JPH1124554A - Map display device, map data memory device and map data memory medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to display maps of more steps of scales with a smaller data quantity by extracting the point data included in the map region to be displayed from the hierarchy above the hierarchy selected in accordance with pointer information and displaying a line connecting the extracted point data on a display means. SOLUTION: One piece of line data has a hierarchical structure in which point data groups are classified by hierarchies. The distances between the pieces of the point data are long in the uppermost first hierarchy and the distance levels between the pieces of the point data are shorter toward the lower hierarchies. Respective pieces of the point data are provided with the pointer information which exists between the point data and the point data adjacent thereto and indicates the point data included in the hierarchy on the lower side. A display processing section selects the hierarchy according to the degree of details of the map display, extracts the point data included in the map region to be displayed from the hierarchy above the selected hierarchy in accordance with the pointer information and displays the line connecting the extracted point data on the display means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a map display device for reading map data stored in a map storage unit and displaying the data on a display or the like. The present invention also relates to a map storage device and a map storage medium for storing map data. Especially,
The present invention relates to a technology capable of reducing the data amount of map data and easily updating map data.

[0002]

2. Description of the Related Art Conventionally, an on-vehicle navigation device has been known as a device having a map display function. The in-vehicle navigation device is, for example, a CD that stores map data.
A storage medium such as a ROM, and a means for detecting a current position. Then, the map around the detected current position is
It is read from the storage medium and displayed on a display in the vehicle. The user can check the current position of the vehicle and the road shape around the vehicle by looking at the display, and can receive route guidance using map data.

[0003] Such a map display device is described in, for example, Japanese Patent Application Laid-Open No. 3-139690. In this publication, map data is stored by being divided into a plurality of segment data, for example, a topographic map, a general road map, a main road map, a toll road map, and the like. The data selected by the user among these segment data is displayed. In this publication, the segment data describes that the map is divided into a plurality of hierarchies.
As described above, it is based on the type of information (topography, road, etc.) and has nothing to do with the hierarchical structure of the present invention described later.

[0004]

It is well known that the shape of a road on a map is represented by a set of points on the road.
That is, the map data includes road data representing the shape of the road, and the road data has a group of point data indicating the positions of points scattered on the road. Each point data includes, for example, coordinates (corresponding to latitude and longitude) of the corresponding point. The data expressed in this manner is also called vector data, and the road shape can be expressed with a relatively small amount of data.

By the way, many map display devices have a function of displaying a map of a plurality of scales such as a large scale, a medium scale, a small scale, and so on. In order to realize this function, it is conceivable to store road data representing the road shape most finely, and to display all scales using the road data. However, in this case, when large-scale display is performed, the amount of data processing increases and the processing speed also decreases. This is because roads are displayed over a long distance as the display range of the map is expanded. A fine road shape is not represented on a large-scale display screen, and processing of such unnecessary data is inefficient.

Therefore, conventionally, a plurality of road data are prepared for one road as shown in FIG. 1 in order to realize a scale change function. Each road data represents a road shape with different fineness. In the large scale road data, the distance level between the point data is set to be long, whereby a rough road shape is specified. In the road data for small scale, the distance level between the point data is set short, and a fine road shape is specified.

However, as is apparent from FIG. 1, a plurality of road data representing one road overlap the spot data of the same spot (dotted line). Therefore, the data amount of the map data increases, and the storage capacity of the storage medium is wasted.

[0008] Further, since the same number of road data as the number of display scales is prepared for one road, if the number of scales is to be increased, the number of road data must be increased. Accordingly, the data amount of the entire map data further increases. Due to the limited capacity of the storage medium, the number of display scale steps is also limited.

When the map data is updated, it is inefficient to read all the new map data and overwrite the storage medium. Therefore, it is common to rewrite the data only at the changed portion. Here, conventionally, a plurality of road data are prepared for one road as described above. Therefore, when the shape of a road changes, it is necessary to rewrite a plurality of road data corresponding to the road. When the function of displaying three scales is provided as in the example of FIG. 1, when one road shape changes, three road data must be corrected. Therefore, there is a problem that the updating work of the map data is large and complicated.

As described above, efficient display processing cannot be performed only with road data representing a fine road shape. Therefore, conventionally, one road,
A plurality of road data has been stored in a storage medium. Therefore, the amount of data is large, the number of display scale steps is limited,
There was a problem that the work of updating the road data was complicated. Such a problem is not limited to road data. Lines other than roads in the map, such as railways and rivers, can be represented by a set of point data, like roads. These data also have the same problem as the road data.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to reduce the amount of map data and to update map data in a map display device, a map data storage device, and a map data storage medium. Another object of the present invention is to make it possible to easily display a map on a smaller scale with a smaller amount of data.

[0012]

In order to solve the above-mentioned problems, the present invention provides a multi-step scale using one line data per one line (road, etc.) as described below. To enable efficient map display.

(1) The map display device of the present invention performs a display means for displaying a map, a map storage unit for storing map data, and a process for displaying the map data read from the map storage unit. A display processing unit. Map data is
It includes line data representing at least one type of line in the map. The line data has a hierarchical structure in which a group of point data indicating the positions of a plurality of points on the line is classified by layer so that the lower the layer, the shorter the distance level between the point data. Each point data has pointer information indicating the point data which is located between the point data and the adjacent point data on the same layer and is included in the lower layer. The display processing unit selects a layer according to the level of detail of the map display, extracts point data included in a map area to be displayed from layers higher than the selected layer based on pointer information, and extracts the extracted point data. Is displayed on the display means.

Here, the line data includes, for example, a road, a railroad, a river, a line indicating topography, a coastline, a contour line of a lake,
It is the border of the administrative area. Roads are classified into general roads, major roads, and toll roads. The present invention can be applied to some or all data of various lines including these examples.

The principle of the present invention will be described with reference to the model diagram of FIG. According to the present invention, one line data is
It has a hierarchical structure as illustrated in FIG. That is, point data groups indicating the positions of a plurality of points on the line are classified by hierarchy. In the uppermost first hierarchy, the distance level between the point data is long. Note that the distance between point data in the same hierarchy may or may not be constant. The distance level between the spot data becomes shorter as going to the lower hierarchy.
The number of layers is at least two, and in the example of FIG. 2, there are three layers.
More points may be set on the line and the number of layers may be increased. As shown by the arrows in FIG. 2, each point data is provided with pointer information indicating the point data between the point data and the adjacent point data and included in the lower layer.

The display processing unit selects a hierarchy according to the level of detail of the map display, and extracts and extracts the point data included in the map area to be displayed from the hierarchy higher than the selected hierarchy based on the pointer information. The display means displays the line connecting the point data. A specific example of the function of the display processing unit will be described below with reference to FIG.

For example, when a large scale map of a wide area is displayed, the degree of detail of the display is low. In this case, the first level is selected. Point data included in the first layer and included in the map area to be displayed (for example, line length 100
km of point data) is extracted. A line formed by connecting the extracted point data is displayed on a display means (CRT, liquid crystal display, or the like).

For example, when displaying a small-scale map in a narrow range, the degree of detail is high, and the lower the level of detail, the lower the hierarchical level is selected. Here, it is assumed that the third hierarchy is selected. Further, it is assumed that the map area to be displayed includes a range X in the line as illustrated. The display processing unit
Based on the pointer information, point data included in the range X is extracted from the third or higher hierarchy. By following the pointer information indicated by the arrow in the figure, the range X
The point data included in can be extracted. A line formed by connecting the extracted point data is displayed on the display means.

As described above, according to the present invention, it is possible to display a map on a plurality of scales using one line data per line. This line data as a whole represents the fine shape of the line.
That is, the position of a plurality of points arranged at short intervals can be known from the point data of all layers. At the time of the display processing, a hierarchy corresponding to the level of detail is selected, and point data is extracted from the hierarchy higher than that hierarchy. Therefore, data of a lower hierarchy than necessary (that is, point data whose interval is too short compared to the display scale) is not processed. As a result, it is possible to display the map on a plurality of scales without reducing the processing efficiency by using one line data.

Further, as shown in FIG. 2, there is no need to have a plurality of line data representing one line. Therefore, the same point data need not be duplicated in a plurality of line data, so that the data amount of map data can be reduced.

Further, if the number of layers in the hierarchical structure of the line data is increased, a map can be displayed with various levels of detail according to the layers. Even when the display scale is set in multiple stages, a map suitable for each stage can be displayed. Therefore, according to the present invention, it is possible to display a large scale with a small amount of data. This is advantageous when, for example, the navigation apparatus attempts to display the current position and the travel destination at predetermined positions on the screen (for example, near both ends). First, the present position and the display position of the travel destination are determined, the scale of the map display is calculated backward from both display positions, and a map display with a degree of detail according to the result of the calculation can be performed.

When the shape of a line changes, in the present invention, one line data may be rewritten. For example, the changed spot data may be replaced with new spot data. Therefore, the updating work by the worker becomes easy,
Further, the efficiency of the update processing in the map display device is improved. When the update data is obtained using the communication means, the communication time is short.

As described above, according to the present invention, the scale change display can be efficiently realized using one line data, whereby the data amount of the map data is reduced, and the map data can be easily updated. With a small amount of data, it is possible to display a map on a larger number of scales.

In FIG. 2, for the sake of explanation, point data of each layer is shown in a discrete manner. Preferably, the data of each layer is continuously recorded on the storage medium so that the data can be read efficiently.

(2) In the map display device according to one aspect of the present invention, the line data includes link data linking a plurality of point data in a portion between two point data in a certain hierarchy in a lower hierarchy. And the pointer information associates the link data with at least one of the two point data.

The link data described above connects the point data surrounded by a dotted line in the example of FIG. In this embodiment, the pointer information of a certain point data may indicate one link data, instead of indicating a plurality of point data of a lower hierarchy. Therefore, the data amount of the pointer information itself is reduced, and the data structure is simplified.

[0027] The map display device of one embodiment of the present invention includes:
A map update processing unit for updating map data stored in the map storage unit, wherein the map update processing unit replaces the link data including the changed point data with a new one, and stores pointer information related to the link data. Change as necessary. Preferably, the link data is
Contains information indicating when the link data was created or changed. Updating can be performed efficiently by updating the data for each link data.

(3) The map data storage device of the present invention is a device having a map storage unit for storing map data and a map update processing unit for updating the map data stored in the map storage unit. The map data includes line data representing at least one type of line in the map, and the line data includes a point data group indicating the positions of a plurality of points on the line. It has a hierarchical structure classified by hierarchy so as to be shorter, and each point data has pointer information indicating the point data included between the point data and adjacent point data on the same layer and included in the lower layer. I have. The map update processing unit includes:
At the time of updating the map data, the changed spot data is replaced with a new one, and the pointer information associated with the spot data and included in the spot data of the upper layer is changed as necessary.

According to this aspect, similarly to the above (1), it is possible to reduce the map data and to facilitate the updating operation. In particular, since the update processing unit only needs to replace the changed spot data with new ones, the number of processes for updating is reduced. When replacing the point data, refer to (2) above.
As a matter of course, the processing may be performed in units of link data as described above.

(4) The map data storage medium of the present invention is a storage medium for storing map data including line data representing at least one type of line in a map. The line data has a hierarchical structure in which point data groups indicating the positions of a plurality of points on the line are classified by layer so that the distance level between the point data becomes shorter in lower layers. It has pointer information indicating the point data that is located between the point data and adjacent point data on the same layer and is included in the lower layer. The storage medium is
In correspondence with the above-mentioned hierarchical structure, it has a plurality of hierarchical point data group storage areas each storing one hierarchical point data group. By using this storage medium, as described in (1) above, it is possible to reduce the amount of data and to facilitate the updating operation.

(5) In the above-described map display device, map data storage device, and map data storage medium, preferably, the map data is a diagram showing line data passing through a leaf area obtained by dividing the map into a predetermined unit size. Includes leaf data. By referring to the map data, line data passing through the displayed map area can be quickly identified. From this line data, point data to be used for display may be searched. Accordingly, the provision of the map data facilitates the process of extracting the spot data.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings.
In the present embodiment, the map display device is provided integrally with the navigation device. FIG. 3 is a block diagram showing the entire configuration of the navigation device. First, an outline of the navigation device will be described with reference to FIG.

The navigation ECU 1 controls the entire apparatus. The navigation ECU 1 is connected to a GPS device 3, a map storage medium 5, an input operation unit 7, and a display 9. The GPS (global positioning system) device 3 detects a current position using radio waves transmitted from an artificial satellite and sends the current position to the navigation ECU 1. The map storage medium 5 stores map data including road information and the like nationwide. For this map data,
This will be described in detail later. The navigation ECU 1 is provided with a map display processing unit 11. The map display processing unit 11 reads a map around the current position from the map storage medium 5 based on the output of the GPS device 3, performs a display process, and displays the map on the display 9. The current position mark is superimposed on the map. In addition, the user can input a desired place to check the map via the loading operation unit 7. The map of the input location is read from the map storage medium 5 and displayed on the display 9.

Further, the user can input a travel destination and various instructions to the navigation device via the input operation unit 7. When the destination is input, the navigation ECU 1 uses the map data in the map storage medium 5 to search for and set an optimal route from the current position to the destination. The route search is performed by an ordinary method using the Dijkstra method or the like. The navigation ECU 1 controls the display on the display 9 so that the set route can be distinguished from other roads.

The navigation ECU 1 further includes C
The D-ROM drive 13 and the external device connection unit 15 are connected. The CD-ROM drive 13 has a CD-ROM 19 on which updated map data indicating the updated contents of the map is recorded.
Is attached. An external device (not shown) such as a computer device is connected to the external device connection unit 15, and the external device sends updated map data to the navigation ECU 1. The navigation ECU 1 includes a map update processing unit 12.
Is provided, and the map update processing unit 12 performs a process of rewriting the data stored in the map storage medium 5 with the updated map data.

A communication device 17 is connected to the navigation ECU 1. The navigation ECU 1 communicates with the information center 21 using the communication device 17. The updated map data can be transmitted from the information center 21. Also in this case, the map update processing unit 12 performs a rewriting process using the updated map data.
The navigation ECU 1 uses the communication device 17 to
Other necessary information can be obtained from the information center 21. The information to be communicated is, for example, a map that is not stored in the map storage medium 5 but needs to be displayed.

Next, the map data stored in the map storage medium 5 will be described. The map data includes information such as shapes of various lines (roads, railways, etc.) on the map, place names, names and places of various facilities, and the like. Here, among the information included in the map data, road data indicating the shape of the road will be described. However, data representing the shape of a line other than a road can also be configured in the same manner as the following road data.

The map data includes map data as shown in FIG. As shown in the figure, the map is divided into leaf areas having a predetermined unit size (for example, 2 km square). Each piece of leaf data includes information (such as a number) indicating a road passing through the area of the leaf data. For example, in FIG. 4, the national road A, the national road B, the prefectural road C, the general road D, and the like are registered in the map data of the map Z.
Note that the map data merely has a list of roads passing through the map area, and does not have information on the shape of the road.

FIGS. 5 to 7 show the structure of road data representing the shape of the national highway A in the leaf data of FIG.
The configuration of one piece of road data will be described with reference to these drawings. As shown in FIG. 5, the road data has a hierarchical structure including four levels from level 1 to level 4. In this hierarchical structure, a number of points are set on a road, and a point data group indicating the position of each point is classified into four levels.

Level 1 includes Pos (1) to Pos (1).
NPos point data up to (nPos) are included. Such a point data string is hereinafter referred to as link data. At level 1, the distance level between the point data is set to be considerably long. The distance level is set such that the data processing amount and the fineness of the road shape are appropriate when the maximum scale (for example, ５０50 km) is displayed using the level 1 point data.

As shown in the figure, the link data of level 2 is the nP set between the two point data of level 1.
It is a point data sequence of os' point data. Therefore,
Level 2 includes (nPos-1) link data. In addition, the distance level between the point data is shorter at level 2 than at level 1. For this distance level, a second scale (for example, 上 記 10 km) smaller than the maximum scale is used by using the point data of level 1 and level 2.
Is set so that the amount of data processing and the fineness of the road shape are appropriate when the display is performed.

As with level 2, level 3, level 4
Has link data indicating a detailed shape between two points in a higher hierarchy. The third scale (third scale, for example, １1 km) can be displayed using the point data of levels 1 to 3, and the minimum scale (for example, １００100 m) can be displayed using the point data of levels 1 to 4. Display can be performed.

FIG. 6 shows the details of the level 1 link data. The link data includes nPos point data and header data. The header is the date when the link data was created or updated (date)
And the number of point data arrays (nP
os) and pointer information (parent) to the parent array. Since level 1 is the highest level, paren
t indicates the number of the leaf data to which the road belongs.

The point data Pos (j) includes the coordinates xj, yj, zj of the point and pointer information next. xj corresponds to longitude, yj corresponds to latitude, and zj corresponds to altitude. The pointer next is link data of level 2 and link data relating to a road portion between Pos (j) and Pos (j + 1) (level 2 of FIG. 5).
Link data). Therefore, the pointer next
By relying on t, link data representing the road shape between Pos (j) and Pos (j + 1) can be searched from the lower hierarchy.

The link data of the other levels have the same structure as the link data of the level 1 in principle. When the pointer next of a certain point data points to link data of a lower layer, the pointer parent in the header of the link data points to point data of an upper layer.

However, as shown in FIG. 5, unlike the level 1, the link data of the level 2 is the vacant spot data Pos.
(0 ′), and the link data of level 3 also has the empty point data Pos (0 ″). Although not shown, the same applies to level 4. The function of the vacant spot data will be described with reference to FIG. The upper part of FIG. 7 shows setting of point data on a road in the vicinity of Pos (j). The point data Pos (j) is included in level 1. The point data Pos (1 ′) is included in level 2. Level 3
Are included in Pos (j) and Pos (j).
Point data string Pos set between (1 ′)
(1 ″) to Pos (nPos ″). Here, the vacant spot data Pos (0 ′) at level 2 has no coordinate data, and is a pointer n indicating the link data Y at level 3.
ext only. Pos than Pos (1 ')
When a detailed road shape on the (j) side is required, the link data Y of level 3 is searched based on the pointer information of the vacant point data Pos (0 ′). Similarly, the vacant spot data Pos (0 ″) of level 3 has only the pointer next indicating the link data included in level 4.

When the above-mentioned national road A is displayed on the display 9 at the maximum scale, the map display processing section 11 of the navigation ECU 1 reads out the level 1 link data from the map storage medium 5. Then, point data included in the map display range is extracted from the level 1 link data,
The line connecting the extracted points is displayed on the display 9. At this time, image data including the line is generated, and the image data is sent to the display 9.
As is well known, place names, peripheral facilities, and the like are also represented in the image data.

The map display at the second scale is performed as follows. For example, assume that the road shape near Pos (j) at level 1 is displayed at the second scale. First, the link data of level 1 is read in the same manner as described above. Then, the link data of level 2 is read based on the pointer next of Pos (j). Also, if necessary, Pos
Point data around (j) (for example, Pos (j-
1), the link data indicated by the pointer Pos (j + 1) is also read. Necessary point data included in the map display range is extracted from these two layers of link data, and a line connecting the extracted point data is displayed on the display 9. When displaying at the third scale,
In the same manner, processing using data of level 1 to level 3 is performed. When displaying at the minimum scale, processing using data of all levels is performed.

Next, the structure of road data representing the shape of a relatively narrow road will be described with reference to FIG. In FIG.
Road data representing a general road D in the leaf data of FIG. 4 is shown. Since the general road D is a thin road, it is not necessary to display the general road D on the large scale display. Therefore, the road data of the general road D has only the empty point data Pos (0) and Pos (0 ′) at the level 1 and the level 2. That is, at level 1 and level 2, there is no point data with position coordinates, but only pointers to lower layers.
Levels 3 and 4 include link data, which is a point data string, as in FIG. 5 described above. Therefore, the general road D is not displayed on the display 9 in the maximum scale display or the second scale display. In the third scale display or the fourth scale display, since the data of level 3 and level 4 are processed, the general road D is displayed.

In addition, some roads may have link data of the second to fourth levels, or only link data of the fourth level. Which level of the link data is provided can be changed according to the thickness and importance of the road. For example, the road data of a narrow street need only have the link data of level 4.

Next, referring to FIG. 9, the map display processing section 11
A description will be given of a processing procedure for reading map data from the map storage medium 5 and displaying the map data on the display 9. Here, a process of displaying a road using the above road data will be described. Other displays, for example, character display of place names, are separately performed by a known method.

In FIG. 9, first, the map display processing unit 11
Specifies the coordinate value (DestPos) of the place to be displayed (S10). DestPos is the coordinates of the current position detected by the GPS device 3, for example. Further, for example, the coordinates of a place input by the user via the input operation unit 7 are shown. The coordinates of the destination at the time of setting the route may be used. Further, the map display processing unit 11 specifies the number of levels (DestLevel) according to the display scale (S12). The display scale is selected, for example, by the user from the four stages described above, and is input from the input operation unit 7 to the navigation ECU 1. Further, the display scale may be automatically set by the navigation ECU 1. For example, when performing route guidance, it is conceivable to reduce the display scale as the vehicle approaches the travel destination. At maximum scale, Des
tLevel is set to level 1. At the second, third, and smallest scales, DestLevel is Level 2,
3 and 4.

The map display processing section 11 performs the processing for DestPos set in S10 and the DestLevel set in S12.
1 and the size of the display screen are used to obtain the necessary figures (S14). The smaller the number of levels in DestLevel, the larger the number of required figures and leaves. This is because the larger the scale, the wider the map is displayed. Even when the size of the display screen is large, a map of a wide range is displayed, so that the number of necessary leaves increases. The map data obtained in S14 is searched from the data in the storage medium 5 (S1).
6) The level 1 link data of the road data registered in the map data is read (S18). At this time, as described with reference to FIG. 8, only the empty spot data is read for the narrow road.

Next, the map display processing section 11 determines whether or not the DestLevel link data set in S12 has already been read (S20). Level 1 in S12
Is set, YES is determined in S20. Then, the process proceeds to S32, where the road is displayed using the point data of the link data of level 1 and the process returns. Here, point data included in the map area displayed on the display 9 is extracted from the level 1 link data. Then, a line connecting the coordinate points indicated by the point data is displayed on the display 9.

At S20, if the link data of DestLevel has not been read yet (NO), S22
Go to and calculate the required data section. For example, the current position is longitude 139 degrees 52 minutes 51 seconds, latitude 35 degrees 38 minutes 0
Suppose that the point was one second. Also, at level 1 in FIG. 5, the x coordinate (longitude) of Pos (j) is 139 degrees 52 minutes,
Assume that the longitude of Pos (j + 1) is 139 degrees 53 minutes. In this case, Pos (j) to Pos (j + 1) are required sections. In addition, the sections around Pos (j) and Pos (j + 1) are also appropriately set according to the display scale and the display screen size. For example, Pos (j-1) and Po
s (j), Pos (j + 1) and Pos (j
+2).

Next, it is determined whether or not there is link data of the next level for the necessary section (S24). Here, it is determined whether or not Pos (j) or the pointer information next included in the peripheral point data related to the necessary section is empty. If it is not empty, there is link data of the next level, so that link data is read (S26). The level 2 link data shown in FIG. 5 is read.
After reading the link data, the process returns to S20, and again returns to De20.
It is determined whether or not the data of stLevel has been read. In this way, from the link data of level 1, S
The link data up to DestLlevel specified in step 12 is read. If YES is determined in S20, S32
And a map display at DestLevel is performed.
From the read point data of all levels, point data included in the range of the map displayed on the screen is extracted. The line connecting the extracted data is displayed on the display 9.

On the other hand, in S24, there may be no link data at the next level of the required section. Pos
This is when pointer information in (j) and surrounding point data is empty. Such a situation occurs, for example, when a detailed map of the input destination is not stored in the storage medium 5 in the route setting. Also, for example,
This is the case where the road data at the scroll destination has only higher-level link data when the map is scrolled as the vehicle travels.

When S24 is NO, the process proceeds to S28, and it is determined whether or not data is obtained from the information center. This determination is made based on, for example, whether or not the communication state of the communication device 17 is currently good. In addition, for example, the determination is made based on whether the data amount of the data to be communicated is not too large. When YES is determined in S28, the map display processing unit 11 uses the communication device 17 to
Request the necessary map data to 1. The information center 21 is provided with map data having the same configuration as that on the vehicle side.
The information center 21 sends the map data in response to the request. The map data is received by the communication device 17 and the map display processing unit 11
(S30). Using the received data and the point data read from the map storage medium 5 so far,
The road is displayed at DestLevel (S3).
2). If the data is not received from the information center 21 due to a bad communication condition in S28, the process proceeds to S34. Then, a map is displayed using the point data read so far. DestL set in S12
Since a map is displayed using data at a higher level than the level, the detailed shape of the road is not represented accordingly.

Next, a method for maintaining road data, that is, a process for updating road data stored in the map storage medium 5 will be described. Updating of road data is performed in units of link data, and only rewriting of changed link data is performed in principle.

For example, consider the case where the link data of level 4 shown in FIG. 5 is rewritten. Updated map data with new contents of link data of level 4
-Read from the ROM 19 into the map update processing unit 12 of the navigation ECU 1. Also, the updated map data
The data is read from the external device to the map update processing unit 12 via the external device connection unit 15. Alternatively, the updated map data
Sent from the information center 21 to the navigation ECU 1,
It is read into the map update processing unit 12. Map update processing unit 1
2 confirms the header of the new link data. The parent of the header is rewritten as necessary so as to indicate Pos (j ″) of level 3. Then, the link data is written to the map storage medium 5. Further, the map update processing unit 12 may store the level 3 point data Pos stored in the map storage medium 5 as necessary.
The pointer next of (j ″) is rewritten so that the pointer next indicates the newly written link data.

The road shape changes when, for example, a certain road extends a little and connects to another road. If this shape change affects only the most detailed map, only the level 4 link data is rewritten as described above.
When the scale of the road shape change becomes large, it becomes necessary to rewrite not only the level 4 but also the link data of the level 3.
When a large national road undergoes a large-scale shape change, it is necessary to rewrite all the data from level 1 to level 4.

When the road disappears, the map update processing section 12 deletes the road data of the lost road from the map storage medium 5. Instead of deleting the road data, the map update processing unit 12 may perform only a process of deleting the registration of the road from the map data.
By this processing, the disappeared road is not displayed. With simple processing, unnecessary roads can be prevented from being displayed.

The embodiment of the present invention has been described. In the present embodiment, map display of all scales is performed using one road data. Therefore, the road data has a large number of point data set at short intervals so as to correspond to the minimum scale display. If such a large number of point data are used as they are for the display processing, the processing efficiency deteriorates. Therefore, in the present embodiment, the road data has a hierarchical structure, and each hierarchy is configured by link data. The distance level between the point data of each layer is set to match the display scale corresponding to each layer. A level is selected according to the display scale, and data of that level or higher is processed. Therefore, map display is performed using the point data group at intervals suitable for the display scale. Thus, map display of all scales can be efficiently performed using one road data.

According to this embodiment, there is no need to have a plurality of road data for one road. Therefore,
Since the spot data of the same spot is not duplicated, the data amount of the map data can be reduced. When the road shape is changed, it is not necessary to change a plurality of road data at the same time, and one road data may be rewritten in link data units. Therefore, the map updating work is greatly facilitated.

FIGS. 10 to 13 show examples of map display realized by the present embodiment. FIG. 10 shows a road displayed using the level 1 data. As shown in the drawing, a large scale map display is performed on a large scale. FIG.
Is a road displayed using data of level 1 and level 2, FIG. 12 is a road displayed using data of level 1 to level 3, and FIG. The road displayed using the data is shown. As shown in these figures, as the data of a larger number of levels is processed, a smaller scale is displayed in a smaller range, and a finer road shape is represented. Also, narrow roads that cannot be represented on a large-scale map appear on the display.

In addition, by using the map data of the present embodiment, as shown in FIG. 14, there is an advantage that the processing amount of data processing for sky view display can be reduced. The sky view display means, as shown in FIG. 14B, that the viewpoint is placed higher than the ground and a display with a perspective is performed. In the sky view display, it is preferable to display a detailed road shape for a portion near the current position. However, for places far from the current position, since the map is displayed in a reduced size, it is not necessary to display a fine road shape. Therefore, as shown in FIG. 14A, in a range close to the current position, a fine road shape is expressed using, for example, data of level 1 to level 3. At a place at a middle distance, a road is represented using data of level 1 and level 2. At a location far from the current position, a road is represented using only level 1 data. As a result, the display of the detailed road shape in the short distance area and the reduction of unnecessary data processing in the long distance area are compatible. Overall,
A sufficiently detailed road shape is displayed while suppressing the amount of data processing.

(1) As a modification, the hierarchical structure of road data may be modified to increase the number of layers without changing the total number of point data. Depending on the number of layers,
The number of display scale steps can be increased. Conventionally, increasing the number of steps of the display scale is not preferable because it increases the data amount. In the present embodiment, the number of display scale steps can be increased without substantially changing the data amount.

(2) As a modification of the present embodiment,
4 may be provided for each level of the hierarchical structure of the road data. For example, the national highway A in FIG. 5 has link data at levels 1 to 4. Therefore, the national road A is registered in the level 1 map leaf data. Since the road data of the general road D shown in FIG. 8 has link data at the level 3 or lower, the general road D is registered in the level 3 map leaf data. In this way, each road is registered in the highest level map data according to the highest level link data of the road data. Therefore, only the roads to be displayed on the maximum scale map, such as expressways and main roads, are registered in the level 1 map leaf data. Roads that are not registered in the upper-level map data are registered in the lower-level map data. In the display process, when a certain level is designated (S12 in FIG. 9), a process using the leaf data of that level or higher is performed. In addition, the vacant spot data of levels 1 and 2 shown in FIG. Further, in this modified example, it is preferable that as the number of levels increases, the size of the leaf area is reduced in accordance with the change in the display range.

When the figure data is provided for each level, the following configuration may be adopted. As described above, only the main road is registered in the level 1 leaf data. In the lower level map data, both the main road registered at level 1 and the narrow road suitable for that level are registered. For example, in the level 3 map leaf data, the national road A in FIG.
Also register both. In the display process, only the leaf data at the designated level is used. This is because leaf data at a higher level than the specified level is unnecessary.

(3) The map storage medium 5 of the present embodiment
May be any medium such as a hard disk, a RAM, a DVD, etc., as long as the medium can be accessed using a means such as optical, magnetic or electric. If the map data is not updated in the navigation device, a read-only medium such as a CD-ROM may be used.

(4) In this embodiment, the map storage medium 5 is mounted on a vehicle. On the other hand, a storage medium and a storage device including the storage medium may be provided in the information center 21. The navigation ECU 1 sends the current position and the travel destination to the information center 21 using the communication device 17. The information center 21 sets a route to the destination and returns map information including necessary road data to the navigation ECU 1.

(5) In addition, the road data of the present embodiment may be used for purposes other than display. For example, road data may be used not only for display but also for map matching processing.

[Brief description of the drawings]

FIG. 1 is a diagram showing a plurality of road data prepared for one conventional road.

FIG. 2 is a diagram showing a hierarchical structure of line data for explaining the principle of the present invention.

FIG. 3 is a block diagram showing a configuration of a preferred embodiment of the present invention.

FIG. 4 is a diagram showing leaf data included in map data.

FIG. 5 is a diagram showing a configuration of road data included in map data.

FIG. 6 is a diagram showing details of level 1 link data in FIG. 5;

FIG. 7 is a diagram illustrating functions of sky point data included in the link data of level 2 in FIG. 5;

FIG. 8 is a diagram showing the configuration of road data representing the shape of a relatively narrow road.

FIG. 9 is a flowchart showing a process for reading and displaying road data.

FIG. 10 is a diagram showing a map of the maximum scale displayed using the map data of the present embodiment.

FIG. 11 is a diagram showing a map of a second reduced scale displayed using the map data of the present embodiment.

FIG. 12 is a diagram showing a map on a third scale displayed using the map data of the present embodiment.

FIG. 13 is a diagram showing a map of a minimum scale displayed using the map data of the embodiment.

FIG. 14 is a diagram illustrating that the amount of data processing for sky view display can be reduced by using the map data of the present embodiment.

[Explanation of symbols]

Reference Signs List 1 navigation ECU, 3 GPS device, 5 map storage medium, 7 input operation unit, 9 display, 11
Map display processing unit, 12 Map update processing unit, 13CD-R
OM drive, 15 external device connection unit, 17 communication device,
19 CD-ROM, 21 information center.

Claims (8)

[Claims] 1. A map display device comprising: display means for displaying a map; a map storage unit for storing map data; and a display processing unit for performing processing for display on the map data read from the map storage unit. Wherein the map data includes line data representing at least one type of line in the map, and the line data includes a group of point data indicating the positions of a plurality of points on the line. Has a hierarchical structure that is classified by layer so that the distance level of the point is shorter. Each point data is a point data that is located between the point data and adjacent point data on the same layer and included in a lower layer. The display processing unit selects a hierarchy according to the level of detail of the map display, and displays the map area from the hierarchy higher than the selected hierarchy based on the pointer information. Map displaying apparatus includes extracting location data is characterized in that it is displayed on the display means line by connecting the extracted location data. 2. The map display device according to claim 1, wherein the line data includes link data linking a plurality of point data in a portion between two point data of a certain layer in a lower layer. A map display device, wherein the pointer information associates the link data with at least one of the two point data. 3. The map display device according to claim 2, further comprising a map update processing unit for updating map data stored in the map storage unit, wherein the map update processing unit includes a link including the changed point data. A map display device, wherein data is replaced with new data and pointer information related to the link data is changed as necessary. 4. The map display device according to claim 2, wherein the link data includes information indicating when the link data was created or changed. 5. A map data storage device comprising: a map storage unit for storing map data; and a map update processing unit for updating map data stored in the map storage unit, wherein the map data is at least one of The line data includes line data representing one type of line, and the line data is classified into a plurality of point data groups indicating the positions of a plurality of points on the line, so that a lower level has a shorter distance level between the point data. Each point data has pointer information indicating the point data included between the point data and the adjacent point data on the same layer and included in the lower layer, and the map update processing unit has a hierarchical structure. When updating the map data, replace the changed location data with a new location data. Map data storage unit and changes as necessary pointer information. 6. A map data storage medium storing map data including line data representing at least one type of line in a map, wherein the line data is a group of point data indicating positions of a plurality of points on the line. Has a hierarchical structure that is classified by hierarchy such that the distance level between the point data becomes shorter in the lower layers, and each point data is located between the point data and the adjacent point data in the same layer and has a lower level. Characterized by having pointer information indicating the point data included in the side layer, and having a plurality of layer point data group storage areas each storing a point data group of one layer corresponding to the layer structure. Data storage medium. 7. The map data storage medium according to claim 6, wherein the line data includes link data linking a plurality of point data in a portion between two point data of a certain layer in a lower layer. Wherein the pointer information associates the link data with at least one of the two point data. 8. The map display device according to any one of claims 1 to 4, or the map data storage device according to claim 5,
8. The map data storage medium according to claim 6, wherein the map data includes map data indicating line data passing through a map area obtained by dividing the map into a predetermined unit size. Map display device or map data storage device or map data storage medium.