed line map, and a process 13 for detecting a dashed line portion not detected by contour tracing from a pixel row in a direction perpendicular to a grid line and registering the dashed line map. . Broken line recognition processing 20
Is a process 21 for generating a dashed line pattern from a dashed line map,
The process includes a process 22 for recognizing the type of the broken line by comparing the generated pattern with the registered broken line pattern, and a process 23 for recognizing the start and end points of the broken line according to the type of the broken line. FIGS. 2 to 6 show each processing 1 except the contour tracking processing 11.
2, 13 and 21 to 23 show a detailed flow.

FIG. 7 is a view showing an example of a grid-like auxiliary line previously written on a sheet of paper including a broken line with a dropout color or the like. This auxiliary line is a line parallel to several directions drawn at equal intervals so that intersections are formed at equal intervals. FIG. 7A shows two types of auxiliary lines in the vertical and horizontal directions, and FIG.
5 degrees of supplementary lines are added.

Hereinafter, as a specific example of the processing according to the present invention,
A case where the present invention is used for recognizing a broken line drawn in a floor plan will be described.

Usually, vertical and horizontal lines as shown in FIG. 7A are drawn at regular intervals as auxiliary lines on a sheet dedicated to a floor plan. An auxiliary line on this drawing is called a grid line, and an intersection of the auxiliary lines is called a grid intersection. The size of many elements (walls, fittings, etc.) constituting the floor plan is expressed by an integer multiple of the grid line interval. For this reason, when drawing a floor plan on dedicated paper, most of the line segments are drawn on the grid, and the start and end points are on the grid intersection. The dashed line recognition method of the present invention makes use of this feature, and draws a dashed line on a grid line as a writing condition.

<Dashed line map creation process 10> In the dashed line map creation process 10, short line segments are extracted as drawing line candidates from drawing data obtained through image scanning or the like, and registered in the dashed line map. The dashed line map is data obtained by approximating a short line segment extracted as a dashed line candidate to the best matching grid line based on its position and direction, and recording the presence or absence of the short line segment on the grid line. More specifically, as shown in FIG. 9, the bit string is prepared for each grid line and records an approximated short line segment area. Hereinafter, the details of the processes 11, 12, and 13 of the broken line map creation process 10 will be sequentially described.

(Contour Tracking Process 11) In the contour tracking process 11, for binary drawing data input via an image scanner or the like, a boundary between a pixel representing a line segment and a pixel representing a background in the drawing is tracked. Some of the tracking results track the outer circumference and inner circumference of the line segment. Out of these, a line segment whose outer periphery is tracked and whose tracking distance is equal to or less than a certain value is extracted as a short line segment forming a broken line.

A specific example will be described. First, pixels are sequentially scanned from the upper left of the input binary data, a pattern in which black pixels come below white pixels is detected, and the white pixels are contoured. This is the starting point of tracking. The next-point candidates are the four directions of up, down, left, and right of the currently located white pixel, and the priority order is right, front, left, and rear with respect to the traveling direction. Among these, the white pixel with the highest priority is the next point. The contour tracing is performed in this procedure, and when returning to the starting point, the search is terminated.
In this tracking result, if the number of cases where the next point at the time of contour tracking is on the right side with respect to the traveling direction is smaller than the left side, it is determined that inner tracking has been performed, and if the reverse is the case, outer tracking has been performed. Also,
It is determined from the number of tracking pixels whether or not it is a short line segment. Since the contour tracking processing itself is well known, a detailed flow thereof is omitted.

(Short line segment approximation process 12) Short line segment approximation process 1
In step 2, based on the center position, circumscribed rectangular shape, and the like, the short line segment extracted by the contour tracking is approximated to a grid line position that is short in distance and matches the drawn direction, and is registered in a dashed line map. FIG. 2 shows a detailed flow of the short line segment approximation processing 12.

From the contour pixels constituting the acquired short line segment,
Find the maximum and minimum values of the x-coordinate and the maximum and minimum values of the y-coordinate, respectively, and based on them, (minimum value of x-coordinate, maximum value of y-coordinate), (maximum value of x-coordinate, maximum of y-coordinate) Value), (x
Coordinate maximum value, y coordinate minimum value), (x coordinate minimum value,
A rectangle having four vertices (minimum value of the y-coordinate) as vertices is set as a circumscribed rectangle of a short line (step 121). Compare whether the shape of this circumscribed rectangle is longer in the horizontal or vertical direction,
The long direction is set as the direction of the short line segment (step 122). The coordinates of the center of gravity of the circumscribed rectangle are obtained, and are registered in the dashed line map by approximation to the grid line position in the direction of the shortest line segment closest to the coordinates (step 123).

FIG. 8 is a diagram for explaining a specific example of approximation to a short-line grid line. 8, a circumscribed rectangle is generated for the short line segment region in FIG. 8A and approximated to a grid line position as shown in FIG.
Is registered in the broken line map. FIG. 9 is a conceptual diagram of a dashed line map.

(Line Segment Extraction Process 13) In the line segment extraction process 13, line segments constituting a broken line, which are not detected in the contour tracking process 11 due to intersection or contact with other line segments, are detected, and a line map is generated. sign up. FIG. 3 shows a detailed flow of the line segment extraction processing 13.

In a grid line in which a short line segment exists on the broken line map, a portion where the short line segment of the grid line is not detected is used as a search area to extract a pixel row having a constant width in the vertical direction (step). 131). The obtained pixel row is 0,
Information on the thickness and the number of line segments is obtained from the state of one continuous portion (black pixel) on the data, which is a bit string of 1 (step 132). For example, when 1 or 2 are continuously arranged, 1 is rewritten to 0 as noise, 3 to 8 are defined as thin lines, 9 to 20 are defined as bold lines, and more are defined as very thick lines. The kind is determined, and how many continuous areas are present is counted, and the number of line segments is obtained. However, since the blur and distortion of the line segment is present, the resulting information when arranged along the grid lines, portions identical line style are not continuous over a predetermined number of considered as noise, adjacent lines Rewrite to the line type of the minute . In the line segment information obtained in this way, if many line segments are detected in the area between the two ends of the search area as compared to both ends, the part is registered in the dashed line map as a short line segment (step 13).
3).

FIG. 10 is a view for explaining a specific example of the line segment extraction processing 13. As shown in FIG. 3A, a portion where a short line segment is not detected due to an intersection with another line segment (vertical line segment) is set as a search area for a grid line having a short line segment on a dashed line map. As shown in FIG. 2B, a pixel row having a constant width in the vertical direction is extracted, and the thickness and the number of line segments are obtained as shown in FIG. For example, in FIG. 3C, there is no line, one thin line, and one very thick line.
It is a continuous area such as a book, one thin line, and no line. In this case, since there is no line at both ends and there is one line in the area between them, a short line segment is registered in the broken line map as shown in FIG.

<Dashed line recognition process 20>
In the dashed line pattern generation process 21, a dashed line candidate portion converted into a numerical pattern is extracted from the data of the dashed line map, and the type of the dashed line is recognized by comparing the pattern with a dictionary pattern in the pattern matching process 22. The start and end points of the broken line are obtained in the start and end point recognition processing 23, and the recognition of the broken line is completed. Hereinafter, these processes will be described in detail in order.

(Dashed line pattern generation process 21) In the dashed line pattern generation process 21, the data portion recorded as the short line segment constituting the dashed line is recognized from the dashed line map acquired by the dashed line map generation process 10 in order to recognize the type of the dashed line. To numeric data. FIG. 4 shows a detailed flow of the broken line pattern generation processing.

As shown in FIG. 11, the broken lines are continuous patterns of short lines, and the types of each broken line are distinguished by a combination pattern of short lines having different lengths.
The length of the short line segment (especially in the case of a handwritten drawing) is not clearly determined, but can be distinguished between a short one and a long one. A broken line is formed for distinction. Therefore, the length (1) of the short line segment area (the area where 1 is recorded) on the broken line map is set.
(How many are continuous) is distinguished by a fixed threshold value between a short line segment and a long short line segment. In addition, the length of the area where the short line segment does not exist (the area where 0 is recorded) is also distinguished by a certain threshold value in order to distinguish the area between the short line segment and the other area.

Here, the pattern conversion conditions are determined as follows. (I) 0 is 3 to 8 consecutive +1 is 3 to 8 consecutive → 1 (ii) 0 is 3 to 8 consecutive + 1 is 9 to 20 consecutive → 2 (iii) Other than the above → 0 In the dashed line pattern generation processing 21, a dashed line map The upper data string is checked in order from the beginning (step 211), and 0
Alternatively, the number of consecutive 1s is counted (step 212), and is converted into “0”, “1”, or “2” in a continuous area of 0 or 1 based on the pattern conversion condition (step 2).
13). In this manner, the start line coordinates of the pattern sandwiched by "0" are read from the broken line map and recorded in association with the pattern (step 214). FIG.
It shows a specific example of patterning a broken line map.

(Pattern Matching Process 22) In the pattern matching process 22, the type of the included broken line is identified from the acquired pattern. FIG. 5 shows a detailed flow of the pattern matching processing 22.

The number of consecutive “1” values included in the pattern obtained in the dashed line pattern generation process 21 is counted (step 221), and the line type is identified based on a predetermined collation condition (step 221). 222). Specifically, for example, in the dashed pattern shown in FIG.
13, the line type B if the counter value is 1, the line type C if the counter value is 1,
If it is 3 or more, the line type is A.

(Start and end point recognition processing 23) Start and end point recognition processing 2
In 3, the start and end points are given to the broken line whose type is recognized. FIG.
3 shows a detailed flow of the start / end point recognition processing 23.

In the case of the broken line A, a point approximate to the position of the grid line in the direction in which the start and end points of the pattern are extended back and forth is set as the start and end points of the broken line (steps 231 and 232). Dashed lines B, C
In the case of, a line segment is detected in the direction in which the start and end points of the pattern are extended back and forth (steps 233 and 235), and a portion where the line segment is interrupted or the thickness or the like changes is found. The approximated point is set as the start and end points of the broken line (steps 234 and 236). Line segment detection is performed, for example, by referring to FIG.
Can be realized in the same manner as the pixel row extraction processing shown in FIG.

After the start / end point process 23 is completed, the process returns to the broken line pattern generation process 21 to extract another broken line, and the process is repeated.

The embodiments of the present invention have been described above, but these are realized using a so-called computer. At this time, the processing flow (procedure) as shown in FIG. 1 and FIGS. 2 to 6 may be prepared in advance in the computer as an application program, or a program describing these procedures may be prepared. The recorded recording medium (floppy disk, optical disk, or the like) may be read (installed) by a computer.

Further, in the embodiment, the position of the auxiliary line printed in advance in the drawing is used as the position approximating the broken line. However, even if it is not the auxiliary line, it is automatically or manually approximated before the recognition processing. This can be dealt with by determining the position.

[0030]

As described above, according to the broken line recognition processing of the present invention, a handwritten drawing,
For example, it is possible to recognize a symbol represented by a broken line drawn on a building floor plan, and the field of use of the recognition system is greatly expanded. In addition, the dashed line recognition method of the present invention is not limited to a floor plan showing a spatial arrangement of a floor plan in a building, and can be used for automatic recognition of dashed lines in a logic circuit drawing showing circuit wiring and other various drawings. .

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall processing flow of a dashed line recognition method of the present invention.

FIG. 2 is a detailed flowchart of a short line segment approximation process.

FIG. 3 is a detailed flowchart of a line segment extraction process.

FIG. 4 is a detailed flow of a broken line pattern generation process.

FIG. 5 is a detailed flow of a pattern matching process.

FIG. 6 is a detailed flowchart of a start point recognition process.

FIG. 7 is a diagram illustrating an example of an auxiliary line written on a drawing sheet.

FIG. 8 is a diagram illustrating approximation of a short line to a grid line.

FIG. 9 is a conceptual diagram of a broken line map.

FIG. 10 is a diagram illustrating a line segment extraction process.

FIG. 11 is a diagram illustrating an example of a broken line pattern.

FIG. 12 is a diagram showing patternization of a dashed line map.

FIG. 13 is a diagram illustrating an example of a matching pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Dashed line map creation processing 11 Contour tracking processing 12 Short line segment approximation processing 13 Line segment extraction processing 20 Dashed line recognition processing 21 Dashed line pattern generation processing 22 Pattern matching processing 23 Start and end point recognition processing

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-113883 (JP, A) JP-A-4-142679 (JP, A) JP-A-1-173178 (JP, A) JP-A-4-173 52774 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G06T 7/00 G06T 7/60 G06F 17/50 G06K 9/36 JICST file (JOIS)

Claims (4)

(57) [Claims] 1. A method for recognizing a dashed line of a handwritten or printed drawing on a sheet on which a grid-shaped auxiliary line is printed, wherein the line does not contact or intersect with another line segment and has a length within a predetermined value. a process of detecting a short line segments constituting the dashed line segments is a, won <br/> local projection information about the broken line portions in contact or intersect with other segments, based on projective data Said breaking
A process of detecting a line portion as a short line segment forming a broken line ;
A method for recognizing a dashed line, comprising: a process of recognizing a type of a detected dashed line based on the arrangement of short lines; and a process of recognizing a start and end point of a dashed line by approximating the position of an auxiliary line in the drawing. 2. The method for recognizing a broken line according to claim 1,
In the process of detecting a line segment having a length within a certain value without contacting or intersecting with another line segment as a short line segment forming a broken line, the short line segment forming the broken line is placed on a boundary between a black pixel and a white pixel. A method for recognizing a dashed line, wherein the extraction is performed using a contour trace to be traced. 3. The method for recognizing a broken line according to claim 1,
Obtain local projection information for a broken line portion that touches or intersects another line segment, and based on the projection information ,
In the process of detecting as a short line segment constituting the broken line, in order to the position where the broken line may be present, information on the thickness and the number of the line segment is obtained from the pixel row in the vertical direction with respect to the broken line, A broken line recognition method characterized by detecting a short line segment that is in contact with or intersects another line segment. 4. The method for recognizing a broken line according to claim 1,
In the process of recognizing the type of the detected dashed line from the arrangement of the short line segments, for the data extracted as the line segments constituting the dashed line, the length of the line segment and the distance of the adjacent line segment are determined by a certain threshold value. A method for recognizing a dashed line, comprising the steps of digitizing and comparing the numerical value with a pre-registered condition to recognize the type of the dashed line.