JP3399779B2 - Road map information reading device, recording medium, and transmission method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road map information reading device, a recording medium, and a transmission method. More specifically, the present invention relates to a road map information reading device, a recording medium, and a transmission method. The present invention relates to a road map information reading device, a recording medium, and a transmission method used for applications such as calculation.

[0002]

2. Description of the Related Art Generally, data containing various road information used for in-vehicle navigation is called vector map data. This vector map data is composed of data of nodes, links, connection information, link shapes and attribute information.

The node data is data that mainly expresses an intersection of roads. The link data is data that represents a road connecting the nodes. This link data is data having vector information, and such a map is called a vector map because a road map is expressed by a set of these links. The connection information data is data indicating the connection relationship of each node and link.
The link shape data is data for complementing a node, a link and connection information of these when the map representation is insufficient. For example, roads in mountainous areas and coastal areas are often curved. In this case, the curved shape of the road cannot be sufficiently expressed with only one piece of link data corresponding to the road. Therefore, in order to properly display the curved shape of the road, it is supplemented as link shape data. The attribute information data includes node attribute data regarding nodes and link attribute data regarding links. The node attribute data is data such as names of intersections and presence / absence of traffic lights. The link attribute data includes road names, road types such as national roads or prefectural roads,
It is data such as the number of lanes and the presence / absence of a median strip.

A conventional map information display device using a vector map composed of various data described above will be described below.

First, the format of vector map data used in a conventional map information display device will be described. As an example of the conventional vector map data format, the text “Trend of practical application of high-precision route guidance system” at a seminar hosted by Japan Industrial Technology Center
(Hereinafter referred to as the first document). The first document describes a link representation method and connection information compression in relation to the data format.

FIG. 18 is a diagram showing a recording method for expressing the road connection relationship described in the first document. First
In order to record the connection between the nodes for each node, the recording method described in the document is the identification data of the connecting node called "index" and the distance to the connection destination node called "cost". And the data of the time required for movement are recorded. FIG. 18A shows an example of a cost table configured by an arbitrary node.
FIG. 18A shows a road network composed of eight nodes. One node in the road network corresponds to the other four nodes (indexes 2, 3, 4).
And 7) are connected.
The cost between the one node and the other node is 16
It is expressed in a base number (for example, it is '2' in index 2). For nodes that are not connected to the one node, the cost is hexadecimal'FF.
It is expressed by setting FF '(corresponding to indexes 1, 5, 6 and 8).

FIG. 18B shows an example of a recording method in which each connection information shown in the cost table of FIG. 18A is accommodated (hereinafter referred to as recording method example 1). In recording method example 1,
The purpose is not to simply record the cost for eight nodes, but to reduce the recording capacity. In recording method example 1, when nodes having the same cost are consecutive,
Only the last node information of the consecutive nodes is recorded, and all the node information of the same cost before that is deleted. Specifically, in the recording method example 1, since the costs for the indexes 3 and 4 are both “7”, the cost for the index 4 is recorded after the cost for the index 2 is recorded. Also, the costs of indexes 5 and 6 are the same, so index 4 above
After recording the cost associated with index 6, the cost associated with index 6 is recorded. Therefore, regarding each connection information shown in the cost table of FIG. 18A, the number of nodes to be recorded is “6” excluding the indexes 3 and 5. In addition, the data capacity of the connection information regarding these nodes is the number of columns of the recording method example 1, that is, '14'.

However, in the recording method example 1, since the connection information is recorded even in the nodes which are not connected, the recording efficiency is poor. Therefore, in the first document, the recording method of FIG. 18C is adopted as another recording method of connection information (hereinafter, referred to as recording method example 2). In recording method example 2,
It records the index and cost only for nodes that have connections. Specifically, as shown in the recording method example 2, only the indexes 2, 3, 4, and 7 in which the cost exists are recorded.

As described above, in the recording method example 1, the connection information recording capacity is basically proportional to the square of the number of nodes, whereas in the recording method example 2, the connection information recording capacity is proportional to the number of nodes connected to each node. The recording capacity can be reduced to a value obtained by multiplying the total number of nodes. Further, usually, map data divided into arbitrary regions is often used as the vector map data. However, even when the area is divided as described above, the number of nodes in the divided area is usually several hundred. On the other hand, the number of nodes connected to each node is 3 to 4 on average. From this, recording method example 2
It can be seen that, compared with the recording method example 1, the capacity of the map information can be significantly reduced, that is, the map information can be compressed. Note that such reduction of connection information will be hereinafter referred to as "compression of connection information".

Basically, the road connection relation can be expressed only by the above-mentioned connection information. However, in reality, in addition to this, a method of grouping links having the same attribute and recording the connection of the links is also commonly used. next,
A method of expressing the link connection described in the first document will be described below.

The method of expressing the connection relation of the links described in the first document, when there are a plurality of links having the same attribute, does not record the same attribute individually for each link, but Links having the same attribute are grouped as one road, and only one road is recorded as the attribute of the grouped road. By this method, a plurality of the same attributes are recorded, but by grouping, only one is required, and the recording efficiency is improved.
This method is specifically used when it is desired to display only national roads on a map.

FIG. 19 is a diagram showing the difference in the method of expressing the link connection information depending on the presence or absence of the grouping process. In FIG. 19, L0 to L3 indicate links. N0b to N3a and N0b-1a to N2b-
Reference numeral 3a indicates an identification code of the node. C1 and C2 indicate the cost of the link, and C01 ~
C32 is data indicating the connection state of each node (for example,
The connection destination node number, offset information, etc.) are shown.

FIG. 19 (a) shows a link unit representation method that is not grouped. This link unit representation method requires all the connection information of the nodes at both ends of the link together with the cost of the link in order to connect the existing links. On the other hand, FIG. 19B shows a method of expressing the grouped link string. The link string is represented by linking link information in the order of connecting links. Therefore, the link string representation method can omit not only the attribute information described above but also the connection information between links, as compared with the link unit representation method. In this specification, such grouping of connection information will be referred to as “road information compression” hereinafter.

On the other hand, as a conventional map information display device, for example, there is a device described in Japanese Patent Application Laid-Open No. 7-37067 (hereinafter referred to as a second document). In Figure 20,
The block diagram of the structure of the map information display device described in the 2nd document is shown. Hereinafter, a conventional map information display device will be described with reference to FIG.

In FIG. 20, the map information display device described in the second document is the vector map data 2001.
, Data conversion means 2002, and first storage means 200
3, second storage means 2008, and position input means 200
7, image processing means 2004, and frame memory 200
5 and display means 2006.

The vector map data 2001 is converted by the data converting means 2002 according to a predetermined thinning method.
The map data capacity is reduced. Here, the predetermined thinning-out method is a method of thinning out vector data for expressing the shape of the road, that is, link shape data.
In the map information display device described in the second document, the shape of a road is a line segment (vector) obtained by linearly approximating the shape.
By utilizing the fact that it is represented as a set of, the redundant points (end points of the vector) that are less affected during road display are determined and thinned out. The reduced vector map data 2001 becomes vector map data after data conversion (hereinafter abbreviated as converted data), and the first storage means 200
3 (a medium such as a hard disk). On the other hand, the second storage means 2008 is composed of a memory that can be accessed at high speed, and stores a necessary part of the conversion data stored in the first storage means 2003. here,
The second storage means 2008 is composed of a memory that has a smaller capacity than the first storage means 2003 but can be accessed at high speed. As a result, the image processing means 2004
The map data stored in the second storage unit 2008 is accessed at high speed according to the user's designation (designation of the map desired to be displayed) instructed via the position input unit 2007, and drawing in the frame memory 2005 is performed. , And the display means 2006 can display.

As described above, the map information display device described in the second document further thins out vector map data and uses an expensive storage medium such as a memory that can be accessed at high speed, It was possible to store a lot of map information. Therefore, the map information display device described in the second document can store a wider range of vector map data if it has the same memory capacity, and conversely if it stores the same map information. It has the advantage of requiring less memory capacity. Note that such thinning of the road shape is hereinafter referred to as "road shape compression".

As described above, the map information display devices described in the first and second documents are "compression of connection information", "compression of road information" and "compression of road shape". The compression of map information is realized by the three compression means. As a result, the map information display devices described in the first and second documents reduce the capacity of the map information recording medium, shorten the map read time, and transfer information other than map information such as tourist information onto the same medium. It was possible to record.

[0019]

In recent years, various practical map information display devices and vehicle-mounted navigation devices have been developed on the premise of vector map data obtained by performing the above-mentioned conventional technique of compressing map information. In these conventional map information display devices and the like, a large-capacity recording medium such as a CD-ROM or a hard disk is currently used as a map information recording medium. However, in the future, it is conceivable that the map information will be transmitted wirelessly or by wire, and that the map information will be used in a portable information device whose recording medium capacity is largely limited. Therefore, under these uses, map information having a smaller capacity than the current large capacity is needed. However, the above conventional map information display device and the like have the following problems,
The problem of capacity reduction cannot be solved.

First, the conventional method of "compressing connection information" in a map information display device or the like has a problem that road connection information is recorded in the same data format for all roads.

Roads can be mainly classified into "main roads" and "narrow streets". The “main road” is a road that is considered to be used by a large number of people, such as a national road and a highway. The "narrow street" refers to a road that is considered to be few in use (or can be used only by a specific person), such as a living road, a farm road, or a forest road in a residential area with respect to a main road. Therefore, when the main road and the narrow street are distinguished in the map information display device and the like, it can be considered that the frequency of using the road connection information is different between the main road and the narrow street. In particular,
In route search processing for calculating a route to a desired point on a map information display device, etc., connection information for main roads is required over a wide area, but connection information for narrow streets is used for the current location (departure point) and destinations. It is only needed to a limited extent. In actual map data, more than half of all roads are often narrow streets in detailed maps of urban areas.

However, in spite of the above contents, the conventional map information display device or the like records road connection information in the same data format for all roads. For this reason,
Most of the map information will be occupied by infrequently used connection information on narrow streets. That is, there is still a problem that the amount of map information is large.

Secondly, the conventional method of "compressing road information" in the map information display device or the like has a problem that roads cannot be sufficiently grouped.

"Compress road information" is the same road type,
And it is a group of links that can be written in a single stroke. However, in reality, there are many roads that cannot be written in a single stroke even though they are of the same road type. For example, on an urban highway (such as the Metropolitan Expressway), ramps exist at relatively short distance intervals. The ramp serves as an entrance / exit that connects the main line of the highway and a general road.
Therefore, the main line of the expressway will be branched for each ramp. For this reason, when the main line is grouped by one stroke, short links that join the general road that branches for each ramp will remain without being grouped. Therefore, these links have the same attributes but are not directly connected to each other and must be recorded one by one with that attribute.

Such a phenomenon is often seen on major roads in urban areas such as roads connecting upper and lower roads that are separated from each other. As described above, in the conventional map information display device and the like, the fact that the groupable links are limited to the set of links that can be written in one stroke is one of the causes of the problem of the large amount of map information. There is.

Thirdly, in the conventional "road shape compression" method in the map information display device and the like, there is a problem in expressing curved roads such as curved roads, gently curved roads, and interchanges of toll roads.

In the conventional "road shape compression" method in a map information display device or the like, a large number of interpolation points for expressing the shape of a road such as a curved road are set and linear approximation is performed between the interpolation points. The shape was close to a curve. Therefore, the data of these many interpolation points also contributes to the large amount of map information.

As described above, the conventional technique has not been able to sufficiently compress the map information due to the above three remaining problems. Therefore, since the volume of map information is still large, there is still a problem that it is difficult to deliver the map information and store the map information in the semiconductor memory.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems and provide a road map information reading device, a recording medium and a transmission method capable of sufficiently compressing road map information. is there.

[0030]

[Means for Solving the Problems and Effects of the Invention] The first invention is to provide an inter-road relation between roads represented on a road map.
The connection information, a road map information readout apparatus for reading out output from the recording medium, roads included in all or part of the road map area is classified into a plurality of groups in accordance with the road type, road type Pre-assigned based on
Each group is recorded according to the recording format of the different data structure
The connection information between roads related to the roads belonging to the loop
The recorded and recorded road map information recording medium, a read range designating means for designating a range on the road map, and a designated range.
The road connection information included in the
And read control means for reading al, of the read road contact
And output means for outputting the connection information, road map information recording
Multiple groups of media are main road group and secondary road
Includes groups, secondary road groups include main road groups
Road map by compressing road connection information compared to
A recording format with good information recording efficiency is assigned,
The output means reads the connection information of the main road group and
When displaying the connection information of the secondary road group and the map
Output in each format to perform route search or position detection.
Connection information of the sub road group, the main road group
It is characterized in that it is output after being converted into the same format as the connection information of .

As described above, the first invention is a road map information reading device including a road map information recording medium, a reading range designating means, a reading control means, and an outputting means. Then, on this road map information recording medium, road maps are classified into a plurality of arbitrary groups and different recording formats are assigned to each other, and the connection information of roads in each group is recorded according to the assigned recording format. To do. That is, it becomes possible to appropriately allocate a recording format adapted to the characteristics of the map range. Therefore, it is possible to reduce the volume of map information of all roads to be recorded in the road map information recording medium. Along with this, the processing speed of the road map information reading device can be increased.

According to a second aspect of the present invention, in the first aspect, the roads belonging to the main road group are roads used by the user more frequently than the roads belonging to the sub road group. road belonging to the sub road group, compared to the road belonging to the relatively main road group, and wherein the frequency of use of the user is lower road.

As described above, in the second invention, the plurality of groups in the first invention are divided into a main road group composed of roads that are used more frequently than the sub road group and a road of the main road group. It is classified into a secondary road group consisting of roads that are less frequently used. Then, a recording format that requires a smaller recording capacity than the recording format assigned to the main road group is assigned to the sub road group. That is, a recording format that emphasizes processing speed is assigned to the main road group, and a recording format that emphasizes reduction in capacity is assigned to the sub road group. By thus classifying and allocating the recording format, the effect of the first invention can be made more practical.

In a third aspect based on the second aspect, the recording format assigned to the main road group is a recording format for recording a table showing a connection state of the node for each node, and the recording format assigned to the sub road group. The format is characterized in that it is a recording format for recording, for each node, information identifying a node that should come next to the node and a flag indicating pen-up or pen-down.

As described above, in the third invention, the recording format of the main road group in the second invention is a format in which the connection state of a certain node (intersection) is recorded as a table. In addition, the recording format of the sub road group is such that, for each node, information for identifying the node that should come next to the node and a pen-up flag indicating connection / non-connection are recorded. Thus, the third invention is a more specific version of the second invention.

A fourth aspect of the present invention is a road shape in which the first road belonging to the main road group and the second road belonging to the sub road group in the second and third inventions intersect each other on the first road. Is recorded on the road map information recording medium, and an auxiliary point indicating the intersection of the second road and the information for identifying the auxiliary point from the second road are further recorded.

As described above, the fourth aspect of the present invention relates to roads belonging to the main road group of the second and third aspects of the present invention (first roads).
This is a recording method in the case of a road shape in which a road belonging to the sub road group and a road belonging to the sub road group (second road) intersect. In this case, information on an auxiliary point indicating an intersection on the first road and information specifying the auxiliary point from the second road are further recorded in the road map information recording medium. As a result, it is possible to obtain the information that the first road and the second road intersect each other without calculating the intersection coordinates while realizing the reduction of the capacity of the connection information about the first road. Therefore, according to the fourth aspect, it is possible to easily obtain such connection information of the intersection road.

In a fifth invention according to the second, third and fourth inventions, the sub road group is further divided into a plurality of small groups, the road connection information in each of the small groups, and adjacent roads. The road connection information connecting one or more small groups to be recorded is further recorded on the road map information recording medium.

As described above, the fifth invention is the second and third inventions.
And the roads belonging to the sub road group in the fourth invention are divided into smaller groups. Thereby, the fifth aspect of the present invention can selectively convert only roads belonging to a necessary small group. Therefore, in addition to the effects of the second, third, and fourth inventions, the fifth invention makes it possible to shorten the time for conversion processing of road connection information, and also reduces the recording capacity of road map information. Even in this case, the result of the road connection processing can be obtained at high speed.

The sixth invention relates to the first and second inventions.
There, the recording format assigned to the main road group is a main road connection state is represented with one stroke, branches from the road
At least one branch road that has the same type of attribute and is associated with both roads in a series.
Record wherein the kite as connection information of roads.

As described above, in the road map information recording medium of the sixth invention, one road group connected in a one-stroke manner has a branched road having the same attribute which is not connected in a one-stroke manner. Also manage and record together.
Therefore, it is possible to reduce the volume of map information of all roads to be recorded in the road map information recording medium. Along with this, the processing speed of the road map information reading device can be increased.

The seventh invention is based on the first and second inventions.
There, the recording format assigned to the main road group, includes the road information for connecting nodes in a curved shape drawn on the basis of the auxiliary between point by a predetermined curve interpolation processing, the interpolation point on the curve shape recording so as to be located and characterized a kite.

As described above, the seventh aspect of the present invention uses a predetermined curve interpolation process for drawing a curve passing over a plurality of interpolation points on the road map information recording medium, and the minimum shape that can express the road shape by the process. Record the interpolation points. Thereby, the number of interpolation points for expressing a curved road can be reduced.
Therefore, it is possible to reduce the volume of map information of all roads to be recorded in the road map information recording medium. Along with this, the processing speed of the road map information reading device can be increased.

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a configuration of a road map information reading device according to a first embodiment of the present invention. In FIG. 1, a road map information reading device according to a first embodiment of the present invention is a map information recording medium 101.
A read range designation means 102, a map read control means 103, and a map output means 104.

The map information recording medium 101 records map information including vector map information and management information.
The map information recording medium 101 according to the first embodiment
May be a map information recording device. The read range designating means 102 is for designating a map range that the user desires to read. Map read control means 103
Reads out the necessary map information from the map information recording medium 101 according to the range designated by the reading range designating means 102. The map output means 104 displays the map information read by the map read control means 103. Further, the map information is used for correction of detection of the current position, route search, etc., in addition to being displayed by the map output means 104.

The operation of the road map information reading device according to the first embodiment of the present invention configured as above will be described below. The road map information reading device according to the first embodiment of the present invention first classifies roads into main roads that frequently use connection information and narrow streets that rarely use connection information. Then, the recording format of the connection information regarding the narrow street is set to a recording format having a smaller capacity than the recording format regarding the main road. Thereby, the capacity of the map information to be recorded in the road map information reading device is compressed.

FIG. 2 is a flowchart showing the map reading procedure of the road map information reading device according to the first embodiment. The operation will be described below with reference to FIG. When the map reading procedure is started, first, a map reading range is designated (step S201). This designation may be performed by the user by directly inputting the range, or by automatically determining an arbitrary range around the current position of the vehicle in an in-vehicle navigation system or the like.
Alternatively, a map required for the route search processing or the like of the road map information reading device may be automatically determined and performed. Then, after the map reading range is designated, the map information of the designated range is searched and read from the map information recording medium 101 (step S202).

FIG. 3 shows an example of an outline of a map used in the road map information reading device according to the first embodiment. As shown in FIG. 3, the map is generally a set of units of various sizes. Then, as the management information of each unit, information about the longitude / latitude of the unit origin (for example, the lower left corner of the unit frame) and the size of the unit in the longitude / latitude direction is usually recorded. This management information is used to search for map units that overlap the specified range.

Referring again to FIG. When necessary map information is read in step S202, the necessity of connection information of the narrow street is determined (step S203). When the connection information of the narrow street is required, the format of the connection information of the narrow street is converted (step S205). On the other hand, when the connection information of the narrow street is not necessary, the map information is output as it is (step S204). This output may be displayed as a map, may be used as a map around the current position used for vehicle position detection processing, or may be used as a map for route search processing. Then, after outputting this map information, the process returns to step S201 and the above processing is repeated again.

The above is the outline of the flow of the map reading process. Hereinafter, steps S203 and S205 will be described in more detail.

FIG. 4 is a diagram showing a recording format of map information used in the road map information reading device according to the first embodiment of the present invention. In FIG. 4, the map unit information, which is information about the entire map, is composed of a “node table” and a “road table” that record information about main roads, and a “narrow street table” that records information about narrow streets. . The "node table" records "node information" which is data of intersections of main roads. "Road table"
Records "road information", which is a set of links connecting the intersections of the main roads. The “narrow street table” records information on the narrow streets as “element point information”. The "node information" consists of "node attributes", which is data such as the presence or absence of traffic lights at intersections, "normalized longitude" and "normalized latitude", which are data indicating the position of intersections, and "connection link pointers". Become. The "road information" is composed of "road attributes" of data such as road types such as national roads and toll roads, which is an outline of links, "head node pointer", and "link information" which is inner data of links. This "link information" consists of "link attributes", which is data such as one-way information and the number of lanes, and a "connection node pointer". The "element point information" includes a "pen-up flag", a "signal flag", a "one-way flag", and "normalized longitude" and "normalized latitude" that are data indicating the position of the element point. .

FIG. 5 shows an example of map information. In FIG. 5, A to C indicate intersections of main roads, a to
f indicates a link connecting the intersections of the main roads. In addition, a plurality of thin lines added to the link b indicate a narrow street.

As described above, in the recording format of the map information of the first embodiment, the information about the main roads is individually stored in the “node table” for the data of the intersections and in the “road table” for the data of the links of the intersections. It is recorded. Therefore, in the map information recording format of the first embodiment, the link connecting to each intersection can be easily known.

First, the recording method regarding the main road will be described in detail with reference to FIGS. 4, 5 and 6. Nodes at both ends of each link are set as a start point node and an end point node. Then, in the “road information”, the start point node of the first link is called the top node of the road. The end point node of each link is assumed to be the start point node of the next link. In FIG. 5, the road 502 is composed of a link e and a link f, and the node B is the road 5
02 is the first node. Also, the road 503
Is composed of only the link d, and the node B is assumed to be the end node of the link d.

FIG. 6 shows an example of records of the "node table" and the "road table" when the node B of FIG. 5 is focused on. Node B "connection link pointer"
The address recording the "connection node pointer" of the link d is recorded in. Here, in the "connection node pointer" of this link d, the address recording the "start node pointer" of the road 502 is recorded. And the "head node pointer" of this road 502
The address recording the “connection link pointer” of the node B is recorded in. In this way, when performing the processing of a certain node, so that the relevant processing can circulate all the parts that record information related to the node,
The pointer sequentially points to the recording portion. As a result, regardless of the number of links connected to the node, only one "connection link pointer" needs to be recorded in the "node information".

Therefore, in the map information recording format of the first embodiment, when investigating a link connecting to a certain node, all the link information to be connected is obtained by sequentially tracing the address pointed to by this "connection link pointer". Will be understood. Therefore, at the time of the link survey, it is not necessary to search from a large amount of map information, and the necessary connection information can be quickly obtained. It should be noted that the high speed of the search of the connection information is especially required in the route search processing. From this,
It is desirable to adopt the recording format described above for the main roads that are often used for route search processing.

Next, the recording format of the information on the narrow streets will be described in detail below. As described above, the recording format of the road connection information of the narrow street is for the purpose of compressing the information, and thus the recording format shown in the explanation of the main roads is not used. The recording format of the road connection information of the narrow street is basically the same data structure as the map information representing the road shape as a simple picture that does not include the connection attribute data, as shown in FIG. This structure approximates the format used for map information for display. Here, "normalized longitude" and "normalized latitude" are relative coordinates within each map unit. Therefore, in order to calculate the true longitude / latitude, it is necessary to add the normalized longitude / latitude to the coordinates of the unit origin.

FIG. 7 is an enlarged view of a narrow street near the link b in FIG. In FIG. 7, numbers 1 to 24
Is an element point that constitutes a narrow street, and a road is formed by connecting the element points. Hereinafter, a method of recording road connection information on a narrow street will be described with reference to FIGS. 4 and 7.

This recording method creates the road network shown in FIG. 7 by connecting each element point of a narrow street in a one-stroke manner and records the contents of the element points in the order of one-stroke writing. Is. However, not all road networks can be written with a single stroke on a single road, so a “pen-up flag” is used here to indicate whether the stroke is continuous or broken. . When the "pen-up flag" is "0", it is assumed that the element point and the element point immediately before are connected by a road. Therefore, normally, "pen-up flag"
Is "0". When the "pen-up flag" is "1", the road cannot be continuously written with one stroke, that is, the start of the next one-stroke writing is indicated. A detailed description will be given with reference to the narrow street of FIG. First, element points 1 → 2 →
Since up to 10 can be written with one stroke, the "pen-up flag" in each element point information becomes "0". Next, since the narrow street does not exist from the element points 10 to 11 (note that the main road (link b) does not exist in this case), the "pen-up flag" of the element point 11 is "1". Becomes From this element point 11, again 11 → 12
→ ‥ → → You can write up to 18 strokes.
The “pen-up flag” up to 18 is “0”. Similarly, the “pen-up flag” of the element points 19 and 23 is “1”, and the “pen-up flags” of the other element points are “0”.

The "signal flag" is a flag indicating the presence or absence of a traffic light at the element point position, and is "1" when there is a traffic light. Also, the "one-way flag" indicates information of one-way using 2 bits. The first bit of the two bits is a flag indicating whether or not there is one-way control, and becomes "1" when the road between the preceding element points is one-way.
The second bit of the 2 bits indicates the direction of traffic when there is one-way traffic control. If the traffic is allowed from the previous element point to the current element point, it is '0'. It becomes "1".

As described above, in the recording format of the first embodiment, it is possible to express the road shape and the connection information of the narrow street in the format of “element point information”. With this recording format, the road map information reading device according to the first embodiment of the present invention reduces the capacity of map information, that is, the information, compared with the conventional device described in the above-mentioned first document. The compression rate is improved.

In order to improve the information compression rate, the road shown in FIG. 7 will be used to compress map information in the recording format of the first embodiment and the recording format described in the first document. The difference in the rate (recording capacity) is calculated and compared. As a precondition for calculation, 2 bytes each for longitude / latitude information, 1 byte for node identification (index or pointer) and cost information, and 1 bit for flag (= 0.125 bytes. However, one-way flag 2 bits) is required.
However, in both formats, "node attribute" and "road attribute" are not considered.

First, with respect to the recording format described in the first document, the capacity required for recording map information will be calculated. The recording format described in the first document is for recording the information of other nodes connected to the node regarding an arbitrary node regardless of whether it is a main road or a narrow street. Therefore, nodes A to F and 1 to 21 (1
If the numbers are duplicated in one node, the smaller number is calculated), and the coordinate information and the connection information may be obtained for each of the two. Since coordinate information requires longitude / latitude information (2 × 2 = 4 bytes) for one node, the capacity required to represent the coordinates of all nodes (23 nodes) is as follows. 23 × 4 = 92 [bytes] As the connection information, as shown in FIG. 21A, the record size may be calculated from the number of connected nodes of each node. For example, let's calculate for node A. Node A
The number of nodes connected to B is three from B to D. Each of the connection nodes requires 1 byte for the information of "index" and "cost". Further, each piece of connection information requires 1 byte for each of the information of "data capacity" and "number of nodes" as shown in FIG. 18 (c). Therefore, the record size of node A is 3 ×
2 + 2 = 8 [bytes] will be required. As described above, the connection information can be obtained by calculating the record sizes of all the 23 nodes and adding them. All the road connection information shown in FIG. 7 is 166 bytes (see FIG. 21A).

Next, for the recording format of the first embodiment, the capacity required for recording map information will be calculated. First, consider the main roads. As mentioned above, the main road is A
~ F has 6 nodes. And the "node table"
Is the longitude / latitude (2
X2 = 4 bytes) and pointer (1 byte) information. Therefore, the capacity of information related to the “node table” is 6 × (4 + 1) = 30 [bytes] (however, 24 bytes correspond to coordinate information and 6 bytes correspond to connection information). On the other hand, the road groups that allow one-stroke writing of main roads include nodes D → A → C → F and nodes A → B.
→ C → E. Therefore, the number of links (“→” in the preceding sentence) for representing the road group is six. Then, the "road table" has a pointer (1 byte) and a link (that is,
The cost. 1 byte) of information. Also, a head node pointer (1 byte) is required for each road group. Therefore, the capacity of information on the “road table” is 6 × (1 + 1) + 2 = 14 [bytes] (however, all 14 bytes correspond to connection information). Next, the required capacity for the road information of the narrow street is calculated. As shown in FIG. 7, the element points of the narrow street are numbered from 1 to
Up to 24. However, unlike the case of the first document,
Since the recording format of the first embodiment processes all roads by the one-stroke writing method, if the numbers are duplicated (for example, 4 and 13), they must be recorded again. Then, the “narrow street table” is composed of information of longitude / latitude (2 × 2 = 4 bytes) and flag (0.125 × 4 = 0.5 bytes) as shown in FIG. 4 for each node. It Therefore, the capacity of the information related to the “narrow street table” is 24 × (4 + 0.5) = 108 [bytes] (however, 96 bytes correspond to coordinate data and 12 bytes correspond to connection data).

Therefore, comparing the respective calculated values, the result shown in FIG. 21 (b) is obtained. That is, when recording the same road information, the recording format of the first embodiment is the first
As compared with the recording format described in the above document, the capacity of 106 bytes can be reduced for the map information shown in FIG. Therefore, the map information can be compressed by using the recording format of the first embodiment of the present invention.

As described above, when the recording format of the first embodiment is used, map information can be compressed. However, the recording format of this narrow street (“small street table”) is different from the recording format used for the main road (“node table” and “road table”). Therefore, in the recording format of the narrow street, in order to obtain the road information connecting to a certain element point, all “element point information” are searched for an element point having the same coordinate value as that element point. There is a need. Although this is a simple process, the processing time cannot be ignored if repeated many times.

On the other hand, in the case of performing the route search processing, as for the information on the narrow streets, it is almost necessary to use only the information on the narrow streets around the current location and the information on the narrow streets around the destination. Therefore, even if it takes some search time to obtain road connection information regarding a narrow street, the influence on the overall processing time of the route search processing is small. In addition, more than half of all roads in the map unit are often narrow streets in the present detailed maps of urban areas.

Therefore, the road map information reading apparatus according to the first embodiment of the present invention determines the necessity of the connection information of the narrow streets for the processing time lengthened with the compression of the road information of the narrow streets. Is provided for shortening (FIG. 2, step S203).

In FIG. 2, when the map information read out in step S202 is simply used for displaying the map, the connection information of the narrow streets is not necessary. Therefore, in this case, the road map information reading device according to the first embodiment of the present invention performs the map display process without the special process of converting the format of the connection information of the narrow street (step S204). On the other hand, when using map information for route search processing, etc.,
The connection information of the narrow street is necessary. Then, the apparatus is required to repeatedly search for a connecting road having the same element point. Therefore, in this case, the device reads the "narrow street table" in the map unit, selects an intersection among the respective element points, searches for the connecting road, and has the same format as the main road (that is, "node"). Table "and" road table "
Format) (step S205). This format conversion can be easily performed by repeating the process of searching the connecting road for all the element points in the “narrow street table”. Then, after performing this format conversion, the device shifts to step S204 and outputs map information based on information on both the main road and the narrow street.

It should be noted that this format conversion processing naturally requires some time. However, rather than recording the information of the main road and the narrow street in the same format and searching for the road connecting to each element point of the narrow street every time in the route search processing,
In the format of the above embodiment, and the determination step S203 described above.
By providing the, the overall processing becomes faster.

As described above, the road map information reading device according to the first embodiment compresses the information size of a narrow street where the frequency of use of road connection information is low, rather than the ease of the process of acquiring the connection information. Is prioritized. As a result, the road map information reading device according to the first embodiment significantly reduces the total amount of map information necessary for the device.

In the road map information reading device according to the first embodiment, the connection information of the narrow streets is calculated in step S2.
Although it is used in the route search processing or the like after the format conversion in 05, the connection information of the narrow street may be directly used in the route search processing or the like. Further, the format converted in step S205 is not limited to the format of the main road of the first embodiment, and may be another format as long as it has connection information instead of simple map information.

(Second Embodiment) Next, a road map information reading device according to a second embodiment of the present invention will be described. A road map information reading device according to a second embodiment of the present invention was invented based on the road map information reading device according to the first embodiment of the present invention, and has a device configuration (FIG. 1), The operation flowchart (FIG. 2) and the map unit (FIG. 3) are common. The device according to the second embodiment is different from the device according to the first embodiment in the recording format of the “narrow street table”.

In the recording format of the "narrow street table" in the above-described first embodiment, in order to obtain the road connecting to a certain element point, all the element points having the same coordinates as the element point have all the "element point information". It was necessary to search for. In addition, in the recording format of the first embodiment, a plurality of element points occur on the same coordinate, so the information must be redundant.

In order to solve the above problem, the recording format of the first embodiment is improved in the road map information reading device according to the second embodiment of the present invention. Less than,
This will be described with reference to FIGS. 8 and 9.

FIG. 8 shows the structure of the "narrow street table" in the second embodiment. In FIG.
The structure of the "element point node information" in the "element point information" is the same as the structure of the "element point information" in the first embodiment (see FIG. 4). Note that the configurations of the “node table” and the “road table” are similar to those shown in FIG. 4, and description thereof will be omitted here. In short, the “small street table” in the second embodiment is newly provided with “element point connection information”. In this "element point connection information", only the connections between the already defined element points are recorded.

FIG. 9 is a diagram showing a map of a narrow street corresponding to FIG. 7 for explaining the recording procedure of the second embodiment. Also in the recording procedure of the second embodiment, the one-stroke writing method is adopted. First, in FIG. 9, element points 1 to 1
Connect up to 0 with a single stroke. Up to this point, the process is the same as in the case of the first embodiment. But the difference here is
In the second embodiment, the one-stroke writing to be drawn next has a condition that the one-stroke writing is drawn so as not to pass the already defined (single-stroke writing) element points. Therefore, in FIG. 9, the road is, for example, the element points 11 → 12 → 15 → 16. After the road is drawn, the remaining element points that can be written with one stroke under the above conditions are element points 13 → 14. By the above processing, the road indicated by the thick broken line in FIG. 9 can be recorded by the one-stroke writing method. Here, the element point 17
Is not recorded in a one-stroke method,
The "pen-up flag" is set to "1" and recorded in the "element point node information" in the form of a point.

By the processing up to this point, all the element points (1 to 17) of the narrow street shown in FIG. 9 could be recorded in the "element point node information". However, since the narrow street cannot be represented by this alone, the connection information is recorded next about the unconnected portion between the element points. That is, in FIG. 9, element points 4 and 12, 4 and 13, 5 and 14, 5 and 15,
Since there is no connection between 6 and 17, 8 and 17, and 15 and 17, the connection information between these is further recorded. Therefore, in order to record this connection information, "element point connection information" is used in the second embodiment. "Element point connection information"
Records the unconnected portion between element points in the order defined by "element point node information" in the form of both element point numbers and their one-way information. As a result, the recording format of the second embodiment can express all narrow streets.

According to the recording format of the second embodiment, when searching for another element point connected to a certain element point, the element point number is searched instead of the coordinate. That is,
Since the search target is reduced from two pieces of information of longitude and latitude to one piece of information of the element point number, the search can be performed at high speed. In addition, the recording format of the second embodiment has an advantage that element point information can be recorded separately for a plurality of element points that have the same coordinates but are not connected, such as a three-dimensional intersection. Of course, the recording format of the second embodiment realizes compression of information as described below.

With respect to the recording format of the second embodiment, the capacity of map information will be calculated. First of all, "narrow street table"
The configuration of the "element point node information" is the same as the configuration of the "element point information" in the recording format of the first embodiment. Therefore, all "element point node information" of 17 element points
The capacity required for recording is 17 × (4 + 0.5) = 76.5 [bytes]. Next, as shown in FIG. 8, the “element point connection information” of the “narrow street table” has the element point numbers (1 × 2 = 2 bytes) at both ends and the one-way flag (0.125) for each connection information. × 2 = 0.25 bytes). Therefore, the capacity of information related to the narrow street table is 7 × 2.25≈16 [bytes]. The required capacities for the “node table” and “road table” of the main road are the same as the values calculated in the description of the first embodiment, and are 30 bytes and 14 bytes, respectively. Therefore, the total capacity required for recording map information is as follows. 76.5 + 16 + 30 + 14 = 136.5 [bytes]

As described above, the recording format of the second embodiment can reduce the recording capacity of the map information more than the recording format of the first embodiment, and the acquisition processing of the connection information of the narrow streets. The speed can also be improved.

(Third Embodiment) Next, a road map information reading device according to a third embodiment of the present invention will be described. A road map information reading device according to a third embodiment of the present invention was invented based on the road map information reading device according to the first embodiment of the present invention, and has a device configuration (FIG. 1), The operation flowchart (FIG. 2) and the map unit (FIG. 3) are common. The device according to the third embodiment is different from the device according to the first embodiment in that the recording format of the "narrow street table" is improved and a "shape table" is further provided.

In the recording format of the "narrow street table" in the above-described first and second embodiments, in order to obtain the intersection of the main street and the narrow street, the element points of the narrow street are arranged on the shape of the main street. It was necessary to determine whether or not the coordinate exists by performing the coordinate calculation. Therefore, the first and second
The road map information reading device according to the embodiment requires a lot of time to process the acquired information in the route search process and the like.

Therefore, in order to solve the above-mentioned problems, the road map information reading device according to the third embodiment of the present invention has improved the recording formats of the first and second embodiments. This will be described below with reference to FIGS. 10 and 11.

FIG. 10 shows the configurations of the "shape table" and the "narrow street table" in the third embodiment. In FIG. 10, the structure of “element point node information (A)” in “element point information” and “element point connection information”
Is similar to the configuration of the “element point information” in the second embodiment (see FIG. 8). Note that the configurations of the “node table” and the “road table” are similar to those shown in FIG. 4, and description thereof will be omitted here. In short, the recording format in the third embodiment is a new “shape table”.
In addition, "element point node information (B)" is provided in the "narrow street table".

First, the "shape table" will be described. As shown in FIG. 10, the “shape table” has “road shape information”. This "road shape information" is composed of "in-road link number" and "interpolation point information". The "interpolation point information" is composed of "interpolation point attribute" and coordinate information of "normalized longitude" and "normalized latitude".

The "road shape information" is recorded for each road in the same sequence as the "road information" in the "road table". The "road shape information" is the "link number" and "interpolation point information" of the road recorded in the order in which the "link information" is recorded in the "road information" in FIG. When a plurality of links each have a shape on the same road (that is, between the same nodes), a plurality of “link numbers” and “interpolation point information” are recorded side by side.

The "interpolation point information" is information indicating the shape of the link. In FIG. 10, the coordinates of the interpolation points are “normalized longitude” and “normalized latitude”, but this may be a difference value from the coordinates of the head node of the link. The “interpolation point attribute” is used here to distinguish an interpolation point for expressing a link shape from an interpolation point (expressed as an auxiliary point in claim 4) that is an intersection of a narrow street. For example, in FIG. 11, the link b (node A to
It is the figure which showed the interpolation point which the link of C) has. Figure 11
In, the filled square points (,, and) are the intersections of the link b and the narrow street, and the white round points () are the interpolation points for expressing the link shape. Therefore, when displaying the link b, it is sufficient to connect the node A and the interpolation point and the interpolation point and the node C with straight lines. A number is assigned to each interpolation point in the recording order. For example, in link b, numbers are given in order from the left (from node A to node C).

Next, the "narrow street table" will be described. As described above, the recording format of the third embodiment has “element point node information (B)” in “element point information” unlike the recording format of the second embodiment. In this "element point node information (B)", when an element point of a narrow street intersects with a main road at an interpolation point, information specifying a main road having the interpolation point and connection information of the element point are used as connection information of the element point. Information for identifying each interpolation point is recorded. However, this interpolation point is an intersection with the main road and is also an element point node of the narrow street. Therefore, the “element point node information (B)” has the “pen-up flag”, the “signal flag”, and the “one-way flag” as in the first embodiment. The "central separation zone flag" is a flag indicating whether or not there is a central separation zone on the main road side at the intersection. The "central separation zone flag" displays "1" when there is a central separation zone on the main road side and "0" when there is no central separation zone.
When there is a median strip, the vehicles cannot turn to each other, so this "median strip flag" information is
It is important in the route search process. The "road number", "link number", and "interpolation point number" are information that records the positions of the main roads that intersect. With this information, the position of the main roads that intersect can be known from the "narrow street table". it can. Thereby, the road map information reading device according to the third embodiment can specify the intersection of the main road and the narrow street without calculating the coordinates. For example, the element point 16 in FIG.
'1' for "road number" and "2" for "link number"
"3" is recorded in the "interpolation point number". Therefore, according to this information, when the destination near the element point 5 in FIG. It becomes possible to calculate the route connecting to the narrow street and display it easily.

As described above, in the recording format of the third embodiment, the interpolation points of the main roads are recorded in the “shape table”, and the “road number”, “link number” and “link number” are recorded in the “narrow street table”. Record each information of "interpolation point number".
As a result, the road map information reading apparatus according to the third embodiment shortens the processing time such as the route search processing by knowing the position of the main road intersecting with the “narrow street table”. Since the purpose of the third embodiment is to shorten the processing time, from the viewpoint of reducing the amount of information, the second embodiment
Compared with the embodiment described above, the amount of information will increase as follows (however, the amount of information will decrease as compared to the conventional form).

With regard to the recording format of the third embodiment, the capacity of map information will be calculated. First of all, "narrow street table"
The configuration of the "element point node information (A)" is the same as the configuration of the "element point information" in the recording format of the second embodiment. However, the element points (1, 10,
11 and 16) are excluded, and there are 13 recording targets.
Therefore, the capacity required to record all “element point node information (A)” of 13 element points is 13 × (4 + 0.5) = 58.5 [bytes]. Next, the “element point connection information” of the “narrow street table” has the same configuration as the “element point connection information” in the recording format of the second embodiment. Therefore, the capacity required to record the “element point connection information” is 7 × 2.25≈16 [bytes]. Next, “element point node information (B)” is as shown in FIG.
As shown in, the element points 1, 10 that intersect the main road,
For each 11 and 16, each flag (0.125 × 5 =
0.625 bytes) and each number (1 x 3 = 3 bytes)
It is composed of information. Therefore, the capacity required to record all “element point node information (B)” of four intersecting element points is 4 × (0.625 + 3) = 14.5 [bytes]. In addition, "road shape information" of "shape table"
Is composed of the intra-road link number (1 byte), the interpolation point attribute (1 byte) in the interpolation point information, and the longitude / latitude coordinates (2 × 2 = 4 bytes) for each interpolation point on the main road. . Therefore, the capacity required to record the “road shape information” is 5 × (1 + 1 + 4) = 30 [bytes]. The required capacities for the “node table” and the “road table” of the main road are the same as the values calculated in the description of the first embodiment and are 30 bytes and 14 bytes, respectively. Therefore, the total capacity required for recording map information is as follows. 58.5 + 16 + 14.5 + 30 + 30 + 14 = 163
[Part-Time Job]

As described above, the recording format of the third embodiment can reduce the recording capacity of map information more than the conventional recording format. Further, in the recording format of the third embodiment, the intersection of the main road and the narrow street can be obtained without calculating the coordinates of the interpolation points, so that the recording format of the narrow street is smaller than that of the recording format of the second embodiment. It is also possible to improve the connection information acquisition processing speed.

In the above description, the method of connecting the interpolation points with a straight line is used to express the shape of the link.
On curved roads and highways with many interpolation points, the number of interpolation points can be significantly reduced by using curve interpolation. Therefore, it is possible to further reduce the capacity of the map information.

For example, the main line of a highway is shown in FIG.
As shown in, the map unit often crosses a gentle curve. At interchanges, ramps, junctions, etc., as shown in FIG.
There are many roads that go around greatly. In order to draw such a road shape smoothly by the linear approximation method, many interpolation points are required (see FIGS. 12A and 12B). However, even in the case of such a road, by using the curve approximation method, interpolation points can be significantly reduced and a smooth road shape can be displayed as shown in FIGS. 12 (c) and 12 (d).

However, some attention must be paid to the curve interpolation method. For example, when the processing is performed using the "B spline function" as the curve interpolation method, the shape of the interpolated curve is a shape that is in contact with the straight line connecting the interpolation points. Therefore, in the method using the B-spline function, the drawn curve does not pass on the interpolation point (see FIG. 12 (e)). Therefore, when the curved road near the map unit boundary is represented by the method using the B-spline function, the position of the interpolation point may be a coordinate value outside the map unit range frame (see FIG. 12 (e)).
This means that a road having an interpolation point outside this frame cannot be drawn.

As described above, the coordinates of the interpolation points generally use the coordinates "normalized longitude" and "normalized latitude" in the map unit frame. Therefore, for the curve interpolation, it is necessary to adopt the curve interpolation method of passing over the interpolation point as shown in FIG. 12F, instead of the B-spline method.

(Fourth Embodiment) Next, a road map information reading device according to a fourth embodiment of the present invention will be described. A road map information reading device according to a fourth embodiment of the present invention was invented based on the road map information reading device according to the first, second and third embodiments of the present invention. The configuration (FIG. 1), the operation flowchart (FIG. 2) and the map unit (FIG. 3) are common. Fourth
The device according to the embodiment is different from the device according to the third embodiment in that a record of “inter-group connection information” is provided in the “narrow street table”.

In the recording format of the "narrow street table" in the above-mentioned first, second and third embodiments, in step S205 of FIG. 2, connection information of all "element point information" in the map unit It was necessary to perform format conversion.
However, in reality, in many cases, the connection information of the narrow streets necessary for performing the route search processing and the like is only a part within the map unit. Therefore, the road map information reading devices according to the first, second, and third embodiments perform the format conversion process even for the unneeded narrow streets, so that it takes time to process the acquired information in the route search process and the like. I needed a lot.

Therefore, in order to solve the above problem, the recording format of the first, second and third embodiments is improved and the narrow streets are divided into groups and managed, which is the fourth embodiment of the present invention. It is a road map information read-out device which concerns on a form. Less than,
This will be described with reference to FIGS. 13 and 14.

FIG. 13A shows the structure of the "narrow street table" in the fourth embodiment. FIG.
In (a), "element point node information (A)", "element point node information (B)" and "element point connection information" in "element point information" are the "element point information" in the third embodiment. The configuration is the same as that of “” (see FIG. 10). Further, the configurations of the “node table”, the “road table” and the “shape table” are the same as those shown in FIGS. 4 and 10, and the description thereof will be omitted here. In short, the recording format in the fourth embodiment is that the "inter-group connection information" is newly provided in the "narrow street table". This "inter-group connection information" records the "group number" indicating the identification number of the narrow street group.

FIG. 14 is a map of a certain area. 14
In, the thick line indicates the main road and the thin line indicates the narrow street. Fourth
As shown in FIG. 14, the recording format in the embodiment of
The narrow streets in the map unit are divided into groups surrounded by main roads (in FIG. 14, narrow street groups 1 to 6). Then, the element point information is defined for each group in the same manner as in the procedure of the third embodiment to express the narrow street. However, the division of the narrow streets requires the identification number of the narrow street group. Therefore, the recording format in the fourth embodiment is “inter-group connection information”.
Records the identification number of each narrow street group.

By grouping the narrow streets in this way, the format conversion of the connection information of the narrow streets in step S205 of FIG. 2 can be performed by selecting only the necessary narrow street group portion. Therefore, it becomes possible to convert the format of the information of the narrow street at high speed. For example, in FIG. 14, when the route search processing from the point A to the point B is performed, only the information of the narrow street groups 1 and 6 is converted for the narrow streets, and the route search may be performed with this.
That is, in the route search of the narrow street group 1, the first route connecting from the point A to the road 1404 (or the road 1402), and in the route search of the narrow street group 6 from the point B to the road 1402 (or the road 1405). All you have to do is find a second route to. By doing this, the route search of the main road will
The main route can be connected to the second route and the second route.

Therefore, by using the recording format of the fourth embodiment, as compared with the first to third embodiments in which the format conversion is performed for all the narrow streets in the map unit, the information amount of the narrow streets to be processed is processed. Can be minimized. Therefore, the recording format can reduce the time required for the entire route search process.

In the fourth embodiment, the grouping is carried out in the range of the narrow street surrounded by the main roads. However, in order to further increase the processing speed, the narrow street group is further subdivided into groups. It doesn't matter. However, in this case, the information required to connect the narrow street groups is required as shown below.

FIG. 15 shows a specific example in which the narrow street groups are further divided into groups. In FIG. 15, roads 1501 and 1502 are narrow street group 1
Since it is a road that is connected across 2 and 2,
The connection information of this road is needed. That is,
Information indicating the element point number 5 of the narrow street group 1 and the element point number 5 of the narrow street group 2 and the passing direction thereof, and the element point number 6 of the narrow street group 1 and the element point number 4 of the narrow street group 2 Information and information about the direction of passage. In order to record these pieces of information, the recording format of the fourth embodiment is such that “inter-group connection information” includes “group number 1” indicating one narrow street group and element points in the one narrow street group. “Element point number 1”, “group number 2” indicating the other narrow street group to which the one element point is connected, “element point number 2” indicating the element point in the other narrow street group, and “ A one-way flag "is required (see FIG. 13B).

(Fifth Embodiment) Next, a road map information reading device according to a fifth embodiment of the present invention will be described. A road map information reading device according to a fifth embodiment of the present invention was invented based on the road map information reading device according to the first embodiment of the present invention, and has a device configuration (FIG. 1), The operation flowchart (FIG. 2) and the map unit (FIG. 3) are common. The device according to the fifth embodiment is different from the device according to the first embodiment in the recording format of the "link information" in the "road table".

In the above-described first embodiment, the links having the same road attributes (for example, highways and national roads) are collectively recorded as one road information to compress the map information capacity. However, since the links that can be put together are limited to those that can be written in a single stroke, there are many links that cannot be put together conveniently.

Therefore, in order to solve the above problem, the recording format of the first embodiment is improved so that links having road attributes of the same kind, which are excluded in one stroke, can be put together. Is a road map information reading device according to a fifth embodiment of the present invention. Below, FIG.
Will be described with reference to FIG.

FIG. 17 is a diagram showing an example of a road network in a section in which toll roads and general roads are not combined into one as described above. In FIG. 17, a road 1701 that is a toll road and a road 1702 that is a general road run in parallel. As shown in the first embodiment, when the roads are put together by the one-stroke writing method, the links a, b and c can be put together for the road 1701 and the links f, g and h can be put together for the road 1702. However, the problem here is the links d and e that connect the ramp of the toll road to the general road. These two links d
Since and are not included in a single stroke, they must be recorded as one independent road. For this reason, it is often found not only on toll roads but also on general roads that one road must be composed of one link.

In order to deal with this problem, the "link information" shown in FIG. 16 is used in the recording format of the fifth embodiment.
In FIG. 16, "link attribute" in "road table"
Has a "pen-up flag". The "pen-up flag" is used in the same manner as when recording the road connection information on the narrow streets described above, and is "1" when expressing a link that cannot be written with one stroke, and is usually "0". For example, in the case of recording the road network shown in FIG. 17, regarding the road 1701, the links adb
Arrange in the order of -ec, and record only "pen-up flag" of links d and e as "1". Regarding the road 1702, all the "pen-up flags" are recorded as "0", along with the links f-g-h.

Note that the connection relation of links on the road can be uniquely specified by defining as follows, for example. 1. The link having the “pen-up flag” of “1” is defined as a branch link (links d and e in FIG. 17). The end node of the branch link is the road end point (see FIG. 17).
Nodes C and D) in. 2. The link recorded next to the branch link shares the starting point node with the branch link recorded immediately before.

As described above, according to the fifth embodiment, even roads including branches (roads as shown in FIG. 17) can be collectively managed with roads having the same type of “road attribute”. . Therefore, the recording format of the fifth embodiment can reduce the number of roads to be recorded and also reduce information such as "road attribute" and "head node pointer", resulting in reduction of map capacity.

In the fifth embodiment, the number of branch links is 1.
Although it is composed of book links, it is also possible to define a branch link composed of a plurality of links by recording the number of links of the branch link in the "pen-up flag".

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a road map information reading device according to all embodiments of the present invention.

FIG. 2 is a flowchart showing the operation of the road map information reading device according to all the embodiments of the present invention.

FIG. 3 is a diagram showing a map unit used in the road map information reading device according to all the embodiments of the present invention.

FIG. 4 is a diagram showing a recording format of map unit information of the road map information reading device according to the first embodiment of the present invention.

FIG. 5 is a diagram showing an example of a road network.

FIG. 6 is a diagram showing a method for recording and recording a traveling address of road connection information of a main road.

FIG. 7 is a diagram relating to the description of the recording format of the first embodiment.
It is the figure which expanded the narrow street of.

FIG. 8 is a diagram showing a recording format of map unit information of a road map information reading device according to a second embodiment of the present invention.

FIG. 9 is a diagram relating to the description of the recording format of the second embodiment.
It is the figure which expanded the narrow street of.

FIG. 10 is a diagram showing a recording format of map unit information of a road map information reading device according to a third embodiment of the present invention.

FIG. 11 is an enlarged view of the narrow street of FIG. 5 related to the description of the recording format of the third embodiment.

FIG. 12 is a diagram showing an example of a road shape represented by interpolation points according to the third embodiment of the present invention.

FIG. 13 is a diagram showing a recording format of map unit information of a road map information reading device according to a fourth embodiment of the present invention.

FIG. 14 is a diagram showing a road network related to a description of a recording format according to a fourth embodiment.

FIG. 15 is a diagram showing a road network regarding a description of a recording format according to a fourth embodiment.

FIG. 16 is a diagram showing a recording format of map unit information of a road map information reading device according to a fifth embodiment of the present invention.

FIG. 17 is a diagram showing a road network related to the description of the recording format of the fifth embodiment.

FIG. 18 is a diagram showing an example of a recording format of a conventional road connection relationship.

FIG. 19 is a diagram illustrating a conventional method of expressing connection information of grouped links.

FIG. 20 is a block diagram showing a configuration of a conventional map information display device.

FIG. 21 is a diagram comparing the map information recording capacities of the conventional map information display device and the road map information reading device according to the first embodiment of the present invention.

[Explanation of Codes] 101 ... Map information recording medium 102 ... Read range designation means 103 ... Map read control means 104 ... Map output means 501-503, 1401-1405, 1501, 15
02, 1701, 1702 ... Road 2001 ... Vector map data 2002 ... Data conversion means 2003 ... First storage means 2004 ... Image processing means 2005 ... Frame memory 2006 ... Display means 2007 ... Position input means 2008 ... Second storage means

Continuation of front page (56) Reference JP-A-7-37067 (JP, A) JP-A-7-272192 (JP, A) JP-A-7-218274 (JP, A) JP-A-7-27568 (JP , A) JP-A-8-320648 (JP, A) US Pat. No. 5285391 (US, A) European patent application publication 346492 (EP, A 1) (58) Fields investigated (Int.Cl. ⁷ , DB name) G09B 29/00-29/14

Claims (7)

(57) [Claims] 1. A road related to a road represented on a road map.
Road for reading connection information between roads from a recording medium and outputting
It is a road map information reading device, and roads included in all or part of the area on the road map
It is classified into a plurality of groups in accordance with the road type, road type
Different data structures pre-allocated based on
Regarding the roads belonging to each group according to the recording format of
A road map information recording medium in which connection information between roads is recorded, a read range designating unit for designating a range on the road map, and the connection information of roads included in the designated range,
The road map information recording medium is provided with a read control unit and an output unit that outputs the read connection information of the road, and the plurality of groups of the road map information recording medium are
Including a road group and a sub road group, the sub road group, compared to the main road group,
The road map information is recorded by compressing the road connection information.
A recording format having a high recording efficiency is assigned, and the output means is connected to the read main road group.
A map display of the connection information and the connection information of the secondary road group is displayed.
In each case, output in each format, route search or position
When performing detection, the connection information of the secondary road group is
After converting to the same format as the connection information of the main road group
A road map information reading device, which is characterized by outputting to . 2. A road belonging before Symbol main road group, compared to the road belonging to relatively said sub road group, a use frequency of the user is high road, the road belonging to said sub road group are relatively The road map information reading device according to claim 1, wherein the road is used less frequently by a user than roads belonging to the main road group. 3. The recording format assigned to the main road group is a recording format for recording a table showing the connection state of the node for each node, and the recording format assigned to the sub road group is for each node. The road map information reading device according to claim 2, wherein the road map information reading device is in a recording format for recording information for identifying a node to be next to the node and a flag indicating pen-up or pen-down. 4. In a road shape in which a first road belonging to the main road group and a second road belonging to the sub road group intersect, an auxiliary point indicating the intersecting point on the first road. 4. The road map information reading device according to claim 2, further comprising: and information for identifying the auxiliary point from the second road, further recorded in the road map information recording medium. 5. The sub road group is further divided into a plurality of small groups, and roads connecting information between roads in each of the small groups and one or more adjacent small groups. 5. The road map information read-out device according to claim 2, further comprising: the connection information of 1.) recorded in the road map information recording medium. 6. A record form assigned to the main road group
Expression, and the main road connection state is represented with one stroke, branched into branch from the road, and, associating the at least one branch road having the attributes of the same type, both of the road connection information of the series of Characterized by being recorded as road connection information
The road map information reading device according to claim 1 or 2 . 7. A record form assigned to the main road group
Wherein it is included the road information for connecting nodes in a curved shape drawn on the basis of the auxiliary between point by a predetermined curve interpolation processing,
The interpolation point was recorded so as to be located on the curve shape.
The road map information reading device according to claim 1 or 2, characterized in that .