JPH04236678A - Method for shaping area - Google Patents

Abstract

PURPOSE:To shape shear between the hatching area of an extracted polygon and an original image. CONSTITUTION:A rectangular area specifying part 1 specifies a sample rectangle for extracting hatching pattern. A hatching pattern extracting part 3 extracts the hatching pattern from the specified rectangle. A link forming part 3 links the extracted hatching pattern to its adjacent parallel lines. An area polygon extracting part 4 extracts a core vector and a connection vector connecting between the end points of the parallel lines and extracts the end points of those vectors and the end points of the parallel lines. An area shaping part 5 searches the end points of the core vector and connects between the end points to form an area contour line extremely approximate to the original image.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hatching area extracting method for extracting a hatching area composed of parallel lines from a vector image, and to an area shaping method for shaping the extracted area.

0002

[Background Art] With the advancement of image processing technology, graphic processing technology using computers is being used in various fields. One such graphic processing technology involves computer processing of line drawings such as maps and illustration images. Research and development is being carried out for this purpose. For example, "Study on automatic extraction of map components", Information Processing Society of Japan 39th National Conference, "Hatching area extraction algorithm and its application to topographic maps", 1982.
Examples include the annual National Conference of the Institute of Electronics and Communication Engineers.

[0003] The above-mentioned processing technology processes figures not as line drawings but as raster image data, which is the same as binary photographic images. There was a problem in that it was difficult to make partial corrections, changes, etc.

On the other hand, it has been considered to process line drawings by vectorizing them (for example, ``Automatic recognition of topographic maps using relationships between line segments'', Institute of Electronics, Information and Communication Engineers PRU8).
9-24P, "Automatic map input system with improved reliability through conversational recognition", Journal of the Institute of Electronics, Information and Communication Engineers,
89/4 Vol, J72-D-2 No4).

However, in the case of line drawings such as hatching patterns, the shapes such as polygons formed by the hatching pattern are more meaningful than the lines or points themselves, and the above-mentioned conventional techniques do not address this point. was not considered.

[0006]

[Problem to be solved by the invention] Therefore, the inventors of the present invention
In a method of outputting line drawing data by vectorizing the outline of a binarized input image, converting it into skeleton lines, and converting the input image into a connecting vector that connects the skeleton vectors, A rectangular area is specified in the area, the hatching pattern is determined from the contour vector in the rectangular area, the constituent lines forming the hatching pattern are searched from the slope of the hatching pattern and the interval between the patterns, and We have proposed a hatching area extraction method that extracts parallel line hatching areas by creating links between component lines and tracing the end points of the component lines from the links to obtain area outlines (Patent Application No.
238464).

According to the above method, by specifying a rectangular area within the hatching area, it is possible to determine whether the hatching pattern is a parallel line hatching pattern or a dot hatching pattern, and it is also possible to determine the hatching area due to parallel lines from the line data. Since it can be extracted as polygon data, the hatched area can be processed as a polygon.

[0008] Since the above method determines the constituent lines only from the positional relationship of the hatching pattern, there was a problem in that line segments near the hatching area were mistakenly recognized as hatching patterns. A further improved hatching region extraction method has already been proposed. According to this method, information on the inclination of hatching patterns and the spacing between the patterns is extracted from the area represented by hatching in a figure, the information is used to search for component lines that make up the hatching pattern, and the adjacent In a method of generating links between lines and extracting an outline representing an area from the link relationship, by checking the connection state between the constituent lines when generating the link, the slope and interval in the vicinity of the hatching area can be adjusted to the hatching area. Line segments similar to pattern composition lines are no longer recognized as pattern composition lines (Patent Application No. 2-2
38465).

[0009] However, in all of the methods proposed above, regions are represented using only the end points of a hatching pattern of parallel lines, and therefore there is a problem in that a misalignment occurs between the extracted region and the original image. To explain this using figures, FIG. 3 shows a hatched area, 31 is a hatching pattern of parallel lines, and 32 is an extracted area outline. FIG. 4 is an enlarged view of portion 33 of FIG. In FIG. 4, 40 is a parallel line, 41 is a skeleton vector of the parallel line, 42 is an end point of the skeleton vector 41, 43 is a region outline, 44 is a skeleton vector of the region outline,
45 is the end point of the core vector 44, 46 and 47 are connecting vectors, and 48 is the actual intersection of the parallel line 40 and the area outline 43.

In the method proposed above, at the intersection of the parallel line 40 and the area outline 43, a skeleton vector 44, an end point 45, a connecting vector 46, an end point 42, a connecting vector 47, an end point 45, and a skeleton vector 44 are created. Since the region outline was extracted at the same time, the problem remained that the extracted region outline did not pass through the actual intersection 48, resulting in a deviation from the original image.

An object of the present invention is to provide a region shaping method for shaping the deviation between the extracted polygonal hatching region and the original image.

0012

[Means for Solving the Problems] In order to achieve the above object, the present invention specifies a rectangular area in the area represented by hatching in a figure, and calculates the slope of the hatching pattern from the contour vector in the rectangular area. In a hatching area extraction method that extracts a parallel line hatching area by searching for parallel lines constituting a hatching pattern, creating links between adjacent parallel lines, and finding the area outline by tracing the end points of the parallel lines from the links. , extract the skeleton vector and connecting vector connecting the end points, trace the connecting vector starting from the end point of the parallel line, find both end points of the skeleton vector, and connect the end points to create a region. It is characterized by generating an outline.

[0013]

[Operation] The rectangular area specification section specifies a sample rectangle for hatching pattern extraction, the hatching pattern extraction section extracts a hatching pattern from the specified rectangle, and the link generation section specifies a sample rectangle for hatching pattern extraction. Create a link between adjacent parallel lines from . The region polygon extraction section extracts the skeleton vectors and connecting vectors connecting the end points of the parallel lines, and extracts the end points of these vectors and the end points of the parallel lines. A region outline is generated by searching for an end point, using the end point as a starting point, searching for the end point of the skeleton vector in the horizontal direction along the connecting vector, and connecting the end points. Therefore, since the extracted region outline passes near the actual intersection, no deviation from the original image occurs.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a functional block diagram according to an embodiment of the present invention, in which 1 is a rectangular area specifying unit that specifies a sample rectangle for hatching pattern extraction, and 2 is a rectangular area specifying unit that extracts a hatching pattern from the specified area. 3 is a link generation unit that extracts parallel lines constituting the hatch pattern and generates links between the parallel lines; 4 is an extraction unit that extracts area polygons from the generated links; , 5 is a shaping unit that shapes the extracted area.

A hatching pattern is extracted by a hatching pattern extracting section 2 from the sample rectangle specified by the rectangular area specifying section 1. Parallel lines are extracted from the extracted hatching pattern, and the processing up to the link generation unit 3 that creates links between adjacent parallel lines is the same as that disclosed in the hatching area extraction method already proposed. , a detailed explanation thereof will be omitted. The features of the present invention reside in the region polygon extraction section 4 and the region shaping section 5.

That is, the link generation unit 3 checks the links of parallel lines, and when creating a link between parallel lines, checks whether the end points of the parallel lines are connected, and creates a line segment connecting the end points. If there is no such end point, connect the end points with a straight line. When the end points are connected, as explained in FIGS. 3 and 4, the area outline is obtained by tracing and connecting the end points of parallel lines. This has caused the problems described above.

In the present invention, when the end points are connected, the region polygon extracting unit 4 extracts the core line vectors and connection vectors connecting the end points, and extracts the end points of these vectors and the end points of the parallel lines. Extract.

FIG. 2 is an enlarged view of the end points extracted by the region polygon extraction section 4. In FIG. 2, 201 is a parallel line, 202 is a core vector of the parallel line, 203 is a region outline, 204 is a core vector of the region outline, 205
is the region outline, 206 is the core vector of the region outline,
207 is the end point of the core vector 202 of the parallel line 201, 2
08 is an end point of the skeleton vector 206, and 209 is an end point of the skeleton vector 204. In addition, circles 210 to 213 are end points of vectors, 214 to 223 are connection vectors, 224 and 225 are contour vectors of parallel line 201, and 22
6, 227 is the contour vector of the outline 203, 228, 2
29 is a contour vector of the outline 205, and 230 and 231 are contour vectors. 232 is the actual intersection of the parallel line 201 and the area contour lines 203 and 205.

The area polygon extraction unit 4 extracts, among the above-mentioned end points, the end point 207 of the skeleton vector of the parallel line, the end points 208 and 209 of the skeleton vector of the outline line, and the end point 2 of the connecting vector.
10 to 213 are identified and marked in a table (not shown). If one end point is, for example, the end point common to the core vector 202 of the parallel line and the connecting vector 216, the parallel line is given top priority so that it is the end point of the core vector of the parallel line, and then the outline Mark the line and finally the connecting vector.

Therefore, 207 is the end point of the core vector 202 of the parallel line 201, and 208 and 209 are the end points of the core vectors 206 and 204 of the outline, respectively.

[0021] Next, the area shaping unit 5 searches the end point of the core vector of the parallel line with reference to the table, and selects the end point 2.
07 as a starting point, the end points of the skeleton vector are searched in the left and right direction along the connection vector. However, the search range is a range 233 that sufficiently covers the intersection of the parallel line and the area outline, and is, for example, about three times the width of the parallel line. The endpoints 208 and 20 of the core vector on both sides within this range
When 9 is found, the end points 208 and 209 are connected, the circle end points are deleted, and the end points are output as area data. As a result, the core vector 206, the end point 208, and the end point 20
9 and the skeleton vector 204 are connected to generate a region outline. Since the region outline extracted in this way passes near the actual intersection 232, no deviation from the original image occurs.

[0022]

[Effects of the Invention] As described above, according to the present invention, the end points of the core vector are found by tracing the connecting vectors from the end points of the parallel lines, and the region outline is generated by connecting the end points. Therefore, the region outline passes near the actual intersection, and therefore a region polygon that more closely matches the original image is obtained.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram according to an embodiment of the present invention.

FIG. 2 is an enlarged view of end points extracted by the area polygon extraction unit of the present invention.

FIG. 3 is a diagram showing hatched areas.

FIG. 4 is a partially enlarged view of a region outline extracted by a conventional method.

[Explanation of symbols]

1 Rectangular area specification part 2 Hatch pattern extraction part 3 Link generation section 4 Area polygon extraction part 5 Area shaping section

Claims (1)

[Claims] Claim 1: Specify a rectangular area in the area represented by hatching in a figure, search for the slope of the hatching pattern and parallel lines constituting the hatching pattern from the outline vector in the rectangular area, and calculate the distance between adjacent parallel lines. In a hatching area extraction method in which a parallel line hatching area is extracted by creating a link and tracing the end points of the parallel line from the link to obtain the area outline, a skeleton vector and a connecting vector connecting the end points are extracted. A region shaping method comprising: tracing the connection vector starting from the end point of the parallel line, finding both end points of the core line vector, and generating a region outline by connecting the two end points.