JPS6313227B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a line type discrimination method for determining the types of lines included in a pattern in a pattern recognition apparatus for recognizing patterns in drawings and the like.

Generally, in design drawings, the meaning of a line is given by changing the line type such as a solid line, a broken line, or a chain line. When inputting line information from drawn drawings into a computer, it is necessary to recognize the line type as well as the route of each line.

Conventionally, it has been known to use a digitizer or the like to manually input drawings into a computer, selectively extracting and registering feature points such as end points of lines and refraction points, but this method is extremely difficult to operate. is troublesome and takes a long time.

The present invention provides a line type discrimination method in a pattern recognition device that can automatically discriminate line types such as solid lines, broken lines, and chain lines.

In order to achieve such an objective, the present invention measures the length of each line segment or the interval between line segments constituting a line, and examines the distribution of appearance frequency for each line segment length or interval. , is characterized in that the line type is determined based on its distribution state.

FIG. 1 shows the configuration of an embodiment of a pattern recognition device according to the present invention, in which 1 is a drawing to be recognized, 2 is a photoelectric conversion device such as a television camera,
3 is an image memory, 4 is a solid line route recognition device, 5 is a feature point memory, 6 is a broken line route recognition device, 7 is a joint information storage memory, and 8 is a line type discrimination device according to the present invention.

In the line type discrimination device, 81 is a line length measurement circuit, 82 is a histogram creation circuit, 83 is a normalization circuit, 84 is a histogram storage memory, and 85 is a line type determination circuit.

In such a configuration, a case where drawing 1 as shown in detail in FIG. 2 is read will be described.

Such a drawing 1 is subjected to photoelectric conversion by a photoelectric conversion device 2, and the result is stored in an image memory 3. Next, the solid line route recognition device 4 can also be realized as a program on a computer or the like. In either case, the recognition device 4 is connected to the image memory 3 and feature point storage memory 5, refers to and analyzes the image memory, and determines the end points, bending points, number of constituent points, etc. of each line segment that makes up the line, It is stored in the feature score memory 5. Various methods have been used for this analysis, but the most common method is to perform thinning processing on the image data, obtain a skeleton image of the line, and convert it into a direction code. In this application, any method may be used for this analysis. However, in the solid line route recognition device 4, if lines of multiple line types are drawn, they are all processed as solid lines. For example, when recognizing line segments l ₁ to l _k as shown in FIG. 2, and assuming that the number of constituent points thereof is n ₁ to n _k , the feature point storage memory 5 stores data as shown in FIG. 3. is stored. In addition, the solid line route recognition device 4
This can be easily realized by introducing line extraction means used in optical, character reading devices, etc.

Next, the broken line route recognition device 6 sequentially reads out the data stored in the feature point storage memory 5, and when the line consists of a broken line or a chain line, connects the line segments that make up these lines. Specifically, first,
Information on a predetermined line segment is read from the feature point storage memory 5, and the end point of the segment is set as a search base point, and the end point of the subsequently read line segment is within a predetermined distance from the search base point, and the angle formed by both segments is Conditions such as whether the values are within a certain range are checked, and line segments that meet these conditions are stored as connectable candidates in the connection information storage memory 7, while line segments read from the feature point storage memory 5 are connectable candidates. A signal indicating that there is a line is sent to the line type discrimination device 8.

In this way, if the line segment read from the memory 5 is a connectable candidate, another end point different from the point connected to the search base point is set as the search base point, and the next read line segment is set as the search base point. We will investigate the relationship as described above. In this way, by repeating the above-mentioned operation for all line segments in the memory 5, line segments are connected in one line such as a broken line or a chain line, and the line is expressed as a solid line to find a route and its end point. , find information about the bending point. In order to further find the next line route, a similar operation can be performed using the end point of a predetermined line segment as a search base. The broken line route recognition device 6 can be easily realized by connecting the memories 5, 7 and the line type discrimination device 8 to a general-purpose microcomputer. Here, since the line type discrimination device 8 can be regarded as a register group from the pipeline route recognition device 6, no special measures are required for its connection.

On the other hand, according to the present invention, the line type discrimination device 8 is a device for discriminating line types such as solid lines, broken lines, chain lines, etc. Every time you enter 6,
The information is also input to the line type discrimination device 8, and based on that information and the connection information sent from the recognition device 6, the type of the corresponding line is determined, and the result is used as the end point and bending point obtained by the recognition device 6. It is stored in the connection information storage memory 7 together with the information. As a result, data as shown in FIG. 4 is stored in the memory 7. however
T ₁ to T ₃ indicate line types, and L ₁ to _{L 4} indicate lines.

The specific operation of the line type discrimination device 8 will be explained below.

The line length measurement circuit 81 calculates the line length of each line segment based on the end point and bending point information of each line segment read from the memory 5 and inputs the result to the histogram creation circuit 82 . In this histogram creation circuit 82, connection information indicating whether or not corresponding line segments can be connected is transmitted to the recognition device 6.
When the line length is entered from the measuring circuit 81, the line length is taken in from the measuring circuit 81 and used as data for determining the appearance frequency of that line length. Similarly, line lengths are determined for line segments read one after another, the information is taken into the creation circuit 82 based on the connection information, the appearance frequency of each line length is created as a histogram, and the result is stored in the memory 84.

On the other hand, the normalization circuit 83 counts the number of connection information sent from the recognition device 6, and normalizes the histogram stored in the memory 84 based on the counted value. Thereby, the rate at which segments of each line length appear can be expressed as a percentage.

Figure 5 shows an example of a histogram obtained in this way, where a is a broken line, b is a dashed line, and c is a dashed line.
indicates the case of a chain double-dashed line and d indicates a solid line. In addition, in FIG. 5d, a line length longer than a predetermined length is treated as a constant value.

As can be seen from the figure, the dashed lines and solid lines represent monophonicity, with the dashed lines being distributed in the shorter line length portions, and the solid lines being distributed in the longer line length portions. In addition, in the case of a dashed-dotted line, it represents bimodality with the same height, and in the case of a dashed-double line, it represents bimodality in which the number of line segments with a short line length is twice as many as the number of long line segments. There is.

Therefore, by examining the number of peaks in the histogram, their positions, and their heights, the line type can be determined. Such determination is performed in the line type determination circuit 85 each time the route of each line is recognized, and the result is stored in the connection information storage memory 7.

6 to 8 show an example of a specific configuration of each circuit in the line type discrimination device 8 shown in FIG. 1. FIG. 6 shows the configuration of the line length measuring circuit 81, and FIG. The configuration of the circuit 82 and the normalization circuit 83, and FIG. 8 shows the configuration of the line type determination circuit 85.

In Figure 6, 11, 12 and 13, 14
are input terminals for the x and y coordinates of an end point or bending point of a line segment read from the feature point storage memory, respectively, and input terminals 11 and 13 contain the coordinate x ₁ and y coordinate y ₁ of a certain end point or bending point. is input, and the x coordinate x _i+1 and y coordinate y _i+1 of the next end point or bending point are input to the input terminals 12 and 14. 15 is an input terminal for inputting the number n of constituent points of a line segment; 16 is an input terminal for a memory read strobe; 17 and 18 are subtraction circuits;
9 and 20 are multiplication circuits, 21 and 23 are addition circuits, 22 is a square root calculation circuit 24 and 25 are latch circuits, 26 is a subtraction counter, 27 is a zero discrimination circuit, 28 and 29 are delay circuits, 30 to 32 are AND gates , 33 indicate flip-flops.

In such a configuration, first, the number n of constituent points and the x coordinate x ₁ and y coordinate y ₁ of the first end point are read from the memory 5 by a memory read strobe input to the input terminal 16. , are input to input terminals 15, 11 and 13, respectively. Of these, the number n of constituent points is input to the counter 26, so the zero determination circuit 27 sends a signal indicating that the content of the counter 26 is not zero to the AND gate 30.
Enter. After a certain period of time, a signal is output from the delay circuit 28 to open the AND gate 30, thereby decrementing the contents of the counter 26 by 1 and setting the flip-flop 33. Since the strobe signal, which is the output of the delay circuit 28, is gone before the output of the AND gate 32 is not opened. When the next memory read strobe enters from input terminal 16, the x and y coordinates x _i+1 and y _i+ 1 of the next endpoint or bend point of the line segment
is supplied to input terminals 12 and 14. Thereby, subtraction circuits 17, 18, multiplication circuits 19, 2
0, the addition circuit 21 and the square root calculation circuit 22 function to obtain √( _i+1 −) ² +( _i+1 −) ² .

On the other hand, the delayed output of the memory read strobe is output from the AND gate 30, but at this time,
Since the flip-flop 33 is in the set state,
AND gate 32 is opened and the output of calculation circuit 22 is inputted to latch circuit 24 through adder circuit 23.

When the next strobe is input, the coordinates of the next end point or bending point are input to the input terminals 11 and 13, and a similar calculation is performed, but at this time, the output of the latch circuit 24 is input to the adder circuit 23. Therefore, the result of their addition is input to the latch circuit 24 by the set signal from the AND gate 30.
By repeating such operations, the following line length L _N is obtained in the latch circuit 24.

L _N = _o-1 〓 ⁱ⁼¹ √( _i+1 −) ² + ( _i+1 −) ² Then, when the content of the counter 26 becomes zero, a signal is output to the AND gate 31, and the next The strobe causes the contents of the latch circuit 24 to be transferred to the latch circuit 25, and after a certain period of time, the latch circuit 24 is reset by the output of the delay circuit 29.

In this way, the line length L _N of the corresponding line segment is stored in the latch circuit.

Next, in FIG. 7, 41 is an input terminal for inputting the connection information of the corresponding line segment from the broken line route recognition device 6 of FIG. 1, 42 is a line length data input terminal from the latch circuit 25 of FIG. 43 is a counter, 44 is a decoder, 45 to 47 are AND gates, 48 to 50 are counters, and 51 to 53 are arithmetic circuits.

In such a configuration, line length data from the latch circuit 25 in FIG. 6 is input to the decoder 44 to generate a signal for each line length, and the AND gates 45 to
47, but at this time, if connection information indicating that the corresponding line segment can be connected is input from the input terminal 41, those AND gates are opened, and the counters 48 to 50 corresponding to the specific line length are input.
are counted. By repeating this operation for each line segment, the counters 48 to 48
50, data C ₁ to C _k representing the appearance frequency of the corresponding line length is obtained. This is the storage memory 84
is stored in

On the other hand, the counter 43 counts the number of connection information, that is, the number of line segments forming a line.

When the route recognition of one line is completed, the arithmetic circuits 51 to 53 are operated by a control signal (not shown), and the information CT of the number of connection line segments from the memory 84 and the outputs C ₁ to C of the counters 48 to 50 are operated. C _k and
Input a constant value S, for example 100, and perform the following calculation.

Hi=Cj×S/CT H ₁ to H _k thus obtained represent the frequency of appearance at each line length of the normalized histogram. This information is stored in storage memory 84.

In FIG. 8, 61 to 64 are threshold circuits;
5 and 66 are read-only memory (ROM),
67 and 68 are output terminals. Note that the threshold circuit 6
1, 62 have a certain threshold value V ₁ and 63, 64 have a certain threshold value V _t
have.

In such a configuration, the appearance frequencies H ₁ to H _k for each line length sent from the normalization circuit by the control signal (not shown) are read out from the storage memory 84 and compared in level with a plurality of threshold values V ₁ to V _t . The resulting output signals H ₁₁ ~ _{H k1} , T _1t ~ H _kt are sent to the ROM65, 66.
The output of the ROM is output as a line type code T from output terminals 67 and 68, and stored in the connection information memory 7 shown in FIG.

Note that instead of multiple ROMs as shown in the figure, one
You may also use ROM.

In the above-described embodiment, the line length of a line segment is determined and a histogram representing the appearance frequency corresponding to the line length is created. You may also create one. In that case, the desired histogram can be obtained by inputting the information of the opposite end points of the two line segments to the input terminals 11 to 14 in FIG. This is effective when the line type is different depending on the line type.

It goes without saying that the present invention is not limited to the above-mentioned example, and that various embodiments and modifications can be considered.

As described above, according to the present invention, line types can be automatically determined with a simple configuration.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of a pattern recognition device according to the present invention, Figs. 2 to 5 are explanatory diagrams for explaining the operation of Fig. 1, and Figs. 6 to 8 are main parts of Fig. 1. FIG. 3 is a diagram showing an example of a specific configuration of the section. 1...Drawing, 6...Dotted line route recognition device, 8...Line type discrimination device.

Claims (1)

[Claims] 1. In a recognition device that recognizes a pattern drawn with multiple line types, the length of each line segment constituting a line or the interval between two line segments constituting a line is determined, and these values are calculated. A method for determining a line type in a pattern recognition device, characterized in that the frequency distribution of the length or interval in each line is examined, and the line type is determined based on the distribution state. 2. In a recognition device that recognizes a pattern drawn with multiple line types, measure the length of each line segment that makes up the line, and use the measured values to create a histogram representing the frequency of appearance of each line segment length,
A method for determining a line type in a pattern recognition device, characterized in that the histogram is normalized, and the line type is determined based on the normalized histogram.