JP2011232444A - Coordinate conversion device, coordinate conversion method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable conversion to a more accurate position even with fewer reference points in coordinate conversion (or opposite conversion thereof) from a map to a deformed map.SOLUTION: A coordinate conversion device which is part of a communication terminal obtains coordinates in a coordinate system after coordinate conversion with respect to a target point whose coordinates in a coordinate system before the coordinate conversion are known. Specifically, the coordinate conversion device selects three reference points in a vicinity of the target point (step S31), and determines validity of use of the selected reference points utilizing a predetermined condition (step S32). The coordinate conversion device selects reference points again if the determination is negative (S33). That is, reference points to be selected are not uniquely fixed in accordance with coordinates of the target point.

Description

  The present invention relates to coordinate conversion between a reference map and a deformed map.

  There are maps that are displayed with the scales distorted in order to emphasize characteristic places or make them easy to understand. Such a map has a complicated correspondence with the coordinates of the map described in actual scale. In Patent Document 1, in order to display actual coordinate information acquired by GPS (Global Positioning System) on a deformed map, a reference point is extracted and selected from a measurement map (actual map) and a deformed map, A method for calculating coordinate information on a deformed map by interpolation calculation is described.

JP 2008-191075 A

The technique described in Patent Document 1 is difficult to function effectively unless a large number of reference points are prepared. However, preparing a large number of such reference points in advance is time consuming and not easy.
Therefore, an object of the present invention is to make it possible to perform conversion to a more accurate position even when there are few reference points in coordinate conversion from a map to a deformed map (or vice versa).

  The coordinate conversion device according to one aspect of the present invention includes a coordinate described in a second coordinate system different from a reference first coordinate system, the coordinates of the first coordinate system, and the coordinates of the second coordinate system. A reference point setting unit for setting a plurality of reference points whose correspondence with coordinates is known; and a first coordinate system corresponding to a target point whose coordinates of the second coordinate system on the map are unknown From the coordinate acquisition unit for acquiring coordinates and the plurality of reference points set by the reference point setting unit, the three reference points in which the coordinates of the first coordinate system are close to the coordinates acquired by the coordinate acquisition unit Using the coordinates of the first coordinate system and the second coordinate system of the three reference points selected by the selection unit, and the coordinates of the second coordinate system of the target point A calculation unit that calculates coordinates, and the selection unit includes a combination of three reference points that satisfies a predetermined condition. If not, the calculation unit re-selects another combination of three reference points, and the calculation unit uses the three re-selected reference points when the selection unit re-selects the combination. Have

In a preferred aspect, the selection unit uses the condition that the target point is included in a parallelogram having the three reference points as vertices in the plane represented by the first coordinate system. It has the determination part which determines the necessity of reselection.
In another preferable aspect, the selection unit has parallel four sides having one of the three reference points as the center of gravity and the other two as the midpoints of the sides in the plane represented by the first coordinate system. A determination unit that determines whether or not the reselection is necessary using the condition that the target point is included in the shape;
In another preferable aspect, the selection unit uses, as the condition, that the target point is included in a quadrilateral that includes the three reference points at a vertex or a side in a plane represented by the first coordinate system. A determination unit for determining whether the reselection is necessary.
In another preferred aspect, the selection unit divides the reference point closest to the target point when the plane represented by the first coordinate system is divided into four or more areas around the target point. One by one is extracted from the divided areas, and the combination is selected and reselected from the extracted reference points. In this aspect, when the number of divisions is 4, and the selection unit uses a combination of selecting three reference points from four reference points extracted from the four divided areas as the combination, More preferred.
In another preferable aspect, when the selection unit divides the plane represented by the first coordinate system into three or more areas around the target point, the three reference points are divided. The determination unit determines whether or not the reselection is necessary using the condition that two or more of the areas are not included in any of the areas.

  According to another aspect of the present invention, there is provided a coordinate conversion method in which the coordinates of the first coordinate system and the second coordinate system are displayed on a map described in a second coordinate system different from the reference first coordinate system. A first step of setting a plurality of reference points whose correspondence to the coordinates of the first coordinate system is known; and a first coordinate system corresponding to a target point whose coordinates of the second coordinate system on the map are unknown From the second step of acquiring the coordinates and a plurality of reference points set in the first step, three reference points whose coordinates in the first coordinate system are close to the coordinates acquired in the second step are obtained. The second coordinate system of the target point using the third step to be selected and the coordinates of the first coordinate system and the second coordinate system of the three reference points selected in the third step And a fourth step of calculating the coordinates of When the combination of the three reference points does not satisfy the predetermined condition, the combination of the other three reference points is reselected, and when the combination is reselected in the third step, The four re-selected reference points are used in four steps.

  According to another aspect of the present invention, there is provided a program that stores, on a map described in a second coordinate system different from a reference first coordinate system, the coordinates of the first coordinate system and the second coordinates. A first step of setting a plurality of reference points whose correspondence with the coordinates of the system is known; and the first coordinate system corresponding to a target point whose coordinates of the second coordinate system on the map are unknown The second step of acquiring the coordinates of the three and the three reference points in which the coordinates of the first coordinate system are close to the coordinates acquired in the second step from the plurality of reference points set in the first step And the second coordinates of the target point using the coordinates of the first coordinate system and the second coordinate system of the three reference points selected in the third step. To execute the fourth step of calculating the coordinates of the system In the third step, when the combination of the three reference points does not satisfy the predetermined condition in the third step, the combination of the other three reference points is reselected, and the combination in the third step When reselected, the three reselected reference points are used in the fourth step.

  According to the present invention, in coordinate conversion from a certain map to a deformed map (or vice versa), it is possible to perform conversion to a more accurate position even when there are few reference points.

Block diagram showing the configuration of the map display system Schematic diagram showing the correspondence between real maps and deformed maps Block diagram showing hardware configuration of communication terminal Functional block diagram showing a functional configuration for coordinate transformation performed by the communication terminal Flow chart showing operations related to coordinate conversion of communication terminal Flow chart showing selection processing (part of coordinate transformation) The figure which illustrates the selection method of the reference point which adjoins the object point The figure which illustrates the parallelogram defined based on the reference point illustrated in FIG. Table illustrating how to reselect reference point combinations Diagram illustrating target points and reference points Figure illustrating a figure used for reference point determination

[Embodiment]
FIG. 1 is a block diagram showing a configuration of a map display system according to an embodiment of the present invention. As shown in FIG. 1, the map display system 10 of this embodiment has a configuration in which a communication terminal 100 and a server device 200 are connected by a network N1. The network N1 enables communication between the communication terminal 100 and the server device 200, and includes, for example, the Internet and a wireless communication network. The communication terminal 100 is, for example, a mobile phone or a smartphone. The communication terminal 100 is assumed to be a wireless communication terminal in the present embodiment, but may be one that performs wired communication. The server device 200 provides a data distribution service to the communication terminal 100. The data distributed by the server device 200 includes at least map data representing a deformed map.

  In the present invention, the deformed map is a map in which a position (that is, coordinates) is described by a coordinate system different from the reference coordinate system, and is deformed (or distorted) as compared to a map described in the reference coordinate system. A map that has In other words, a deformed map is a map in which the distance on a deformed map between two points does not necessarily match the distance between the two points on a map described in a reference coordinate system. Here, the reference coordinate system does not have to represent a real space, and may be a virtual space, for example. Typically, deformed maps are hand-drawn maps (including old maps) and schematic maps (route maps, etc.) that emphasize topologies using topology (topology). Applicable.

  The deformed map is often expressed without the concept of “coordinate system” in the first place. Even in such a case, it is necessary to define some coordinate system in order to represent the deformed map with data. The coordinate system of the deformed map is a concept including a coordinate system defined after the fact. For example, if the deformed map is a bitmap image, an orthogonal coordinate system in which the horizontal direction of the image is the X axis and the vertical direction of the image is the Y axis can be defined.

  In this embodiment, a coordinate system in which coordinates are described by the latitude and longitude of the earth is used as the reference coordinate system. That is, in this embodiment, the map described in the reference coordinate system represents a certain area that exists on the earth. Such a map is hereinafter referred to as a “real map”. The real map does not need to represent the entire earth, and may represent a specific country or region or a specific facility (such as an entertainment facility).

  The real map of this embodiment is assumed to be a rectangular map representing a specific area. In addition, it is assumed that the deformed map of the present embodiment is a schematic diagram corresponding to a specific area of the real map. The coordinate system of the deformed map is assumed to be the orthogonal coordinate system described above. Hereinafter, for convenience of explanation, the coordinates on the actual map are also referred to as “latitude and longitude coordinates”, and the coordinates on the deformed map are also referred to as “XY coordinates”.

  The map data includes reference point information and content information regarding the deformed map. The reference point information is information representing a point on the deformed map (hereinafter referred to as “reference point”) whose correspondence between the XY coordinates and the longitude and latitude coordinates is known. The deformed map has a plurality of reference points. The reference point preferably includes at least the coordinates of the four corners of the real map which are rectangular. The greater the number of reference points, the higher the possibility that the coordinates of the target point described later can be calculated more accurately. The content information is information representing content displayed on the deformed map. The content here includes at least an icon image (symbol, pictograph, image imitating a building, etc.) displayed on the deformed map. Further, the content may include other information as necessary. For example, if the icon image can be selected (clicked) by the user, the content may include detailed information (characters, images, hyperlinks to a website, etc.) displayed after the selection. It should be noted that the reference point information and the content information are not limited to being preliminarily included in the map data, but can be associated with the deformed map by an aspect that is subsequently added to the map data.

FIG. 2 is a schematic diagram showing the correspondence between a real map and a deformed map. As shown in FIG. 2, the real map M1 and the deformed map M2 are associated by reference points P1 to P6. The reference point P1 has known XY coordinates (x1, y1) and corresponding longitude and latitude coordinates (lng1, lat1). Similarly, the XY coordinates and the longitude and latitude coordinates are also associated with the reference points P2 to P6. It can be said that the deformed map is more likely to cause an error in the calculation of a target point, which will be described later, as the distortion from the actual map is larger. Therefore, in the deformed map, if there is a portion with a large distortion from the actual map, it is desirable that more reference points are gathered in that portion.
Note that the number of reference points illustrated is merely an example, and there may actually be more reference points.

  FIG. 3 is a block diagram illustrating a hardware configuration of the communication terminal 100. As illustrated in FIG. 3, the communication terminal 100 includes a control unit 110, a storage unit 120, a communication unit 130, a display unit 140, an operation unit 150, and a positioning unit 160. The control unit 110 includes an arithmetic processing unit such as a CPU (Central Processing Unit) and a storage unit (main memory) corresponding to a main storage device, and controls the operation of each unit of the communication terminal 100 by executing a program.

  The storage unit 120 includes storage means corresponding to an auxiliary storage device such as a flash memory, and stores data used by the control unit 110 for processing. When the map data is transmitted from the server device 200, the storage unit 120 stores the map data. Note that the storage unit 120 may include a removable disk (detachable storage means) and store map data therein. In this case, the communication terminal 100 does not necessarily obtain map data via the server device 200. The storage unit 120 may store a plurality of map data. In this case, a part of the deformed map represented by each map data may overlap. For example, the map data may include a deformed map for a certain large division (region, state, etc.) and a deformed map for a smaller regional division (prefecture, city, etc.).

  The communication unit 130 is an interface for transmitting and receiving data to and from the server device 200 via the network N1. The display unit 140 includes a liquid crystal display and its driving means, and displays an image such as a deformed map. The operation unit 150 includes input means such as a keypad and accepts user operations. The operation unit 150 supplies operation information representing a user operation to the control unit 110. Note that the operation unit 150 may be a mouse or a touch screen provided on a liquid crystal display.

  The positioning unit 160 is means for supplying position information to the control unit 110. Here, the position information refers to information representing the position of the own device (or a position that can be identified with this). The position information is information represented by longitude and latitude coordinates in the present embodiment. The positioning unit 160 receives position information or information having a correspondence relationship with position information from the outside. The method for receiving the position information is, for example, GPS. Further, the information having a correspondence relationship with the position information is, for example, a lot number or an address. When receiving the information, the positioning unit 160 can calculate and obtain the position information by storing the correspondence between the information and the position information.

  The configuration of the communication terminal 100 is as described above. Under this configuration, the communication terminal 100 receives a user operation and performs control so that a point whose XY coordinates are unknown is displayed on the deformed map. Hereinafter, this point is referred to as “target point”. That is, the target point is a point to be displayed. The target point is, for example, the position of the communication terminal 100, that is, the position where the user is at that time, but is not necessarily limited thereto.

  Since the XY coordinates are unknown, the target point cannot be displayed on the deformed map as it is. Therefore, the communication terminal 100 acquires the longitude and latitude coordinates corresponding to the XY coordinates of the target point, and further uses the coordinates and XY of the reference point close to the target point to calculate the XY coordinates of the target point. Perform conversion.

  FIG. 4 is a functional block diagram illustrating a functional configuration related to coordinate transformation performed by the communication terminal 100. The control unit 110 of the communication terminal 100 implements functions corresponding to the reference point setting unit 111, the coordinate acquisition unit 112, the selection unit 113, and the calculation unit 115 illustrated in FIG. 4 by executing a program. The control part 110 functions as a coordinate transformation device according to the present invention by realizing these functions.

  The reference point setting unit 111 sets a plurality of reference points on the deformed map. The reference point setting unit 111 acquires the map data received by the communication unit 130 or stored in the storage unit 120, and sets the reference point based on the reference point information included in the map data. The reference point setting unit 111 can also set a reference point by a user operation.

  The coordinate acquisition unit 112 acquires longitude and latitude coordinates corresponding to the target point. The coordinate acquisition unit 112 acquires longitude and latitude coordinates based on the position information supplied by the positioning unit 160, for example. In addition, the coordinate acquisition unit 112 can request the user to input longitude and latitude coordinates, and can acquire longitude and latitude coordinates based on operation information supplied from the operation unit 150 in response to the request.

  The selection unit 113 selects three reference points from the plurality of reference points set by the reference point setting unit 111. The reference point selected by the selection unit 113 is a longitude / latitude coordinate acquired by the coordinate acquisition unit 112, that is, a point close to the target point. Here, “close to” the target point means being near the target point. However, the selection unit 113 does not necessarily select the three reference points in the order closer to the target point.

  In more detail, the selection unit 113 has a function corresponding to the determination unit 114. The determination unit 114 determines whether the combination of the three reference points selected by the selection unit 113 may be used for coordinate conversion. The determination by the determination unit 114 is performed using a predetermined condition determined in advance. When the determination unit 114 determines that the use for the coordinate conversion is not appropriate, the selection unit 113 cancels the selection made immediately before and selects the other three reference point combinations again. In the following, of the selections performed by the selection unit 113, the second and subsequent selections are also referred to as “reselection”. It can be said that the determination unit 114 determines whether or not reselection is necessary by determining whether or not the three selected reference points can be used.

  Note that the selection unit 113 may re-select the same reference point that has been selected so far as long as the combination is not the same as the previously selected combination. That is, the reselection by the selection unit 113 allows the reference points included in the canceled combination to overlap unless they are the same as the combination.

  The calculation unit 115 calculates the XY coordinates of the target point using the three reference points selected by the selection unit 113. When the selection by the selection unit 113 is canceled, that is, when the combination is reselected by the selection unit 113, the calculation unit 115 uses the combination of the three reselected reference points as a target point. XY coordinates are calculated.

  FIG. 5 is a flowchart showing operations related to coordinate transformation of the communication terminal 100. First, the control unit 110 of the communication terminal 100 sets a plurality of reference points (step S1). At this time, the control unit 110 may read the map data and recognize the reference point from the reference point information, or may accept a user operation and set a new reference point that does not exist in the map data. For example, the control unit 110 displays a deformed map on the display unit 140, prompts the user to select an arbitrary position on the deformed map, and inputs the longitude and latitude coordinates of the position. Can be set. In this case, the longitude and latitude coordinates may be obtained from the position information. For example, when the user is at a characteristic place on the deformed map, the user selects the position by an operation such as clicking, and the communication terminal 100 operates to acquire the position information according to the operation. The reference point can be newly set (added).

  Next, the control unit 110 acquires the longitude and latitude coordinates of the target point (step S2). For example, if the position at which the user is present is the target point, the control unit 110 causes the positioning unit 160 to acquire position information and uses the acquired position information as longitude and latitude coordinates. Such a method for acquiring longitude and latitude coordinates is suitable for the case where the user knows where on the deformed map the position at which the user is currently located corresponds. Further, if the target point is not limited to the position of the user, the control unit 110 may acquire the longitude and latitude coordinates by causing the user to input the longitude and latitude coordinates without using the positioning unit 160. Such a method of acquiring longitude and latitude coordinates is suitable for knowing where on the deformed map the position of a specific facility or the like whose longitude and latitude coordinates are known in advance corresponds.

  In addition, the control part 110 may reverse the execution order of the process of step S1 and the process of step S2. For example, if the target point is a position other than the position where the user is located and the longitude and latitude coordinates of the target point are known in advance, the target point may be determined before the reference point. . That is, either the reference point or the target point may be determined first.

  The difference between the reference point and the target point is whether or not the XY coordinates are known. While both the longitude and latitude coordinates and the XY coordinates are known and the position where the correspondence between both is known is the reference point, the target point is the position where only the longitude and latitude coordinates are known and the XY coordinates are unknown. When the XY coordinates corresponding to the longitude and latitude coordinates of the target point are known, such as when the target point coincides with a known reference point, the control unit 110 performs the processes of steps S3 and S4. Can be omitted.

  When the target point and the plurality of reference points are determined in this way, the control unit 110 selects a combination of three reference points from the plurality of reference points (step S3). The process of step S3 is hereinafter referred to as “selection process”. Specifically, the selection process is a process of selecting appropriate three reference points, determining the validity of the selected reference point using a predetermined condition, and performing reselection if the determination result is negative It is.

  FIG. 6 is a flowchart showing the selection process. In this selection process, the control unit 110 first selects three reference points close to the target point (step S31). Note that “selection” in the process of step S31 is a provisional selection, and does not necessarily mean that it is used for calculation of coordinates. Further, “proximity” here means close to the target point, but does not mean closest to the target point. Specifically, the reference point close to the target point is determined as follows.

  FIG. 7 is a diagram illustrating a method of selecting a reference point close to the target point. First, as shown in FIG. 7A, the control unit 110 defines four areas that are equally divided around a target point with respect to a plane (that is, a real map) represented by a reference coordinate system. In this example, the actual map is equally divided into the east, west, north, and south directions (that is, the direction along the latitude and the direction along the longitude), but the dividing direction itself is arbitrary. Next, the control unit 110 extracts the reference points closest to the target point one by one from these four areas as shown in FIG. That is, the reference points extracted at this time are one for each area, for a total of four. Therefore, if the distance between the reference point closest to the target point in a certain area and the target point is shorter than the distance between the reference point closest to the target point in another area and the target point However, the former reference point is not extracted.

After that, the control unit 110 excludes one farthest from the target point from the extracted four reference points, and adopts the remaining three reference points as shown in FIG. 7C. In the example shown in FIG. 7, the reference point P _a, is P _b and P _c is adopted, the reference point P _d is excluded. In this example, the reference point P _a, P _b and P _c is the reference point P _a is closest to the target point, the reference point P _c is farthest from the target point, the reference point P _b is assumed to be those of the intermediate .

  When three reference points are selected in this way, the control unit 110 determines the appropriateness of use of the three reference points (step S32). The control unit 110 performs this determination using a predetermined condition. Here, the predetermined condition uses the relationship between the figure and the position of the target point determined based on the position of the selected reference point. The determination of the present embodiment is performed based on whether or not the target point is included in the parallelogram whose shape is determined based on the selected reference point.

FIG. 8 is a diagram illustrating a parallelogram defined based on the reference points illustrated in FIG. Parallelogram used to determine the present embodiment, (see FIG. 8 (a)) in the case where the reference point P _a, a P _b and P _c defines the first parallelogram vertex, the first This is a figure obtained by enlarging a parallelogram so that it is four times as large as a certain vertex. In addition, the vertex which becomes the center of this expansion is also called "center point" below. In the example shown in FIG. 8 (a), the reference point P _a is the center point.

The parallelogram used in the determination of the present embodiment is a parallelogram having apexes at points P ₁ , P ₂ , P ₃ and P _{4 shown} in FIG. The parallelogram used in the determination of this embodiment can include the center point as the center of gravity of the figure and the reference point at the midpoint (or vertex) of the side. The first parallelogram described above, the reference point P _a, P _b, the P _c and the point P ₃ is a parallelogram having vertices.

The control unit 110 determines whether or not the target point is included in (inside) the predetermined parallelogram (parallelogram P ₁ P ₂ P ₃ P _{4 in} FIG. 8) in the coordinate system of the real map. If the target point is included in this, the reference points P _a , P _b and P _c in this case are adopted to be used for calculating the coordinates (step S34), and the selection process is completed. On the other hand, if the target point is not included in the predetermined parallelogram, the control unit 110 reselects the reference point (step S33). For reselecting the reference points (and combinations thereof), the four reference points extracted in the process of step S31 can be used.

FIG. 9 is a table illustrating a method for reselecting a combination of reference points. FIG. 9 is a diagram for explaining a reselection method using the reference points illustrated in FIG. The control unit 110 performs the selection and determination according to the order shown in FIG. 9 and repeats the operation of performing the next selection and determination if the determination is negative (unsuitable for use). That is, in this reselection method, selection by a combination of selecting three from four reference points is repeated while changing the center point. Therefore, since the reference point selection method in this case is a combination of selecting three reference points from three reference points other than the center point ( ₃ C ₂ = 3) for the four center points, There are 12 (= 3 × 4) ways in total. The center point is preferably selected in order from a reference point closer to the target point.

  The control unit 110 notifies the user that the coordinate conversion is impossible when the appropriate combination is not obtained even after repeating the reselection illustrated in FIG. 9, or “proximity” in the process of step S31 is performed. ”And expand (relieve) the range to reselect the reference point. Specifically, the control unit 110 extracts, from each of the four equally divided areas, one reference point that is not the closest to the target point, but the second closest to the target point, and three reference points from here. Can be selected.

  When appropriate three reference points are selected, the control unit 110 calculates the XY coordinates of the target point using the coordinates of these reference points (step S4). For the calculation of the coordinates, a known method may be used. For example, it is as follows. Here, the target point is P, and the three reference points are A, B, and C. In addition, the latitude, longitude, x coordinate, and y coordinate of the point P are set to latP, lngP, xP, and yP, respectively (the same applies to other points). FIG. 10 is a diagram illustrating the target point P and the reference points A, B, and C.

Now, the relationship shown in the following equations (1) and (2) is established between the longitude and latitude coordinates of the target point P and the reference points A, B, and C. Here, m and n are appropriate coefficients.
lngP-lngA = n (lngB-lngA) + m (lngC-lngA) (1)
latP-latA = n (latB-latA) + m (latC-latA) ... (2)

  Here, values other than m and n are known. Therefore, it is possible to specify the values of m and n by solving the simultaneous equations (1) and (2) described above. The values of m and n are both 1 or less as long as the target point P is included in the parallelogram. If the values of m and n are both 1, the target point P coincides with the vertex of the parallelogram. That is, at this time, when considering the parallelogram ADPE which is a similar shape of the parallelogram defined by the reference points A, B and C, AC: AE = 1: m and AB: AD = 1: n. It is.

If the values of m and n can be specified, the relationship shown in the following formulas (3) and (4) is established in the same manner as the formulas (1) and (2) described above for the XY coordinates.
xP = {n (xB-xA) + m (xC-xA)} + xA (3)
yP = {n (yB-yA) + m (yC-yA)} + yA (4)
The right sides of the expressions (3) and (4) are both configured with known values. Therefore, xP and yP, that is, the XY coordinates of the target point can be specified by solving equations (3) and (4).

  The communication terminal 100 can determine the suitability of the selected reference point by performing coordinate conversion as described above, and can reselect the reference point as necessary. In this way, the communication terminal 100 can perform coordinate conversion using a more appropriate reference point, that is, a reference point that is less likely to cause an error. When the absolute number of reference points is small, if the reference point is not properly selected, there is a high possibility that the error will increase. Therefore, determining whether or not the reference point is appropriate as in the present embodiment can contribute to reducing errors in coordinate conversion.

  When the reference point is selected so that the target point is included in the parallelogram as in the present embodiment, there is a higher possibility that the error is smaller than when the reference point is not. This is because if the target point is included in the parallelogram, the error that can occur in the target point is likely to be less than or equal to the error that occurs in the reference point (however, deformation of the deformed map is significant). This does not apply to cases).

  The communication terminal 100 can also perform coordinate conversion from the coordinate system of the deformed map to the coordinate system of the real map, that is, reverse conversion of the coordinate conversion, in the same manner as described above. That is, in this embodiment, both the coordinate system of the deformed map and the coordinate system of the actual map can be the reference coordinate system. In other words, it can be said that the reference coordinate system in the present embodiment is a coordinate system in which the coordinates of the target point are known. In short, the “first coordinate system” according to the present invention corresponds to either the coordinate system of the deformed map or the coordinate system of the real map, and the “second coordinate system” according to the present invention is the deformed map. This means that the map coordinate system and the actual map coordinate system that are not the first coordinate system fall under this category.

[Modification]
The above-described embodiment is merely an example of the implementation of the present invention. The present invention can also be implemented in a mode in which the following modifications are applied to the above-described embodiments. In addition, the modification shown below may be implemented combining each suitably as needed.

(Modification 1)
The reference point determination method in the present invention may be used on condition that the target point is included in the first parallelogram described above. In this case, compared to the determination method of the above-described embodiment, the size of the parallelogram is ¼, so that it is possible to increase the possibility of reducing errors in coordinate conversion. On the other hand, since the size of the parallelogram is reduced, it can be said that the possibility of increasing the number of reselections increases. Therefore, the condition (size of the figure) used for the determination may be determined appropriately in consideration of a trade-off that occurs between the accuracy of coordinate conversion and the simplicity of processing.

In the present invention, the figure used for determining the reference point is not necessarily a parallelogram. The figure used for the determination of the reference point may be, for example, a triangle having three reference points as vertices or a symmetrical shape thereof, or a rectangle other than a parallelogram.
FIG. 11 is a diagram illustrating a figure used for determining the reference point. FIG. 11A shows a triangle having three reference points as vertices, and FIG. 11B shows a symmetrical shape of the triangle shown in FIG. 11A, which is symmetrical with respect to one side of the triangle ( This is an example showing a line-symmetric quadrilateral. FIG. 11C shows an example of a rectangle including three reference points at sides or vertices.

(Modification 2)
In the present invention, the number of plane divisions in the selection process is not limited to “4”. In the present invention, the purpose of dividing the plane represented by the reference coordinate system is to prevent the reference points from being concentrated in a specific direction when viewed from the target point, in order to appropriately distribute the reference points. is there. Therefore, as long as such a purpose can be achieved, the plane dividing method may divide the plane into three areas, or may divide the plane into five or more areas. It is not necessary to limit to equal division.

  For example, when a plane represented by the reference coordinate system is equally divided into three areas, the selection process extracts one reference point from each area. In this case, the combination of the reference points cannot be changed, but the above-described center point can be changed. Therefore, even in this case, reselection can be performed. In addition, when the plane represented by the reference coordinate system is divided into five or more areas, the selection process extracts one reference point from each area, and three reference points from the extracted plurality of reference points. A point may be selected.

  Further, in the present invention, it may be used as a determination condition that the reference points are appropriately dispersed. In other words, the selection process of the present invention does not determine the area to be divided in advance, but selects three reference points close to the target point and then selects any of the areas into which each reference point is divided. When two or more are not included (that is, 1 to 0), it may be determined that the use of these reference points is appropriate.

(Modification 3)
In the present invention, a real map or a deformed map may be shared by a plurality of users, and each user may add a reference point or content information. This makes it easier to increase the reference points of the deformed map.
Moreover, although embodiment mentioned above applies this invention to a two-dimensional map, this invention is applicable also to a three-dimensional solid map.

  The present invention is grasped not only as a communication terminal and a map display system including the communication terminal, but also as a method for realizing them and a program for causing a computer to realize the functions shown in FIG. Such a program may be provided in the form of a recording medium such as an optical disk storing the program, or may be provided in the form of being downloaded to a computer via a network such as the Internet, and installed and made available. Is something that can be done.

DESCRIPTION OF SYMBOLS 10 ... Map display system, 100 ... Communication terminal, 110 ... Control part, 111 ... Reference point setting part, 112 ... Coordinate acquisition part, 113 ... Selection part, 114 ... Determination part, 115 ... Calculation part, 120 ... Storage part, 130 ... Communication unit 140 ... Display unit 150 ... Operation unit 160 ... Positioning unit 200 ... Server device

Claims (9)

A plurality of criteria whose correspondences between the coordinates of the first coordinate system and the coordinates of the second coordinate system are known on a map described in a second coordinate system different from the first coordinate system of the reference A reference point setting unit for setting points;
A coordinate acquisition unit that acquires coordinates of the first coordinate system corresponding to a target point whose coordinates of the second coordinate system on the map are unknown;
A selection unit that selects, from a plurality of reference points set by the reference point setting unit, three reference points whose coordinates in the first coordinate system are close to the coordinates acquired by the coordinate acquisition unit;
A calculation unit for calculating coordinates of the second coordinate system of the target point using the coordinates of the first coordinate system and the second coordinate system of the three reference points selected by the selection unit; With
The selection unit re-selects the other three reference point combinations when the combination of the three reference points does not satisfy the predetermined condition,
The calculation unit uses the three reselected reference points when the combination is reselected by the selection unit. The selection unit includes:
Judgment for determining whether the reselection is necessary using the condition that the target point is included in a parallelogram having the three reference points as vertices in the plane represented by the first coordinate system. The coordinate conversion device according to claim 1, further comprising a unit. The selection unit includes:
In the plane represented by the first coordinate system, the target point is included in a parallelogram having one of the three reference points as a center of gravity and the other two as midpoints of the sides. The coordinate conversion apparatus according to claim 1, further comprising a determination unit that determines whether or not the reselection is necessary using a condition. The selection unit includes:
Judgment for determining whether or not the reselection is necessary using the condition that the target point is included in a quadrangle including the three reference points at the apex or the side in the plane represented by the first coordinate system. The coordinate conversion device according to claim 1, further comprising a unit. The selection unit includes:
When the plane represented by the first coordinate system is divided into four or more areas around the target point, the reference points closest to the target point are extracted one by one from the divided area, The coordinate transformation device according to any one of claims 1 to 3, wherein the combination is selected and reselected from the extracted reference points. The number of the divisions is 4,
The selection unit includes:
The coordinate transformation device according to claim 5, wherein a combination of selecting three reference points from four reference points extracted from the four divided areas is used as the combination. The selection unit includes:
When the plane represented by the first coordinate system is divided into three or more areas around the target point, two or more of the three reference points are included in any of the divided areas. The coordinate conversion apparatus according to claim 1, further comprising: a determination unit that determines whether or not the reselection is necessary using the absence as the condition. A plurality of criteria whose correspondences between the coordinates of the first coordinate system and the coordinates of the second coordinate system are known on a map described in a second coordinate system different from the first coordinate system of the reference A first step of setting points;
A second step of obtaining coordinates of the first coordinate system corresponding to a target point whose coordinates of the second coordinate system on the map are unknown;
A third step of selecting, from a plurality of reference points set in the first step, three reference points whose coordinates of the first coordinate system are close to the coordinates acquired in the second step;
4th which calculates the coordinate of the said 2nd coordinate system of the said object point using the coordinate of the said 1st coordinate system of the three reference points selected in the said 3rd step, and the said 2nd coordinate system. Perform steps and
In the third step, when the combination of the three reference points does not satisfy the predetermined condition, the other three reference point combinations are reselected,
When the combination is reselected in the third step, the three reference points reselected in the fourth step are used. On the computer,
A plurality of criteria whose correspondences between the coordinates of the first coordinate system and the coordinates of the second coordinate system are known on a map described in a second coordinate system different from the first coordinate system of the reference A first step of setting points;
A second step of obtaining coordinates of the first coordinate system corresponding to a target point whose coordinates of the second coordinate system on the map are unknown;
A third step of selecting, from a plurality of reference points set in the first step, three reference points whose coordinates of the first coordinate system are close to the coordinates acquired in the second step;
4th which calculates the coordinate of the said 2nd coordinate system of the said object point using the coordinate of the said 1st coordinate system of the three reference points selected in the said 3rd step, and the said 2nd coordinate system. A program for executing steps,
In the third step, when the combination of the three reference points does not satisfy the predetermined condition, the other three reference point combinations are reselected,
When the combination is reselected in the third step, the three reselected reference points are used in the fourth step.

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