JP2653847B2 - Navigation apparatus and route search method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device and a route search method for searching for a route (route) in a hierarchical structure of map data.

[Conventional technology]

2. Description of the Related Art A navigation device provides a route guidance to a driver whose geography is unknown, and in recent years, this navigation device has been actively developed.

The navigation device sets a route from a departure place to a destination by inputting a departure place and a destination before traveling, and performs navigation according to the set route. In navigation, when instructing a route, a map is displayed on the CRT screen and the route is superimposed on it, or information on the intersection to be turned next according to the preset route, until the intersection to be turned next In some cases, the distance is displayed as a number or a graph, and the characteristic scenery of an intersection or a passing point is displayed as a photograph, and further, audio output is also used.

In a road network, generally, there are a plurality of routes between a starting point and a destination. for that reason,
In a navigation device, when a departure point and a destination are input, an attempt has been made to adopt a route search method of searching for a route of the shortest time or the shortest distance (shortest route) therebetween. For example, in the case of an intersection at a four-way intersection, an intersection is represented by eight nodes and sixteen directional links in order to express a right / left turn, going straight, and a U-turn, and the intersections are connected to each other. It has been reported that a road branch is represented by two directional links. The other is a method of searching for the shortest route that does not include the no-progress route by searching for the shortest route, comparing with the no-progress route, and removing the shortest route that includes the no-progress route (for example, Japanese Patent Application Laid-Open No. 62-91811). Publication).

[Problems to be solved by the invention]

However, the former method has a problem that the amount of data is large and the storage capacity is large, because all the information on turning right and left at an intersection is represented by directional links. Also,
In the conventional data structure, when a right / left turn is detected and weighted by the right / left turn to perform a route search in the shortest time, the calculation of the right / left turn determination becomes complicated and takes time.
In particular, when the four-way road is represented by eight nodes and 16 directional links, the data volume of the 16 directional links must be weighted because the data must have weighted distance or time. More.

In addition, in the route search, as the distance from the departure point to the destination increases, and as the density of the road network increases, the number of intersections subject to the route search increases accordingly. Therefore, there is a problem that the calculation time required for the route search and the storage capacity of the memory used for the search process increase.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a navigation device and a route search method thereof that shorten the calculation time of the route search.

[Means for solving the problem]

Therefore, the present invention is a navigation device that performs a route search from a designated departure point to a destination, sets a route, and provides route guidance according to the set route, and based on the information amount of the road network. Storage means for expanding a hierarchy from a lower hierarchy having a large amount of road network information to an upper hierarchy having a small amount of road network information, and storing map data having connection information between the respective layers; Based on the connection information between the respective layers, based on the connection information between the respective layers, a route search is performed up to a point connecting to a higher layer, based on the connection information between the respective layers,
Route search means for performing a route search from the departure point to the destination by repeatedly performing a route search from the connecting point by shifting to a higher hierarchy, further comprising: It is characterized in that a route search is performed in accordance with the positional relationship between the blocks including the departure place and the destination, after division.

Further, when a departure place and a destination are set as a route search method, respective blocks including the departure place and the destination are specified, and whether the blocks including the departure place and the destination are the same or adjacent to each other is determined. By deciding whether they are away from each other,
Check the positional relationship of each block including the departure point and the destination, and if the block including the departure point and the destination is the same, input the intersection and road data of the block and start from the departure point. A route search to the destination is performed, and when the block including the departure point and the destination are adjacent to each other, the intersection and the road data of the block including the departure point are read, and the block including the departure point is read. After detecting a connecting intersection connecting the blocks including the destination and performing a route search from the starting point to the connecting intersection in the block including the starting point, the intersection and the road data of the block including the destination are read. In the block including the destination, a route search from the connecting intersection to the destination is performed, and the block including the departure point and the destination is performed. When the blocks are separated from each other, the intersection of the block including the departure point and the road data are read to detect the connection intersection of the block including the departure point connected to the block of the upper hierarchy, and the connection intersection is determined as described above. In the block including the departure point, a route search from the departure point to the connection intersection is performed in the block including the departure point, and the intersection and road data of the block including the destination are read to read the block in the upper layer. Detecting a connecting intersection of a block including the destination to be connected to and setting the connecting intersection as a destination of the block of the upper hierarchy, and performing a route search from the destination to the connecting intersection in the block including the destination. In the above hierarchy, the same processing is performed until the blocks including the departure place and the destination are the same or are adjacent to each other. It is characterized in that to carry out returns Ri.

[Action and effect of the invention]

In the navigation device and the route search method of the present invention, the map data is further divided into blocks in a hierarchical structure based on the information amount of the road network, and the hierarchy and blocks including the designated starting point and destination are specified. The route and the block are connected in order based on the connection information of the layer and the block, and the route search from the departure point to the destination is performed. When the distance between the departure point and the destination is short, the route search is performed in the lower hierarchy, and when the distance between the departure point and the destination is long, the route is shifted to the higher hierarchy. It is possible to search for a route that passes through a high-ranked road such as a main trunk line or an expressway. In addition, the upper layer does not include low rank roads such as branch roads, and when the block of the departure point and the block of the destination become the same block or an adjacent block when transitioning to the block of the upper layer, the departure point between them becomes the same. Since the route search to the destination is terminated, an efficient route search can be performed.

In addition, since the blocks are divided in each layer so that the data amount is substantially the same, even for a complicated road network having a large amount of information, it is only necessary to always repeat the route search within the same capacity. Therefore, the storage capacity required for the route search may be small, the route search can be performed efficiently, and the calculation time for the route search can be reduced.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a diagram for explaining one embodiment of a navigation device according to the present invention.

In FIG. 1, layer 1 includes intersection numbers I, II,
It is a map of the main arterial road network having III,..., And is composed of one block 1. Layer 2 is a map including a road network of branch lines connected to the main arterial road network of Layer 1, and is composed of six blocks 1 to 6. And
The connecting roads between the blocks include blocks 1 and 2 of layer 2
Like the intersection numbers V and II between the intersections, the intersections are set in a pseudo manner so that the processing unit can be constituted by blocks. The number of blocks is set so that the amount of information is substantially the same for each. Therefore, each of the block 1 of the layer 1 and the blocks 1 to 6 of the layer 2 have the same information amount as the road network data, and correspond to the rank of the road (main road, branch road, and the like). Expands the hierarchical structure from below. The navigation device according to the present invention has such a hierarchical structure, further stores map data divided into blocks in each hierarchy according to the amount of information as appropriate, and designates the map data using the hierarchical structure of the map data. From the departure point to the destination, a route search for smoothly connecting the main road and the branch roads is performed by an arithmetic processing device (route search device).

The route search method of the present invention uses, as map data, a hierarchical structure composed of layers 1, 2,. The route to the ground is searched. Therefore, when there is a branch road further below the road network of layer 2, layer 3 is set, and the number of blocks increases according to the information amount. Similarly, when not only the block 1 of the layer 1 but also the surrounding road network is targeted, the layer 1 is composed of the block 1 and the blocks of the road network around it. And in this case,
The upper layer of layer 1 is set.

Next, an example of a route search method by an arithmetic processing device (route search device) using the map data of FIG. 1 will be described.

For example, the departure point and the destination are respectively the intersection number I in block 1 of layer 2 and the intersection number II in block 6
Let it be I.

First, the departure point of the intersection number I in the block 1 is an intersection number that does not exist in the layer 1 of the upper hierarchy. Then, find the intersection number in layer 1 of the upper hierarchy,
The intersection numbers III and IV (intersection numbers I and I
Search for the route to I) and go up to the upper level.

On the other hand, since the intersection number III in the block 6 is the intersection number VIII in the layer 1 of the upper hierarchy, it goes up to the upper hierarchy as it is.

In the upper layer 1, a route search from the intersection number I or II to the intersection number VIII is performed together with the information on the route search performed in the lower layer 2.

As is clear from the above example, according to the blocks where the departure place and the destination exist, the blocks can be classified into three types: the same block, the adjacent block, and the distant block. Therefore, the route search method of the present invention performs a route search as follows according to each of them.

First, if the starting point and the destination are in the same block, a route search is performed in that block. Also,
If the starting and destination blocks are adjacent to each other, the intersection (connection intersection) connecting the starting and destination blocks is detected, and from the starting point, the connecting intersection,
The route search is performed twice from the destination to the connecting intersection. However, if the departure point and the destination block are far apart, a route search is performed from the departure point to the intersection connected to the upper layer in the departure point block as in the above example, and In the destination block, a route search from the destination to the intersection connected to the upper layer is performed. Then, the same route search is performed on the upper layer until the above or the condition is satisfied.

Next, a specific configuration example of road data suitable for use in the above route search method will be described.

FIG. 2 is a diagram showing an example of the data structure of block 1 in layer 2 of FIG. 1, FIG. 3 is a diagram showing an example of the data structure of block 4 in layer 2 of FIG. 1, and FIG.
FIG. 5 is a diagram showing an example of a data structure of a block 6 in a layer 2 in FIG. 5, and FIG. 5 is a diagram showing an example of a data structure of a block 1 in a layer 1 in FIG.

The data of each block is composed of road data (FIG. 2A) and intersection data (FIG. 2B), as shown in FIGS. For example, as shown in FIG. 2, the road data includes the intersection number of the starting point, the intersection number of the ending point, the road number having the same starting point, the road number having the same ending point, the guidance information corresponding to each road number in the block. Information such as unnecessary roads, relative lengths of roads, and layers is stored. The unit of the road number usually consists of a plurality of nodes. The node data, which is not shown, is data relating to one point on the road, and what connects the nodes is called an arc.
A road is represented by connecting each of the plurality of node rows with an arc. In addition, the intersection data includes east longitude, north latitude, outgoing road number, incoming road number, intersection number of upper layer, intersection number of lower layer, intersection number of horizontal block (continuous (Intersection number).

Among these, the road number having the same start point (end point) and the road number exiting (entering) are information of connecting roads at the intersection, respectively. Usually, since there are a plurality of road numbers, the smallest road number among them is provided. Is registered. This makes it easy to search for a connecting road at an intersection as described later. Further, the relative lengths of the guide-unnecessary roads and roads are information necessary for calculating a substantial time required for traveling. For example, even if the roads have the same width and length, the actual travel time can be converted into a shorter travel time on a road that does not require guidance than a road that requires guidance. Or if the road is easily congested, the relative length will be long. The layer indicates the rank of the road. That is, the information indicates the order of the layer of the road. Intersection number of the upper (lower) layer, for example, 1
-1-2 indicates a layer 1-block 1-intersection number in the layer block. The same applies to the intersection numbers of the horizontal blocks.

Next, a route search method of the navigation device according to the present invention will be described according to a processing flow.

FIG. 6 is a diagram showing the structure of the work file and the index file, FIG. 7 is a diagram for explaining the overall processing flow in the route search, and FIG. 8 is for explaining the processing flow of the same block search routine. , FIG. 9 is a diagram for explaining the flow of processing of the adjacent block search routine, and FIG. 10 is a diagram for explaining the flow of processing of the remote block search routine.

The work file is used by reading intersection data and road data in a block when performing a route search in block units, and as shown in FIG. 6A, the number of intersections, the number of roads, the start point, and the end point. And information such as a road number entering an intersection obtained as a result of a block search, a flag indicating a departure place and a destination of a block route search, and the like. The index file manages block information, and has information such as the number of blocks and the block number as shown in FIG.

In the route search performed by the arithmetic processing device (route search device), first, as shown in FIG. 7, the positional relationship between the starting and destination blocks is checked from the index file. The process branches to one of the block search and remote block search processing routines.

In the same block search, as shown in FIG. 8, intersection data and road data are input, a work area is initialized, and a departure place and a destination are set. Thereafter, the flow branches to a route search subroutine, and the generated route is output.

In the adjacent block search, the intersection number is expressed in the form of C (layer-block-intersection number), the road number is expressed in the form of R (layer-block-road number), and the departure point is C (2-1-
1) Assuming that the destination is C (2-4-4), the following processing is performed in the steps shown in FIG.

Read the data of layer 2 and block 1 where the departure point is.

 The connection intersection S is stored in the memory as described below.

All the intersections in the block in the work area are set and initialized as follows.

Road coming to the intersection ← 0 Flag ← Not searched Distance ← 7FFFFFFFH Departure intersection C in the work area (2-1
"Tentative" is set in the flag of 1) and "0" is set in the distance.

Continuous intersection (2-1-6), C (2-
1-7) is set.

A route search is performed from the departure point intersection (2-1-1) to the continuous intersections (2-1-6) and C (2-1-7), which are temporary destinations.

Save the work area. At this time, the distance to the connecting intersection is stored in the memory as described below.

The same route search as that described above is performed by setting the departure point C (2-4-1) and the destination as connection intersections C (2-4-5) and C (2-4-4).

-Select the connecting intersection that will be the shortest course. For example, the distance from the departure point and the distance from the destination , The connecting intersections are C (2-1-6) and C (2-4-4) whose distances are shorter from (6 + 5) <(11 + 8).
5).

Route C (2-4-1) -C (2
-4-5) is created.

~ Load the work area, and route C (2-1-1) -C (2-1-3) -C (2-1) of the departure block
-6) is created.

The above respective routes are synthesized, and C (2-1-
1) -C (2-1-3) -C (2-1-6)-(2-4)
-1) -C (2-4-5) is output.

Next, the remote block search will be described. Here, it is assumed that the departure place is C (2-1-1) and the destination is C (2-6-2).

-Read data of layer 2 and block 1 where the departure point is.

 A connection intersection S2 to a higher layer is detected.

~ Departure point is C (2-1-1), destination is C (2-1-1)
Perform search as 1-3) and C (2-1-4), and save the work area.

The distance from the departure point to the connection intersection S2 is stored in the memory.

-Data of layer 2 and block 6 having a destination are read.

 The connection intersection D2 of the upper layer is detected.

~ The starting point is C (2-6-2) and the destination is C (2- 6-2).
6-1), search is performed as C (2-6-3), and the work area is saved.

The distance from the departure point to the connection intersection D2 is stored in the memory.

-Data of upper layer 1 and block 1 are input.

Intersection S2 (C (1-1-1), C
(1-1-2)) is set. In addition, a distance from the departure point to the connecting intersection S2 is set as an initial value of the distance.

Connection destination D2 (C (1-1-7), C
(1-1-8)) is set.

Connection intersection S2 (C (1-1-1), C (1-1-
From 2), the connecting intersection D2 (C (1-1-7), C (1-1)
Perform route search up to -8)).

The distance from the starting point to the connecting intersection D2 is compared with the distance from the destination to the connecting intersection D2. For example, the distance from the departure point and the distance from the destination , The connecting intersection is C (2-6-3) and C (1-1-1) whose distances are shorter from (22 + 3) <(21 + 2).
8) is the connection intersection D2 that is the shortest route.

Layer 1 route C (1-1-8) -C (1-1-
6) Take out -C (1-1-5) -C (1-1-2).

~ Load the work area of the departure block and route C (2-1-4) -C (2-1-
2) Take out -C (2-1-1).

~ Load the work area of the destination block, and route C (2-6-3) -C (2-6
Remove 2).

The above respective routes are synthesized, and C (2-1-
1) -C (2-1-2) -C (2-1-4) -C (1-
1-5) -C (1-1-6) -C (2-6-3) -C
(2-6-2) is output.

 Next, the route search subroutine will be described.

FIG. 11 is a diagram for explaining the flow of the processing of the route search subroutine.

Here, L (c) is distance, F (c) is a flag, and R (c)
The passage to have the road number, s _0, s ₁ intersection number of two neighboring point of departure, e _0, e ₁ is the intersection number of two neighboring destinations. Also, c is the intersection number, and the flag F (c) is “0” not yet searched, “1” is being searched, and “2” is the end of the search.

For all intersections, the distance L (c) is set to infinity (∞) and the flag F (c) is set to “0” (not searched). By this initial setting, all the intersections are not searched at first, and the distance from the departure point becomes infinite.

Distances from the departure place are entered in the distances L (s ₀ ) and L (s ₁ ) corresponding to the intersection numbers s ₀ and s ₁ on both sides of the departure place, and the intersection numbers s ₀ and s on both sides of the departure place _The flag F (s
₀ ) and F (s ₁ ) are each set to “1”, and the road number R (c) that has passed is set to the road number from the departure place.

The intersection number c _{0 in} which the flag F is not “2” and the distance L (c) is minimum is searched.

Execute the surrounding road search subroutine to obtain the intersection number c ₀
Search for surrounding roads starting from.

 Check if there is a surrounding road.

If YES, the process proceeds to the next process. If NO, the process proceeds.

A description will be given of road conditions and other conditions for executing the optimum route condition setting subroutine to search for the optimum route.

The intersection number of the end point of the road is c ₁ , and the length of the road is l
And

 The distance P to the intersection at the end point of the road is calculated.

Calculate P = L (c ₀ ) +1.

Here L (c ₀₎ is the distance from the departure point to the intersection number c _0, P is the distance to the intersection number c ₁ endpoint through the road from the intersection number c ₀ (road being searched) .

It is checked whether P <L (c ₁ ) and F (c ₁ ) ≠ 2.

If YES, the process proceeds to the next process. If NO, the process returns.

The distance from the starting point to the intersection number c ₁ in the search L
The (c ₁₎ P, the intersection number flag F (c ₁₎ to "1" in the c _1, the intersection number c ₁ road number has been passed up to the R (c ₁₎ and a road number of the search in I do.

If NO in the processing, F (c ₀ ) is set to “2”.

 Execute the end condition confirmation subroutine.

It is determined whether or not the processing has been completed. If NO, the process returns to the process. If YES, the process is terminated.

By performing the above processing, the road numbers of the optimum course from the departure point to the intersection number are set for each intersection number in correspondence with each intersection number.

FIG. 12 is a diagram for explaining a process flow of a surrounding road search subroutine, FIG. 13 is a diagram for explaining a process flow of an optimal route condition setting subroutine, and FIG. 14 is a diagram for explaining a process of an end condition confirmation subroutine. It is a figure for explaining a flow.

The surrounding road search subroutine of the above processing performs the processing shown in FIG. That is, it is checked whether or not the search for the surrounding road is the first time.

In the case of YES, the processing shifts to processing. In the case of NO, the processing shifts to processing.

Intersection c ₀ which are here from the intersection data stores removed road number that is the starting point.

Retrieve the prohibition road in the road number comes to the intersection c ₀ in the search with reference to the road data. Check whether the road taken out is a prohibited road.

If YES, the process proceeds to the process. If NO, the process proceeds to the next process.

The road that has just been taken out is stored as the surrounding road, and the process returns (moves to the processing in FIG. 11).

From the road data, a road number having the same starting point as the previously searched road and having the next number is extracted.

It is checked whether the road searched first and the road taken out are the same.

If YES, the process proceeds to the next process. If NO, the process returns.

 Judge that there is no surrounding road and return.

Further, the optimal route condition setting subroutine of the process shown in FIG. 11 performs a process as shown in FIG. That is, the relative length 1 is read from the road data.

The guidance unnecessary data of the road that has passed to the intersection currently being searched is read from the road data.

It is checked whether there is a surrounding road that matches the guidance unnecessary data.

If YES, the process returns. If NO, the process proceeds to the next step.

Further, a value obtained by adding bm to the length l is set as a new length l, and the process returns. That is, for intersections that do not require guidance,
Intersections that require guidance such as turning left and right are converted to distances and evaluated with bm added.

The termination condition confirmation subroutine, checks the match of the first 14 intersection number c ₀ and the intersection number of the destination of the two neighboring search target as shown in the figure, setting conditions, for example, the end flag that matched.

As described above, in the route search, the distance between the intersections is weighted in consideration of the driving conditions such as the size of the surrounding road and the necessity / unnecessity of guiding the road, and the shortest route is searched.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, the route search is performed by moving up to the upper layer until the departure point and the destination become the same block or adjacent blocks. However, in the case of the adjacent block, the route search is performed and the upper layer is searched. And finally, the starting point and the destination may be connected by searching for a route in the same block. However, in this case, even if there is no route in the upper layer between adjacent blocks, but a route more appropriate than the route of the main road in the upper layer, this route is not set. Therefore, in the case of an adjacent block, it can be said that it is more efficient to end the route search at that level.

As is apparent from the above description, according to the present invention, the road network data such as the intersection data and the road data is provided in a hierarchical structure, and the route search is performed by sequentially moving up from the lower hierarchy (layer) to the upper hierarchy. , The search range can be limited, and the speed of the search process can be increased.
In addition, since each layer is divided into blocks according to the data amount and the route search is performed in block units, the work area required for the route search can be reduced, and the storage area can be saved.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining one embodiment of a navigation device according to the present invention, FIG. 2 is a diagram showing an example of the data structure of block 1 in layer 2 of FIG. 1, and FIG. 3 is FIG. FIG. 4 shows an example of the data structure of block 4 in layer 2 of FIG. 1, FIG. 4 shows an example of the data structure of block 6 in layer 2 of FIG. 1, and FIG. 5 shows block 1 of layer 1 in FIG. FIG. 6 is a diagram showing an example of the data structure of FIG. 6, FIG. 6 is a diagram showing the structure of a work file and an index file,
FIG. 7 is a diagram for explaining the flow of the entire process in the route search, FIG. 8 is a diagram for explaining the flow of the process of the same block search routine, and FIG. 9 is a flow of the process of the adjacent block search routine. FIG. 10 is a diagram for explaining a processing flow of a remote block search routine, FIG. 11 is a diagram for explaining a processing flow of a route search subroutine, and FIG. 12 is a surrounding road. FIG. 13 is a diagram for explaining a processing flow of a search subroutine, FIG. 13 is a diagram for explaining a processing flow of an optimum route condition setting subroutine, and FIG.
The figure is a diagram for explaining the processing flow of the end condition confirmation subroutine.

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Claims (15)

(57) [Claims] 1. A navigation device that searches for a route from a designated departure point to a destination, sets a route, and provides route guidance according to the set route. A storage unit configured to expand a hierarchy from a lower hierarchy having a large amount of road network information to an upper hierarchy having a small amount of road network information, and to store map data having connection information between the respective hierarchies; The hierarchy including the designated starting point and destination is specified, and based on the connection information between the respective hierarchies, a route search is performed up to a point where the specified hierarchy is connected to the upper hierarchy, and further moved to the upper hierarchy. A route search means for performing a route search from a departure place to a destination by repeatedly performing a route search from the connecting point. 2. The navigation device according to claim 1, wherein the map data stored in said storage means is divided into blocks based on the information amount of a road network in each hierarchy. 3. A navigation device that searches for a route from a designated departure point to a destination, sets a route, and provides route guidance according to the set route. Storage means for expanding a hierarchy from a lower hierarchy having a large amount of road network information to an upper hierarchy having a small amount of road network information, dividing the blocks into blocks at each hierarchy, and storing map data having connection information between each hierarchy. And specifying a hierarchy and a block including the specified departure place and destination based on the map data, determining whether or not the departure place and destination are connected by the specified block, Performs a route search in the specified block, and when the departure point and the destination are not connected, based on the connection information between the respective layers, the level specified until the departure point and the destination are connected. Navigation system, characterized in that it comprises a route searching means for performing a route search Yuki raised successively hierarchy hierarchy Luo higher. 4. The navigation apparatus according to claim 2, wherein the map data is developed in a hierarchical structure from an upper level to a lower level in correspondence with a rank of a road. 5. The navigation apparatus according to claim 2, wherein each of the map data is divided into blocks so that the information amount is substantially the same. 6. The map data is characterized by storing road data and intersection data, and providing connection information between the respective hierarchies in intersection data connecting a lower hierarchical road network to an upper hierarchical road network. The navigation device according to claim 2 or 3, wherein 7. The route search means determines whether the departure point and the destination are connected by determining whether the block including the departure point and the block including the destination are the same block in the same hierarchy or an adjacent block. It is determined whether or not the block is the same or the adjacent block in the same layer, and a route search is performed in the block in the same layer. The route search is performed from the hierarchy of each block including the above to the intersection connecting to the higher hierarchy, and the above determination and the route search process are repeatedly performed at the higher hierarchy using the connecting intersection as the departure point and the destination. 7. The navigation device according to claim 6, wherein: 8. A route search method of a navigation device for performing a route search from a designated departure point to a destination, setting a route, and performing route guidance according to the set route, wherein the information amount of the road network is determined. Based on the hierarchical structure, a hierarchy is developed from a lower hierarchy with more information on the road network to an upper hierarchy with less information on the road network, and map data having connection information between each hierarchy is stored. Based on the connection information between the respective layers, a route search is performed up to a point where the specified layer is connected to an upper layer, and a higher level is determined. A route search from a starting point to a destination by repeatedly performing a route search from the connecting point. 9. A route search method for a navigation device according to claim 8, wherein the map data is divided into blocks based on the information amount of the road network in each hierarchy. 10. A route search method of a navigation device for performing a route search from a designated departure point to a destination, setting a route, and performing route guidance according to the set route, wherein the information amount of the road network is determined. Based on a hierarchical structure, the hierarchy is expanded from a lower hierarchy with more information on the road network to an upper hierarchy with less information on the road network. At the same time, map data having connection information between each hierarchy is divided into blocks at each hierarchy. When storing, specifying a hierarchy and a block including the specified departure place and destination based on the map data, determining whether the departure place and the destination are connected by the specified block, and connecting. In the specified block, a route search is performed, and when the departure place and the destination are not connected, the route is specified until the departure place and the destination are connected based on the connection information between the respective layers. A route search method for a navigation device, wherein a route search is performed by sequentially moving up a hierarchy from a hierarchy to a higher hierarchy. 11. The route search method for a navigation device according to claim 9, wherein the map data is developed in a hierarchical structure from an upper level to a lower level in correspondence with a rank of a road. 12. The method according to claim 9, wherein the map data is divided into blocks so that the information amount is substantially the same. 13. The map data includes road data and intersection data, and connection information between the respective layers is provided in intersection data connecting a lower layer road network to an upper layer road network. The route search method for a navigation device according to claim 9 or 10, wherein: 14. When a route search is performed by determining whether or not a departure point and a destination are connected in the specified block,
By judging whether the block including the departure place and the block including the destination are the same block in the same hierarchy or adjacent blocks, it is determined whether or not the departure place and the destination are connected, and the same block in the same hierarchy Alternatively, if the block is an adjacent block, a route search is performed in the block of that layer. If the block is neither the same block nor an adjacent block of the same layer, the higher layer from the layer of each block including the departure place and the destination 7. The navigation device according to claim 6, wherein a route search is performed up to an intersection connected to the navigation system, and the determination and the route search process are repeatedly performed at the higher hierarchy with the connected intersection as a departure point and a destination. Route search method. 15. Hierarchical structure based on the amount of information of the road network is developed from a lower layer with more information on the road network to an upper layer with less information on the road network, and is divided into blocks at each layer. A route search method of a navigation device for searching for a route from a designated departure point to a destination based on intersection data including connection information between respective layers and map data including road data, wherein the departure point and the destination are set. Then, each block including the departure place and the destination is specified, and by determining whether the block including the departure place and the destination is the same, adjacent to each other, or separated from each other, the departure place and the destination are determined. Check the positional relationship of each block including the destination, and if the block including the departure point and the destination is the same, enter the intersection and road data of the block. A route search from the departure point to the destination is performed.If the blocks including the departure point and the destination are adjacent to each other, the intersection and road data of the block including the departure point are read and the departure point is determined. After detecting a connecting intersection connecting the block including the destination and the block including the destination, and performing a route search from the starting point to the connecting intersection in the block including the starting point, the intersection of the block including the destination and The road data is read and a route search from the connecting intersection to the destination is performed in the block including the destination. If the block including the departure point and the destination is separated from each other, the block including the departure point is included. To read the intersection and road data and detect the connecting intersection of the block including the departure point to be connected to the upper layer block. The connecting intersection is set as the starting point of the block of the upper hierarchy, a route search from the starting point to the connecting intersection is performed in the block including the starting point, and the intersection and road data of the block including the destination are read. Detecting the connecting intersection of the block including the destination connected to the block of the upper layer, setting the connecting intersection as the destination of the block of the upper layer, and setting the connecting intersection from the destination to the block including the destination in the block including the destination. A route search method for a navigation device, wherein the same process is repeated until blocks including a departure place and a destination are the same or adjacent to each other in the hierarchy.