JPH0488569A - Method and device for displaying objective area - Google Patents

Abstract

PURPOSE:To decrease the number of objective points to be actually displayed by displaying only the most outside display object point in an objective area. CONSTITUTION:A space dividing part 1 divides a space including the area into the previously set number of grids in respective axial directions and while allocating points to respective grids, a display object point setting part 2 respectively sets points belonging to the areas as the display object pints and sets the other points as display non-object points. Afterwards, a display object point extraction part 3 successively extracts only the display object points, adjacent point extraction parts 4, 5 and 6 extract right, left, upper, lower, front and rear points respectively adjacent to the relevant display object point, and 1st-3rd discrimination parts 7, 8 and 9 and a display possibility discrimination part 10 discriminate whether the relevant display object point is the most outside point in the area or not. Then, a display part 11 displays only the display object point which is discriminated as the most outside point in the area.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method and apparatus for displaying a target region of a molecule or the like.

<Prior art and problems to be solved by the invention> Conventionally, when displaying a target area such as a molecule, all points are divided into points that belong to the target area and points that do not belong to the target area, and It is common practice to display all points.

Therefore, the target area can be displayed by classifying all the points based on an equation or the like that indicates the target area, and performing simple discrimination and processing to unconditionally display points belonging to the target area.

However, when this conventional method is adopted, all points belonging to the target area become display target points, and a significantly large number of points must be drawn, which significantly increases the time required to display the target area. This has the disadvantage of causing a problem. Furthermore, if the target area is three-dimensional, there is a problem that it may become difficult to see as all the points belonging to the target area are drawn. In other words, when display target points are set at intervals coarser than the pixel interval on the display screen, even if the inner display target point and the outermost display target point overlap and are displayed clearly, For example, if rotation processing is applied, the inner display target point and the outermost display target point will no longer overlap, and the number of display target points displayed on the screen will increase significantly, making it difficult to see as a whole. .

Further, there are cases where it is required to display the outline of a region obtained by cutting a two-dimensional target region or a three-dimensional target region along an arbitrary plane by connecting it with line segments. In order to meet this demand, conventionally, a ranking is specified for all points forming the outline, and a line segment connecting the points in the specified ranking is displayed.

However, the process of specifying rankings for all points in advance is quite complicated and takes a considerable amount of time, resulting in an increase in processing load and a longer time required. There is.

<Object of the invention> This invention was made in view of the above problems,
The first object of the present invention is to provide a target area display method and device that can speed up the display of an area by reducing the number of points to be displayed, and the target area display method and device can simplify the display of the outline of a region. Second to provide
The purpose is to

Means for Solving the Problems) In order to achieve the above object, the target area display method of the first invention is such that when displaying a predetermined area, This is a method of determining whether all points belong to a region or not, and displaying only those display target points for which it has been determined that at least one of the adjacent points does not belong to the region.

In the target area display method of the second invention, when displaying a predetermined area, it is determined whether all points adjacent to a display target point belonging to the area belong to the area, and the adjacent points Only the display target points for which at least one of the extracted display target points is determined not to belong to the area are extracted, and adjacent display target points are extracted in a predetermined order using any display target point among the extracted display target points as a reference point. The extracted point is used as a new reference point, and the operation of extracting the next adjacent display target point in a predetermined order is repeated until the reference point or the next display target point is extracted, and the display target points are extracted in the order of extraction. This is a method of displaying line segments that connect .

A target area display device according to a third aspect of the present invention includes an information holding means for holding information indicating whether or not each point belongs to a predetermined area in correspondence with each other; display target point extracting means for sequentially extracting points belonging to an area as display target points; information reading means for reading information of all points adjacent to the extracted display target point from the information holding means; and information reading means for reading information from the information holding means. A determining means for determining whether all points adjacent to the corresponding display target point belong to the area based on the output information, and a display indicating that at least one of the adjacent points does not belong to the area. and display means for displaying only the target point.

A target area display device according to a fourth aspect of the present invention includes an information holding means for holding information indicating whether or not each point belongs to a predetermined area in correspondence with each other; display target point extracting means for sequentially extracting points belonging to an area as display target points; information reading means for reading information of all points adjacent to the extracted display target point from the information holding means; and information reading means for reading information from the information holding means. A determining means for determining whether all points adjacent to the corresponding display target point belong to the area based on the output information, and a display indicating that at least one of the adjacent points is determined not to belong to the area. a boundary point extraction means for extracting only the target point as a boundary point; an adjacent boundary point detection means for detecting adjacent boundary points in a predetermined order using an arbitrary boundary point among the plurality of extracted boundary points as a reference point; an iterative control means for repeating the operation of detecting the next adjacent boundary point in a predetermined order using the detected boundary point as a new reference point until the detected boundary point is detected as the reference point or the next boundary point;
and line segment display means for displaying line segments connecting boundary points in the order of detection.

Effect> According to the target area display method of the first invention, when displaying a predetermined area, all points are divided into display target points that belong to the area and points that do not belong to the area. It is determined whether all points adjacent to the display target point belonging to the area belong to the area, and only display target points for which at least one of the adjacent points is determined not to belong to the area are displayed. Since only the outermost display target points of the target area are displayed, the number of display target points that should actually be displayed can be significantly reduced, so the display speed can be increased. Since the display target point is not displayed, the target area can be displayed clearly and easily.

In the target area display method of the second invention, when displaying a predetermined area, all points are divided into display target points that belong to the area and points that do not belong to the area, and display that belongs to the area is performed. Determine whether or not all points adjacent to the target point belong to the area, extract only the display target points for which at least one of the adjacent points is determined not to belong to the area, and display the extracted multiple points. Adjacent display target points are extracted in a predetermined order using any display target point among the target points as a reference point, and the next adjacent display target points are extracted in a predetermined order using the extracted point as a new reference point. The operation is repeated until the reference point is extracted as the next display target point, and the line segments connecting the display target points are displayed in the extraction order, so first extract only the outermost display target point of the target area. In this state, the outline of the target area can be displayed simply by sequentially extracting adjacent display target points using a predetermined display target point as a reference and displaying line segments connecting the display target points in the extraction order. Therefore, it is no longer necessary to specify the order of display target points in advance, simplifying the processing and achieving high speed outline display.

In the target area display device of the third invention, information indicating whether or not each point belongs to a predetermined area is stored in the information holding means, and the information is held in the information holding means. Points belonging to the area are sequentially extracted as display target points by the display target point extracting means based on the information. Then, the information reading means reads information on all points adjacent to the extracted display target point from the information holding means, and the discriminating means selects the corresponding display target point based on the information read from the information holding means. Determine whether all adjacent points belong to the area. If all adjacent points belong to the area, the corresponding display target point is a point inside the area, and if at least one of the adjacent points does not belong to the area, the corresponding display target point is within the area. Since it can be seen that this is the outermost point, only the latter point is displayed by the display means. That is, the number of display target points to be actually displayed can be significantly reduced, so the display speed can be increased, and since the display target points located inside the target area are not displayed, the target area can be displayed clearly and easily. become.

In the target area display device of the fourth invention, information indicating whether or not each point belongs to a predetermined area is stored in the information holding means, and the information is held in the information holding means. Points belonging to the area are sequentially extracted as display target points by the display target point extracting means based on the information. Then, the information reading means reads information on all points adjacent to the extracted display target point from the information holding means, and the discriminating means selects the corresponding display target point based on the information read from the information holding means. Determine whether all adjacent points belong to the area. In this case, if all adjacent points belong to the area, the corresponding display target point is a point inside the area, and if at least one of the adjacent points does not belong to the area, the corresponding display target point Since it is known that the latter point is the outermost point of the area, only the latter point is extracted as a boundary point by the boundary point extracting means. After that, an arbitrary boundary point is set as a reference point from among the extracted boundary points, adjacent boundary points are detected in a predetermined order with respect to the reference point by an adjacent boundary point detection means, and the detection is performed by an iterative control means. Using the detected boundary point as a new reference point, the operation of detecting the next adjacent boundary point in a predetermined order is repeated until the reference point is detected as the next boundary point. Therefore, adjacent boundary points can be sequentially detected using an arbitrary boundary point as a reference point.

Thereafter, the line segment display means displays line segments connecting the boundary points in the order of detection. As is clear from the above description, it is no longer necessary to specify the order of display target points in advance, simplifying the process and achieving high speed outline display.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 1 is a flowchart showing an embodiment of the target area display method of the present invention, in which a point is selected in step (2), and in step (2) it is determined whether the selected point is a display target point, If there is no point to be displayed, the process of step (2) is performed again.

On the other hand, if it is a display target point, in step 2, it is determined whether the points adjacent to the left and right of the corresponding display target point are both display target points, and whether the points adjacent to the left and right of the corresponding display target point are both display target points. If so, in step (2), it is determined whether or not the points adjacent above and below the corresponding display target point are both display target points,
If the vertically adjacent points are both display target points, step ■
In this step, it is determined whether or not the adjacent points before and after the corresponding display target point are both display target points, and if both the front and rear adjacent points are display target points, the process of step (2) is performed again.

Conversely, if at least one point is determined not to be the display target point in any of the steps above,
In step ■, the corresponding display target point is displayed, and in step ■, it is determined whether or not processing for all points has been completed.If it is determined that processing for all points has been completed, the series of processing is continued. finish. On the other hand, if it is determined that there are unprocessed points, the process of step (2) is performed again.

In summary, display target points are extracted from all the points, and for each extracted display target point, it is determined whether or not all of the points adjacent vertically, horizontally, front and back are display target points. If all of these points are display target points, they are not displayed because the corresponding display target points are inside the area, and conversely, if at least one of them is not a display target point, the corresponding display target points are not displayed. The display target point is displayed because it is the outermost point of the area. As a result, it is possible to display the area by displaying only the outermost points, and it is also possible to achieve high-speed display. Furthermore, if the spacing between the above points is set coarser than the pixel spacing on the display screen, points inside the area will not be displayed regardless of whether rotation processing is performed or not. The display can be made clear and easy to read.

Figure 2 is a diagram showing a specific example of applying the target area display method to the display of molecules. When the molecule shown in the figure is selected, the width of the molecule in the x, y, and z axis directions is calculated. The maximum molecule width is extracted, the crit width is calculated based on the maximum molecule width and the preset number of space divisions, and a cubic grid with the calculated grid width as one side is created in advance in each axis direction. By arranging the grids by a set number of divisions, the space in which the molecules can enter is divided into a predetermined number of grids (dashed line 1 in FIG. 2).

Then, one point is assigned to each grid.

In addition, in order to hold information indicating whether each point is a display target point, for example, the space in which the molecules enter is 64x64
When dividing data into 64 grids and processing using a processor with a data width of 32 bits, conventionally 32 bit data was allocated corresponding to all of these grids, or for example, 64 bits in the z-axis direction were allocated. By using two pieces of 32-bit data as data indicating whether the grid is a grid or a display point, and assigning each bit of these 32-bit data to the corresponding grid, the data area can be significantly reduced. . That is, 1 vol
(J, ni, i, im) (where) is the grid position in the X-axis direction, k is the grid position in the X-axis direction, and 1 is any 32
It is sufficient to allocate an array of information indicating bit data (im is the molecule number), and the grid position jz in the z-axis direction of the j-th bit of 32-bit data is expressed as jz = (i-1)X32+j. will be done. I want to, (J, kjz)
If you want to check the status of points on the grid, use 1vol
It is sufficient to check whether the j-th bit of (), i, im) is set to "1".

When carrying out the above method under these conditions, 32
Among the bit data, for example, grids set to "1" are extracted as display target points, and the 32-bit data adjacent to the top, bottom, left and right of the 32-bit data containing the information of the extracted display target points is extracted. Whether "1" is set in the same bit position of the data, and whether "1" is set in the adjacent bits before and after the corresponding bit of the 32-bit data containing the information of the extracted display target point. All you have to do is decide whether or not. Since these discriminations can be easily obtained by performing logical AND operations, the processing load associated with these discriminations does not increase much, and the number of display target points that are actually displayed is significantly reduced. Achieves faster display speed.

FIG. 3 is a flowchart illustrating the target area display operation based on the above specific example. In step ■■■■, +-f and L+J are each initialized to 1, and in step The adjacent bit position is determined as the number jwl of any 32-bit data iν1, and in step 2, the adjacent bit position on the rear side in the z-axis direction is determined as the number jν2 of any 32-bit data iv2. , and in step ■, 1vo
It is determined whether "1" is set in the j-th bit of l (Jk, i, im), and if "1" is set, 1vol (J'-1, i, im
) and 1vol (, l'+1., iim) are both set to "1", and if both are set to "1", in step ■, 1vol([ k+1., i, im) and 1vol
It is determined whether “1” is set in both the j-th bits of (J, k-1iim), and if “1” is set in both bits, 1vol (J
kiwl, im)'s jwlth bit and 1vol(
J.

k, iw2. It is determined whether "1" is set in the j second bit of im), and if "1" is set in both, it is determined whether j=32 in step (2), If j≠32, set j to 1 in step 0.
Increment by 0 and perform the process of step (2) again. Conversely, if j-32, i in step [Yes]
It is determined whether w=2 or not, and if im2, in step (2), l is incremented and the process of step (2) is performed again. On the other hand, if it is 1-2, it is determined whether it is J-64 or not in step ≠6.
If it is 4, J is incremented by 1 in step (2) and the process of step (2) is performed again.

On the other hand, if it is J-64, -64 is set in step ■.
If k≠64, step ■
, increment k across k and step again ■
Process. On the other hand, if it is -64, the series of processing is immediately terminated.

Further, if the determination is NO in any of the steps from step (2) to step [phase], the display target point corresponding to the corresponding grid is displayed in step (2), and the determination in step 0 is performed. In step ① above, N
If it is determined that it is o, the determination in step (2) is immediately performed.

<Embodiment 2> FIG. 4 is a block diagram showing an embodiment of the target area display device of the present invention.
A space dividing section (1) that divides into a preset number of grids in the axial direction, assigns points corresponding to each crit, sets points belonging to the area as display target points, and hides other points. A display target point setting unit (2) that sets each point in the Z-axis direction as a target point and holds each point as the value of each bit of two 32-bit data, and a display target point extraction unit that sequentially extracts only display target points. (3), a left and right adjacent point extraction unit (4) that extracts points adjacent to the left and right of the extracted display target point, and a vertical adjacent point extraction unit that extracts points that are vertically adjacent to the extracted display target point. section (5), and a front and rear adjacent point extraction section (6) that extracts adjacent points before and after the extracted display target point.
a first determining unit (7) that determines whether the extracted left and right adjacent points are display target points; and a first determining unit (7) that determines whether the extracted upper and lower adjacent points are display target points. 2 discriminating unit (8), a third discriminating unit (9) that discriminates whether both the extracted front and rear adjacent points are display target points, and each discriminating unit (7).
) (8) A displayability determination unit (10) that determines whether the corresponding display target point is the outermost point of the area based on the determination result signal from (9), and the outermost point of the area. A display section that displays only the display target points determined to be
11).

The operation of the target area display device having the above configuration is as follows.

First, the space including the area is divided into a preset number of grids in each axis direction by the space dividing section (1), points are assigned to each grid, and the display target point setting section (2)
), points belonging to the area are set as display target points, and other points are set as display non-target points. However, by holding each point in the Z-axis direction as the value of each bit of two 32-bit data, the data area is significantly reduced.

After that, the display target point extraction unit (3) sequentially extracts only the display target points, and the adjacent point extraction unit f4) (5) (6) extracts the points that are adjacent to the left and right, above and below, and before and after the corresponding display target point. is extracted, and the determination units (7), (8), and (9) and the displayability determination unit (10) determine whether the corresponding display target point is the outermost point of the area. Then, only the display target point determined to be the outermost point of the area is displayed on the display unit (11).

Therefore, the number of points actually displayed can be significantly reduced, speeding up the display, and making it easier to see the displayed area.

<Embodiment 3> FIG. 5 is a flowchart showing another embodiment of the target area display method of the present invention, in which the display target points on the outermost side of the area extracted based on the first embodiment are Line segments are sequentially displayed between adjacent display target points on a predetermined plane.

In step (■), an arbitrary display target point is set as a reference point, and in step (2), eight points adjacent to the reference point are extracted in a predetermined order, as shown in FIG. It is determined whether the displayed adjacent point is the displayed point or not.

If it is determined that the adjacent point is not the display target point, the process of step (2) is performed again. On the other hand, if it is determined that the adjacent point is the display target point, it is determined in step 2 whether or not the corresponding adjacent point is the first reference point, and it is determined that it is not the first reference point. If so, the coordinate values of the adjacent point are stored as the next point in step (2), the adjacent point is set as a new reference point in step (2), and the process of step (2) is performed again. On the other hand, if it is determined that the corresponding adjacent point is the first reference point in the above step (■), then in step (■) the adjacent point is read out into the storage unit starting from the first reference point, and the adjacent point is displayed as a starting point. Display lines between points.

As is clear from the above explanation, there is no need to assign a line segment display order in advance based on multiple points; instead, the first display target point detected among adjacent points is stored sequentially. By displaying line segments in can be displayed.

However, in the above flowchart, the adjacent point is 1pos
(a, b) (However, in the case of axl, the X coordinate is a-2
In the case of
However, a is IP.

Line segment display can be easily achieved by storing the coordinates in the order in which the line segments are displayed in the array s (a, b), where b is the order in which the line segments are displayed.

<Embodiment 4> FIG. 7 is a block diagram showing another embodiment of the target area display device of the present invention. a display target point extraction unit (12) that extracts display target points located on a plane (e.g., x-y plane, x-z plane, etc.); and an arbitrary display target point among the extracted display target points. a starting point selection unit (13) that selects 8 adjacent points as a starting point; an adjacent point selection unit (14) that sequentially selects 8 adjacent points using the starting point as a reference point; an adjacent point discriminator (15) that discriminates the point, and a first iterative control section (16) that repeatedly operates the adjacent point selector (14) and the adjacent point discriminator (15) until the adjacent point that is the display target point is selected. ), an end point determination unit (17) that determines whether the adjacent point that is the display target point matches the starting point, and an adjacent point that stores the coordinate values of the adjacent point that does not match the starting point as the next display target point. Point storage section (18)
and a second iterative control unit (19) that supplies the stored adjacent point as a new reference point to the adjacent point selection unit (14), and on the condition that the adjacent point that is the display target point coincides with the starting point. , and a line segment display unit (20) that reads coordinate values of adjacent points from the adjacent point storage unit (18) into the storage unit and displays line segments.

The operation of the target area display device described above is as follows.

The display target point extraction unit (12) selects a predetermined plane (for example, the X-y plane,
Extract the display target point located on the x-z plane, etc.
(see figure), the starting point extraction unit (13) selects an arbitrary display target point from among the extracted display target points. Then, the adjacent point selection unit (14) sequentially selects eight adjacent points using the starting point as a reference point, and the adjacent point determination unit (
15), it is determined whether the selected adjacent point is a display target point or not.

The adjacent point selection section (14) selects an adjacent point and the adjacent point determination section (15) determines whether or not it is a display target point.
The process is repeated by the first iteration control unit (16) until an adjacent point that is a point to be displayed is selected. When an adjacent point that is a display target point is selected, the end point determination unit (17) determines whether or not the selected adjacent point matches the starting point, and determines whether or not the selected adjacent point matches the starting point, and The coordinate values of the point are stored in the adjacent point storage unit (18) as the next display target point, and the second iterative control unit (19) uses the stored adjacent point as a new reference point in the adjacent point selection unit (14). and repeat the above operation again.

Then, on the condition that it finally matches the adjacent point that is the display target point or the starting point, the line segment display unit (20)
The coordinate values of the adjacent points are read out from the adjacent point storage section (18) into the storage section and a line segment is displayed (see the broken line in FIG. 8).

As is clear from the above explanation, when the outermost display target point of the area located on a predetermined plane is extracted,
There is no need to assign a display order to these display target points in advance, and it is sufficient to simply detect adjacent display target points in a predetermined order, which simplifies the process. The display of the area can be achieved by displaying the line segments connecting the .

Therefore, when the three-dimensional area shown in FIG. 9(A) is given, by displaying the outline based on the x-y plane and the x-z plane that change by a predetermined distance, the three-dimensional area shown in FIG. )
Since it is possible to display the area shown in (1) and the points inside the area are not displayed, the area can be clearly displayed in a clear and easy-to-see manner even when rotation processing is performed.

<Effects of the Invention> As described above, in the first invention, by displaying only the outermost display target points of the target area, the number of display target points to be actually displayed can be significantly reduced. This has the unique effect of increasing the speed and displaying the target area clearly and easily because the display target points located inside the target area are not displayed.

In the second invention, first, only the outermost display target point of the target area is extracted, and in this state, adjacent display target points are sequentially extracted using a predetermined display target point as a reference, and the display target points are connected in the extraction order. Since the outline of the target area can be displayed by displaying the line segments connecting the points, there is no need to specify the order of the display target points in advance, which has the unique effect of simplifying processing and achieving faster outline display. .

In the third invention, by displaying only the outermost display target points of the target area, the number of display target points to be actually displayed can be significantly reduced, so the display speed can be increased, and the target area Since the display target points located inside the display target area are not displayed, the target area can be displayed clearly and easily, which is a unique effect.

In the fourth invention, first, only the outermost display target point of the target area is extracted, and in this state, adjacent display target points are sequentially extracted using a predetermined display target point as a reference, and the display target points are connected in the extraction order. Since the outline of the target area can be displayed simply by displaying the line segments connecting the points, there is no need to specify the order of the display target points in advance, which has the unique effect of simplifying processing and achieving faster outline display. .

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an embodiment of the target area display method of the present invention, FIG. 2 is a diagram showing a specific example of applying the target area display method to display of molecules, and FIG. 3 is a specific example of FIG. 2. FIG. 4 is a block diagram showing an embodiment of the target area display device of the present invention; FIG. 5 is a flow chart showing another embodiment of the target area display method of the present invention. , FIG. 6 is a schematic diagram illustrating the order of adjacent point extraction, FIG. 7 is a block diagram showing another embodiment of the target area display device of the present invention, and FIG. 8 is a diagram showing the extraction of the outermost display target point of the area. FIG. 9 is a schematic diagram showing an example of displaying a three-dimensional area with a plurality of outline lines. (2)...Display target point setting unit, (3)...Display target point extraction unit, (4)...Left and right adjacent point extraction unit, (5)...
・Upper and lower adjacent point extraction unit, (6)... Front and rear adjacent point extraction unit,
(7)...first discrimination section, (8)...second discrimination section, (
9)...Third discrimination unit, (10)...Displayability discrimination unit,
(11) Display unit, (12) Display target point extraction unit, (13) Starting point selection unit, adjacent point selection unit, (15) Adjacent point determination unit, (16 )・First iteration control section, (17)...End point determination section, (19)...Second iteration control section, (20)...Line segment display section

Claims (1)

[Claims] 1. When displaying a predetermined area, it is determined whether all points adjacent to the display target point belonging to the area belong to the area, and at least one of the adjacent points is A target area display method characterized by displaying only display target points determined not to belong to the area. 2. When displaying a predetermined area, it is determined whether all points adjacent to the display target point belonging to the area belong to the area, and at least one of the adjacent points does not belong to the area. Extract only the display target points that have been determined as such, use any display target point among the extracted display target points as a reference point, extract adjacent display target points in a predetermined order, and use the extracted points as a new display target point. The operation of extracting the next display target point next to each other in a predetermined order as a reference point is repeated until the reference point is extracted as the next display target point, and the line segments connecting the display target points in the extraction order are displayed. Characteristic target area display method. 3. Information holding means (2) that holds information indicating whether or not each point belongs to a predetermined area in correspondence with each other; Display target point extracting means (3) that sequentially extracts the corresponding points as display target points, and information reading means (4) that reads information on all points adjacent to the extracted display target points from the information holding means (2) (
5) (6) and determining means (7) for determining whether or not all points adjacent to the corresponding display target point belong to the area based on the information read from the information holding means (2). 8)(9)(10)
and display means (11) for displaying only display target points for which it has been determined that at least one of the adjacent points does not belong to the area. 4. Information holding means (2) that holds information indicating whether or not each point belongs to a predetermined area in correspondence with each other; Display target point extracting means (3) that sequentially extracts the corresponding points as display target points, and information reading means (4) that reads information on all points adjacent to the extracted display target points from the information holding means (2) (
5) (6) and determining means (7) for determining whether or not all points adjacent to the corresponding display target point belong to the area based on the information read from the information holding means (2). 8)(9)(10)
a boundary point extracting means (12) for extracting as a boundary point only the display target point for which at least one of the adjacent points is determined not to belong to the area; and an arbitrary boundary point among the plurality of extracted boundary points. Adjacent boundary point detection means (13), (14), (15), and (16) detect adjacent boundary points in a predetermined order using the detected boundary points as a new reference point; Repetitive control means (17) and (19) for repeating the operation of detecting the next matching boundary point until the reference point is detected as the next boundary point, and line segment display means for displaying line segments connecting the boundary points in the order of detection. (20) A target area display device comprising: