JP2004226730A - Map data preparation method and device, recording medium, user device and preparation program for map data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose, for example, a map data preparation method that reduces deviation of map components between new and old map data in the case of partial renewal of map data. <P>SOLUTION: With nation wide map data read in, areas are divided using roads of the highest-level selection reference (e.g., national routes or toll roads except elevated highways or ferry lines) as a boundary (a-c). Then, if the data size in a state with the divided areas converted into navigation data is in excess of the upper limit, the areas are redivided using roads of the next-highest-level selection reference (e.g., roads of the highest grade in prefectural roads and city/town/village roads) as a boundary (d, e). Thus, the map data are divided using roads as a boundary; hence, in the case of partial renewal, roads in the adjacent areas are guaranteed to be the same roads. Accordingly, at least connection upto the roads serving as the boundary can be secured. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for creating map data used for displaying a map on a navigation device or the like.
[0002]
[Prior art]
For example, in a navigation device, various functions such as map display and route calculation are realized using map data. As illustrated in FIG. 8, the map data used for the map display and the like is obtained by dividing a map into rectangular shapes and generating divided map data 80 that is map data for each area on the divided map. In general, the map data 100 is configured by combining the generated divided map data 80 of each area. As the unit of the rectangular division, for example, an area of a unit of a primary mesh or a secondary mesh defined by JIS (Japanese Industrial Standard) based on a certain longitude width can be considered.
[0003]
Such map data is stored in a recording medium (hereinafter, also referred to as CD / DVD) such as a CD-ROM or DVD-ROM, and the navigation device sends the map data from the CD / DVD via a map data input device. Read out. For example, the divided map data 80 included in the drawing range 90 is acquired from the map data 100, drawn, and a map is displayed. For example, when drawing a map in the drawing range 90 shown in FIG. 8A, the navigation device acquires the divided map data 80a from the map data 100 (hereinafter, when a specific map data is indicated, the divided map data 80a is divided). As in the case of the map data 80a, a suffix is added, and when not particularly distinguished, it is expressed as the divided map data 80.) The drawing range 90 drawn by the navigation device is the range shown in FIG. If there is, the divided map data 80a to 80d are acquired.
[0004]
If the divided map data 80 is a rectangular area, the length of the side of the rectangle or the like is defined in advance, so that if only the latitude and longitude of one vertex or center point of the rectangle is stored as information, Which part corresponds to the divided map data can be specified. Therefore, for example, the divided map data 80a to 80d for drawing the drawing range 90 as shown in FIG. 8B can be easily specified and obtained.
[0005]
By the way, the map data in the CD / DVD provided to such a navigation device may not be available for several years due to various situations such as opening of a new road, change of road shape and traffic regulation, establishment and closing of various facilities, and the like. It will be old. For this reason, CDs and DVDs are sold with their contents updated periodically (for example, every year). The procedure will be described. First, map data (hereinafter referred to as map source data) serving as a source of map data stored on a CD / DVD is newly created. Then, the latest map source data is created, and thereafter, the map source data is edited to create the latest version of CD / DVD, which is sold. Editing a map source data to create a CD / DVD means editing the map source data and writing the edited map data to a CD / DVD in a data unwritten state.
[0006]
In the conventional in-vehicle navigation device, the user has to purchase a new version of CD / DVD every time a new version is sold in order to always obtain the latest information.
On the other hand, from the center as the external information providing station to the navigation device of the vehicle, difference information between the old map data in the CD / DVD held by the device and the newer map data (that is, additional or additional information). Information about the deleted or changed data) is supplied using wireless communication or the like, and the navigation device updates its own map data to new contents based on the difference information from the center. , A map data update system (hereinafter referred to as a differential update system) has been proposed. If such a differential update system is put into practical use, the user of the in-vehicle navigation device always obtains road information based on the latest information without purchasing the latest CD / DVD each time. (For example, see Patent Document 1).
[0007]
[Patent Document 1]
JP 2001-109373 A
[0008]
[Problems to be solved by the invention]
However, even if such a concept of the difference update exists, the difference update of the map data is not actually operated, and the examination of a specific problem that occurs when the operation is actually performed is not enough. Was. The inventors of the present application have paid attention to the following problem as a result of considering a problem that may occur when such a difference update of map data is actually operated. In this case, the map data is updated, for example, in units of the divided map data 80 described above, but the updated map data (new map data) and the unupdated map data (old map data) are connected. This is a problem in that a deviation between map data in a portion occurs. At first glance, it seems that there is no shift between the old and new map data, but in fact, it is considered that the shift occurs in the map data due to the following reasons.
[0009]
(1) Although the road itself exists in both the new and old map data, for example, when the position of the road itself is changed, if the new and old map data are mixed, a deviation naturally occurs.
(2) If the position of the road itself is not changed, but the data creation standards and the like of the old and new map data are different, it is conceivable that a shift occurs due to the mixture of the new and old map data. For example, when the accuracy of indicating the road position is improved, the old map data is shifted from the actual position, but the new map data matches or becomes closer to the actual position. This is the case, for example, in which different companies perform different standards of creation.
[0010]
When such a shift occurs, the road is divided in the middle of the connection portion of the map data, so that a road that is originally continuous becomes discontinuous. In addition, the cause as described in the above (2) occurs not only in roads but also in other map components.
If these map components are displayed displaced at the connection between the new and old maps, they will look very bad. In addition, there is a possibility that the map matching accuracy is reduced. The map matching specifies the current position on which road the current position is located using, for example, the current location information detected using GPS or the like and the road shape data of the map data. Is difficult to specify around the map connection. Furthermore, inappropriate right / left turn guidance may be executed due to such a decrease in map matching accuracy or a sudden change in shape due to a deviation. As described above, the navigation function is not properly exhibited, and the partially updated effect is diluted.
[0011]
As one of the causes of such a shift, the present inventors paid attention to the structure of the divided map data. In other words, in view of the merit that it is easy to specify which part of the whole map corresponds to the divided map data, rectangular divided map data is assumed. The reason for this is that the road is often split on the way.
[0012]
It is therefore an object of the present invention to propose a method of creating map data in which, when such a partial update of map data is performed, the deviation of map components between new and old map data is reduced.
[0013]
Means for Solving the Problems and Effects of the Invention
(A) According to the map data generating method according to the first aspect, road data having a predetermined selection criterion is selected from among the original map data to be divided including at least road data, and the original map data to be divided is selected. Is divided into a plurality of areas surrounded by the divided road data, and divided map data that is map data for each of the divided areas is created.
[0014]
It is conceivable that the selection criterion of the road that becomes the boundary of the divided map data is determined based on at least one or more of the road type, the road attribute, the number of lanes, and the road width, for example. For example, it is conceivable to adopt a main road such as a main national road as a boundary road. In addition, for example, it is conceivable to determine the route based on the “road case” which is a factor that makes the cost when performing the cost calculation in the route search relatively high.
[0015]
By using such a main road as a boundary, even when a road network is updated and partially updated to new data in units of divided map data, the network including the updated road is interrupted. Can never be.
This is because, in the case of a conventional method in which map data is divided into, for example, rectangles regardless of the road network, a state may occur in which the updated road is interrupted and not connected to another road at the boundary of the divided map data. On the other hand, in the case of the method of the present invention, since the road is used as the boundary of the divided map data, at least the connection to the road at the boundary can be secured. In addition, if a road is used as a boundary, the possibility that the map components other than the road will be divided is very low, which is advantageous in that respect. By doing so, the effect of partially updating the map data in units of the divided map data can be enhanced.
[0016]
However, if any road can be a boundary, the map data may be too small. In addition, low-grade roads tend to be newly constructed or changed in a relatively short period of time as compared with main roads. Conversely, since the main road is unlikely to be changed, it is preferable to set a boundary based on the main road because the road itself at the boundary is unlikely to be changed.
[0017]
(B) Also, the frequency of existence of a road according to a predetermined selection criterion differs depending on the region. Therefore, it is assumed that an area surrounded by a road having the same selection criterion is relatively wide in a place and relatively narrow in another place. Then, you may make it show in Claim 3.
[0018]
That is, a plurality of stages are prepared as a predetermined selection criterion, and first, the road data of the highest selection criterion is selected from the original map data to be divided. Then, the original map data to be divided is divided into a plurality of regions surrounded by the road data of the highest selection criterion, and at least one of the area or the data size of the divided region is determined as a determination target. It is determined whether the value exceeds the upper limit. Then, based on the determination result, when the determination target is equal to or smaller than the predetermined upper limit value, divided map data that is map data for each divided region is created. On the other hand, when the determination target exceeds the predetermined upper limit value, the road data of the next selection criterion existing in the divided area is selected, and further divided using the road data, and the determination in the divided area is performed. It is determined whether or not the target exceeds the predetermined upper limit value. Thereafter, based on the determination result, the divided map data is created, or until the divided map data is created, the selection criterion in the next step is determined. Of the road data, region division using the road data, and determination as to whether or not the determination target of the divided region exceeds a predetermined upper limit.
[0019]
As described above, by recursively dividing using the selection criteria of a plurality of stages, at least one of the area and the data size of the divided divided map data can be equal to or less than the upper limit value. Since the data size and area are dependent on the buffer size and processing capacity of a device (for example, a navigation device) that performs processing using map data, there is an upper limit for each actual device. Therefore, it is possible to create divided map data that matches this upper limit value.
[0020]
Since the upper limit may be different for each actual device, it is preferable that the upper limit can be changed and set.
(C) In the case where the divided map data has a relatively large area, it can be dealt with by performing the re-division as shown in claim 3. On the other hand, in the case where the divided map data has a relatively narrow area, A problem may occur because the area or data size of the map data is too small. For example, if the data size is too small, the number of maps to be read in an apparatus that performs processing using map data, such as the above-described navigation apparatus, increases, so that the processing speed decreases. Therefore, as described in claim 4, after the above-described division, integration may be performed as necessary.
[0021]
In other words, when the area is divided into a plurality of areas surrounded by the selected road data, at least one of the area and the data size of the divided area is determined and integrated with another divided area (adjacent area) adjacent to the divided area. In this case, it is determined whether or not the determination target exceeds the upper limit value, and if integrated with any adjacent region exceeds the upper limit value, the divided map data is not integrated with the adjacent region. If the upper limit value is not exceeded, the divided map data is created in a state of being integrated with the adjacent area.
[0022]
In this way, it is possible to prevent the divided map data from being too large and too small in area, or from being too large and too small in data size.
Further, as set forth in claim 5, it is more appropriate to integrate one or more adjacent regions so that the determination target is maximized within a range in which the determination target does not exceed the upper limit value. It is possible to create simple divided map data.
[0023]
(D) By the way, as a method of creating map data, for example, in the case of a wide area map, a hierarchical structure may be provided because it is sufficient to display only main roads. That is, the types of roads constituting the map are changed according to the hierarchy. In the case of creating map data having such a hierarchical structure, roads having a predetermined deletion criterion corresponding to the hierarchy are deleted from the map data created by the map data creation method. Then, it is considered that the map data after the road deletion is integrated within a range in which the determination target in the integrated map data is less than a predetermined upper limit value according to the hierarchy, and map data according to the hierarchy is created. Can be
[0024]
(E) The invention according to claim 8 uses input means for inputting original map data to be divided including at least road data, and uses the original map data input via the input means. A map data creation device that creates the map data by executing the map data creation method according to any one of the above. This map data creation device can create the above-described divided map data.
[0025]
In addition, if only the method of automatically determining the division boundaries of map data by a computer in such a map data creation device is used, there is a possibility that boundaries at inappropriate locations may be set in reality. is there. For example, if roads serving as boundaries are arranged side by side at relatively narrow intervals and relatively long distances, an elongated divided map will result. In such a case, the practicality is relatively low in terms of practicality, and it is more efficient to set either one as a boundary. Also, for example, in the area along the coast or in the mountains, inappropriate boundaries may be set from the viewpoint of the road network, or there may be no appropriate boundaries that reduce the data size to the upper limit or less. possible.
[0026]
Therefore, in reality, it is also a preferable measure to display the divided area and manually set the boundary so that a more appropriate area is displayed while a person checks the area. In this case, as set forth in claim 9, a display means capable of displaying a map based on the map data created by the creation means, and designation of an arbitrary road in the map displayed by the display means And receiving means for receiving an instruction to set the designated road as a new boundary, wherein the creating means creates map data based on the specification and instruction received by the receiving means, using the designated road as a new boundary. It is conceivable to configure so as to re-execute.
[0027]
(F) The map data created as described above can be recorded on a recording medium such as a CD-ROM, a DVD-ROM, or a hard disk (claim 10). Then, the present invention can be used in a map data using apparatus using map data as described in claim 11. As one example, a map data utilization device having a navigation function including at least a map display can be considered. For example, when performing a process of drawing and displaying a map near the current position as a navigation function, the position of the drawing range often changes continuously, but by using such map data, The connection between map data becomes more appropriate. In other words, when the map is divided into meshes as in the past, the accuracy of specifying the connection relation of the divided roads at the boundary of the divided map becomes a problem, but in the case of the present invention, the road itself is identified. The reason for this is that the accuracy of the connection is relatively high because of the boundary.
[0028]
(G) A map data creation program according to claim 13 is a program for causing a computer to realize a function as a creation unit in the map data creation device according to claim 8 or 9.
If the computer according to claim 8 or 9 executes the program according to claim 13, the map data creation device according to claim 8 or 9 can be configured. Therefore, the same effects as those of the map data creation device according to the eighth or ninth aspect can be obtained. This program can be stored and distributed on a recording medium such as a magnetic disk such as a flexible disk or a magneto-optical disk or a compact disk, and can be loaded from the recording medium into a computer system as required and activated. Can be used. It can also be distributed via a network, and can also be used by loading and activating over a network.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments to which the present invention is applied will be described with reference to the drawings. It is needless to say that the embodiments of the present invention are not limited to the following examples, and can take various forms within the technical scope of the present invention.
[0030]
[Overview of the entire system]
FIG. 1 is an explanatory diagram showing an outline of an entire system including a processing device 1 as a map data creation device and a navigation device 20 as a map data utilization device according to an embodiment. The processing device 1 reads the original data from the disk D1 in which the original data of the map data produced by a map production company or the like is stored, and creates map data to be used by the navigation device 20. The created map data is stored and distributed on the navigation disk D2, and the navigation device 20 executes navigation processing such as map display using the map data read from the navigation disk D2. The map data created by the processing device 1 is sent to an information center (hereinafter, simply referred to as “center”) 50 as an external information providing station provided on the ground, and the center 50 sends the map data to the navigation device 20. The map data can be transmitted also by wireless communication.
[0031]
[Description of Processing Apparatus 1]
The processing device 1 includes a control unit 11 having a microcomputer as a main unit, a storage unit 12 for storing calculation results and map data by the control unit 11, a display as display means (not shown), various key switches, and the like. And a communication unit 14 for performing wireless communication with the center 50.
[0032]
The storage unit 12 is capable of holding a record even when the power supply to the processing device 1 is cut off, and is, for example, an EEPROM, a flash ROM, or a hard disk.
As described above, the processing device 1 reads the original data from the disk D1 storing the original data of the map data via the input / output unit 13. For this reading, for example, the input / output unit 13 has a disk drive, and data may be read by the disk drive, or the disk may be read by an external device connected to the processing apparatus 1 via a communication line (not shown). Data may be read from D1 and the data may be input via the input / output unit 13. The input / output unit 13 corresponds to an “input unit”.
[0033]
Then, the control unit 11 creates a later-described divided map or the like, converts the divided map into navigation data, merges the divided maps, and creates map data to be stored in the distribution navigation disk D2. . Note that the control unit 11 corresponds to “creating means”. This map data is output to an external device via the input / output unit 13, and is stored in the navigation disk D2 in the external device. The navigation disk D2 in which the map data is stored is distributed to the user of the navigation device 20 as described above, and is used for the navigation device 20 owned by the user.
[0034]
The created map data is also transmitted to the center 50 via the communication unit 14.
[Description of Center 50]
The center 50 creates a map database (hereinafter referred to as a map DB) based on the map data transmitted from the processing device 1. The center 50 creates a yearly version of the map database each time the map data for each year is transmitted from the processing device 1 (every time it is received). Further, the center 50 compares the latest XY year map data with the old XX year map data, for example, when the XY year map data is received, and compares the difference data between the new and old map data (ie, , Added or deleted or changed data), and updating information (XX) for the navigation device 20 to upgrade the XX year version map data to the XY year version map data from the extracted difference data. Year-XY year update information). The unit of extraction of the difference data is the unit of the divided map area created by the processing device 1.
[0035]
Specifically, of the difference data, update information indicating that the data should be deleted is added to each of the data included only in the old map data, and is included only in the new map data. Update content information indicating that it should be added is added to each data. Also, of the difference data, the data that is included in both the new and old map data but whose content has been changed is included in each of the old data with information indicating that the data should be changed and a change. Update information including new data to be added is added. Then, the data group to which each of the update content information is added is stored as update information in a predetermined storage medium.
[0036]
Similarly, at the time of receiving the XZ year map data, the center 50 compares the latest XZ year map data with the old XY year map data in exactly the same manner as described above, and compares the new and old map data. Information for updating between the XY year version map data and the XZ year version map data by the navigation device 20 from the extracted difference data (XY year-XZ year update). Information).
[0037]
When the center 20 receives a request for update information from the navigation device 20, the center 20 updates the map data held by the navigation device 20 to the latest contents based on the version information from the navigation device 20. And transmits the update information.
[0038]
[Description of Navigation Device 20]
As shown in FIG. 2, the navigation device 20 includes a control device 21 having a microcomputer as a main part, an input / output device 22 including a display as a display device (not shown) and various key switches, and a center 50. A communication device 23 for performing wireless communication between them, a map data input device 24 for inputting map data from a navigation disk D2 in which map data is stored, and a calculation result by the control device 21 and map data are stored. And a storage medium 25.
[0039]
The storage medium 25 can retain the stored contents even when the power supply to the navigation device 20 is cut off, and is, for example, an EEPROM, a flash ROM, or a hard disk.
The input / output device 22 also includes a position detection device (not shown). This position detection device includes a well-known gyroscope, a distance sensor, a GPS receiver that detects the position of a vehicle based on radio waves from satellites, and the like.
[0040]
Further, the control device 21 realizes functions such as map data acquisition, map matching, route calculation, route guidance, drawing, screen control management, and the like. Each function will be briefly described.
The map matching is a function of specifying on which road the current position is located, using the current position information detected by the position detection device and the road shape data of the map data stored in the storage medium 25.
[0041]
Further, the user can input an instruction to display a desired map by using a key switch, and can further set a destination. In the route calculation, information on the current position calculated by the map matching and the route from the departure point set by the user to the destination are calculated. As a method for automatically setting the optimum route, a method such as the Dijkstra method is known. The route guidance calculates points required for route guidance based on the calculation result of the route calculation and road shape data stored in the map data, position information of intersections, and position information of level crossings. It is determined whether such guidance (for example, whether to turn right or left) is required.
[0042]
In the drawing, a map of the current position, a schematic diagram of an expressway, an enlarged view of an intersection near an intersection, and the like are drawn in a drawing memory unit composed of a VRAM or the like, and the drawn map or the like is displayed on a display.
In the map data acquisition, the map data required for each of the above processes is acquired from the navigation disk D2 via the map data input device 24 and supplied to each processing unit. Each of the above processes is executed based on a program in the storage medium 25, and is also executed using a work memory in the storage medium 25.
[0043]
When the distribution of the updated map data is received from the center 50 via the communication device 23, the control device 21 partially updates the map data stored in the storage medium 25 using the updated map data. .
First, when a user (user) of the navigation device 20 issues an input command to start data update via a key switch or the like of the input / output device 22, the control device 21 connects to the center 50 via the communication device 9, Further, information on the version of the map data currently owned and used by the navigation device 20 (information on when the map data is) is read from the navigation disk D2 or the storage medium 25, and the read version information is read. To the center 50 via the communication device 23.
[0044]
Then, based on the version information from the navigation device 20, the center 50 determines whether or not the map data held by the navigation device 20 is the latest version, and returns the determination result to the navigation device 20.
Therefore, the control device 21 of the navigation device 20 obtains the determination result from the center 50 via the communication device 23, decodes the determination result, and connects to the center 50 if the map data is the latest version. Disconnect. That is, there is no need to update the map data.
[0045]
On the other hand, if the map data is not the latest version, the control device 21 transmits a signal for requesting information for updating the map data to the center 50 via the communication device 23. Then, the center 50 transmits update information for updating the map data currently held by the navigation device 20 to the latest content to the navigation device 3. The update information is acquired from the center 50 via 23.
[0046]
Then, after that, the control device 21 disconnects the connection with the center 50 and uses the update information obtained (supplied) from the center 50 to update the map data held by itself. Perform processing. The outline of the updating process will be described.
[0047]
For example, if the map data has never been updated, the map data in the navigation disk D2 is transferred to the storage medium 25 that can be read and written. The update information received from the center 50 is analyzed, and if there is data to which update content information indicating “delete” is added in the update information, the data is read from the map data in the storage medium 25. If there is data to which update content information indicating "addition" is added in the update information, the data is added to the map data in the storage medium 25. Further, if there is data to which update content information indicating "change" is added in the update information, the data is searched for from the map data in the storage medium 25 and deleted, and the data is replaced with the deleted data. Then, the new data included in the update content information indicating “change” is added to the map data in the storage medium 25. That is, the data found from the map data is replaced with the new data.
[0048]
When the map data is updated for the second time or later, the above process is performed without transferring the map data in the navigation disk D2 to the storage medium 25. If the navigation disk D2 is a data rewritable storage medium and the map data input device 24 can execute not only reading but also replacement processing, the storage contents of the navigation disk D2 itself may be rewritten. Can be
[0049]
[Description of map data creation processing in processing device 1]
Next, processing related to the creation of map data executed by the control unit 11 of the processing device 1 will be described with reference to the flowcharts of FIGS.
(Segmented map boundary determination processing)
FIG. 3 shows the process of determining the boundaries of the divided maps. This process is started, for example, when a person inputs a creation start instruction via the input / output unit 13.
[0050]
First, the map data of the whole country, which is the original data, is read from the disk D1 in which the original data of the map data is stored via the input / output unit 13 (S110). It should be noted that, even though this nationwide map data can be divided into meshes as in the conventional method, for example, the entire map data is processed as one map here.
[0051]
Next, area division is performed using the road of the selection criterion at the highest stage as a boundary (S120). As the “road of the selection criteria at the highest stage”, it is conceivable to adopt a national road or a toll road excluding an elevated road and a ferry route. FIGS. 6A and 6B show examples of this area division. In the map data (nationwide) in which the boundaries are not determined as shown in FIG. 6A, an area surrounded by roads serving as boundaries as shown in FIG. 6B is defined as a divided area.
[0052]
Then, the number of areas divided in S120 is set as the initial value of the variable N (S130), and the processing of S150 to S190 below is looped by the number of divided areas.
First, in S150, an area to be processed is determined. For example, in the case of map data in which the latitude and longitude are smaller, that is, in the case of map data in which the upper part is north, it is prescribed that the processing is sequentially performed from the lower left divided area to the upper right divided area, and the processing target area is determined in accordance with the order. To determine.
[0053]
Next, the data in the processing target area is converted into navigation data (S160), and the converted data size is calculated (S170). Then, it is determined whether the data size is equal to or smaller than a predetermined upper limit (S180). This upper limit is determined from the following viewpoints. That is, in the navigation device 20 that finally performs processing such as map display using the map data, there is a limit in the buffer size and the processing capability at the time of the drawing process. And set the upper limit. It is preferable that the upper limit can be changed and set. That is, it may be better to change the upper limit value depending on the type of the navigation device 20.
[0054]
If the data size is equal to or smaller than the upper limit (S180: YES), the variable N is decremented (N ← N−1) (S200), and it is determined whether or not the variable N is 0 (S140). If N is not 0 (S140: NO), the next processing target area is determined (S150), and the same processing is performed, that is, conversion to navigation data → data size calculation → whether the data size is equal to or smaller than the upper limit value. The determination (S160 to S180) is performed.
[0055]
On the other hand, if the data size exceeds the upper limit (S180: NO), the area is subdivided with the next selection reference road as a boundary among the roads in the area, and the data of each subdivided area is used for navigation. After converting to data and checking the data size, if it exceeds the upper limit, the area is further subdivided with the next selection reference road as the boundary, and the data size of each subdivided area is checked. The process is recursively executed until the data size of the divided area becomes equal to or smaller than the upper limit (S190).
[0056]
As a selection criterion at each stage, it is supposed that an elevated road or a ferry route is excluded, and the following setting can be considered. In other words, the top-level selection reference road is, for example, a national road or a toll road as described in S120, and the next-step selection reference road is, for example, the highest grade road among prefectural roads and municipal roads, and the next-level selection reference road. For example, it is the next highest road among prefectural roads and municipal roads. The “road case” here is known as a factor that relatively increases the cost when performing cost calculation when searching for a route. Specifically, for example, it is determined based on a road type (a national road, a prefectural road, a municipal road, etc.), a road attribute (for example, free of charge), the number of lanes (how many lanes each way), a road width (how many meters or more, etc.), and the like. Is what is done. In the above example, the road type is distinguished from the national road to the prefectural road and the municipal road. However, the case of the road used in the route calculation may be higher than the national road, for example, even if the road is a prefectural road. Therefore, the selection criterion may be determined simply based on the “grade of the road” without setting a condition for the road type.
[0057]
FIGS. 6C to 6E show examples of the subdivision. In this example, as shown in FIG. 6C, it is assumed that the data size of the divided area to be processed is 200 KB (kilobytes). If the upper limit value is set to 128 KB, the data size of the divided area to be processed exceeds the upper limit value. Therefore, as shown in FIG. I do. In this case, for example, as shown in FIG. 6E, the data size of one area (Map1.dat) after the subdivision is 110 KB, and the data size of the other area (Map2.dat) is 90 KB. It is less than the upper limit of 128 KB.
[0058]
After the process of S190, the process proceeds to S200, and the variable N is decremented. When the processing for all the processing target areas is completed in this way (S140: YES), the process proceeds to S210 and the integration processing is executed.
(Integrated processing)
First, the intention of executing this integration processing will be described. Even in a state where the area is divided using the road at the highest level as the reference in S120 in FIG. 3, if the boundary road exists in the vicinity, it is assumed that the divided area becomes extremely small. Is done. Further, even if the data size in the case where the data is divided using the relatively higher-level selection reference road as a boundary, the data size exceeds the upper limit value. Also, it is assumed that the subdivision area becomes extremely small because of the reason that the road that is the boundary exists in the vicinity. Although the problem when the data size is too large has been described above, there may be a problem that the data size is too small. For example, if the data size is too small, the number of maps to be read when performing processing using the map data in the navigation device 20 increases, and the processing speed relatively decreases. Therefore, in the integration processing, the integration is performed as much as possible within a range where the data size of the integrated area does not exceed the upper limit value.
[0059]
The details of this integration process (S210 in FIG. 3) will be described with reference to the flowchart in FIG.
First, the number of divided areas is set as an initial value of the variable M (S211). The number of divided areas is not limited to the number in the state where the area is divided in S120 of FIG. 3, and when the division is performed again in S190, the number of divided areas naturally increases. That is, it indicates the number of divided areas existing at the time of shifting to the process of S210 in FIG. Therefore, the relationship between the variable M and the variable N is M ≧ N.
[0060]
Next, the variable M is decremented (M ← M−1), and it is determined whether the variable M is 0 (S213). If the variable M is not 0 (S213: NO), a processing target area is determined (S214). The determination of the processing target area may be performed in the same manner as in the case of S150 in FIG. 3. For example, in the case of map data in which the latitude and longitude are small, that is, in the case of map data in which the upper part is north, the lower left divided area to the upper right divided area , And the processing target area may be determined according to the order.
[0061]
Next, all areas adjacent to the processing target area are selected (S215), and the number of the adjacent areas is set as an initial value of the variable α (S216). Then, an adjacent area to be integrated is determined (S217), the data is converted into navigation data while being integrated with the determined adjacent area (S218), and the converted data size is calculated (S219). Then, it is determined whether or not the data size is equal to or smaller than a predetermined upper limit (S220). This upper limit is the same as the value used in the determination in S180 of FIG.
[0062]
If the data size is equal to or smaller than the upper limit (S220: YES), the integrated area is determined as a new divided area (S221). Then, the variable α is decremented (α ← α−1), and it is determined whether or not the variable α is 0 (S223). If the variable α is not 0 (S223: NO), since there is another adjacent area, the process proceeds to S217, and the same processing is performed, that is, the adjacent area to be integrated is determined → integrated and converted into navigation data. → Calculation of data size → Judgment as to whether the data size is equal to or smaller than the upper limit value (S217 to S220). Therefore, if the data size after integration is equal to or smaller than the upper limit value, all existing adjacent areas may be integrated. When all areas are integrated, an affirmative determination (variable α = 0) is made in S223 in a state where the area after integration is determined as a new divided area, and the process returns to S212.
[0063]
Also, at least one adjacent area is integrated and determined as a new divided area (S221). However, if the data size after integration exceeds the upper limit before integrating all adjacent areas (S220: NO) ), And again returns to S212. In this case, the new divided area after integration determined in S221 in the processing loop (S217 to S223) immediately before a negative determination is made in S220 is valid.
[0064]
On the other hand, if the data size has already exceeded the upper limit in a state where the adjacent area to be integrated has been integrated (S220: NO), the process returns to S212 without performing integration, and the processing from S214 onward for the next area to be processed. The processing of is performed.
Note that there are various methods for determining the adjacent area to be integrated in S217. Since the adjacent area exists so as to surround the area to be processed determined in S214, for example, if the map data has an upper side of north, the map data is located on the lower side → left side → upper side → right side of the area to be processed The priority of the integration target is determined in the order of the adjacent areas (that is, clockwise). In addition, even if it says lower side → left side → upper side → right side, it does not necessarily mean that only one adjacent area exists on any side. Since the boundary is a road, depending on the arrangement of the road network, there may be two or more adjacent areas on each side, and conversely, there is only one adjacent area, for example, spans both the left side and the upper side It is possible. FIG. 7 illustrates an example in which the processing target area and the adjacent area are integrated.
[0065]
Also, in S214 after the second time of the processing loop of S212 to S223, the following points are noted. That is, with respect to the determination of the processing target area, for example, in the case of map data in which the upper part is north, it is defined that the processing is performed in order from the lower left divided area to the upper right divided area, and according to the order. It has been described that the processing target area may be determined. Here, for example, in the processing loop (S212 to S223) relating to the first processing target area, the area that should be the second processing target area in the above order is integrated with the first processing target area. In some cases. In this case, in the processing loop (S212 to S223) for the second processing target area, the divided area after the integration is treated as a processing target. Therefore, in the above order, the area to be the second processing target area may be selected as the adjacent area. However, since the above-mentioned “first processing target area” has already been integrated, it is determined as the adjacent area. Is not selected. It should be noted that the data size may be smaller than or equal to the upper limit value even if the data is integrated with the area to be the third processing target area in the above-described order. For example, areas to be the first to third processing target areas are integrated and determined as a new divided area.
[0066]
In this way, the integration with the adjacent area is performed as much as possible within the range that is equal to or less than the upper limit value. When the variable M becomes 0 (S213: YES), the integration processing ends. As a result, the process of determining the boundaries of the divided maps in FIG. 3 also ends. Note that when the variable M becomes 0 (S213: YES), it means that the processes from S214 onward are executed only once—the number of divided areas set as the variable M in S211. That is, the processes after S214 are not executed for the last (M-th) processing target area. However, the adjacent area corresponding to the M-th processing target area is always the processing target area before the (M-1) -th processing area. If the M-th processing area is not integrated during the processing for the (M-1) -th processing area before the M-th processing area, the M-th processing area is integrated. There is no case where the target area can be integrated with the adjacent area. Therefore, it is not necessary to execute the processing for the last processing target area.
[0067]
When the boundaries of the divided map are determined in this way, the control unit 11 divides the map data of the whole country according to the determined boundaries to create the divided map data.
(Higher hierarchy creation processing)
In this embodiment, map data is created for each level from level 5 to level 0 for each level of detail. Level 5 is the widest level on the map in which each divided map data is recorded, and stores only topographic data. Level 4 is the one in which the recording range of each divided map data is set wider than that of level 5, and stores terrain data and highway road data. Level 3 is a range in which the recording range of each divided map data is set in a size following Level 4, and stores road data of national roads in addition to terrain data and road data of expressways. Level 2 is a range in which the recording range of each divided map data is set in the area following Level 3 and stores road data of prefectural roads in addition to terrain data and road data of expressways and national roads. Level 1 is a range in which the recording range of each divided map data is set in the area following Level 2 and stores road data of city roads in addition to terrain data and road data of expressways, national roads and prefectural roads. I have. At level 0, the recording range of each divided map data is set in the area following level 1, and in addition to topographic data and road data of expressways, national roads, prefectural roads, and city roads, road data of narrow streets is Stored. That is, level 5 stores the widest area data, and level 0 stores the most detailed data. The divided map data created by the procedure shown in FIGS. 3 and 4 is the lowest layer, that is, the unit data of level 0.
[0068]
Therefore, based on the level 0 divided map data, upper layers (levels 1 to 5) are sequentially created. The upper layer creation processing will be described with reference to the flowchart of FIG. Note that the processing in FIG. 5 is performed only for the upper hierarchy to be created, and as described above, if there are six layers from level 5 to level 0, map data creation from five layers from level 5 to level 1 is performed. Respectively.
[0069]
First, data is created by extracting roads for upper layers from unit data (divided map data) of lower layers (S310). For example, in the case of creating unit data of level 1 using unit data of level 0, in addition to terrain data and road data of expressways, national roads, prefectural roads, and city roads, level 0 including road data of narrow streets is included. The road data of narrow streets is removed from the unit data of, that is, topographic data and road data of expressways, national roads, prefectural roads, and city roads are extracted.
[0070]
Then, a table having a flag area corresponding to the unit number is prepared as a management table corresponding to the lower layer unit (S320). This unit number is defined, for example, in the case of map data in which the latitude and longitude are smaller, that is, in the case of map data in which the upper part is north, the processing is performed in order from the lower left unit to the upper right unit. The unit number may be assigned according to the following.
[0071]
Then, the unit to be processed is determined, and a flag is set in the management table (S330). The unit to be processed may be determined according to the unit number described above (for example, in ascending order of the number).
Then, all the units adjacent to the processing target unit are selected (S340). The number of adjacent units is set as an initial value of the variable β (S350). Then, an adjacent unit to be integrated is determined (S370), the data is converted into navigation data while being integrated with the determined adjacent unit (S380), and the converted data size is calculated (S390). Then, it is determined whether or not the data size is equal to or smaller than a predetermined upper limit (S400). This upper limit is the same as the value used in the determination in S180 of FIG.
[0072]
If the data size is equal to or smaller than the upper limit (S400: YES), the unit after the integration is determined as a unit of a higher hierarchy (S410). Then, a flag is set in the management table for the integrated adjacent unit (S410), the variable β is decremented (S420), and it is determined whether or not the variable β is 0 (S360).
[0073]
If the variable β is not 0 (S360: NO), since there is another adjacent unit, the process proceeds to S370, and the same processing is performed, that is, the adjacent unit to be integrated is determined → integrated and converted into navigation data. → Calculation of data size → Determination of whether or not the data size is equal to or smaller than the upper limit value (S370 to S400). Therefore, if the data size after integration is equal to or smaller than the upper limit, all existing adjacent units may be integrated. When all are integrated, the variable β becomes 0 in S360 (S370: YES), and the process shifts to S440 to determine whether or not the processing has been completed for all the processing target units by referring to the management table. to decide. That is, when the unit to be processed is determined, a flag is set in the management table in S330, and the adjacent unit integrated with the unit to be processed is flagged in the management table in S420. If a unit that has not been processed remains in the management table, a negative determination is made in S440, and the process returns to S320.
[0074]
On the other hand, if the data size has already exceeded the upper limit value in the state where the unit has been integrated with the adjacent unit to be integrated (S400: NO), the process directly proceeds to S440. Is not valid.
When the processing is completed for all units in this way, unit data of the upper hierarchy is created. Note that there is a possibility that there is a processing target unit that is not integrated with an adjacent unit at all, but in that case, the processing unit is treated as an upper layer unit by itself.
[0075]
As described above, after the unit data (divided map data) of each layer is created, the control unit 11 converts the unit data into navigation data, merges the divided maps, and stores the merged map in the navigation disk D2. The map data to be created is created, and the map data is output to an external device via the input / output unit 13. Then, the data is stored in the navigation disk D2 in the external device. The navigation disk D2 is distributed to the user of the navigation device 20 and is used for the navigation device 20 owned by the user. The created map data is also transmitted to the center 50 via the communication unit 14.
[0076]
[Effects of the present embodiment]
(1) When the navigation device 20 receives the updated map data from the center 50 via the communication device 23, the control device 21 uses the updated map data to store the map data stored in the storage medium 25. Is partially updated. When the map data is partially updated, it is necessary to specify a connection relationship with adjacent divided map data. The adjacency can be determined from “absolute latitude / longitude” which is data of a set separately from a map.
[0077]
In the case of such a partial update of the map data, the divided map data of the present embodiment is divided with the road as a boundary, and therefore, it is guaranteed that the roads of the adjacent parts are the same road. By superimposing them, the coordinates, the road type, and the connection relationship with the surrounding roads are checked, and connection processing with the surroundings is performed. For example, in addition to network pattern matching and its connection relation, identification information (ID) may be attached to a connection location, and connection may be made based on these.
[0078]
In addition, since the roads with the highest “grade” are set as boundaries as much as possible, even if the road network is updated and partially updated to new data in units of divided map data, the network including the updated roads Can be prevented from being interrupted. That is, in the case of the conventional method in which the map data is divided into, for example, rectangles regardless of the road network, a state in which the updated road is interrupted at the boundary of the divided map data and not connected to another road may occur. On the other hand, if the divided map data with the road as the boundary is created as in the present embodiment, at least the connection to the road at the boundary can be secured. In addition, if a road is used as a boundary, the possibility that the map components other than the road will be divided is very low, which is advantageous in that respect. By doing so, the effect of partially updating the map data in units of the divided map data can be enhanced.
[0079]
(2) Further, in the present embodiment, not only the road is divided as a boundary but also if the data size of the divided map data is too small, the divided map data is appropriately integrated with the divided map data of the adjacent area. If the data size is too small, the number of maps to be read in the case of performing processing using map data in the navigation device 20 will increase and the processing speed will decrease, but such integration causes such disadvantages. Can be avoided. That is, it is possible to prevent the divided map data from being too large and too small in data size.
[0080]
[Others]
(A) If only the method of automatically executing the process of determining the boundaries of the divided map data by the computer is used, there is a possibility that boundaries at inappropriate locations may be set in reality.
[0081]
For example, if roads serving as boundaries are arranged side by side at relatively narrow intervals and relatively long distances, an elongated divided map will result. This is relatively low in terms of practicality, and it is more efficient to set either one as the boundary.
Also, for example, in the area along the coast or in the mountains, inappropriate boundaries may be set from the viewpoint of the road network, or there may be no appropriate boundaries that reduce the data size to the upper limit or less. possible.
[0082]
Therefore, in reality, it is preferable to display the divided area on the display of the input / output unit 13 of the processing device 1 and manually set a boundary so that a more appropriate area can be obtained while a person checks the area. Note that a pointing device such as a mouse may be prepared in the input / output unit 13 of the processing device 1 in order to set the boundary. In this case, the input / output unit 13 corresponds to “accepting means”.
[0083]
(B) In the above embodiment, the determination of the subdivision or integration of the divided map data is performed based on the data size. However, the determination may be based on, for example, the area, or both the data size and the area. The area may not be an accurate area, but may be a rectangle circumscribing the divided map area, for example, and that area may be used instead.
[0084]
(C) In the above embodiments, the in-vehicle navigation device 20 has been described as an example of the map data using device. However, the present invention is not limited to this, and for example, a map display function for displaying a map on a predetermined display device, a route, and the like. The present invention can be applied to various electronic devices (a personal computer, a portable navigation device, and the like) having a function of executing various processes using map data, such as a search function and a route guidance function.
[0085]
(D) In the above-described embodiment, the system in which the update information is supplied to the navigation device 20 by wireless communication with the center 50 has been described. However, the present invention is not limited to this. For example, a CD-ROM, DVD- The present invention can be similarly applied to a system performed through various storage media such as a ROM, an FD, a PC card, and an IC card.
[0086]
Conversely, it is also possible to realize a system in which the navigation device 20 acquires all map data by communication from the center 50 without using the navigation disk D2.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating an overview of an entire system according to an embodiment.
FIG. 2 is an explanatory diagram illustrating a schematic configuration of a navigation device according to an embodiment.
FIG. 3 is a flowchart showing a boundary determination process of a divided map performed by the processing device.
FIG. 4 is a flowchart illustrating an integration process performed during the boundary determination process of FIG. 3;
FIG. 5 is a flowchart illustrating an upper layer creation process executed by the processing device.
FIG. 6 is an explanatory diagram showing an example of boundary determination and area division.
FIG. 7 is an explanatory diagram showing an example of area integration.
FIG. 8 is an explanatory diagram showing a configuration of conventional map data.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Processing device, 11 ... Control part, 12 ... Storage part, 13 ... Input / output part, 14 ... Communication part, 20 ... Navigation device, 21 ... Control device, 22 ... Input / output device, 23 ... Communication device, 24 ... Map Data input device, 25: storage medium, 50: center, D1: disk storing original data of map data, D2: disk for navigation, 80, 80a to 80d: divided map data, 90: drawing range, 100: map data.

Claims (13)

From the original map data to be divided including at least road data, select road data of a predetermined selection criterion,
A map data creation method for dividing the original map data to be divided into a plurality of regions surrounded by the selected road data, and creating divided map data that is map data for each of the divided regions. The map data creation method according to claim 1,
The map data creation method, wherein the predetermined selection criterion is determined based on at least one of a road type, a road attribute, the number of lanes, and a road width. The map data creation method according to claim 1 or 2,
The predetermined selection criterion is prepared in a plurality of stages,
First, the highest-level selection reference road data is selected from the original map data to be divided,
Dividing the original map data to be divided into a plurality of areas surrounded by the road data of the selection criterion at the highest level,
At least one of the area or the data size of the divided region is set as a determination target, and it is determined whether the determination target exceeds a predetermined upper limit value,
Based on the determination result, if the determination target is equal to or less than the predetermined upper limit, create divided map data that is map data for each of the divided regions,
On the other hand, when the determination target exceeds the predetermined upper limit value, the road data of the selection criterion of the next stage existing in the divided area is selected, and further divided using the road data, and the division is performed. It is determined whether or not the determination target in the region exceeds the predetermined upper limit, and thereafter, based on the determination result, the divided map data is created, or until the divided map data is created, Map data generation for repeatedly executing the selection of the road data of the selection criterion in the next step, the area division using the road data, and the determination as to whether or not the determination target of the divided area exceeds the predetermined upper limit value. Method. The map data creation method according to claim 3,
When the area is divided into a plurality of areas surrounded by the selected road data, at least one of the area and the data size of the divided area is set as a determination target, and another divided area adjacent to the divided area (hereinafter, referred to as an adjacent area) ) Is determined whether or not the determination target exceeds the upper limit value. If the integration target exceeds the upper limit value regardless of which adjacent region is integrated, the integration with the adjacent region is not performed. A map data creation method that creates the divided map data in a state, and if the divided map data does not exceed the upper limit, creates the divided map data in a state where the divided map data is integrated with the adjacent area. The method for creating map data according to claim 4,
A map data creation method for integrating with the adjacent area, wherein one or more adjacent areas are integrated such that the determination target is maximized within a range where the determination target does not exceed the upper limit value. The map data creation method according to any one of claims 1 to 5,
When creating map data with a hierarchical structure,
From the map data created by the map data creation method, delete roads below a predetermined deletion criterion according to the hierarchy,
A map data creation method for creating map data according to a hierarchy by integrating the map data after the road deletion in a range in which the determination target in the integrated map data is less than a predetermined upper limit value according to the hierarchy. . The map data creation method according to any one of claims 3 to 6,
The map data creation method, wherein the predetermined upper limit value can be changed and set. Input means for inputting original map data to be divided including at least road data;
A creation means for creating map data by executing the map data creation method according to any one of claims 1 to 7, using the original map data input via the input means.
A map data creation device comprising: The map data creation device according to claim 8,
Further, a display means capable of displaying a map based on the map data created by the creation means, designation of an arbitrary road in the map displayed by the display means, and setting the designated road as a new boundary. And receiving means for receiving instructions.
The map data creation device, wherein the creation unit re-creates map data based on the designation and instruction received by the reception unit with the designated road as a new boundary. A map data recording medium which records map data created by the map data creation device according to claim 8. A map data use device that uses map data created by the map data creation device according to claim 8. The map data utilization device according to claim 11,
A map data utilization device that realizes a navigation function including at least a map display using the map data. A map data creation program for causing a computer to realize a function as creation means in the map data creation device according to claim 8.

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