JP7630352B2 - Map generation device, map generation method, and map generation program - Google Patents

Description

This disclosure relates to a map generation device, a map generation method, and a map generation program.

Patent documents 1 and 2 disclose map update technology for car navigation systems.

Patent No. 4446252 Patent No. 4962484

The techniques described in Patent Documents 1 and 2 allow for efficient updating of part of map data. However, the higher the information density of map data, the larger the data size becomes. Map data stored in a car navigation system that is required to depict detailed roads and detailed road shapes has a high information density. Therefore, when updating the entire map data, it increases transmission load and takes time for the update.
An object of the present disclosure is to provide a map generating device, a map generating method, and a map generating program that are capable of generating map data with a small data size while maintaining the accuracy required for the map data.

According to one aspect of the present invention, a map generating device includes a request acquisition unit that acquires request information indicating a position in map data that requires a certain level of accuracy, and a map generating unit that generates map data including a base mesh that does not include a position indicated by the request information among the multiple base meshes and an extended mesh that includes a position indicated by the request information, based on a map database that stores multiple base meshes that store map information indicating a relationship between a position in a certain range on the ground and an attribute of the position, and multiple extended meshes that store map information with a higher density than the multiple base meshes.

According to the above aspect, it is possible to generate map data with a small data size while maintaining the accuracy required for the map data.

1 is a schematic diagram showing a configuration of a map updating system according to a first embodiment. 1 is a schematic block diagram showing a configuration of a map generating device according to a first embodiment. FIG. 2 is a diagram showing an example of map data according to the first embodiment; 4 is a flowchart showing a map data updating method performed by the map updating system according to the first embodiment. FIG. 11 is a diagram illustrating an example of map data according to the second embodiment. FIG. 1 is a schematic block diagram illustrating a configuration of a computer according to at least one embodiment.

First Embodiment
Map update system configuration
Hereinafter, the embodiments will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing the configuration of a map updating system 1 according to the first embodiment.
The map updating system 1 according to the first embodiment updates map data used for charging a toll road. The map updating system 1 according to the first embodiment includes a map generating device 11, an in-vehicle device 13, a charging server 15, and a map database 17.

The map generating device 11 generates map data used by the vehicle-mounted device 13 and the billing server 15 for calculation processing, and outputs the map data to the vehicle-mounted device 13 and the billing server 15. The map data is transmitted, for example, via the Internet. The map generating device 11 generates map data based on data stored in the map database 17. The map database 17 may be, for example, a database managed by a country or the like.

The vehicle-mounted device 13 is mounted on the vehicle V. The vehicle-mounted device 13 acquires position data of the vehicle V from the Global Navigation Satellite System (GNSS) and corrects the position data based on map data. Specifically, the vehicle-mounted device 13 performs a map matching process to correct the position data to match the road shape indicated by the map data. The vehicle-mounted device 13 transmits the corrected position data to the billing server 15. The map data is recorded in a storage medium of the vehicle-mounted device 13.

The billing server 15 performs billing processing for travel on toll roads based on the position data and map data received from the vehicle-mounted device 13. Specifically, the billing server 15 determines whether the vehicle V is traveling on a toll road by determining whether the position data received from the vehicle-mounted device 13 indicates a position on the toll road indicated by the map data. When the vehicle V is traveling on a toll road, the billing server 15 calculates the fee based on the traveling speed, the traveling section, the traveling time, etc.

In other words, when the purpose is to charge for toll roads as in the first embodiment, high accuracy is required for the map data in areas that include toll roads, but high accuracy is not required for areas that do not include toll roads (for example, areas that include only non-toll roads). Therefore, the map generating device 11 according to the first embodiment reduces the data size of the map data by differentiating the information density between areas that include toll roads and areas that do not.

About Map Database 17
The map database 17 stores mesh data relating to different accuracy levels for a predetermined area (e.g., national land). Specifically, the map database 17 stores a first mesh M1 divided into partial areas of 20 km x 20 km, a second mesh M2 divided into partial areas of 10 km x 10 km, and a third mesh M3 divided into partial areas of 1 km x 1 km for the predetermined area. Of these mesh data, the third mesh M3 has the highest information density, and the first mesh M1 has the lowest information density. Note that the partial area represented by the third mesh M3 is the narrowest, and the partial area represented by the first mesh M1 is the widest, so the data sizes of the meshes may be approximately the same. In this embodiment, the accuracy level of the first mesh M1 is set to "1", the accuracy level of the second mesh M2 is set to "2", and the accuracy level of the third mesh M3 is set to "3". The first mesh M1 is an example of a basic mesh that stores map information indicating the relationship between a position in a predetermined range on the ground and the attribute of the position. The second mesh M2 and the third mesh M3 are examples of extended meshes that store map information with a higher density than the basic mesh. In other words, if the amount of information of attribute data contained in one mesh is constant, the smaller the mesh area, the higher the information density, and the larger the mesh area, the lower the information density. The higher the information density, the higher the accuracy level of the mesh, and the lower the information density, the lower the accuracy level of the mesh.

The mesh data includes at least the ID and accuracy level of each mesh, as well as the latitude and longitude of a representative point of the partial area (for example, the positions of the most northwestern position, the most northeastern position, the most southwestern position, and the most southeastern position). If the partial area represented by the mesh data includes a road, the mesh data may further include node N and link L data representing information about the road included in the partial area. Mesh data relating to an area without roads or an area where road data is unknown does not include node N and link L data. Even if the mesh data relates to an area with roads, the mesh data may not include node N and link L data if it is not subject to charges or if the data size is reduced. A node N is information representing the position of a characteristic point of a road (such as an intersection or a corner). A link L is information representing a line segment connecting two nodes N. In map data and mesh data, a road is represented by a node N and a link L. In mesh data, a node N may be represented by an ID that identifies the node N. In this case, the map database 17 stores the latitude, longitude, and attribute data of the node N in association with the ID of the node N. In the mesh data, the link L may be represented by an ID that identifies the link L. In this case, the map database 17 stores the ID of the node N at the starting point, the ID of the node N at the end point, and attribute data in association with the ID of the link L. The attribute data may represent, for example, the intersection name, the road name, whether the road is subject to toll charges, the frequency of congestion, and the risk of accidents. The node N may also represent a landmark, such as a specific point such as a toll booth, rather than a road. The link L is not connected to the node N that represents the landmark. Therefore, a mesh that includes a landmark but does not include a road includes data on the node N, but does not include data on the link L. In other words, when the node N represents a landmark, the mesh data includes at least the mesh ID, the accuracy level, and the latitude and longitude of the representative point of the partial area (for example, the positions of the most northwestern position, the most northeastern position, the most southwestern position, and the most southeastern position), as well as the node N.

Configuration of map generating device 11
FIG. 2 is a schematic block diagram showing the configuration of the map generating device 11 according to the first embodiment.
The map generating device 11 includes a request input unit 111 , a request storage unit 112 , a request acquisition unit 113 , a mesh acquisition unit 114 , a map generating unit 115 , a map storage unit 116 , and an updated map output unit 117 .

The request input unit 111 receives input of request information indicating a position for which a certain level of accuracy is required in the map data from the manager of the map data. The request information is data that associates the ID of a node N or a link L with the accuracy level of a position including the node N or the link L. In the map generating device 11 according to the first embodiment, in order to generate map data used for charging a toll road, in the request information, the ID of the link L representing the toll road is set to an accuracy level of 2, and the node N representing the boundary between the toll road and the non-toll road and the node N representing the intersection of the toll road are set to an accuracy level of 3. This is because, in the charging process, it is important to accurately determine whether or not a toll road has been entered and when a branch point of a toll road has been passed. The request information input to the request input unit 111 is recorded in the request storage unit 112. Note that the request information may specify a node N or a link L by the name of an intersection or a road, or a combination of latitude and longitude, instead of an ID. In other words, for mesh data that does not have links L and nodes N, the desired level of accuracy can be set by specifying the position using a combination of latitude and longitude.

The request input unit 111 may input difference data indicating a difference from the request information already recorded in the request storage unit 112. The difference data includes, for example, a classification of addition, change, or deletion, the ID of the target link L or node N, and a precision level when the classification indicates addition or change. The request input unit 111 updates the request information recorded in the request storage unit 112 based on the input difference data.

The request acquisition unit 113 acquires request information from the request storage unit 112 when the map data is to be updated. Examples of map data update timing include timing determined at a fixed interval, timing when an update to the map database 17 is notified, timing when data is input to the request input unit 111, timing specified by an administrator, etc.

The mesh acquisition unit 114 acquires meshes to be used for generating map data from the map database 17 based on the request information acquired by the request acquisition unit 113. Specifically, the mesh acquisition unit 114 reads out the first mesh M1 relating to the entire target area of the map data from the map database 17. That is, the mesh acquisition unit 114 acquires not only the first mesh M1 including the position specified in the request information, but also the first mesh M1 including the position not specified in the request information. The mesh acquisition unit 114 reads out the second mesh M2 including the node N or link L associated with the ID for which the accuracy level 2 is specified from the map database 17. The mesh acquisition unit 114 reads out the third mesh M3 including the node N or link L associated with the ID for which the accuracy level 3 is specified and the third mesh M3 in the vicinity thereof from the map database 17. The third mesh M3 in the vicinity is the third mesh M3 included in the partial area of the second mesh M2 including the third mesh M3. That is, the mesh acquisition unit 114 acquires from the map database 17 a mesh of the corresponding accuracy level, in which the position of the node N or link L indicated by the request information exists inside the partial area indicated by the mesh.

The map generation unit 115 generates map data by combining the meshes acquired by the mesh acquisition unit 114. Specifically, the map generation unit 115 generates map data in the following procedure. First, the map generation unit 115 generates draft map data (basic map data) composed of the first mesh M1 acquired by the mesh acquisition unit 114. Next, the map generation unit 115 replaces a portion of the draft map data that overlaps with the second mesh M2 acquired by the mesh acquisition unit 114 with the second mesh M2. Furthermore, the map generation unit 115 replaces a portion of the draft map data that overlaps with the third mesh M3 acquired by the mesh acquisition unit 114 with the third mesh M3. In this way, the map generation unit 115 generates map data. The map generation unit 115 records the generated map data in the map storage unit 116.

Figure 3 is a diagram showing an example of map data according to the first embodiment. As shown in Figure 3, the map data according to the first embodiment is composed of a combination of meshes of different sizes. All links L (2) for which accuracy level 2 is specified are drawn on the second mesh M2 or the third mesh M3. All nodes N (3) for which accuracy level 3 is specified are drawn on the third mesh M3.

The update map output unit 117 outputs the map data recorded in the map storage unit 116 to the vehicle-mounted device 13 and the billing server 15. The update map output unit 117 may output map data in response to a distribution request from the vehicle-mounted device 13 and the billing server 15, or may output an update instruction including the map data to the vehicle-mounted device 13 and the billing server 15 at the timing when the map generation unit 115 generates the map data. When the vehicle-mounted device 13 and the billing server 15 acquire the map data output by the update map output unit 117, they overwrite the old map data already stored with the newly acquired map data.

Operation of map update system 1
A method for updating map data in the vehicle-mounted device 13 and the billing server 15 by the map updating system 1 according to the first embodiment will be described. Fig. 4 is a flowchart showing a method for updating map data by the map updating system 1 according to the first embodiment. It is assumed that the administrator has input request information in advance, and the request storage unit 112 has stored the request information.

The request acquisition unit 113 acquires request information from the request storage unit 112 when the map data is updated (step S1). The mesh acquisition unit 114 reads out a first mesh M1 relating to the entire target area of the map data from the map database 17 (step S2). The mesh acquisition unit 114 also reads out a second mesh M2 including a node N or link L associated with an ID for which an accuracy level of 2 is specified in the request information from the map database 17 (step S3).

The mesh acquisition unit 114 identifies the second meshes M2 read in step S3 that include a node N or a link L associated with an ID for which accuracy level 3 is specified in the request information (step S4). The mesh acquisition unit 114 reads a third mesh M3 that covers the partial area represented by the second mesh M2 identified in step S4 from the map database 17 (step S5).

The map generation unit 115 generates draft map data consisting of the first mesh M1 read in step S2 (step S6). Next, the map generation unit 115 replaces the portion of the draft map data that overlaps with the second mesh M2 read in step S3 with the second mesh M2 (step S7). If the first mesh M1 partially overlaps with the second mesh M2, the second mesh M2 generates a partial mesh by cutting out a portion of the first mesh M1 that does not overlap with the second mesh M2. The map generation unit 115 replaces the portion of the draft map data that overlaps with the third mesh M3 acquired in step S5 with the third mesh M3 (step S8).

The map generation unit 115 records the generated map data in the map storage unit 116 (step S9). The updated map output unit 117 outputs the map data recorded in the map storage unit 116 to the vehicle-mounted device 13 and the billing server 15 (step S10). When the vehicle-mounted device 13 and the billing server 15 acquire new map data, they overwrite the old map data with the new map data.

<Action and Effects>
In this way, the map generating device 11 according to the first embodiment acquires request information indicating a position in the map data where a certain level of accuracy is required, and generates map data including a basic mesh that does not include the position indicated by the request information, and an expanded mesh that includes the position indicated by the request information. In other words, the map data generated by the map generating device 11 does not include an expanded mesh related to a partial area away from the position indicated by the request information. This allows the map generating device 11 to generate map data with a small data size while maintaining the required accuracy. This allows the map generating device 11 to reduce the cost of transmitting map data to the vehicle-mounted device 13 and the billing server 15.

In addition, the map generating device 11 according to the first embodiment can set the accuracy of the map data in stages by acquiring requirement information that associates the location for which accuracy is required with the accuracy level.

The map generating device 11 according to the first embodiment generates map data in which a first mesh including the position indicated by the request information is replaced with a second mesh or a third mesh including the position indicated by the request information, among basic map data composed of basic meshes. In other words, the map data generated by the map generating device 11 does not have overlapping portions among the first mesh, the second mesh, and the third mesh. This enables the map generating device 11 to reduce the data size of the map data.

Second Embodiment
The map generating device 11 according to the first embodiment generates map data in which there are no overlapping portions between meshes, as shown in Fig. 3. In contrast, the map generating device 11 according to the second embodiment generates map data in which there are overlapping portions between meshes.

The configuration of the map generating device 11 according to the second embodiment is the same as that of the first embodiment. The map generating device 11 according to the second embodiment differs from the first embodiment in the operation of the mesh acquisition unit 114 and the map generating unit 115. Furthermore, the request information according to the second embodiment indicates the ID of the node indicating the position for which accuracy is required. In other words, the request information according to the second embodiment does not specify the accuracy level and the ID of the link.

In the second embodiment, the mesh acquisition unit 114 reads from the map database 17 not only the first mesh M1, but also a 5 x 5 third mesh M3 centered on the third mesh M3 that contains the node N associated with the ID specified in the request information.

The map generation unit 115 according to the second embodiment generates basic map data consisting of the first mesh M1 acquired by the mesh acquisition unit 114. The map generation unit 115 also generates extended map data consisting of the third mesh M3 acquired by the mesh acquisition unit 114. Note that since the mesh acquisition unit 114 acquires only the third mesh M3 in the vicinity of the node N associated with the ID specified in the request information, the extended map data includes a portion that does not have information. The map generation unit 115 generates map data including a layer of basic map data and a layer of extended map data. FIG. 5 is a diagram showing an example of map data according to the second embodiment.

In this way, the map generating device 11 according to the second embodiment generates map data having a hierarchical structure. Furthermore, the map data includes a first mesh that includes the position indicated by the request information, but does not include a third mesh that relates to a partial area away from the position indicated by the request information. This allows the map generating device 11 to generate map data with a small data size while maintaining the required accuracy. This allows the map generating device 11 to reduce the cost of transmitting map data to the vehicle-mounted device 13 and the billing server 15.

Other Embodiments
Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes are possible. That is, in other embodiments, the order of the above-mentioned processes may be changed as appropriate. Also, some of the processes may be executed in parallel.

The map generating device 11 according to the above-described embodiment may be configured as a single computer, or the configuration of the map generating device 11 may be distributed across multiple computers, and the multiple computers may work together to function as the map generating device 11.

The map generating device 11 according to the embodiment described above generates map data for road pricing, but is not limited to this. For example, the map generating device 11 according to another embodiment may generate a map for a car navigation system. In this case, for example, the request information includes IDs of nodes and links representing roadways. This allows the map generating device 11 to generate map data with high accuracy for partial areas that include roadways and reduced data size for partial areas that do not have roadways.

Computer Configuration
FIG. 6 is a schematic block diagram illustrating a computer configuration according to at least one embodiment.
The computer 50 includes a processor 51 , a main memory 53 , a storage 55 , and an interface 57 .
The above-mentioned map generating device 11 is implemented in a computer 50. The operations of each of the above-mentioned processing units are stored in the storage 55 in the form of a program. The processor 51 reads the program from the storage 55, loads it in the main memory 53, and executes the above-mentioned processing in accordance with the program. The processor 51 also secures storage areas in the main memory 53 corresponding to each of the above-mentioned storage units in accordance with the program. Examples of the processor 51 include a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), and a microprocessor.

The program may be for implementing some of the functions to be performed by the computer 50. For example, the program may be for implementing the functions by combining with other programs already stored in the storage or with other programs implemented in other devices. In other embodiments, the computer 50 may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions implemented by the processor 51 may be implemented by the integrated circuit. Such an integrated circuit is also included as an example of a processor.

Examples of storage 55 include a magnetic disk, a magneto-optical disk, an optical disk, and a semiconductor memory. Storage 55 may be an internal medium directly connected to the bus of computer 50, or an external medium connected to computer 50 via interface 57 or a communication line. In addition, when this program is distributed to computer 50 via a communication line, computer 50 that receives the program may expand the program in main memory 53 and execute the above-mentioned processing. In at least one embodiment, storage 55 is a non-transitory tangible storage medium.

The program may be for realizing some of the functions described above. Furthermore, the program may be a so-called differential file (differential program) that realizes the functions described above in combination with other programs already stored in storage 55.

<Additional Notes>
The map generating device, the map generating method, and the map generating program described in each embodiment can be understood, for example, as follows.

(1) According to a first aspect, a map generating device (11) includes a request acquisition unit (113) that acquires request information indicating a position in map data for which a specified accuracy is required, and a map generating unit (115) that generates map data including a basic mesh (M1) among the multiple basic meshes (M1) that does not include a position indicated by the request information, and an extended mesh (M2, M3) that includes the position indicated by the request information, based on a map database (17) that stores multiple basic meshes (M1) that store map information indicating a relationship between a position in a specified range on the ground and attributes of the position, and multiple extended meshes (M2, M3) that store map information with a higher density than the basic mesh (M1).
According to the first aspect, the map generating device (11) can generate map data with a small data size while maintaining the required accuracy.

Note that "obtaining" means getting a new value. For example, "obtaining" includes receiving a value, accepting input of a value, reading a value from a storage medium, calculating one value from another, etc. Note that because an extended mesh is a mesh with a higher information density than the base mesh, the extended mesh does not necessarily have to represent a sub-area smaller than the base mesh.

(2) According to a second aspect, in the map generating device (11) relating to the first aspect, the map database (17) stores multiple extended meshes (M2, M3) by accuracy level, the higher the accuracy level, the higher the density of map information, the request information includes the accuracy level required for the position, and the map generating unit (115) may generate map data including the extended meshes (M2, M3) associated with the accuracy level indicated by the request information.
According to the second aspect, the map generating device (11) can suppress the data size of the map data to the minimum necessary data size according to the required accuracy.

(3) According to the third aspect, in the map generating device (11) according to the first or second aspect, the map generating unit (115) may generate map data in which, among basic map data composed of a plurality of basic meshes (M1), a basic mesh (M1) including a position indicated by the request information is replaced with an extended mesh (M2, M3) including the position indicated by the request information. In other words, according to the third aspect, the map data generated by the map generating device (11) can reduce the amount of data in the overlapping portions between the basic mesh and the extended mesh. In other words, the map generating device (11) can reduce the data size of the map data.

(4) According to a fourth aspect, in the map generating device (11) according to any one of the first to third aspects, the request information may include a position of a toll road.
(5) According to the fifth aspect, in the map generating device of the second aspect, the request information may include a position of a toll road associated with a first accuracy level and a boundary position between a toll road and a non-toll road or a position of an intersection of a toll road associated with a second accuracy level higher than the first accuracy level.
According to the fourth and fifth aspects, the map generating device (11) can generate map data suitable for use in tolling of toll roads.

(6) According to the sixth aspect, the map generating device (11) according to any one of the first to fifth aspects may include an update map output unit (117) that outputs the generated map data to a device (13, 15) that stores old map data. According to the sixth aspect, the map generating device (11) can output map data with a small data size to the device (13, 15), thereby reducing the amount of communication and communication time required for updating the map data.

(7) According to the seventh aspect, the map generating method includes the steps of: acquiring request information indicating a position in map data for which a specified accuracy is required (S1); and generating map data including a base mesh that does not include a position indicated by the request information among the multiple base meshes and an extended mesh that includes a position indicated by the request information, based on a map database that stores multiple base meshes that store map information indicating a relationship between a position in a specified range on the ground and an attribute of the position, and multiple extended meshes that store map information with a higher density than the multiple base meshes (S6-S8).

(8) According to the eighth aspect, the map generation program causes a computer to execute the steps of: acquiring request information indicating a position in map data for which a specified accuracy is required (S1); and generating map data including a base mesh that does not include a position indicated by the request information among the multiple base meshes and an extended mesh that includes a position indicated by the request information, based on a map database that stores multiple base meshes that store map information indicating a relationship between a position in a specified range on the ground and an attribute of the position, and multiple extended meshes that store map information with a higher density than the multiple base meshes (S6-S8).

1...Map update system 11...Map generation device 111...Request input unit 112...Request storage unit 113...Request acquisition unit 114...Mesh acquisition unit 115...Map generation unit 116...Map storage unit 117...Updated map output unit 13...Vehicle-mounted device 15...Billing server 17...Map database 50...Computer 51...Processor 53...Main memory 55...Storage 57...Interface M1...First mesh M2...Second mesh M3...Third mesh

Claims (5)

a request acquisition unit that acquires request information indicating the location of a toll road in map data;
a map generating unit that generates map data including a basic mesh that does not include the position indicated by the request information and an extended mesh that includes the position indicated by the request information, based on a map database that stores a plurality of basic meshes that store map information indicating the relationship between positions within a predetermined range on the ground and attributes of the positions, and a plurality of extended meshes that store map information with a higher density than the basic meshes;
A map generating device comprising: The map generating unit generates the map data by replacing a basic mesh including the position indicated by the request information, among basic map data constituted by the plurality of basic meshes, with the extended mesh including the position indicated by the request information.
The map generating device according to claim 1 . 3. The map generating device according to claim 1, further comprising: an updated map output unit that outputs the generated map data to a device that stores old map data. obtaining request information indicating the location of a toll road in map data;
generating map data including a basic mesh that does not include the position indicated by the request information and an extended mesh that includes the position indicated by the request information, based on a map database that stores a plurality of basic meshes that store map information indicating a relationship between positions in a predetermined range on the ground and attributes of the positions, and a plurality of extended meshes that store map information with a higher density than the basic meshes;
A map generating method comprising: On the computer,
obtaining request information indicating the location of a toll road in map data;
A map generation program for executing a step of generating map data including a basic mesh among the plurality of basic meshes that does not include the position indicated by the request information, and an extended mesh that includes the position indicated by the request information, based on a map database that stores a plurality of basic meshes that store map information indicating the relationship between positions within a specified range on the ground and attributes of the positions, and a plurality of extended meshes that store map information with a higher density than the basic meshes.

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