JP2007328050A - Map display device and map display method - Google Patents

Abstract

A map display device capable of reducing the possibility of misrecognition of a reachable range is provided.
A map display device 1 displays a range reachable within a predetermined time on a map with a predetermined position as a base point, and a control unit 70 of the map display device 1 A search means (route search section 71) for searching for required times to a plurality of points on the map, and a search by the search means in each area obtained by dividing the map into a plurality of parts by dividing the direction around the base point If there is a non-reference nearest point β that is the closest point to the base point among points where the required time exceeds the predetermined time, a linear distance between the non-reference nearest point β and the base point Representative point extraction means (representative point extraction unit 72) that extracts points that do not exceed Dβ as representative points, and display means (isochronous line drawing) that superimposes and displays isochron lines connecting the representative points on the map. Part 73).
[Selection] Figure 1

Description

  The present invention relates to a map display device and a map display method, and more particularly to a technique for displaying on a map a range that can be reached from a base point within a predetermined time from a base point.

  In recent years, as an application of taxi dispatch and car navigation, a map display device has been developed that displays a range that can be reached within a predetermined time from a predetermined position on a map, based on a predetermined position (for example, , See Patent Document 1).

  The conventional map display device searches for an intersection that can be reached within a certain time from the current position, and the car can reach within a predetermined time from the departure point for each area that is divided in all directions around the current position of the car For the direction in which it is determined that there is an intersection, the intersection that is farthest from the current position is extracted as a display node, and an isochron that connects the display nodes is superimposed on the map. The reachable range is displayed.

As a result, in a dispatch / command system in a taxi, a security company, etc., it is possible to appropriately display and manage the moving body and optimally dispatch / command.
JP-A-11-16094

  However, in the conventional map display device, an isochron is obtained by connecting the farthest points α in the reference time in order.

  For this reason, a lot of out-of-reference points representing all intersections that can be reached over a certain time within a predetermined range are included in the isochronous line, and there is a high possibility that the reachable range will be misidentified. There is a first problem.

  FIG. 20 is a schematic diagram illustrating a state in which an outside reference time point is included in an isochronous line.

  In FIG. 20, the inside of the isochron 100 represents the reachable range within 10 minutes, for example. In the terrain including a river as shown in FIG. 20, a situation occurs in which an outside point of reference time is included in the isochron. For this reason, the user who sees this display mistakes that it can reach the reference time point beyond the river.

  In addition, although the conventional map display device can display a reachable range in a certain time, the search method is merely determined based on the current speed of the mobile object, and the mobile object is in the middle The traffic jam information in the time zone that will pass the point when passing through is not considered. For this reason, even if it is not such special terrain, when the local traffic congestion has occurred, it often occurs that the reference time outside point is included in the isochron. In other words, even if it is not special terrain, if there is a traffic jam on the way, it is completely unknown whether the point indicated by the isochron can be reached within a certain time, and the reliability of the reachable range is lacking. There is a problem.

  Accordingly, a first object of the present invention is to provide a map display device and a map display method capable of solving the first problem and reducing the possibility of misrecognition of the reachable range. .

  A second object of the present invention is to provide a map display device and a map display method capable of solving the second problem and improving the reliability of the reachable range.

  In order to achieve the above object, the map display device according to the present invention is a map display device that displays a range reachable within a predetermined time on a map with a predetermined position as a base point. The search means for searching for the required time to a plurality of points on the map, and the time required for searching by the search means in each region obtained by dividing the map into a plurality of parts by dividing the direction around the base point, A point that does not exceed a straight line distance Dβ between the reference non-standard time closest point β and the base point when the non-standard time closest point β that is the closest point to the base point exists among the points that exceed the predetermined time. And representative point extracting means for extracting as representative points, and display means for displaying an isochron line connecting the representative points in a superimposed manner on the map.

  As a result, when the road is intricate and the straight line distance between the departure point and the farthest point in the reference time α is represented by Dα, and the straight line distance between the departure point and the nearest reference point non-standard time β is represented by Dβ in a certain direction, Dγ In the case of <Dβ, the farthest point α within the reference time is conventionally set as the representative point, and the reference time outside point is included in the isochronous line. Since the point that does not exceed the linear distance Dβ between the reference point and the base point is set as the representative point, it is possible to generally exclude the reference point outside the isochronous line. Therefore, it is possible to perform isochronous drawing with higher reliability, and it is possible to reduce the possibility of misrecognition of the reachable range.

  Specifically, in the map display device according to the present invention, the representative point extraction means does not exceed the predetermined time as a point that does not exceed a linear distance Dβ between the base point and the reference non-reference nearest point β. Among the points, the optimal distance γ within the reference time, which is the point where the distance from the base point is the farthest from the base point and the distance from the base point does not exceed the straight line distance Dβ between the base point and the nearest reference point non-reference time β It can be characterized by extracting as points.

  As a result, the road is complicated, and in a certain direction, the straight line distance between the departure point and the farthest point α within the reference time is Dα, the straight line distance between the departure point and the nearest reference point β is Dβ, and the departure point and the reference time When the linear distance from the inner optimal point γ is expressed by Dγ, the reference non-reference nearest point β and the reference inner optimal point γ are obtained for each direction even if Dγ <Dβ <Dα. Since the optimum point γ within the reference time close to the departure point is set as the representative point, the point outside the reference time can be more reliably excluded from the inside of the isochron.

  Further, in the map display device according to the present invention, the search means sets a new representative point by applying a repulsive force in a direction opposite to the base point with respect to the reference point optimum point γ extracted as the representative point. It is also possible to adjust the position as follows.

  Thereby, the shape of the isochron can be approximated to a circle, and the reachable range can be expanded in a range that does not cause misidentification.

  More specifically, in the map display device according to the present invention, the representative point extracting means is the farthest point in the reference time that is the farthest point from the base point among the points that can be reached within the predetermined time. A representative point corresponding to the presence state of α and the non-reference-time closest point β may be extracted.

  This also makes it possible to extract representative points according to the existence status of the farthest point α within the reference time and the nearest point β outside the reference time, expanding the reachable range, and from the inside of the isochronous line to the reference time Outer points can be largely eliminated. Therefore, it is possible to draw an isochronous line with higher reliability, and it is possible to reduce the possibility of misrecognition of the reachable range.

  Further, in the map display device according to the present invention, the representative point extracting means includes both the reference non-reference nearest point β and the reference reference farthest point α for each region obtained by dividing the map into a plurality of regions. In addition, when the straight line distance Dβ between the base point and the nearest reference point non-reference time β is greater than or equal to the straight line distance Dα between the base point and the reference point innermost point α, the reference point innermost point α Is extracted as a representative point, and both the non-reference-time nearest point β and the reference-time farthest point α exist, and the linear distance Dβ is less than the linear distance Dα, the predetermined time Among the points that do not exceed the base point, a straight line distance to the base point does not exceed the straight line distance Dβ, and an optimum point γ within the reference time that is the farthest distance from the base point is extracted as a representative point, and the reference time When the outer nearest point β does not exist and the farthest point α within the reference time exists, the reference When the farthest point α within the time is extracted as a representative point, and the nearest point β outside the reference time exists, and when the farthest point α within the reference time does not exist, the nearest point β outside the reference time is used as the representative point. It can also be characterized by extracting.

  In the map display device according to the present invention, when the search means extracts the non-reference nearest point β as a representative point, the search means applies an attractive force toward the base point with respect to the non-reference nearest point β. When the position is adjusted as a new representative point, and the reference point optimal point γ is extracted as a representative point, a point where a repulsive force is exerted on the reference point optimal point γ in the direction opposite to the base point is obtained. The position may be adjusted as a new representative point.

  Thereby, the shape of an isochron can be brought close to a circle, and visibility can be improved.

  In order to achieve the second object, in the map display device according to the present invention, the plurality of points include nodes that are intersections, and the search means has searched for the required time. Map information related to the map indicating the total cost cost value acquisition means for acquiring the total time cost value until reaching a searched node, and the link cost of a link that is a road to a connection destination node connected to the searched node Link cost acquisition means to acquire, current time acquisition means to acquire the current time, first addition means for adding the total time cost value to the current time, and time added by the first addition means Predicted traffic jam information acquisition means for acquiring predicted traffic jam information from the searched node to the connection destination node, and the link cost acquired by the link cost acquisition means for the prediction Link transit time calculating means for calculating link transit time taking into account delay information, and the search means sequentially adds a result of adding the link transit time to the total time cost as a total time cost value to the connection destination node. It can be characterized by searching.

  As a result, the possibility of reaching an isochron within a predetermined time is increased, and the reliability of the reachable range can be improved.

  The present invention can be realized not only as such a map display device, but also as a map display method using steps characteristic of the map display device as a step. It can also be realized as a program to be executed. Needless to say, such a program can be distributed via a recording medium such as a CD-ROM or a transmission medium such as the Internet.

  As is clear from the above description, the map display device according to the present invention can reduce the possibility of misrecognition of the reachable range. In addition, the reliability of the reachable range can be improved.

  Therefore, according to the present invention, the reliability of the map display device is improved, and the practical value of the present invention at present when navigation devices such as cars are widespread is extremely high.

  Hereinafter, a map display device according to an embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing the overall configuration of the map display device according to the first embodiment. Here, an example in which the moving body is an automobile and the map display device is applied to a navigation apparatus installed in the automobile will be described.

  As shown in FIG. 1, the map display device 1 according to the present embodiment includes a map information storage unit 10, a positioning unit 20, an input unit 30, an output unit 50, a traffic information receiving unit 40, a working area. Unit 60 and control unit 70. The output unit 50 includes a display device 51 as a part of its constituent elements. In addition, the control unit 70 includes a route search unit 71, a representative point extraction unit 72, and an isochronous drawing unit 73 as some of the components. In each drawing, components not related to the present invention are omitted.

  The map information storage unit 10 is, for example, an HDD or a DVD in which map information such as data on intersections (nodes) and roads (links) connecting the intersections is stored. However, the present invention is not limited to this, and a configuration in which information stored in the map information storage unit 10 is downloaded from the center facility (not shown) by a communication unit (not shown) (for example, a mobile phone, a PHS, etc.) is also possible.

  Intersection and road data are stored in the map information storage unit 10 as a node data table 11, a link data table 12, a road type data table 13, and the like.

  FIG. 2 is a diagram showing the configuration of the node data table 11, the link data table 12, and the road type data table 13 stored in the map information storage unit 10.

  The node data table 11 is a table that defines the attributes of a node that is a point where a road branches in several directions, such as an intersection or a junction, and for each node, as shown in FIG. Is associated with position information such as latitude and longitude, the number of links that are roads connected to the node, and a link ID that identifies the link.

  The link data table 12 is a table that defines the attribute of a link representing a road connecting nodes, and as shown in FIG. 2B, for each link, a link ID for specifying the link, and the link The start node ID and end node ID, which are the end points, are linked to the link length (units are meters, kilometers, etc.), the link width (units are meters, etc., indicating the road width), and the road type. Configured. The link length is a reference for calculating the time required to travel on the road, and can be used as a cost value when performing a route search. Further, the value of the road type that is one of the attributes of the link data table 12 can be identified by the road type data table 13 shown in FIG. , Each has a unique value.

  In general, not only such road information but also background data (rivers, green spaces, etc.), facility information (for example, information for managing the location of family restaurants and gas stations), etc. are included in the map information storage unit 10, It is omitted in the description of this embodiment.

  Returning to FIG. 1, the positioning unit 20 is attached to the vehicle on which the map display device 1 is installed, and is a means for positioning the current position, speed, all directions, and the current time. For example, GNSS (Global Navigation Satellite) A system) receiver, a vehicle speed sensor, a gyro (angular velocity) sensor, an acceleration sensor, and the like. The GNSS receiver is, for example, a GPS receiver that receives radio waves from a plurality of satellites and demodulates them to measure the absolute position of the receiver. Note that the GNSS receiver and various sensors are used alone or in combination for the current position, speed, and omnidirectional positioning.

  The input unit 30 is used to input an instruction from the user. The input unit 30 has a configuration in which a predetermined number of push-type switches are arranged, a touch panel type, a remote controller, or a user's voice to the map display device. It is composed of a microphone, a speech recognition engine, etc.

  The traffic information receiving unit 40 can use various types of traffic congestion information (VICS information, probe information, etc.) provided, such as FM broadcast wave, optical / radio wave beacon, DSRC (Dedicated Short Range Communication); (Bandwidth communication) A receiving device corresponding to a receiver, a mobile phone, or the like is used. Further, the present invention is not limited to this, and the map information storage unit 10 is provided with a predicted traffic jam database in which past traffic statistics data (data representing road congestion according to past time zones, days of the week, dates, etc.) is stored. You may receive traffic jam information. The traffic information is information indicating how much time it can pass through the section of the link length in the link data table 12 described above, and average speed data in the section of the link length is used. By using this traffic jam information, it is possible to determine a required time with high accuracy in consideration of the degree of congestion. In the present embodiment, the traffic information receiving unit 40 will be described below assuming that it is a predicted traffic jam database.

  The display device 51 is, for example, a liquid crystal display, a plasma display, or an organic EL display that displays an image according to display image data created by the control unit 70.

  The control unit 70 includes a CPU (MPU) that controls the operation of the entire map display device 1, and a ROM (Read) that stores a program for causing the route search unit 71, the representative point extraction unit 72, and the isochronic drawing unit 73 to function in advance. It is comprised by only memory (RAM) and RAM (Random Access Memory). In addition, the control unit 70 may proceed the process while reading and writing information necessary for the process in a memory (typically a RAM (Random Access Memory)) as the working area unit 60. A detailed operation flow representing the processing content will be described later.

  Next, components of the control unit 70 will be described.

  The route search unit 71 has a function for determining a search range such as a range of points for calculating the required time, that is, a search range and a road type used for the search, a reference point (0) for starting the search based on the determined search range and the road type. In the following description, the present vehicle position will be described as an example), and the time required for all points (routes) that may travel is calculated.

  The reason for having the function of determining the search condition will be described next.

  In a normal navigation device, the time required to the destination designated by the user may be calculated, and the search range is between the search start position and end position (destination). In the present embodiment, Since the reachable range display in a situation where the destination is not set to one by the user is targeted, it is necessary to fulfill the function of determining an appropriate area for searching. Note that the search range basically includes at least the map area displayed on the display device 51. Further, in a normal navigation device, a search is performed based on a road type specified by the user (for example, input such as general road priority or expressway priority is performed). In this embodiment, the user sets a destination. Therefore, the map display device itself determines the road type to be used in consideration of the situation. Further, in the following description, the search range is a circle that is sufficiently wide to calculate the required time and is a certain distance away from the departure point, and all nodes included in this circle are the search targets.

  The calculation of the required time by the route search unit 71 is performed by expanding the road network including the nodes and links described above radially from the reference point for starting the search. At this time, the search range is gradually expanded by sequentially following the links connected to the search target node (hereinafter also referred to as “parent node”) in the process of expanding the search. As a search method, a route search method typified by a known Dijkstra method can be used, but an improvement for increasing time accuracy is required for the link cost addition processing described later. In addition, the search is not stopped even if the total (accumulated time) of link costs exceeds a certain time. This is for calculating the reference point non-reference nearest point β.

  The representative point extraction unit 72 has a function of extracting representative points for connecting isochronous lines. The representative points are basically obtained by equally dividing the target map in the m direction and extracting each direction from the direction 1 to the direction m. By changing the value of m by 8, 16, 24, 32, 36, etc., the display accuracy can be increased proportionally. The omnidirectional division can be made not only the number of divisions but also the angle. This is useful when the display of the display device 51 is horizontally long.

  In addition, the structure which arrange | positions the route search part 71 and the representative point extraction part 72 in center equipment (not shown) is also possible. At this time, the map display device 1 downloads the coordinate data of the representative point from the center facility each time by communication means (not shown).

  The isochronous line drawing unit 73 has a function of drawing an isochronous line on the display device 51 by sequentially connecting the representative nodes extracted by the representative point extracting unit 72. As for the connection order, for example, the representative nodes are connected clockwise starting from true north. The isochron can be drawn using a known curve drawing method such as a Bezier curve or a spline curve.

  In the map display device 1 configured as described above, the overall processing flow of the control unit 70 will be described with reference to FIG.

  FIG. 3 is a flowchart showing the overall processing flow of the control unit 70.

  The route search unit 71 of the control unit 70 first determines the search conditions described above (S10). Next, the route search unit 71 performs route search processing (S20). Next, the representative point extraction unit 72 extracts representative points (S30). Then, the isochronous drawing unit 73 draws an isochronous line (S40).

  Next, the link cost addition processing (route search processing) operation by the route search unit 71 will be described in detail.

  FIG. 4 is a flowchart showing a subroutine of the route search process (S20) shown in FIG.

  In FIG. 4, the route search unit 71 first determines whether or not all nodes that satisfy the search condition have been searched (S201). If all the nodes have not been searched yet (No in S201), the route search unit 71 repeatedly executes the processes of Steps S202 to S209 described later until the search for all the nodes is completed.

  In step S202, the route search unit 71 acquires a total time cost value (T1) until reaching the parent node. Next, the route search unit 71 acquires the link cost to reach the connection destination node connected to the parent node (S203). Then, the route search unit 71 acquires the current time (S204). This current time is acquired from a GPS receiver of the positioning unit 20, for example. Next, the route search unit 71 adds the time T1 to the current time, and obtains T2 as a result (S205). Next, the route searching unit 71 requests the predicted traffic jam information of the link from the parent node to the connection destination node at the time T2 to the predicted traffic jam database as the traffic information receiving unit 40 (S206), and receives the result. (S207). Further, the route search unit 71 calculates a link passing time (T3) in which the predicted traffic information is added to the link cost obtained in step S203 (S208). Next, the route search unit 71 stores a result T4 obtained by adding T3 to T1 as a total time cost value up to the connection destination node (S209). Note that there are a plurality of routes that reach a certain node, but at this time, a route having the minimum total time cost value is adopted.

  If all the nodes have been searched (Yes in S201), the route search unit 71 ends the route search process.

  By this process, the route search unit 71 searches for a more accurate reachable intersection because the route search unit 71 performs a route search in consideration of traffic jam information in a time zone in which the vehicle will pass the link from the parent node to the connection destination node. be able to. In particular, even if the time for obtaining an isochron is increased, the time calculation accuracy can be suppressed to an error within a certain range.

  Next, the operation in which the representative point extraction unit 72 extracts representative points will be described in detail.

  FIG. 5 is a flowchart showing a subroutine of representative point extraction processing (S30) shown in FIG.

  In FIG. 5, first, the representative point extraction unit 72 calculates the non-reference time closest point β (S301). Here, the non-standard-time closest point β is managed for each region obtained by dividing all directions around the departure point, and represents all intersections that can be reached within a predetermined range over a certain time (for example, 10 minutes). This is the intersection closest to the starting point among the points outside the standard time.

  Next, the representative point extraction unit 72 performs loop processing for the number of divisions divided in the m direction (range from S302 to S308).

  In step S303, the representative point extraction unit 72 determines whether or not the non-reference time closest point β exists in one divided area. When the reference point closest point β exists (Yes in S303), the representative point extraction unit 72 calculates the reference time optimal point γ, and sets the reference time optimal point γ as the representative point (S304). Here, the optimum point γ within the reference time is an intersection that can be reached within a certain time, and the straight line distance from the departure point does not exceed the straight line distance Dβ between the departure point and the nearest reference point β outside the reference time. A point far from.

  On the other hand, when the non-reference nearest point β does not exist (No in S303), the representative point extraction unit 72 sets the representative point to be non-set (S305). This non-reference-time nearest point β does not exist, for example, when there is a sea in that direction.

  Next, the representative point extraction unit 72 determines whether or not the representative point non-setting section is 180 degrees or more (S306). When the representative point non-setting section is 180 degrees or more (Yes in S306), the representative point extracting unit 72 adds the departure place to the representative point (S307), and proceeds to the next divided area. This is to prevent the departure place from going out of the isochron. On the other hand, if the angle is less than 180 degrees (No in S306), the representative point extraction unit 72 proceeds to the next divided area without adding the departure point to the representative point.

  By repeating such processing for the number of divisions, a representative point (reference point optimum point γ) is extracted for each direction.

  By the way, conventionally, only the farthest point α within the reference time that is the farthest from the departure point (for example, the current position of the moving object) among the intersections that can be reached within a certain time is obtained as a representative point. The dots are connected with an isochron. However, when the road is complicated, in a certain direction, the linear distance between the departure point and the farthest point in reference time α is Dα, the straight line distance between the departure point and the nearest reference point non-reference time D is β, And Dγ <Dα <Dα in some cases, the straight line distance between the reference point and the optimum point γ within the reference time is represented by Dγ. In this case, as shown in FIG. 20, many reference time out points are included inside the isochron 100.

  On the other hand, by executing the representative point extraction process shown in FIG. 5, the non-reference-time closest point β and the reference-time optimal point γ are obtained for each direction, and each reference-time optimal point γ is the representative point. Set to That is, also in the direction when Dγ <Dβ <Dα described above, the reference point optimum point γ whose linear distance is close to the departure point is set as the representative point. When the representative points are extracted in this way and the isochronous line drawing unit 73 draws the isochronous line connecting the representative points (the optimum point γ within the reference time) in step S40, the same region as FIG. 20 is also shown in FIG. An isochron 100 is drawn, and the reference outside point can be generally excluded from the inside of the isochron.

  Therefore, it is possible to prevent the user who sees this display from misidentifying that the user can reach the reference time point beyond the river, and it is possible to draw a more reliable isometric line.

  Moreover, even when there is a traffic jam on the way, the time accuracy of the route search by the route search unit 71 is high, so if it is within the range indicated by the isochron, it can be reached reliably within a certain time. It is possible to improve the reliability of area display.

(Embodiment 2)
Next, a map display device according to Embodiment 2 of the present invention will be described. Here, since the representative point extracting process executed by the representative point extracting unit 72 is different, the illustration of the entire configuration of the map display device and the description of each part are omitted, and only the different part of the processing of the representative point extracting unit 72 is described. This will be described in detail.

  By the way, according to the representative point extraction process shown in FIG. 5, although the representative point can be extracted by a simple process, the reference point optimal point γ is set as the representative point, so the isochron is closer to the departure side, There is a tendency that the range of the area that can be reached within a certain time is too small than the actual range.

  Therefore, in the representative point extraction processing of the map display device according to the second embodiment, a pattern in which the farthest point α within the reference time and the nearest point β outside the reference time exist in one region obtained by equally dividing the target map in the m direction. The representative points are extracted according to the above.

  FIG. 7 is a schematic diagram exemplifying the existence pattern of the farthest point α at the reference time and the nearest point β outside the reference time in one area divided into m.

  In the existence pattern 81 shown in FIG. 7A, the farthest point α within the reference time and the nearest point β outside the reference time both exist, and the linear distance Dα between the departure point and the farthest point α within the reference time is the departure point. Represents a situation where Dα ≦ Dβ. The existence pattern 82 shown in FIG. 7B represents a situation where the farthest point α within the reference time and the nearest point β outside the reference time both exist and Dα> Dβ. The existence pattern 83 shown in FIG. 7C represents a situation where only the farthest point α within the reference time exists and the nearest point β outside the reference time does not exist. The existence pattern 84 shown in FIG. 7D represents a situation in which only the non-reference time closest point β exists and the reference time farthest point α does not exist. A presence pattern 85 shown in FIG. 7E represents a situation in which neither the farthest point α in the reference time nor the nearest point β outside the reference time exists. The representative points are dynamically determined according to these existence patterns 81-85.

  Next, the representative point determination algorithm of the representative point extraction unit 72 will be described.

  FIG. 8 is a flowchart showing a representative point determination algorithm of the representative point extraction unit 72.

  As shown in FIG. 8, the representative point extraction unit 72 first calculates the farthest point α within the reference time and the nearest point β outside the reference time (S321). Note that the calculation of the farthest point α within the reference time and the nearest point β outside the reference time may be performed simultaneously in the course of the route search.

  Next, the representative point extraction unit 72 performs loop processing for the number of divisions divided in the m direction (range from S322 to S333).

  Then, the representative point extraction unit 72 performs pattern determination and the like. That is, in step S323, the representative point extraction unit 72 determines whether or not the reference time farthest point α exists. The representative point extraction unit 72 proceeds to step S324 when the reference farthest point α exists (Yes in S323), and when the reference farthest point α does not exist (No in S323). Then, the process proceeds to step S328. In step S324, the representative point extraction unit 72 determines whether or not the non-reference time closest point β exists. The representative point extraction unit 72 proceeds to step S325 when the non-reference time closest point β exists (Yes in S324), and proceeds to step S326 when the non-reference time closest point β does not exist (No in S324). Proceed with the process. In step S325, the representative point extraction unit 72 determines Dα ≦ Dβ. If Dα ≦ Dβ (Yes in S325), the representative point extraction unit 72 proceeds to Step S326. If Dα ≦ Dβ, that is, if Dα> Dβ (No in S325), Step S327 is performed. Proceed to the process.

  When the pattern determination is finished, the representative point extraction unit 72 sets a representative point and the like. That is, in step S326, the representative point extracting unit 72 sets the reference time farthest point α as a representative point, and the process proceeds to step S331. On the other hand, in step S327, the representative point extraction unit 72 sets the reference time optimum point γ as a representative point, and the process proceeds to step S331. In step S328, the representative point extraction unit 72 determines whether or not the non-reference time closest point β exists. When the reference non-standard time closest point β exists (S28: Yes), the representative point extraction unit 72 advances the processing to step S329. On the other hand, when the non-reference time closest point β does not exist (No in S328), the process proceeds to Step S330. In step S329, the representative point extracting unit 72 sets the reference non-reference closest point β as a representative point, and the process proceeds to step S331. On the other hand, the representative point is not set in step S330, and the representative point extracting unit 72 advances the processing to step S331.

  When the setting of the representative points is completed, the representative point extracting unit 72 determines whether or not the representative point non-setting section is 180 degrees or more (S331). If the angle is less than 180 degrees (No in S331), the representative point extraction unit 72 proceeds to the next divided area. On the other hand, when the representative point non-setting section is 180 degrees or more (Yes in S331), the representative point extracting unit 72 adds the departure place to the representative point (S332).

  If all the division numbers are looped, the process proceeds to step S400.

  In step S400, the representative point extraction unit 72 further adjusts the position of the representative point. Finally, the adjusted position is determined as a representative point, and an isochron is drawn.

  Here, the reason for adjusting the position of the representative point in step S400 will be described.

  When the road network is very dense in adjacent divided areas, the representative points are far apart (the linear distance between the departure point and the representative point is greatly different), so the isochronous line shape becomes uneven and the visibility is high. It has the problem of being lowered.

  For this reason, visibility is avoided by adjusting the position of the representative point within a range that does not violate the policy of eliminating the non-reference-time node inside the isochron. Note that it is possible to select not to perform the position adjustment of the representative point, and when it is performed, the processing of the method 1 or the method 2 described later is performed.

  In the method 1, the position of the representative point is determined by the successive sections of the representative points (the farthest point α within the reference time, the nearest point β outside the reference time, and the optimum point γ within the reference time) determined up to S333 in the flowchart of FIG. Adjust.

  On the other hand, in the method 2, the position of the representative point in the divided predetermined area is adjusted by the position of the representative point in the areas on both sides sandwiching the predetermined divided area.

  FIG. 9 is a schematic diagram illustrating the representative points and isochrones obtained by the representative node determination process in the flowchart shown in FIG. FIG. 9 illustrates a case where position adjustment is not performed in the position adjustment in step S400.

  In FIG. 9, the inside of the isochron 200 represents a range that can be reached within 10 minutes, for example. Further, the division number m is 8, which is divided from direction 1 to direction 8. Here, direction 1 and direction 8 are existence patterns 81, direction 2 and direction 6 are existence patterns 82, direction 3 and direction 8 are existence patterns 83, direction 4 is existence pattern 84, direction Reference numeral 5 denotes an existence pattern 85. In such a presence pattern of the farthest point α within the reference time and the nearest point β outside the reference time, the representative points are extracted as shown in FIG. 9 according to the flowchart shown in FIG.

  This makes it possible to extract representative points according to the existence status of the farthest point α within the reference time and the nearest point β outside the reference time, broadening the usable range, and roughly setting the reference point outside the isochronous line. Can be eliminated. Therefore, it is possible to draw an isochronous line with higher reliability, and it is possible to reduce the possibility of misrecognition of the reachable range.

  Next, the position adjustment of representative points by method 1 will be described.

  FIG. 10 is a flowchart showing the representative point position adjustment process of method 1.

  As shown in FIG. 10, the representative point extraction unit 72 first performs a loop process for the number of divisions divided in the m direction (S441 to S453).

  Next, the representative point extraction unit 72 determines whether a representative point has been determined in the divided area (S442). If the representative point has not been determined (No in S442), the representative point extracting unit 72 proceeds to the next divided region. On the other hand, if the representative point has been determined (Yes in S442), the process proceeds to step S443. In step S443, the representative point extraction unit 72 determines whether or not the representative point is the reference point farthest point α in the existence pattern 81. If it is not the farthest point α within the reference time in the existence pattern 81 (No in S443), the process proceeds to step S444.

  On the other hand, when it is the farthest point α in the reference time in the existence pattern 81 (Yes in S443), the process is moved to step S447.

  In step S444, the representative point extraction unit 72 determines whether or not the representative point is the reference point farthest point α in the existence pattern 83. When it is not the farthest point α within the reference time in the existence pattern 83 (No in S444), the process proceeds to Step S445. On the other hand, when it is the farthest point α in the reference time in the existence pattern 83 (Yes in S444), nothing is performed, that is, the position of the representative point is not adjusted, and the process proceeds to the next divided region.

  In step S445, the representative point extraction unit 72 determines whether or not the representative point is the reference point optimum point γ. If it is not the optimum point γ within the reference time (No in S445), the process proceeds to step S446. On the other hand, when the reference point is the optimum point γ (Yes in S445), the process proceeds to step S449.

  In step S446, the representative point extracting unit 72 determines whether or not the representative point is the non-reference time closest point β. If it is not the non-reference time closest point β (No in S446), that is, the representative point is the starting point, and at this time, the position of the representative point is not adjusted and the process proceeds to the next divided region. On the other hand, if it is the non-reference time closest point β (Yes in S446), the process proceeds to step S451.

  In step S447, the representative point extraction unit 72 counts the continuous sections of the reference time farthest point α. In step S448, the representative point extraction unit 72 applies the repulsive force according to the continuous section of the reference farthest point α to perform the next division. Proceed to the area. Here, repulsion means shifting the position of the representative point in a direction away from the departure place.

  In step S449, the representative point extraction unit 72 counts the continuous sections of the reference point optimum point γ, and in step S450, applies the repulsive force according to the continuous section of the reference point optimum point γ to generate the next divided region. Proceed to the process.

  Further, the representative point extraction unit 72 counts the continuous sections of the reference non-standard nearest points β in step S451, and in step S452, applies the attractive force according to the continuous sections of the non-reference non-adjacent closest points β to the next divided region. Proceed to the process. Here, the attractive force represents shifting the position of the representative point in a direction approaching the departure place.

  The reason why the repulsive force is not applied to the farthest point α within the reference time in the existence pattern 83 is that it is not possible to determine how much repulsive force should be applied because the non-reference nearest point β does not exist. is there.

  Further, the processing from step S442 to step S452 can be performed between the processing of step S322 to step S333 in FIG.

  Next, the process of applying a repulsive force to the farthest point α in the reference time shown in steps S447 and S448 in FIG. 10 will be described in detail with reference to FIG.

  As shown in FIG. 11A, when the difference between the linear distance Dα and the linear distance Dβ is large, the isochron is excessively pulled to the farthest point α in the reference time, so that the isochron is extremely small. End up. That is, it becomes a concave state. For this reason, a repulsive force is applied to the farthest point α in the reference time in a direction away from the starting point, and the position of the representative point is adjusted. The repulsive force must work within a range where the linear distance between the starting point and the representative point does not exceed Dβ.

  FIG. 11B is a graph showing that the repulsive force is variably applied according to the section where the existence pattern 81 continues. Thus, when the continuous section of the existence pattern 81 is 1, the repulsive force is a maximum of Dβ / Dα times, that is, the linear distance between the departure point and the representative point is equal to Dβ. On the other hand, when the continuous area of the existence pattern 81 is m / 2 or more (for example, when it is 16 divisions, it is 8 or more, that is, 180 degrees or more), the repulsive force is at least 1 time, that is, the representative point is the farthest point in the reference time α remains unchanged.

  As described above, the reason why the repulsive force is variably applied according to the section where the existence pattern 81 continues is that the isochronous shape is complicated and swells and swells, and the isochronic visibility is deteriorated. This is to avoid this. Of course, the repulsion can always be maximized.

  Next, a process for applying a repulsive force to the reference point optimum point γ shown in steps S449 and S450 in FIG. 10 will be described in detail with reference to FIG.

  As shown in FIG. 12 (a), when the difference between Dγ and Dβ is large, the isochron is excessively pulled by the optimum point γ within the reference time, and thus becomes extremely small. For this reason, the position of the representative point is adjusted by exerting a repulsive force in a direction away from the starting point with respect to the reference point optimum point γ. Similar to the process of applying a repulsive force to the farthest point α in the reference time, the repulsive force must be applied within a range where the linear distance between the starting point and the representative point does not exceed Dβ.

  FIG. 12B is a graph showing that the repulsive force is variably applied according to the section where the existence pattern 82 continues. Thus, when the continuous section of the existence pattern 82 is 1, the repulsive force is a maximum of Dβ / Dγ times, that is, the linear distance between the departure point and the representative point is equal to Dβ. On the other hand, when the continuous section of the existence pattern 82 is m / 2 or more (for example, when it is 16 divisions, it is 8 or more, that is, 180 degrees or more), the repulsive force is a minimum of 1, that is, the representative point is the optimum point γ within the reference time There will be no change.

  As described above, the reason why the repulsive force is variably applied according to the section where the existence pattern 82 is continuous is that the shape of the isochron is complicated and swells and swells, and the visibility of the isochron is deteriorated. This is to avoid this. Of course, the repulsion can always be maximized.

  Next, the process of applying an attractive force to the non-reference nearest point β shown in steps S451 and S452 in FIG. 10 will be described in detail with reference to FIG.

  As shown in FIG. 13 (a), when Dβ is too far from the departure point, the isochron is excessively pulled because it is pulled too far by the nearest reference point β outside the reference time. That is, it becomes a convex state. Therefore, the position of the representative point is adjusted by applying an attractive force in the direction approaching the departure point with respect to the nearest point β outside the reference time. The attractive force must work within a range not exceeding Dβ, which is the linear distance between the starting point and the representative point.

  FIG. 13B is a graph showing that the attractive force is variably applied according to the section where the existence pattern 84 continues. As described above, when the continuous section of the existence pattern 84 is 1, the attractive force is at least one time, that is, the representative point remains the closest point β outside the reference time and remains unchanged. On the other hand, when the continuous section of the existence pattern 84 is m / 2 or more (for example, when it is 16 divisions, it is 8 or more, that is, 180 degrees or more), the attractive force is a maximum of Dβ, that is, the representative point is the starting point.

  As described above, the reason why the attractive force is variably applied according to the section in which the existence pattern 84 is continuous is that the isochronous shape is complicated and swelled and swells, and the isochronic visibility is deteriorated. This is to avoid this. Of course, the attractive force can always be maximized.

  Further, the method of applying an attractive force to the non-reference nearest point β in the presence pattern 84 is not limited to the method shown in FIG. 13, and the following method (FIG. 14) can be used.

  In FIG. 14A, the direction 2 to the direction 6 are regions where the existence pattern 84 continues. That is, only the non-reference-time closest point β exists in the directions 2 to 6 (referred to as non-reference-time closest point β1 to non-reference-time closest point β5, respectively). In addition, the non-reference-time closest point β having the shortest straight line distance Dβ from the departure point among the reference-time closest point β1 to the reference-time closest point β5 is set as the non-reference-time closest point β4. That is, the minimum value of Dβ1 to Dβ5 is Dβ4. At this time, instead of adjusting the position of the representative point by applying an attractive force in the direction of the departure point to all the non-reference-time closest points β1 to β5, the representative point is one of the non-reference-time closest points β4. (Other representative points are not set), and an attractive force is applied only to the nearest reference point non-standard time β4.

  Here, as shown in FIG. 14 (b), when the required time for the closest point β4 outside the reference time is now 15 minutes and the reference time for drawing an isochron is 10 minutes, The position of the representative point is adjusted to a point that divides the starting point and the nearest non-standard time point β4 into 2: 1. In other words, it is placed at a point corresponding to 10 minutes.

  By determining the representative point as described above, the reference time outside point inside the isochron can be surely removed. Moreover, the distance from the departure point can be rotated and moved so that the non-reference-time closest point β4 is located in the direction 4 which is just in the center of the directions 2 to 6.

  Next, the position adjustment of representative points by method 2 will be described.

  FIG. 15 is a flowchart showing the representative point position adjustment processing of method 2.

  As shown in FIG. 15, the representative point extraction unit 72 first performs loop processing for the number of divisions divided in the m direction (range from S461 to S475). Next, it is determined whether or not a representative point is determined in the divided area (S462). If the representative point has not been determined (No in S462), the process proceeds to the next divided area. On the other hand, if a representative point has been determined (Yes in S462), the process proceeds to step S463.

  In step S <b> 463, the representative point extraction unit 72 determines whether the representative point is the reference time farthest point α in the existence pattern 81. If it is not the farthest point α within the reference time in the existing pattern 81 (No in S463), the process proceeds to step S464. On the other hand, when it is the farthest point α in the reference time in the existence pattern 81 (Yes in S463), the process proceeds to step S467.

  In step S464, the representative point extraction unit 72 determines whether or not the representative point is the farthest point α in the reference time in the existence pattern 83. If it is not the farthest point α within the reference time in the existence pattern 83 (No in S464), the process proceeds to step S465. On the other hand, if it is the farthest point α in the reference time in the existence pattern 83 (Yes in S464), the process proceeds to step S468.

  In step S465, the representative point extracting unit 72 determines whether or not the representative point is the reference point optimum point γ. If it is not the optimum point γ within the reference time (No in S465), the process proceeds to step S466. On the other hand, when it is the optimum point γ within the reference time (Yes in S465), the process proceeds to step S469.

  In step S466, the representative point extracting unit 72 determines whether or not the representative point is the non-reference time closest point β. If it is not the reference point non-standard time closest point β (No in S466), that is, the representative point is the starting point, and at this time, the position of the representative point is not adjusted and the process proceeds to the next divided region. On the other hand, if it is the non-reference time closest point β (Yes in S466), the process proceeds to step S470.

  In step S467, step S468, step S469, and step S470, the representative point extraction unit 72 determines whether or not a representative point exists in an outer divided area sandwiching the divided area. If either one does not exist (No in S467, No in S468, No in S469, or No in S470), the process proceeds to the next divided region without adjusting the position of the representative point. On the other hand, if there is a representative point in the outer divided area sandwiching the divided area (Yes in S467 or Yes in S468, Yes in S469 or Yes in S470), the process is performed in step S471 or step S472 or step S473 or step S474. Proceed.

  In step S471, the representative point extraction unit 72 exerts a repulsive force on the farthest point α within the reference time, and proceeds to the next divided region. Details on how to work will be described later. In step S472, the representative point extraction unit 72 exerts a repulsive force on the farthest point α in the reference time and advances the process to the next divided region. Details on how to work will be described later. In step S473, the representative point extraction unit 72 exerts a repulsive force on the reference time optimum point γ and advances the process to the next divided region. Details on how to work will be described later. In step S474, the representative point extraction unit 72 applies an attractive force to the non-reference-time closest point β, and proceeds to the next divided region. Details on how to work will be described later. Note that the repulsive force represents shifting the position of the representative point in a direction away from the departure place, and the attractive force represents shifting the position of the representative point in a direction approaching the departure place. It should be noted that the outer divided areas sandwiching the divided area in step S470 are not necessarily adjacent areas, and it is only necessary that representative points exist in areas separated by a certain angle (for example, 90 degrees).

  Next, the process of applying a repulsive force to the farthest point α at the reference time shown in step S471 in FIG. 15 will be described in detail with reference to FIG.

  As shown in FIG. 16, now consider directions 3 to 5. Since there are representative points in the direction 3 and the direction 5, which are the outer divided regions sandwiching the direction 4, a repulsive force is applied to the farthest point α in the reference point reference time in the direction 4. Here, L is a line segment connecting the starting point and the farthest point α in the reference time, and M1 is a line segment L from the representative point of the outer divided area (direction 3) sandwiching the divided area (direction 4). It is the intersection with the perpendicular line. M2 is an intersection point with a perpendicular drawn from the representative point of the outer divided area (direction 5) sandwiching the divided area (direction 4) to the line segment L. M3 is an intersection with a perpendicular line drawn from the nearest non-reference point β existing in the divided area (direction 4) to the line segment L.

  At this time, the repulsive force is a range in which the distance from the farthest reference point farthest point α among the crossing points M1 to M3 that are farther away from the departure point than the farthest point α in the reference time does not exceed the shortest intersection M1. Apply repulsive force to the farthest point α in the reference time. If all the intersections are in front of the farthest point α within the reference time (starting side), the repulsive force is not applied and the representative point remains the farthest point α within the reference time.

  In this way, by using the repulsive force, it is possible to avoid that the shape of the isochron line is extremely depressed in the direction 4, and the isoline visibility can be kept constant.

  Next, the process of applying a repulsive force to the farthest point α in the reference time shown in step S472 in FIG. 15 will be described in detail with reference to FIG.

  As shown in FIG. 17, now consider directions 3-5. Since there are representative points in the direction 3 and the direction 5, which are the outer divided regions sandwiching the direction 4, a repulsive force is applied to the farthest point α in the reference point reference time in the direction 4. L is a line segment connecting the starting point and the farthest point α at the reference time, and M1 is lowered to the line segment L from the representative point of the outer divided area (direction 3) across the divided area (direction 4). It is the intersection with the perpendicular. M2 is an intersection point with a perpendicular drawn from the representative point of the outer divided area (direction 5) sandwiching the divided area (direction 4) to the line segment L. Since there is an existing pattern 83, the point other than the reference time nearest point β does not exist, which is different from FIG. At this time, the repulsive force is a range in which the distance from the farthest reference point farthest point α among the intersecting points M1 to M2 that are farther away from the starting point than the farthest point α in the reference time does not exceed the shortest intersection M1. Apply repulsive force to the farthest point α in the reference time. If all the intersections are in front of the farthest point α within the reference time (starting side), the repulsive force is not applied and the representative point remains the farthest point α within the reference time.

  In this way, by using the repulsive force, it is possible to avoid that the shape of the isochron line is extremely depressed in the direction 4, and the isoline visibility can be kept constant.

  Next, the process of applying a repulsive force to the reference point optimum point γ shown in step S473 in FIG. 15 will be described in detail with reference to FIG.

  As shown in FIG. 18, now consider directions 3-5. Since there are representative points in the direction 3 and the direction 5, which are the outer divided regions across the direction 4, a repulsive force is applied to the representative point reference optimal point γ in the direction 4. L is a line segment connecting the starting point and the reference point optimum point γ, and M1 is a perpendicular line drawn from the representative point of the outer divided area (direction 3) across the divided area (direction 4) to the line segment L. Is the intersection of M2 is an intersection point with a perpendicular drawn from the representative point of the outer divided area (direction 5) sandwiching the divided area (direction 4) to the line segment L. M3 is an intersection with a perpendicular line drawn from the nearest non-reference point β existing in the divided area (direction 4) to the line segment L. At this time, the repulsive force is a reference within a range in which the distance from the optimum point γ within the reference time is less than the shortest intersection M1 among the intersections M1 to M3 that are farther away from the starting point than the optimum point γ within the reference time. Apply repulsion to the optimal point γ within the hour. If all the intersections are in front of the optimum point γ within the reference time (starting side), the repulsive force is not applied and the representative point remains the optimum point γ within the reference time.

  In this way, by using the repulsive force, it is possible to avoid that the shape of the isochron line is extremely depressed in the direction 4, and the isoline visibility can be kept constant.

  Next, the process of applying an attractive force to the non-reference nearest point β shown in step S474 in FIG. 15 will be described in detail with reference to FIG.

  As shown in FIG. 19, now consider directions 3-5. Since there are representative points in the direction 3 and the direction 5, which are the outer divided regions sandwiching the direction 4, an attractive force is applied to the representative point reference non-time closest point β in the direction 4. L is a line segment connecting the starting point and the non-reference nearest point β, and M1 is a perpendicular line drawn from the representative point of the outer divided area (direction 3) across the divided area (direction 4) to the line segment L. Is the intersection of M2 is an intersection point with a perpendicular drawn from the representative point of the outer divided area (direction 5) sandwiching the divided area (direction 4) to the line segment L. At this time, the gravitational force is within the reference non-standard time range within the range where the distance from the shortest non-standard time point β exceeds the shortest cross point M2 among the cross-points M1 to M2 existing closer to the starting point than the non-standard time closest point β. An attractive force is applied to the point β. If all the intersections are on the back side (the side opposite to the departure point) from the non-standard time closest point β, the attractive force is not applied and the representative point remains the non-standard time closest point β.

  In this manner, by applying the attractive force, it is possible to avoid the shape of the isochronous line from being extremely expanded in the direction 4, and the isoline visibility can be kept constant.

  In the above-described embodiment, the case where the moving body is a car and the map display device is applied to the navigation device has been described. However, the moving body is a person and a range within a predetermined time is displayed on the map. The map display device may be applied to a portable information terminal such as a mobile phone, or the map display device alone may be configured.

  Although the present invention has been described in detail above, the above description is merely illustrative of the present invention in all respects and is not intended to limit the scope thereof. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. In particular, the map display device of the present invention can be used as a portable navigation device, a map display application for displaying on a personal computer, a taxi, a dispatching / command system in a security company, and the like. It can also be applied to other mobile objects such as aircraft, ships and trains.

  The map display device according to the present invention can be applied to all devices and systems capable of displaying a map, such as a navigation device, a personal computer, a mobile phone, a taxi, a dispatch / command system in a security company, and the like.

It is a block diagram which shows the whole structure of the map display apparatus in this Embodiment 1. It is a figure which shows the structure of the node data table 11, the link data table 12, and the road classification data table 13 which are stored in the map information storage part 10. FIG. 3 is a flowchart showing the overall processing flow of a control unit 70. It is a flowchart which shows the subroutine of the route search process (S20) shown by FIG. It is a flowchart which shows the subroutine of the representative point extraction process (S30) shown by FIG. It is a figure which shows an example of the isochronism drawn about the same area | region as FIG. 20, in order to compare with a prior art example. It is a schematic diagram which illustrates the presence pattern of the farthest point α in the reference time and the nearest point β outside the reference time in one area divided into m. It is a flowchart which shows the representative point determination algorithm of the representative point extraction part 72 in Embodiment 2 of this invention. FIG. 9 is a schematic diagram illustrating a representative point and an isochron obtained by a representative node determination process in the flowchart illustrated in FIG. 8. 12 is a flowchart showing a representative point position adjustment process of method 1; It is a schematic diagram which shows the representative point position adjustment method about the area | region where the presence pattern 81 continues. It is a schematic diagram which shows the representative point position adjustment method about the area | region where the presence pattern 82 continues. It is a schematic diagram which shows the representative point position adjustment method about the area | region where the presence pattern 84 continues. It is a schematic diagram which shows the other representative point position adjustment method about the area | region where the presence pattern 84 follows. 10 is a flowchart showing a representative point position adjustment process of method 2; FIG. 16 is a schematic diagram showing a process for applying a repulsive force to a reference innermost farthest point α shown in step S471 in FIG. 15. FIG. 16 is a schematic diagram showing a process for applying a repulsive force to a reference innermost farthest point α shown in step S472 in FIG. 15; FIG. 16 is a schematic diagram showing a process of applying a repulsive force to the reference time optimum point γ shown in step S473 in FIG. 15. FIG. 16 is a schematic diagram showing a process for applying an attractive force to a non-reference-time closest point β shown in step S474 in FIG. 15. It is a schematic diagram which shows a mode that the reference | standard outside point is contained inside the isochronous line as a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Map display apparatus 10 Map information storage part 20 Positioning part 30 Input part 40 Traffic information receiving part 50 Output part 51 Display apparatus 60 Working area part 70 Control part 71 Path | route search part 72 Representative point extraction part 73 Isochronous line drawing part 100, 200,300 isochronous

Claims (9)

A map display device that displays a reachable area within a predetermined time on a map with a predetermined position as a base point,
Search means for searching for a required time from the base point to a plurality of points on the map;
In each region obtained by dividing the map by dividing the direction around the base point, the required time searched by the search means is a point closest to the base point among points exceeding the predetermined time. Representative point extraction means for extracting, as a representative point, a point that does not exceed a straight line distance Dβ between the reference non-reference closest point β and the base point when the reference non-reference closest point β exists;
And a display means for displaying an isochronous line connecting the representative points superimposed on the map. The representative point extracting means determines that the linear distance between the base point and the base point is a point that does not exceed the predetermined time as the point that does not exceed the linear distance Dβ between the base point and the non-reference nearest point β. 2. The map according to claim 1, wherein a reference point optimal point γ that is a point farthest from the base point and does not exceed a straight line distance Dβ with the reference point closest point β is extracted as a representative point. Display device. The search means adjusts a position where a repulsive force is applied in a direction opposite to the base point with respect to the reference point optimum point γ extracted as the representative point as a new representative point. The map display device described. The representative point extracting unit is configured to respond to the presence of the farthest point α in the reference time that is the farthest from the base point among the points that can be reached within the predetermined time and the nearest point β outside the reference time. The map display device according to claim 1, wherein a representative point is extracted. The representative point extracting means, for each area obtained by dividing the map into a plurality of areas,
Both the non-reference time closest point β and the reference time most distant point α exist, and a linear distance Dβ between the base point and the non-reference time closest point β is the base point and the reference time most distant point If it is greater than or equal to the linear distance Dα with α, the reference farthest point α is extracted as a representative point,
If both the reference outside nearest point β and the reference time farthest point α exist, and the linear distance Dβ is less than the linear distance Dα, the point within the predetermined time is not exceeded. The reference point optimal point γ that is the point farthest from the base point and the distance from the base point does not exceed the straight line distance Dβ is extracted as a representative point.
In the case where the reference point closest point β does not exist and the reference point farthest point α exists, the reference point farthest point α is extracted as a representative point,
5. The map according to claim 4, wherein when the reference outside nearest point β exists and the reference time farthest point α does not exist, the reference outside nearest point β is extracted as a representative point. 6. Display device. The search means includes
When the reference non-standard time closest point β is extracted as a representative point, a position where an attractive force is applied to the base point direction with respect to the non-standard time closest point β is adjusted as a new representative point,
When the optimum point γ within the reference time is extracted as a representative point, a position where a repulsive force is exerted on the optimum point γ within the reference time in a direction opposite to the base point is adjusted as a new representative point. The map display device according to claim 5. The plurality of points include nodes that are intersections;
The search means includes
A total time cost value acquisition means for acquiring a total time cost value until reaching a searched node that has been searched for a required time;
Link cost acquisition means for acquiring a link cost of a link that is a road to a connection destination node connected to a searched node from map information related to the map;
Current time acquisition means for acquiring the current time;
First addition means for adding the total time cost value to the current time;
Predicted traffic jam information acquiring means for acquiring predicted traffic jam information from the searched node to the connection destination node at the time added by the first adding means;
Link passing time calculating means for calculating a link passing time in which the predicted traffic jam information is added to the link cost acquired by the link cost acquiring means,
The map display device according to claim 1, wherein the search unit sequentially searches a result of adding the link transit time to the total time cost as a total time cost value reaching a connection destination node. A map display method for displaying on a map a range that can be reached within a predetermined time from a predetermined position,
A search step for searching for a required time from the base point to a plurality of points on the map;
In each of the areas obtained by dividing the map by dividing the direction around the base point, a reference that is the closest point to the base point among the points where the required time searched by the search step exceeds a predetermined time A representative point extracting step of extracting, as a representative point, a point that does not exceed a linear distance between the reference non-temporal closest point β and the base point when an out-of-time closest point β exists;
A map display method comprising: a display step of superimposing and displaying an isochron line connecting the representative points on the map.   A program for causing a computer to execute the steps included in the map display method according to claim 8.

Images