JPH0816309A - Tracer - Google Patents

Abstract

(57) [Abstract] [Object] The present invention relates to a tracer that displays a line or an area on a display screen by operating an operator such as a trackball or a mouse. Trace to surround only the desired area. [Structure] A first line segment newly input by operation of an operator is a second line segment input immediately before inputting a first line segment of line segments forming a broken line stored in a memory. The first determination means for determining whether or not the line segment overlaps
1 or multiple thirds entered before the line segment of
For each line segment, the angle between two line segments connecting the first line segment start point and the third line segment start point and end point and a predetermined reference line, and the first line segment end point. A second determining means is provided for determining the intersection of the line segments based on the angle between two line segments connecting the start point and the end point of the third line segment and a predetermined reference line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracer for displaying a line or area on a display screen by operating an operator such as a trackball or a mouse.

[0002]

2. Description of the Related Art Conventionally, tracers for displaying lines and areas on a display screen have been widely used. Here, an ultrasonic diagnostic apparatus will be described as an example of its application field.
The ultrasonic wave is transmitted to the subject, particularly the human body, and the received ultrasonic wave is returned by being reflected by the tissue inside the subject, and a reception signal is obtained.
A device for displaying a tomographic image of the inside of a subject based on this received signal has been widely used, and this device is generally used.
It is called an ultrasonic diagnostic device. In this ultrasonic diagnostic apparatus, in order to make the diagnosis of the disease easier, the tissue appearing in the tomographic image, for example, the area of the left ventricle of the heart or the volume (volume) of the left ventricle estimated from the contour of the left ventricle It is desired to obtain the time variation of. In order to obtain this area or volume, it is first necessary to know the contour of the tissue and extract the region of the tissue. Although various researches have been conducted to automatically recognize the contour in obtaining the contour, the most reliable method is to display the tomographic image on the display screen and allow the operator to display the tomographic image. A method of tracing the desired contour of a tissue by operating an operator such as a trackball or a mouse while watching is adopted.
By making full use of such a tracing function, for example, by inputting contours for each tomographic image with various time lags based on the heartbeat of the heart and determining the area or volume, the time change can be known and the disease It is used for diagnosis.

[0003]

FIG. 7 is a schematic diagram showing traced lines on a display screen. For example, when the above tracing operation is performed using a trackball, it is difficult to trace as intended by the operator, and areas D2 and D3 other than the area D1 intended to be surrounded by the trace line are not intended. The regions that are not formed are also formed by the trace lines, and in this case, there is a problem that the areas of the regions D2 and D3 that are not intended become an error.

In order to avoid this, the intersections of the trace lines should be obtained and the regions D2 and D3 should be excluded from the area calculation. However, there is a practical limit to the calculation processing to find the intersection point during the trace operation in real time, and it has been difficult to realize so far. In addition, areas D1, D2, D3
In some cases, it is not clear which of these areas is the area intended by the operator.

In view of the above circumstances, it is an object of the present invention to provide a tracer which solves a problem at the time of tracing and can trace with high accuracy so as to surround only a desired area.

[0006]

The tracer of the present invention which achieves the above-mentioned object is formed by successively inputting a plurality of line segments according to an input operation.
A tracer comprising an operator for instructing a polygonal line on a two-dimensional screen, a memory for storing the polygonal line instructed by the operator, and a display unit for displaying the polygonal line stored in the memory. The first line segment newly input by the child operation is the same as the second line segment input immediately before the input of the first line segment among the line segments forming the broken line stored in the memory. First determining means for determining whether or not to overlap (2) Of the line segments forming the broken line stored in the memory, one or a plurality of third lines input before the second line segment. For each of the line segments, the second determination means for determining whether or not the first line segment and the third line segment intersect is provided.

Here, the first determination means of the above (1) is
For example, by comparing the angle formed by the (1_1) first line segment and a predetermined reference line with the angle formed by the second line segment and the reference line, the first line segment is It may be one that determines whether or not it overlaps with a line segment. The second determination means of (2) may be, for example, (2_1) one of the start point and the end point of the first line segment and the start point and the end point of the third line segment. First sub-judging means for judging whether or not one of the points coincides with each other (2_2) A reference line extending from the start point of the first line segment to the end point of the first line segment, and the first sub-determination means. Let α and β be respective angles formed by the two line segments connecting the start point of the line segment and the start point and the end point of the third line segment, respectively, where α · β ≦ 0, and , | Α-β | ≦ 180 ° where α and β are | α | ≦ 180 ° and | β | ≦ 180 °
And -180 [deg.] Or 180 [deg.] Is an angle within the excluded range. Second sub-judgment means (2_3) for judging whether or not the above condition is satisfied, and a reference line from the end point of the first line segment to the start point of the first line segment, and the first line segment. Let α ′ and β ′ be respective angles formed by the two line segments connecting the end point and the start point and end point of the third line segment, respectively, where α ′ and β ′ ≦ 0, and , | Α′−β ′ | ≦ 180 ° where α ′ and β ′ are | α ′ | ≦ 180 °, | β ′ | ≦
It is 180 °, and either −180 ° or 180 ° is an angle within the range excluded. A third sub-judging means for judging whether or not the condition of (3) is satisfied may be provided.

Further, in the case where the above-mentioned (2) second judging means comprises the above-mentioned (2_1) to (2_3) sub-judging means, (3) the second judging means is the above-mentioned By applying only one of the second sub-determination means and the third sub-determination means to each of the third line segments, there is a possibility that the third line segment may intersect with the first line segment. Of the second sub-judging means and the third sub-judging means of the second sub-judging means is applied to the extracted third line segment. .

Further, in the tracer of the present invention, (4) area calculation for calculating an area of a region surrounded by the polygonal line displayed on the display means and a line segment connecting the start point and the end point of the entire polygonal line Means are preferably provided. Further, in the tracer of the present invention, (5) when the first determination means detects the superposition of the first line segment and the second line segment, the content of the memory is changed to the second
Except for the line segment No., the line segment is changed to a polygonal line that is input before the second line segment, and the third line segment that intersects the first line segment is detected by the second determination means. If
The memory rewriting means for changing the contents of the memory into a broken line formed by a line segment input before the third line segment, excluding the third line segment, is provided, and the display means stores the memory by the memory rewriting means. It is preferable that the display of the line segment of the portion corresponding to the difference between the polygonal lines before and after the rewriting is erased when the content of (1) is rewritten.

Further, in the tracer of the present invention, (6) a timer is provided which is reset by the operation of the operator and measures a predetermined time from the time when the operation of the operator is stopped, and the display means increases the time of the timer. It is preferable that the polygonal line which is received and stored in the memory is displayed again.

[0011]

In the tracer of the present invention, in the first determination means of (1) above, whether or not the newly input first line segment overlaps with the immediately preceding second line segment. It is detected whether or not the line has returned on the same trace line, and in the second determination means of (3), the newly input first line segment is the second line input immediately before. It is detected whether or not the trace lines intersect with each other by determining whether or not they intersect with one or a plurality of third line segments input before the line segment of Among the trace lines, a valid portion intended by the operator is distinguished from an invalid portion where the operator mistakenly moves back or crosses. Therefore, when a certain area is designated by the trace line, the area, volume, etc. of the area can be obtained with high accuracy. These first determination means, the second
The determination means of the above are (1_1) and (2_1), respectively.
The configurations (1) to (2_3) can be adopted, and the determination can be performed in real time at high speed by a simple calculation such as angle determination without causing the operator to wait.

Further, the second determining means is the above (2_
1) to (2_3), if the second determination means is configured to perform the intersection determination based on the sequence of (3), the amount of calculation can be further reduced. The calculation time can be further shortened. Further, in the tracer of the present invention, the area calculating means of the above (4) is provided, and by calculating the area even in the middle of tracing, it is possible to give the operator an indication of the area of the desired region even in the middle of tracing. preferable.

Further, in the tracer of the present invention, the memory rewriting means of the above (5) is provided, and the trace portion is traced by erasing an invalid portion of the trace line which is mistakenly moved back or crossed by the operator. Only a valid portion of the line intended by the operator is displayed, and a screen that is easier to see is provided as compared with a case where the invalid portion is displayed as it is, and the operation efficiency is improved.

By the way, if the memory rewriting means of the above (5) is provided and the trace line on the display screen is erased in correspondence therewith, inconvenience may occur. This inconvenience will be described with reference to FIG. FIG. 8 is an enlarged view showing a portion of the race line on the display screen where the trace lines intersect with each other.

A large number of square areas in the figure represent each display pixel on the display screen. In the figure, line segment a → line segment b → ...
When tracing is performed in the order of line segment c → line segment d, and line segment e is further input, the line segment b and the line segment e just input are obtained by the second determination means in (2) above. Is determined to intersect, and the line segment b is determined by the memory rewriting means in (5) above.
Subsequent trace lines are erased.

At this time, in the display means, the display of the display pixels hatched in the figure is erased, but due to this erasure, the display pixels corresponding to the line segment a to be left in the displayed state are displayed. Of these, the display pixels in the pixel regions R1 and R2 are also erased. It is conceivable to perform re-display processing immediately after erasing pixels that should not have been erased, which has been erased in this way, but it takes some time to re-display, and the trace of the operator It will interrupt the operation.

In this case, the timer (6) is provided,
By re-displaying the trace line in anticipation of the trace operation being interrupted by the operator's intention, the display as shown in FIG. 8 is made without inevitably interrupting the operator's trace operation. A screen with a clean trace line without any gaps is provided.

[0018]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing the configuration of an embodiment of the tracer of the present invention. This tracer is provided with a trackball 1, a display line management memory 2, a line display erasing control unit 3, a calculation control unit 4, a line drawing memory 5, a character memory 6 and a CRT display 7. The management memory 2 includes an operator according to the present invention,
This corresponds to each example of the memory, and the combination of the line display erasing control unit 3, the line drawing memory 5, and the CRT display 7 corresponds to an example of the display means according to the present invention. The function of rewriting the contents of the display line management memory 2 of the line display erasing control unit 3 corresponds to an example of the memory rewriting means according to the present invention. Further, the arithmetic control unit 4 corresponds to one example of each of the first and second determination means, the area calculation means, and the timer according to the present invention, depending on its function.

When the trackball 1 is operated, vector information (dx, dy) representing each line segment is sequentially input,
The vector information sequentially input from the trackball 1 is normally stored in the display line management memory 2 via the line display erasing control unit 3. The line segments sequentially input by operating the trackball 1 are also input to the image memory 5, and the CRT display 7 displays a trace line consisting of a series of these line segments. Further, the arithmetic control unit 4 obtains the area of the trace line and the closed region connecting the start point and the end point of the trace line, the character information representing the area is input to the character memory 6, and the area is displayed on the CRT display 7. The numerical value is displayed.

The display line management memory 2 stores display last line information, vector information, and line pattern start information. 2A and 2B are explanatory diagrams of information stored in the display line management memory 2. FIG. 2A is a schematic diagram of a registered line pattern, and FIG. 2B is a trace line displayed on the CRT display 7. FIG.

The registered line pattern shown in FIG. 2A is
It defines the line type of the trace line displayed on the CRT display 7, for example, a solid line, a broken line, a dash-dotted line, etc. In this example, it consists of 10 bits, and each bit written with "1" or "0" is , That is, the display pixel corresponding to each bit on the display screen is placed in a state in which it is brightly turned on or turned off, for example.

The registered line pattern shown in FIG. 2A is '1111100000', and this registered line pattern is cyclically used. That is, in this registered line pattern, 5 pixels are continuously turned on along the trace line, the next 5 pixels are turned off, and the next 5 pixels are turned on. It means to do.

In the schematic diagram of the trace line shown in FIG. 2B, the on / off state is shown, and the line segment 1 → 2.
When traced as → 3 → 4 → 5, only the pixels with "1" written in the square indicating each display pixel actually light up on the display screen, and the pixels with "0" are displayed on the display screen. It is placed in the off state above. Here, the vector information (ex, ey) in the display line management memory 2 shown in FIG.
Vector information (d
x, dy). In the example shown in FIG. 2 (B),
First, as vector information of line segment 1, (dx, dy) =
(3, 0) is input, then (dx, dy) = (0, 3) is input as vector information of the line segment 2, and further vector information (dx, dy) of the line segments 3, 4, 5 is input. = (-8,
0), (0, -6), (6, 0) are sequentially input and stored as vector information (ex, ey) in the display line management memory 2. In the line pattern start information in the display line management memory 2, the last pixel of the line segment, that is, the first pixel of the next line segment corresponds to what bit of the registered line pattern shown in FIG. The last pixel of the line segment 1, 2, 3, 4, 5 or the first pixel of the line segment 2, 3, 4, 5, 6 is the registration line. Each of the patterns 4, 7, 5, 1, 7
Equivalent to the bit eye. The display last line information in the display line management memory 2 indicates the line number of the last line segment forming the trace line currently displayed on the CRT display 7 and the coordinates of the end point of the last line segment. In the example shown in FIG. 1, line number = 5, coordinates of the end point (P _x , P _y ) = (252, 200) are stored.

In the above example, the trackball 1 to the line segment 1
There is no overlap or intersection of line segments as will be described later while inputting ~ 5. Therefore, every time each line segment 1 to 5 is input, the line display deletion determining unit configuring the line display deletion control unit 3 is input. In 3a, it is determined that the line segment input this time is displayed based on the information from the arithmetic control unit 4 that the line segments do not overlap or intersect, and the line display deletion control unit 3
The display line management memory 2 stores necessary information corresponding to the line segment input this time. At the same time, the line display erasure control unit 3 follows the registered line pattern
The case of this input is stored in the line drawing memory 5, whereby the line segment input this time is displayed on the CRT display 7 in addition to the trace lines up to that point.

Next, line segments 1 to 5 are input from the trackball 1 as described above, and then the vector information (dx, of the line segment 6 indicated by the broken line in FIG. A case where dy) = (0,4) is input will be described. This vector information (dx, dy) = (0,
4) is input to the arithmetic control unit 4 via the line display deletion control unit 3 shown in FIG. In the calculation control unit 4, the vector-angle converter 4a calculates the gradient dy / dx based on the vector information (dx, dy) input this time. In this case, the gradient dy / dx = 4/0 = +
It becomes ∞. The vector angle converter 4a has a gradient dy / d
A gradient-angle conversion table for converting x into an angle θ between the reference line and the line segment when the positive direction of the x-axis shown in FIG. 2B is used as a reference line is stored. This gradient-angle conversion table is referred to, and the angle (θ = 90 ° in this case) is obtained from the obtained gradient dx / dy. In the vector-angle converter 4a, the line segment 5 (see FIG.
When the vector information of (see) is input, the angle θ = 0 ° from the reference line of the line segment 5 is obtained in the same manner as above.

FIG. 3 is a schematic diagram of trace lines. FIG.
(A) is a schematic diagram showing a state when line segments 1 to 5 have already been input and a new line segment 6 has been input, as in FIG. In Part 4,
When the line segment 6 is input, its vector information (dx, d
The angle θ is calculated based on y) = (0,4).

In the arithmetic control unit 4, whether or not the angle between the line segment 5 input immediately before and the line segment 6 input this time is 180 °, that is, as shown in FIG. It is determined whether the created line segment 6 is a line segment traced in the reverse direction of the line segment 5 input immediately before. In the example shown in FIG. 3A, it is determined that the line segment 6 input this time is not a line segment that overlaps the line segment 5. However, as shown in FIG. If the line segment overlaps the line segment 5, the information is input to the line display erasure control unit 3, and the line display erasure determination unit 3a determines that the line segment 5 should be erased.
The vector information (ex, ey) = (6, 0) corresponding to the line segment 5 of the display line management memory 2 and the line pattern start information '7' are erased, and the display last line information is the line number = 4, End point coordinates of line segment 4 ( _Px , _Py )
= (246,200). At the same time, the information of the line segment 5 among the information of the trace lines stored in the line drawing memory 5 is erased, and the line segment 5 displayed on the CRT display 7 is erased accordingly. Further, in the arithmetic control unit 4, the area of the region connecting the start point and the end point of the entire trace line is changed in accordance with the deletion of the line segment 5, and the character information representing the new area is stored in the character memory 6.
And the area display of the CRT display 7 is changed.

However, here, as shown in FIG. 3A, it is assumed that the line segment 6 input this time does not overlap with the line segment 5 input last time. In that case, in the arithmetic control unit 4,
As described below, for each of the line segments 1, 2, 3, 4 input before the line segment 5, whether or not the line segment 6 intersects each line segment 1, 2, 3, 4 Is determined.
The criteria for this intersection are as follows.

(A) Any one of the start point and the end point of the line segment 6 and a certain line segment A (line segments 4, 3, 3)
It is checked whether or not any one of the start point and the end point of (2, 1) is coincident with each other, and when it is determined that they coincide with each other, the line segment 6 and the line segment A cross each other. Determine that When it is determined that none of these points match each other, (b) the line segment 6 from the start point of the line segment 6 is further added.
Let α and β be the angles formed by the reference line toward the end point of and the two line segments that connect the start point of line segment 6 and the start point and end point of line segment A, respectively. And | α-β | ≦ 180 ° (1) where −180 ° <α ≦ 180 °, −180 ° <β ≦ 1
It is 80 °. (C) A reference line extending from the end point of the line segment 6 to the start point of the line segment 6 and the end point of the line segment 6 and the start point and end point of the line segment A are connected to each other. Two
Let α ′ and β ′ be the angles formed by the line segments of the book, including the sign, respectively, α ′ · β ′ ≦ 0 and | α′−β ′ | ≦ 180 ° (2) , -180 ° <α '≤ 180 °, -180 ° <β'
≦ 180 °. It is determined whether or not the condition of is satisfied, and the above equation (1),
If both of the expressions (2) are satisfied, it is determined that the line segment 6 intersects with the line segment A.

In the example shown in FIGS. 3C to 3F, FIG.
Only (C) and (D) satisfy this condition, and it is determined that the line segment 6 and the line segment A intersect. Of the line segments 1, 2, 3, and 4 shown in FIG. 3A, the line segment that satisfies this condition (that is, the line segment that intersects the line segment 6) is the line segment 1. In this embodiment, the angles α, β; α ′, β ′ are −180 ° <α ≦ 180 °, −180 ° <β ≦ 180 ° −180 ° <α ′ ≦ 180 °, −, respectively. 180 ° <β '≤ 18
Although it is assumed that it is 0 °, instead of these, −180 ° ≦ α <180 °, −180 ° ≦ β <180 ° −180 ° ≦ α ′ <180 °, −180 ° ≦ β ′ <18
It may be 0 °.

The arithmetic control unit 4 performs the above-described intersection determination, and in the example shown here, notifies the line display erasure control unit 3 that the line segment 1 intersects the line segment 6 input this time. To be done. Then, the line display deletion determination unit 3a includes the intersecting line segment (line segment 1 in the example shown here),
It is determined that all the line segments input thereafter are lines to be erased, and the line display erase control unit 3 changes the contents of the display line management memory 2 and trace lines stored in the line drawing memory 5. Among these, the erasing process of the line segment including the intersecting line segment and the lines input thereafter is performed.

In the example shown here, since the newly input line segment 6 intersects with the first input line segment 1, all the trace lines input so far are erased, but the trace line When the line segment intersects with the line segment in the middle of, the line segment input after the line segment including the line segment in the middle of the intersection is deleted. Next, when a new line segment is input from the trackball 1, the input line segment is processed as a line segment subsequent to the final line segment of the trace lines remaining without being erased. In the above example, since all the trace lines have been erased, the newly input line segment becomes the first line segment of the trace lines.

FIG. 4 is a flow chart showing the procedure of intersection determination. First, as described above, it is determined whether or not the line segment 6 and the immediately preceding line segment 5 overlap (step 4).
_1). Here, it is assumed that the line segment 5 does not overlap, but if it does, it proceeds to step 4_4 and the line segment 1 immediately before the intersection line segment (here, line segment 5; overlap is also considered to be an intersection). Others (here, the line segment 5) are deleted except for 4 to 4.

When it is determined in step (4_1) that the line segment 6 and the line segment 5 do not overlap, the process proceeds to step 4_2.
The intersection determination operations (a) to (c) described above are performed to determine whether the line segment 6 and the line segment immediately preceding it (here, the line segment 4) intersect, and in step 4_3. If it is determined that they intersect, the process proceeds to step 4_4. On the other hand, if it is determined that they do not intersect, the process returns to step 4_2 and the line segment 6
And an intersection determination calculation with the immediately preceding line segment (line segment 3 in this case) are performed.

In this way, in the present embodiment, the intersection determination is performed in the order of going back from the line segment input later to the line segment input earlier. FIG. 5 is a schematic diagram of trace lines for explaining another method of intersection determination in the arithmetic control unit 4 shown in FIG. Here, description will be given by returning to the time point when line segments 1 to 5 are input and a new line segment 6 is input.

When the line segment 6 is input, the arithmetic control unit 4 determines, as shown in FIG. 5A, the starting point of the line segment 6 and a determination target whether or not the line segment 6 intersects. Two line segments that connect the start point and the end point of each of the line segments 1, 2, 3, and 4 (here, the line segment 4) and a reference from the start point of the line segment 6 to the end point The angles α and β with the line are obtained, and it is determined whether or not the above expression (1) is satisfied. For the line segment 4 shown in FIG. 5 (A), α.beta.> 0 is not satisfied and therefore the formula (1) is not satisfied. Therefore, no further calculation is performed for the line segment 4, and this time, FIG. As shown in B), the same determination is made for the line segment 3.

Since the line segment 3 satisfies the above equation (1), as shown in FIG.
The angles α ′ and β ′ between the end point of the line segment 6 and the two line segments connecting the start point and the end point of the line segment 3 and the reference line extending from the end point of the line segment 6 to the start point are obtained, and It is determined whether or not the expression (2) is satisfied. Here | α'-β '|
Is greater than 180 °, it is determined that line segment 3 does not intersect line segment 1.

Then, as shown in FIG.
For the line segment 2, since α · β> 0 is satisfied, the above equation (1) is not satisfied. Therefore, as shown in FIG. The determination of the above equation (1) is performed for the line segment 1. Since the line segment 1 satisfies the above equation (1), the line segment 1 shown in FIG.
As shown in (F), it is determined whether or not the above expression (2) is satisfied in the same manner as in the case of FIG. 5C. here,
Since the equation (2) is also satisfied for the line segment 1, it is determined that the line segment 1 intersects with the line segment 6.

FIG. 6 is a flow chart showing the procedure of the intersection determination in the case where only the determination of the above equation (1) is performed first. Since Steps 6_1 and 6_6 are the same as Steps 4_1 and 4_4 of FIG. 4 described above, description thereof will be omitted here. In step 6_2, the determination calculation of the above equation (1) is performed for the line segment immediately before (line segment 4 here), and whether or not the line segment (line segment 4 here) is an intersection determination candidate That is, it is determined whether or not the line segment may intersect with the line segment 6 (step 6).
_3). If it is determined that the candidate is not an intersection determination candidate, the process returns to step 6_2, and the determination calculation of the above formula (1) is performed for the line segment immediately before (line segment 3 here).
Since the line segment 3 satisfies the above expression (1), step 6_
In 3, it is determined that the line segment is an intersection determination candidate, and the process proceeds to step 6_4. In step 6_4, the above (2)
Expression determination is performed, and in step 6_5, it is determined whether the line segment (here, line segment 3) intersects the line segment 6, that is, whether or not the above equation (2) is satisfied. When it is determined that they do not intersect, the process returns to step 6_2, and when it is determined that they intersect, the process proceeds to step 6_6.

When the intersection determination is performed according to the flow shown in FIG. 6, it is determined whether or not each of the line segments 4, 3, 2 and 1 satisfies both the above equations (1) and (2). The calculation time is further shortened as compared with the method. FIG.
Return to to continue the explanation. The trackball 1 is operated, and the overlap and intersection of line segments are determined as described above.
When there is an overlap or an intersection, the line segments are erased while the trace lines are sequentially extended as a whole, and when a closed loop is formed by the trace lines, the arithmetic control unit 4 sequentially calculates the trace lines until then. And the area of the area in the closed loop formed by the line segment connecting the start point and the end point of the trace line is determined as the area in the closed loop only by the trace line, and the area in the closed loop is displayed on the CRT display 7. To be done.

Whether the trackball 1 is formed or not before or after the closed loop formed by the trace line is formed.
When the input of the line segment from is interrupted, the arithmetic control unit 4 starts a timer. This timer is reset when the input of the line segment from the trackhole 1 is restarted before the time is up. If the time is up without this reset being performed, the line display erasing control unit 3 is notified of that fact, and the line display erasing control unit 3 receives the notification, and the trace line information stored in the display line management memory 2 is notified. Then, the entire trace line is written again in the line drawing memory 5. As a result, even if there is a partial omission of the trace line display as described with reference to FIG. 8, a clean trace line in which the partial omission has been repaired is CR.
It is displayed on the T display 7.

[0042]

As described above, according to the tracer of the present invention, since the tracer of the present invention is provided with the first determining means and the second determining means, it is possible to trace the desired area with higher accuracy than the conventional one. can do. In the tracer of the present invention, first, it is determined whether or not the condition of the above formula (1) is satisfied, and only when the condition of the above formula (1) is satisfied, the condition of the above formula (2) is satisfied. When it is configured to determine whether or not to perform the determination, the calculation time until the determination result by the second determination means is obtained is further shortened. Furthermore, in the tracer of the present invention, the memory rewriting means described above is provided,
By deleting the invalid portion of the trace line where the operator mistakenly goes back or crosses the operation, only the valid trace line intended by the operator is displayed, and an easy-to-see screen is provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a tracer of the present invention.

FIG. 2 is an explanatory diagram of information stored in a display line management memory.

FIG. 3 is a schematic diagram of a trace line.

FIG. 4 is a flowchart showing a procedure for intersection determination.

FIG. 5 is a schematic diagram of a trace line.

FIG. 6 is a flowchart showing a procedure of intersection determination.

FIG. 7 is a schematic diagram showing traced lines on a display screen.

FIG. 8 is an enlarged view showing a portion of trace lines on a display screen where the trace lines intersect with each other.

[Explanation of symbols]

 1 Trackball 2 Display line management memory 3 Line display erasing control unit 4 Calculation control unit 5 Line drawing memory 6 Character memory 7 CRT display

Claims (7)

[Claims] 1. A plurality of line segments are successively input by sequentially inputting a plurality of line segments according to an input operation.
A tracer including an operator for indicating a polygonal line on a three-dimensional screen, a memory for storing the polygonal line instructed by the operator, and a display means for displaying the polygonal line stored in the memory, wherein an operation of the operator The first line segment newly input by is superposed on the second line segment input immediately before the input of the first line segment among the line segments forming the broken line stored in the memory. First determining means for determining whether or not the one line or one third line input before the second line segment among the line segments forming the broken line stored in the memory A tracer comprising second determination means for determining whether or not the first line segment and the third line segment intersect for each of the minutes. 2. The first determination means compares the angle formed by the first line segment and a predetermined reference line with the angle formed by the second line segment and the reference line. The tracer according to claim 1, wherein the tracer determines whether or not the first line segment overlaps the second line segment. 3. The second determination means includes one of a start point and an end point of the first line segment and one point of a start point and an end point of the third line segment. A first sub-judgment means for judging whether or not the two coincide with each other, a reference line extending from a start point of the first line segment to an end point of the first line segment, and a start point of the first line segment. Two line segments connecting the start point and the end point of the third line segment,
When each angle including the sign is α and β, α · β ≦ 0 and | α−β | ≦ 180 °, where α and β are | α | ≦ 180 ° and | β | ≦ 180 °
And -180 [deg.] Or 180 [deg.] Is an angle within the excluded range. Second sub-judging means for judging whether or not the above condition is satisfied, a reference line from the end point of the first line segment to the start point of the first line segment, and the end point of the first line segment. And two line segments connecting the start point and the end point of the third line segment,
When each angle including the sign is α ′ and β ′, α ′ · β ′ ≦ 0 and | α′−β ′ | ≦ 180 °, where α ′ and β ′ are | α ′ | ≦ 180 °, | β '| ≦
It is 180 °, and either −180 ° or 180 ° is an angle within the range excluded. The tracer according to claim 1, further comprising a third sub-judging means for judging whether or not the condition of is satisfied. 4. The second determining means applies only one of the second sub-determining means and the third sub-determining means to each of the third line segments, whereby the second Third that may intersect the line segment of 1
Of the second sub-judging means and the third sub-judging means are applied to the extracted third line segment. The tracer according to claim 3. 5. An area calculation means for calculating an area of a region surrounded by the polygonal line displayed on the display means and a line segment connecting the start point and the end point of the entire polygonal line is provided. The tracer according to Item 1. 6. The contents of the memory excluding the second line segment when the first determination unit detects a superposition of the first line segment and the second line segment, When the polygonal line is made up of line segments input before the second line segment, and the third line segment intersecting the first line segment is detected by the second determination means, A memory rewriting unit for changing the contents of the memory to a broken line formed by a line segment input before the third line segment, excluding the third line segment; and the display unit, the memory rewriting unit. 2. The tracer according to claim 1, wherein when the contents of the memory are rewritten, the display of the line segment of the portion corresponding to the difference between the polygonal lines before and after the rewriting is erased. 7. A timer, which is reset by the operation of the operation element, for measuring a predetermined time from the time when the operation operation of the operation element is stopped, and the display means stores the time in the memory in response to the time-up of the timer. The tracer according to claim 1, wherein the traced line is displayed again.