WO2011101895A1

WO2011101895A1 - Map display device and map display method

Info

Publication number: WO2011101895A1
Application number: PCT/JP2010/000992
Authority: WO
Inventors: 野口素継
Original assignee: 三菱電機株式会社
Priority date: 2010-02-17
Filing date: 2010-02-17
Publication date: 2011-08-25

Abstract

Disclosed is a map display device provided with a map data acquisition unit (4). When a map scrolling operation is received by a drawing control unit (2), the map data acquisition unit (4) acquires, from among map data stored by a map database (1), map data having the same scale as map data being used in a drawing of a map currently being displayed; the map data acquired can be used to draw a map having a greater range than the map currently being displayed. When a map scrolling operation is not received by the drawing control unit (2), the map data acquisition unit (4) acquires, from among the map data stored by the map database (1), a plurality of map data items having a different scale from the map data being used in the drawing of the map currently being displayed; the map data acquired can be used to draw a map having the same range as the map currently being displayed.

Description

Map display device and map display method

The present invention relates to a map display device mounted on a car navigation system, for example, and relates to a map display device capable of changing the scale of a map.

When a user uses a car navigation system equipped with a map display device, a map scroll operation or a map scale change operation may be performed in order to display a map of a desired point.
When a user performs a map scale change operation, it is rare to store the correspondence between the map scale and the map display range, so check the map display range while repeating the scale change operation multiple times. Thus, it is common to determine a desired scale.
However, since map data is large-capacity data, it is generally stored in a low-speed large-capacity storage device such as a hard disk.
Therefore, it takes a lot of time to read map data of a corresponding scale from a low-speed large-capacity storage device every time a scale change operation is performed, and it is difficult to draw a map at high speed.

The map display device disclosed in Patent Document 1 below discloses a method for drawing a map at high speed.
That is, in the map display device disclosed in Patent Document 1, a map database storing a plurality of map data (map data in units of rectangular areas called meshes) having different scales is prepared and stored in the map database. Among the map data in units of meshes, the map data used in the past is cached in the internal high-speed main memory.
Thus, when the map scale change operation is performed, if the map data of the corresponding scale is stored in the main memory, it is not necessary to read the map data from the low-speed mass storage device. Drawing is possible.

However, since the capacity of the internal high-speed main memory is generally small, a lot of map data cannot be cached in the main memory.
In view of this, in this map display device, reference is made to the access frequency of recent map data, and map data having a reduced scale with high access frequency is preferentially cached in the main memory.

JP 2002-290718 A (paragraph numbers [0012] [0013] [0037] [0038], FIGS. 2 and 5)

Since the conventional map display device is configured as described above, map data having a reduced scale with high access frequency is preferentially cached in the internal main memory, but map data having a desired scale is cached in the main memory. If not, map data must be read from a low-speed mass storage device, and there is a problem that the map cannot be drawn at high speed.
Further, the map data is cached in the internal main memory in units of meshes, but the map range displayed in the window does not always match the mesh range in the map data. For this reason, when drawing a map, for each drawing item (for example, a symbol such as a building) included in the map data, it is necessary to determine whether or not the drawing item is located within the display range of the map. However, there was a problem that prevented high-speed drawing of maps.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a map display device and a map display method capable of drawing a map at high speed.

The map display device according to the present invention is capable of drawing a map having a wider range than the currently displayed map from the map data stored in the map database when a map scroll operation is received by the operation receiving means. Map data that is the same scale as the map data currently used for drawing the currently displayed map, and is stored in the map database if the map scroll operation is not accepted by the operation accepting means Map data that can draw a map in the same range as the currently displayed map from the displayed map data, and the map data used for drawing the currently displayed map has a different scale Map data acquisition means for acquiring map data and map data stored in the internal memory for the map data acquired by the map data acquisition means Data provided a cache unit, using the map data map drawing means are stored in the internal memory, in which so as to draw the map.

According to the present invention, when a map scroll operation is accepted by the operation accepting means, map data that can draw a map having a wider range than the currently displayed map from the map data stored in the map database. If map data having the same scale as the map data currently used for drawing the map being displayed is acquired and the map scroll operation is not accepted by the operation accepting means, it is stored in the map database. Map data that can be drawn from the map data in the same range as the currently displayed map, and that is different from the map data used to draw the currently displayed map. Map data acquisition means for acquiring, and map data cache for storing the map data acquired by the map data acquisition means in the internal memory And means is provided, by using the map data map drawing means are stored in the internal memory, since it is configured so as to draw a map, there is an effect that can draw a map at a high speed.

It is a block diagram which shows the map display apparatus by Embodiment 1 of this invention. It is a flowchart which shows the processing content (processing content at the time of caching map data) of the map display apparatus by Embodiment 1 of this invention. It is a flowchart which shows the processing content (processing content at the time of drawing a map) of the map display apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows an example of the map data acquired when it is in scroll operation. It is explanatory drawing which shows an example of the map data acquired when scrolling is stopping. It is a block diagram which shows the map display apparatus by Embodiment 2 of this invention. It is explanatory drawing which shows a mode that the scale of a map is changed continuously. It is a flowchart which shows the processing content (processing content at the time of caching map data) of the map display apparatus by Embodiment 3 of this invention. It is a flowchart which shows the processing content (processing content at the time of drawing a map) of the map display apparatus by Embodiment 3 of this invention. It is explanatory drawing which shows an example of the map data acquired when it is during the scroll stop or the own vehicle following display. It is explanatory drawing which shows an example of the map data acquired when it is during scale change operation. It is explanatory drawing which shows the node information (information which shows the latitude and the longitude of each point in a road) of the same road contained in the several map data from which a reduced scale.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a map display device according to Embodiment 1 of the present invention.
In FIG. 1, a map database (hereinafter referred to as “map DB”) 1 is composed of a low-speed large-capacity storage device such as a hard disk and stores a plurality of map data having different scales.
However, the map data stored in the map DB 1 is data in units of small rectangular areas (mesh) obtained by finely dividing the map in the latitude and longitude directions.
The map data stored in the map DB 1 is vector format data having the coordinates and attributes of each drawing item.

The drawing control unit 2 is, for example, a man-machine interface 2a that accepts a user operation (for example, a keyboard, a mouse, a touch panel, an operation switch of a car navigation system, a signal receiving circuit that receives a signal output from an operation remote control of the car navigation system). Or, the user's operation accepted by the man-machine interface 2a is analyzed, and a drawing data creation command (the drawing data creation command includes the user's operation content accepted by the man-machine interface 2a) according to the analysis result. The control circuit 2b for outputting a drawing command (the drawing command includes information indicating the scale of the map to be drawn) and the like.
The control circuit 2b of the drawing control unit 2 is constituted by, for example, a semiconductor integrated circuit on which a CPU is mounted, a one-chip microcomputer, or the like.
The drawing control unit 2 constitutes an operation accepting unit.

The drawing data cache creation unit 3 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted or a one-chip microcomputer, and is output from the drawing control unit 2 from the map data stored in the map DB 1. The map data corresponding to the drawing data creation command is acquired, and the map data is cached in the drawing data storage unit 6 as the drawing data.

When the drawing data creation command output from the drawing control unit 2 includes information indicating that a scroll operation is being performed, the map data acquisition unit 4 of the drawing data cache creation unit 3 stores it in the map DB 1. Map data that can draw a wider range of maps than the map currently displayed on the display 8 (map data that can draw a map of the area around the currently displayed map). Thus, a process of acquiring map data having the same scale as the map data used for drawing the currently displayed map is performed.
If the map data acquisition unit 4 includes information indicating that the scrolling is stopped in the drawing data creation command output from the drawing control unit 2, the map data stored in the map DB 1 The map data can be drawn in the same range as the map currently displayed on the display 8, and the map data used for drawing the currently displayed map has a plurality of different scales. Implement the process of acquiring map data.
The map data acquisition unit 4 constitutes map data acquisition means.

The drawing data cache unit 5 of the drawing data cache creation unit 3 performs processing to cache the map data in the vector format acquired by the map data acquisition unit 4 in the drawing data storage unit 6 as drawing data. The drawing data cache unit 5 constitutes map data cache means.
The drawing data storage unit 6 is a high-speed main memory (internal memory) composed of, for example, a RAM, and stores drawing data in vector format.

The drawing processing unit 7 is configured by, for example, a GPU (Graphics Processing Unit), and corresponds to the scale indicated by the drawing command output from the drawing control unit 2 from the drawing data cached in the drawing data storage unit 6. The drawing data to be acquired is acquired, and a process of drawing a map on the display 8 is performed using the drawing data.
The display 8 is a display device such as a liquid crystal display, for example, and displays a map by the drawing processing of the drawing processing unit 7.
The drawing processing unit 7 and the display 8 constitute a map drawing unit.

In FIG. 1, it is assumed that the drawing control unit 2, the drawing data cache creation unit 3, and the drawing processing unit 7 that are components of the map display device are configured by dedicated hardware. When configured by a computer, a program describing the processing contents of the drawing control unit 2, the drawing data cache creation unit 3 and the drawing processing unit 7 is stored in the memory of the computer, and the CPU of the computer is stored in the memory. The program may be executed.
FIG. 2 is a flowchart showing the processing contents (processing contents when the map data is cached) of the map display device according to Embodiment 1 of the present invention.
FIG. 3 is a flowchart showing the processing contents (processing contents when drawing a map) of the map display device according to Embodiment 1 of the present invention.

Next, the operation will be described.
First, the processing content when map data is cached will be described.
The man-machine interface 2a of the drawing control unit 2 detects a user operation and outputs operation information indicating the operation content to the control circuit 2b.
For example, it is detected whether or not the user is depressing an operation switch that requests scrolling of the map, and operation information indicating the presence or absence of depressing is output to the control circuit 2b.
When the control circuit 2b of the drawing control unit 2 receives the operation information from the man-machine interface 2a, the control circuit 2b analyzes the operation information and determines whether the user is scrolling the map or not. Is discriminated (step ST1 in FIG. 2).

When the control circuit 2b of the drawing control unit 2 determines that the user is performing a scroll operation on the map, the control circuit 2b sends a drawing data creation command including information indicating that “the scroll operation is being performed” to the drawing data cache creation unit 3. Output.
On the other hand, if it is determined that the user has not performed the scrolling operation of the map, a drawing data creation command including information indicating that “the scrolling is stopped” is output to the drawing data cache creation unit 3.

When the map data acquisition unit 4 of the drawing data cache creation unit 3 receives a drawing data creation command from the drawing control unit 2, the creation command includes information indicating that “the scroll operation is being performed”. In this case, in order to prepare for the next scrolling operation, the map data that can draw a wider range of maps than the map currently displayed on the display 8 from the map data stored in the map DB 1 (the currently displayed map) Map data that can be used to draw a map of the peripheral area of the map), and map data having the same scale as that of the map data currently used for drawing the map (step ST2).
For example, if the map data used for drawing the currently displayed map is a scale of 1/10000, map data having a scale of 1/10000 is acquired and used for drawing the map currently being displayed. If the map data is 1/20000 scale, map data of 1/20000 scale is acquired.

Here, FIG. 4 is an explanatory diagram showing an example of map data acquired when the scroll operation is being performed.
In FIG. 4, when a map of a range slightly smaller than the range of four meshes is displayed (in the figure, a solid square frame is the current map display range), for example, the vertical direction and the horizontal direction are In both cases, map data for 16 meshes is acquired with reference to the current display center in order to enable display of a map in the range of about twice.
Thus, if map data for 16 meshes is cached as drawing data in the drawing data storage unit 6 by the drawing data cache unit 5 described later, even if a further scroll operation is accepted by the drawing control unit 2, The drawing processing unit 7 to be described later moves the map display range using the drawing data already cached in the drawing data storage unit 6 without newly acquiring map data from the map DB 1 (in the figure, the solid line in the figure). It is possible to draw the map after the scroll operation in which the square frame is moving.

When the map data acquisition unit 4 acquires vector-format map data from the map DB 1, the drawing data cache unit 5 of the drawing data cache creation unit 3 caches the map data as drawing data in the drawing data storage unit 6 (step ST3). ).
As a result, as shown in FIG. 4, drawing data capable of drawing a map (map of a drawable range) in the peripheral area of the currently displayed map is stored in the drawing data storage unit 6.

If the map data acquisition unit 4 includes information indicating that “scrolling is stopped” in the drawing data creation command output from the drawing control unit 2, in order to prepare for the next scale change operation, Map data that can be drawn in the same range as the map currently displayed on the display 8 from the map data stored in the map DB 1 and used for drawing the currently displayed map. A plurality of map data different in scale from the existing map data is acquired (step ST4).
For example, when N-stage scale map data is stored in the map DB 1, N-stage scale map data is acquired.
However, when it is impossible to cache the map data at the N scales due to the capacity of the drawing data storage unit 6, for example, the map data for two stages in the wide area direction from the current scale is acquired, You may make it acquire the map data for two steps in the detailed direction.

Here, FIG. 5 is an explanatory diagram showing an example of map data acquired when scrolling is stopped.
In the example of FIG. 5, map data for four meshes is acquired as map data having a scale different from the current scale with reference to the current display center.

When the map data acquisition unit 4 acquires a plurality of scale map data, the map range that can be drawn using the map data (in the example of FIG. 5, a range of four meshes: Compared with the range of the map currently displayed on the display 8 (hereinafter referred to as “display range”), the “drawable range” matches the “display range”. It is determined whether or not (step ST5).
When the “drawable range” does not match the “display range”, that is, when the “drawable range” is wider than the “display range”, the map data acquisition unit 4 changes the “drawable range” to the “display range”. A range (hereinafter referred to as “data unnecessary range”) is excluded.

Even if the next scale change operation is accepted, the map data acquisition unit 4 does not display the “data unnecessary range” on the display 8, and the map data related to the “data unnecessary range” is extra data. By removing the map data of the “data unnecessary range” from the map data of a plurality of scales acquired from the map DB 1, the “drawable range” by the map data of a plurality of scales matches the “display range”. (Step ST6).
Accordingly, in the example of FIG. 5, the “drawable range” based on the map data having a scale different from the current scale becomes a slightly smaller range than the range of four meshes.
However, for the map data having the same scale as the current scale, in order to prepare for the next scroll operation, the map data for four meshes is maintained without performing a process of removing some data.

When the drawing data cache unit 5 receives a plurality of scale map data from the map data acquisition unit 4, the drawing data cache unit 5 caches the plurality of map data as drawing data in the drawing data storage unit 6 (step ST7).
Thereby, even if the scale is changed to a scale different from the current scale, the drawing data storage unit 6 stores the drawing data that can draw the map of the scale after the change.

Next, processing contents when drawing a map will be described.
When the control circuit 2b of the drawing control unit 2 receives the operation information from the man-machine interface 2a, the control circuit 2b analyzes the operation information and determines whether the user is scrolling the map (step ST11 in FIG. 3). It is determined whether or not a scale changing operation is being performed (step ST12).
When it is determined that the user is performing a map scroll operation, the control circuit 2b of the drawing control unit 2 specifies the display center of the map after scrolling associated with the scroll operation (step ST13).

For example, when the user performs an operation of scrolling the map upward once, the display center of the map before scrolling moves 1 cm downward in the map, and the user performs an operation of scrolling the map downward once. When the display center of the map before scrolling moves 1 cm upward in the map, the display center of the map moves by a distance proportional to the number of scroll operations in the upward or downward direction. If the number of scroll operations is counted, the display center of the map after scrolling can be specified.
Here, the scroll operation in the vertical direction is shown, but the same applies to the scroll operation in the horizontal direction.
When specifying the display center of the map after scrolling, the control circuit 2b of the drawing control unit 2 outputs a drawing command including information indicating the display center to the drawing processing unit 7 (step ST14).

When the drawing processing unit 7 receives a drawing command including information indicating the display center of the scrolled map from the drawing control unit 2, the drawing processing unit 7 displays the currently displayed map from the drawing data cached in the drawing data storage unit 6. Drawing data that is capable of drawing a wider range of maps and that has the same scale as the drawing data used to draw the currently displayed map is acquired (step ST15).
Then, the drawing processing unit 7 uses the drawing data acquired from the drawing data storage unit 6 so that the display center of the map matches the display center indicated by the information included in the drawing command. Drawing is performed (step ST16).
In this case, since the “drawable range” based on the drawing data acquired from the drawing data storage unit 6 is wider than the “display range”, the “data unnecessary range” that is a range obtained by excluding the “display range” from the “drawable range” is set. In particular, it is necessary to remove the map data of the portion related to the “data unnecessary range”.

When the control circuit 2b of the drawing control unit 2 determines that the user is performing a map scale changing operation, the control circuit 2b specifies the scale after the change, and sends a drawing command including information indicating the scale after the change to the drawing processing unit 7. Output (step ST17).
When the drawing processing unit 7 receives a drawing command including information indicating the scale after the change from the drawing control unit 2, the drawing processing unit 7 selects the drawing command from among a plurality of drawing data cached in the drawing data storage unit 6. Drawing data corresponding to the scale indicated by the included information is acquired (step ST18).
Then, the drawing processing unit 7 draws a map on the display 8 using the drawing data acquired from the drawing data storage unit 6 (step ST19).
In this case, since the “drawable range” based on the drawing data acquired from the drawing data storage unit 6 matches the “display range”, the process of removing the map data of the portion related to the “data unnecessary range” is unnecessary. .

As can be seen from the above, according to the first embodiment, when a map scroll operation is accepted by the drawing control unit 2, the map data stored in the map DB 1 is selected from the currently displayed map. Map data that can be drawn in a wide range of maps, the map data that is the same scale as the map data currently used for drawing the map is acquired, and the map control operation 2 accepts the map scroll operation If not, the map data stored in the map DB 1 can be drawn in the same range as the currently displayed map, and is used for drawing the currently displayed map. A map data acquisition unit 4 for acquiring a plurality of map data having a different scale from the map data being stored, and the map data acquired by the map data acquisition unit 4 as internal drawing data A drawing data cache unit 5 for caching is provided in the high-speed drawing data storage unit 6, and the drawing processing unit 7 is configured to draw a map on the display 8 using the drawing data cached in the drawing data storage unit 6. As a result, the map can be drawn at high speed.

That is, at the timing of “stopping scrolling”, a plurality of map data having different scales from the map data used for drawing the currently displayed map is cached as drawing data in the internal high-speed drawing data storage unit 6. Therefore, when a scale change operation is performed, the drawing data of different scales already cached in the drawing data storage unit 6 are used without newly acquiring map data from the map DB 1. It becomes possible to draw the map after the scale change, and the speed of the map drawing process can be increased.

Moreover, according to this Embodiment 1, the map data acquisition part 4 removes the map data of the part which concerns on a "data unnecessary range" from the map data of the some scale acquired from map DB1, and is made into several scales. Since the “drawable range” according to the map data is changed to match the “display range”, when the drawing processing unit 7 draws the map on the display 8, the drawing items included in the drawing data (for example, It is not necessary to determine whether or not the drawing item is located within the display range of the map for each symbol). Therefore, it becomes possible to draw a map at high speed.

Embodiment 2. FIG.
6 is a block diagram showing a map display device according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG.
The drawing processing unit 9 is composed of, for example, a GPU, and the drawing scale changing operation is accepted by the drawing control unit 2, and the scale after the change is smaller than the drawing data scale cached in the drawing data storage unit 6. , The drawing data having a scale closest to the scale after the change is obtained from the drawing data storage unit 6 among the drawing data having a scale larger than the scale after the change, and the drawing data is used. Then, a process of enlarging and drawing the map on the display 8 is performed.
The drawing processing unit 9 and the display 8 constitute a map drawing unit.

Next, the operation will be described.
In the first embodiment, the map DB 1 stores map data at an N-stage scale, and the scale after change accepted by the drawing control unit 2 matches any of the N-stage scales. Although described as a premise, in this case, the scale is changed in stages.
In the second embodiment, a map display device capable of receiving a scale designation in units smaller than N scales will be described.
However, also in the second embodiment, the map data stored in the map DB 1 is N-scale map data.

FIG. 7 is an explanatory diagram showing a state in which the scale of the map is continuously changed.
In FIG. 7, P1 is a display screen of the display 8 displaying the map, and P2 is a display screen of the display 8 displaying the map at the scale after change.
The scale change bar B is a bar indicating the degree of scale. If a button C described later is at the top, the scale is set to the widest scale, and if the button C is at the bottom, the most detailed scale is set. Suggests that it is set to.
The button C is a GUI (Graphical User Interface) button used when the user changes the scale. For example, the button C is vertically positioned on the scale change bar B while maintaining the user touching the button C. By moving, the scale continuously changes, and the state where the user is touching the button C is released at an arbitrary position, so that the scale corresponding to that position is set.
In the second embodiment, description will be made assuming that the drawing control unit 2 accepts an operation of changing the scale by using the GUI shown in FIG.

In the same manner as in the first embodiment, the drawing control unit 2 caches a plurality of scale drawing data (for example, N-stage scale map data) in the drawing data storage unit 6, and then the user reduces the map scale. It is determined whether or not a change operation is being performed.
That is, the drawing control unit 2 monitors the pressing state of the button C, and when detecting that the button C is pressed, recognizes that the user is performing a map scale changing operation.
Thereafter, when the press of the button C is released, the drawing control unit 2 specifies a scale (scale S after change) corresponding to the position where the press is released.
When specifying the scale S after the change, the drawing control unit 2 outputs a drawing command including information indicating the scale S after the change to the drawing processing unit 9 as in the first embodiment.
However, the scale S after the change is specified in units smaller than the N scales of the drawing data.

When the drawing processing unit 9 receives a drawing command including information indicating the scale S after the change from the drawing control unit 2, the drawing processing unit 9 selects the changed drawing data cached in the drawing data storage unit 6 from the changed drawing data. Drawing data corresponding to the scale S is acquired.
If there is drawing data with the same scale in the drawing data cached in the drawing data storage unit 6, the drawing data is acquired. As described above, the scale S after the change is the N of the drawing data. Since it is specified in a unit smaller than the scale of the stage, drawing data having the same scale is not necessarily cached.

When there is no drawing data with the same scale in the drawing data cached in the drawing data storage unit 6, the drawing processing unit 9 is larger than the scale S after the change in the drawing data of N scales. Specify scale drawing data.
Then, drawing data having a scale closest to the scale S is acquired from drawing data having a scale larger than the scale S.
For example, the scale of the drawing data cached in the drawing data storage unit 6 is 1/1500, 1/3000, 1/6000, 1/12000, 1/20000, 1 / 50,000, 1/100000, 1/200000, When the scale S is 1/15800 when the scale is 1/400000, 1/800000, drawing data with a scale of 1/20000 is acquired, and when the scale S is 1/257000, the drawing with a scale of 1/400000 is obtained. Get the data.

When the drawing processing unit 9 acquires the drawing data from the drawing data storage unit 6, the drawing processing unit 9 draws a map on the display 8 using the drawing data.
However, if the drawing processing unit 9 obtains drawing data having a scale larger than the specified scale S when drawing the map on the display 8, the display range of the map based on the drawing data is the display size of the display 8. The map is enlarged and drawn so as to match (when drawing data having a scale larger than the scale S is acquired, if the map is drawn without being enlarged, the display range of the drawn map becomes smaller than the display size of the display 8. , Enlarge the map to make it difficult to see).
The drawing data cached in the drawing data storage unit 6 is map data in vector format, and is not converted into image data such as bitmap format. Therefore, the map can be easily enlarged or reduced. It can be carried out.

As is apparent from the above, according to the second embodiment, the map scale change operation is accepted by the drawing control unit 2, and the scale after the change is based on the scale of the drawing data cached in the drawing data storage unit 6. When designated in fine units, the drawing processing unit 9 obtains drawing data having a scale closest to the changed scale from the drawing data storage unit 6 among the drawing data having a larger scale than the changed scale. However, since the map is enlarged and drawn on the display 8 using the drawing data, even when the designation of the scale in units smaller than the N scales can be accepted, as in the first embodiment. The map after the scale change can be drawn at high speed.
Further, according to the second embodiment, when drawing data having a scale larger than the designated scale S is acquired, the map is displayed so that the display range of the map based on the drawing data matches the display size of the display 8. Since the enlarged drawing is performed, it is possible to present an easy-to-see map.

Embodiment 3 FIG.
In the first and second embodiments, the map data acquisition unit 4 acquires a plurality of map data having different scales from the map DB 1 at the timing when the scroll is stopped, and the drawing data cache unit 5 acquires the map data acquisition unit 4. In the above description, the plurality of map data acquired by the above is cached in the drawing data storage unit 6 as drawing data. However, the timing for acquiring the map data is not limited to the above timing, and the map DB 1 is used at other timings. The map data may be acquired from and cached in the drawing data storage unit 6.

Specifically, it is as follows.
FIG. 8 is a flowchart showing the processing contents (processing contents when the map data is cached) of the map display device according to the third embodiment of the present invention.
FIG. 9 is a flowchart showing the processing contents (processing contents when drawing a map) of the map display device according to Embodiment 3 of the present invention.

Next, the operation will be described.
First, the processing content when map data is cached will be described.
As with the first and second embodiments, the man-machine interface 2a of the drawing control unit 2 detects a user operation and outputs operation information indicating the operation content to the control circuit 2b.
For example, it is detected whether or not the user is depressing an operation switch requesting a map scroll or a map scale change, and operation information indicating the presence or absence of the depressing is output to the control circuit 2b.
When receiving the operation information from the man-machine interface 2a, the control circuit 2b of the drawing control unit 2 analyzes the operation information and performs a map scroll operation by the user, as in the first and second embodiments. Or whether the map is not scrolled (step ST21 in FIG. 8).

In addition, when the map control operation 2b of the drawing control unit 2 is not performing a map scrolling operation, the operation information output from the man-machine interface 2a is analyzed, and whether or not the user is performing a map scale changing operation. Is discriminated (step ST22).
Note that the control circuit 2b of the drawing control unit 2 displays the current position of the host vehicle when the map display device is currently mounted when the map scroll operation or the map scale change operation is not performed. It is determined whether or not it is a mode to follow (a mode in which a map is displayed so that the vehicle is always positioned at the center of the display screen following the host vehicle) (step ST23).
The mode determination process can be performed by receiving information indicating the current mode from the car navigation system.

When the control circuit 2b of the drawing control unit 2 determines that the user is performing a scroll operation on the map, the control circuit 2b sends a drawing data creation command including information indicating that “the scroll operation is being performed” to the drawing data cache creation unit 3. Output.
When the control circuit 2b of the drawing control unit 2 determines that the user has not performed the map scrolling operation or the map scale changing operation, the drawing data generation command including information indicating that “scrolling is stopped” is issued. Is output to the drawing data cache creation unit 3.
When the control circuit 2b of the drawing control unit 2 determines that the user is performing a map scale changing operation, the control unit 2b issues a drawing data creation command including information indicating that “the scale changing operation is in progress”. 3 is output.
When the control circuit 2b of the drawing control unit 2 determines that the mode of the car navigation system is a mode for displaying the current position of the host vehicle, the control circuit 2b includes a drawing including information indicating that the host vehicle following display is being performed. A data creation command is output to the drawing data cache creation unit 3.

When the map data acquisition unit 4 of the drawing data cache creation unit 3 receives a drawing data creation command from the drawing control unit 2, the creation command includes information indicating that “the scroll operation is being performed”. In this case, in order to prepare for the next scrolling operation, a map having a wider range than the map currently displayed on the display 8 is selected from the map data stored in the map DB 1 as in the first and second embodiments. Map data (map data that can be used to draw a map of the area around the currently displayed map) that is the same scale as the map data used to draw the currently displayed map. Obtain (step ST24).
For example, if the map data used for drawing the currently displayed map is a scale of 1/10000, map data having a scale of 1/10000 is acquired and used for drawing the map currently being displayed. If the map data is 1/20000 scale, map data of 1/20000 scale is acquired.

In the example of FIG. 4, when a map of a range slightly smaller than the range of four meshes is displayed (in the figure, the solid line square frame is the current map display range), for example, the vertical direction and the horizontal direction In order to enable the display of a map whose direction is approximately doubled, map data for a range of 16 meshes is acquired with reference to the current display center.
Thus, if map data for 16 meshes is cached as drawing data in the drawing data storage unit 6 by the drawing data cache unit 5 described later, even if a further scroll operation is accepted by the drawing control unit 2, The drawing processing unit 7 to be described later moves the map display range using the drawing data already cached in the drawing data storage unit 6 without newly acquiring map data from the map DB 1 (in the figure, the solid line in the figure). It is possible to draw the map after the scroll operation in which the square frame is moving.

When the map data acquisition unit 4 acquires the map data in the vector format from the map DB 1, the drawing data cache unit 5 of the drawing data cache creation unit 3 uses the map data as the drawing data as in the first and second embodiments. The drawing data storage unit 6 is cached (step ST25).
As a result, as shown in FIG. 4, map data (map data in a drawable range) capable of drawing a map in the peripheral region of the currently displayed map is stored in the drawing data storage unit 6.

The map data acquisition unit 4 includes the information indicating that “scrolling is stopped” in the drawing data creation command output from the drawing control unit 2, or “in-vehicle tracking display”. Is included in the map data stored in the map DB 1, the map data can be drawn in a wider range than the map currently displayed on the display 8 (current display) Map data that can be used to draw a map of the peripheral region of the map in the middle), and map data having the same scale as the map data currently used for drawing the currently displayed map is acquired (step ST26).
The map data stored in the map DB 1 is map data capable of drawing a map in the same range as the map currently displayed on the display 8 and is used for drawing the currently displayed map. A plurality of map data having different scales from the map data being acquired are acquired (step ST27).

Here, FIG. 10 is an explanatory diagram illustrating an example of map data acquired when scrolling is stopped or the vehicle following display is being performed.
In the example of FIG. 10, when a map of a range slightly smaller than the range of four meshes is displayed (in the figure, the solid line square frame is the current map display range), it is the same as the current scale. As scaled map data, map data for 16 meshes is acquired based on the current display center.
In addition, map data of a scale larger than one scale and map data of a scale smaller than one scale are acquired as map data of a scale different from the current scale, and map data for four meshes based on the current display center. Is getting.

When the map data acquisition unit 4 acquires map data at a scale different from the current scale, the map range that can be drawn using the map data (see FIG. 10) as in the first and second embodiments. In the example, a range of four meshes (hereinafter referred to as “drawable range”) is compared with a “display range” which is the range of the map currently displayed on the display 8, and the “drawable range” is compared. "Is in agreement with the" display range "(step ST28).
When the “drawable range” does not match the “display range”, that is, when the “drawable range” is wider than the “display range”, the map data acquisition unit 4 changes the “drawable range” to the “display range”. The “data unnecessary range”, which is a range excluding, is specified.

Even if the next scale change operation is accepted, the map data acquisition unit 4 does not display the “data unnecessary range” on the display 8, and the map data related to the “data unnecessary range” is extra data. By removing the map data corresponding to the “data unnecessary range” from the map data at different scales acquired from the map DB 1, the “drawable range” by the map data at different scales matches the “display range”. (Step ST29).
Thereby, in the example of FIG. 9, the “drawable range” based on map data of different scales is a range slightly smaller than the range of four meshes.

When the drawing data cache unit 5 receives map data of a plurality of scales (same scale as the current scale, one step larger scale, one step smaller scale) from the map data acquisition unit 4, the drawing data cache unit 5 draws the map data of a plurality of scales. The drawing data storage unit 6 is cached as data (step ST30).
As a result, even when the host vehicle moves, map data that can draw a map of the peripheral area of the currently displayed map is stored in the drawing data storage unit 6 and is changed to a scale different from the current scale. Also, the map data that can be drawn on the scale after the change is stored in the drawing data storage unit 6.

When the drawing data creation command output from the drawing control unit 2 includes information indicating that “the scale change operation is being performed”, the map data acquisition unit 4 stores the map stored in the map DB 1. A plurality of map data capable of drawing a map in the same range as the map currently displayed on the display 8 and having different scales from the map data used for drawing the currently displayed map. Map data is acquired (step ST31).
For example, when N-stage scale map data is stored in the map DB 1, N-stage scale map data is acquired.
However, when it is impossible to cache the map data at the N scales due to the capacity of the drawing data storage unit 6, for example, the map data for two stages in the wide area direction from the current scale is acquired, You may make it acquire the map data for two steps in the detailed direction.

Here, FIG. 11 is an explanatory diagram showing an example of map data acquired when the scale changing operation is being performed.
In the example of FIG. 11, map data for four meshes is acquired with reference to the current display center as map data having a scale different from the current scale.

When the map data acquisition unit 4 acquires map data of a plurality of scales, a map range that can be drawn using the map data (in the example of FIG. 11, a range corresponding to four meshes: Is referred to as “possible range”) and the “display range” that is the range of the map currently displayed on the display 8, and whether or not the “drawable range” matches the “display range”. Determination is made (step ST32).
When the “drawable range” does not match the “display range”, that is, when the “drawable range” is wider than the “display range”, the map data acquisition unit 4 changes the “drawable range” to the “display range”. The “data unnecessary range”, which is a range excluding, is specified.

Even if the next scale change operation is accepted, the map data acquisition unit 4 does not display the “data unnecessary range” on the display 8, and the map data related to the “data unnecessary range” is extra data. By removing the map data of the “data unnecessary range” from the map data of a plurality of scales acquired from the map DB 1, the “drawable range” by the map data of a plurality of scales matches the “display range”. (Step ST33).
Accordingly, in the example of FIG. 11, the “drawable range” based on a plurality of scale map data is a range slightly smaller than the range of four meshes.

The drawing data cache unit 5 caches map data of a plurality of scales whose “drawable range” matches the “display range” as drawing data in the drawing data storage unit 6 (step ST34).
Thereby, even if the scale is changed to a scale different from the current scale, the map data that can be drawn on the map at the scale after the change is stored in the drawing data storage unit 6.

Next, processing contents when drawing a map will be described.
In the third embodiment, an example in which the drawing processing unit 7 in FIG. 1 is mounted on the map display device will be described for the sake of simplicity. However, the drawing processing unit 9 in FIG. 6 is mounted on the map display device. It may be.
When the control circuit 2b of the drawing control unit 2 receives the operation information from the man-machine interface 2a, the control circuit 2b analyzes the operation information and determines whether the user is scrolling the map (step ST41 in FIG. 9). It is determined whether the scale change operation is being performed (step ST42) or whether the own vehicle following display is being performed (step ST43).
When the control circuit 2b of the drawing control unit 2 determines that the user is performing a map scrolling operation, the display center of the map after scrolling accompanying the scrolling operation is specified as in the first and second embodiments. (Step ST44).

For example, when the user performs an operation of scrolling the map upward once, the display center of the map before scrolling moves 1 cm downward in the map, and the user performs an operation of scrolling the map downward once. When the display center of the map before scrolling moves 1 cm upward in the map, the display center of the map moves by a distance proportional to the number of scroll operations in the upward or downward direction. If the number of scroll operations is counted, the display center of the map after scrolling can be specified.
Here, the scroll operation in the vertical direction is shown, but the same applies to the scroll operation in the horizontal direction.
When specifying the display center of the map after scrolling, the control circuit 2b of the drawing control unit 2 outputs a drawing command including information indicating the display center to the drawing processing unit 7 (step ST45).

When the drawing processing unit 7 receives a drawing command including information indicating the display center of the scrolled map from the drawing control unit 2, the drawing processing unit 7 displays the currently displayed map from the drawing data cached in the drawing data storage unit 6. Drawing data that is capable of drawing a wider range of maps and that has the same scale as the drawing data that is used to draw the currently displayed map is acquired (step ST46).
Then, the drawing processing unit 7 uses the drawing data acquired from the drawing data storage unit 6 so that the display center of the map matches the display center indicated by the information included in the drawing command. Drawing is performed (step ST47).
In this case, since the “drawable range” based on the drawing data acquired from the drawing data storage unit 6 is wider than the “display range”, the “data unnecessary range” that is a range obtained by excluding the “display range” from the “drawable range” is set. In particular, it is necessary to remove the map data of the portion related to the “data unnecessary range”.

When the control circuit 2b of the drawing control unit 2 determines that the user is performing a map scale changing operation, the control circuit 2b specifies the scale after the change, and sends a drawing command including information indicating the scale after the change to the drawing processing unit 7. Output (step ST48).
When the drawing processing unit 7 receives a drawing command including information indicating the scale after the change from the drawing control unit 2, the drawing processing unit 7 selects the drawing command from among a plurality of drawing data cached in the drawing data storage unit 6. Drawing data corresponding to the scale indicated by the included information is acquired (step ST49).
And the drawing process part 7 draws a map on the display 8 using the drawing data acquired from the drawing data memory | storage part 6 (step ST50).
In this case, since the “drawable range” based on the drawing data acquired from the drawing data storage unit 6 matches the “display range”, the process of removing the map data of the portion related to the “data unnecessary range” is unnecessary. .

When the control circuit 2b of the drawing control unit 2 determines that the vehicle following display is in progress, the control circuit 2b collects the position information of the vehicle from the car navigation system and checks the position of the vehicle on the map (step ST51).
When the control circuit 2b of the drawing control unit 2 confirms the position of the host vehicle, the control circuit 2b outputs a drawing command including information indicating the position of the host vehicle to the drawing processing unit 7 (step ST52).

When the drawing processing unit 7 receives a drawing command including information indicating the position of the host vehicle from the drawing control unit 2, the drawing processing unit 7 has a wider range of drawing data cached in the drawing data storage unit 6 than the currently displayed map. Drawing data that is capable of drawing a map and that has the same scale as the drawing data used to draw the currently displayed map is acquired (step ST53).
The drawing processing unit 7 displays the map using the drawing data acquired from the drawing data storage unit 6 so that the display center of the map matches the position of the host vehicle indicated by the information included in the drawing command. 8 is drawn (step ST54).
In this case, since the “drawable range” based on the drawing data acquired from the drawing data storage unit 6 is wider than the “display range”, the “data unnecessary range” that is a range obtained by excluding the “display range” from the “drawable range” is set. In particular, it is necessary to remove the map data of the portion related to the “data unnecessary range”.

According to the third embodiment, it is possible to cache drawing data in a range that is likely to be used next without greatly increasing the amount of memory used, and to increase the drawing speed of the map. There is an effect that can be done.

Embodiment 4 FIG.
In the first to third embodiments, the drawing data cache unit 5 caches a plurality of map data in the drawing data storage unit 6 when a plurality of map data having different scales are acquired by the map data acquisition unit 4. Although shown, when a plurality of map data is cached in the drawing data storage unit 6, the data indicating the same point in the plurality of map data may be excluded from the detailed scale map data.

Specifically, it is as follows.
FIG. 12 is an explanatory diagram showing node information (information indicating latitude and longitude of each point on the road) included in a plurality of map data having different scales.
In FIG. 12, M1 is a map drawn using drawing data of the scale S1, and M2 is a map drawn using drawing data of the scale S2 that is one step more detailed than the scale S1.
P11 to P14 are node information of roads displayed on the map M1, and P21 to P27 are node information of roads displayed on the map M2 (the same roads displayed on the map M1). is there.

In the case of FIG. 12, the map data in the map M1 is data including node information P11 to P14, and the map data in the map M2 is data including node information P21 to P27.
Therefore, the map data of the map M2 with a detailed scale includes more node information than the map data of the map M1 with a large scale.
At this time, P12 in the map M1 and P23 in the map M2 are node information of the same point, and P13 in the map M1 and P26 in the map M2 are node information of the same point.

In the fourth embodiment, in order to reduce the amount of memory used, the node information at the same point is excluded from the detailed scale map data.
That is, when the map data acquisition unit 4 acquires the map data of the map M1 and the map data of the map M2, the drawing data cache unit 5 includes the node information P11 to road information included in the map data of the map M1. P14 is cached in the drawing data storage unit 6 as drawing data.
However, among the node information P21 to P27 of the road included in the map data of the map M2, the node information P23 that is the node information at the same point as P12 and the node information P26 that is the node information at the same point as P13 are as follows. Instead of caching the drawing data in the drawing data storage unit 6, only the node information P21, P22, P24, P25, and P27 is cached in the drawing data storage unit 6 as drawing data.

However, the drawing data cache unit 5 applies the node information P22 and P24 to the node information P22 and P24 so that the

drawing processing units

7 and 9 can draw the map M2 even if the node information P23 and P26 are not cached. Connection information indicating that the node is connected to the node P12 is stored, and connection information indicating that the node is connected to the node P13 is stored for the node information P25 and P27. .
Therefore, when the

drawing processing units

7 and 9 draw the map M2, the node information P21, P22, P24, P25, and P27 are referred to to recognize the latitude and longitude of each point on the road, and the connection information described above. Referring to the node information P12 and P13, the latitude and longitude of the points P23 and P26 are recognized.

As apparent from the above, according to the fourth embodiment, when a plurality of map data is cached in the drawing data storage unit 6, data indicating the same point in the plurality of map data is excluded from the detailed scale map data. Thus, the capacity of the drawing data storage unit 6 can be reduced.

This invention is suitable, for example, for a map display device that has a high need to draw a map after changing the scale at high speed when changing the scale of the map.

Claims

A map database storing a plurality of map data of different scales, an operation receiving means for receiving user operations, and a map stored in the map database when a map scroll operation is received by the operation receiving means Map data that is capable of drawing a wider range of maps than the currently displayed map, and that has the same scale as the map data used to draw the currently displayed map, Map data that is capable of drawing a map in the same range as the currently displayed map from the map data stored in the map database when a map scroll operation is not accepted by the operation accepting means. Map data that obtains multiple map data with different scales from the map data used for drawing the currently displayed map. Data acquisition means, map data cache means for storing the map data acquired by the map data acquisition means in an internal memory, map drawing means for drawing a map using the map data stored in the internal memory, and A map display device comprising:
2. The map data acquisition unit according to claim 1, wherein, when a map scroll operation is received by the operation reception unit, the map data acquisition unit acquires map data capable of drawing a map of a peripheral region of the currently displayed map. Map display device.
The map drawing means obtains map data corresponding to the scale after the change from the internal memory when the map scale changing operation is received by the operation receiving means, and draws the map using the map data. The map display device according to claim 1.
2. The map display device according to claim 1, wherein the map database stores map data expressed in a vector format.
The map drawing means receives the map scale change operation by the operation accepting means, and when the scale after the change is designated in a unit smaller than the scale of the map data stored in the internal memory, the map drawing means 5. The map according to claim 4, wherein map data having a scale closest to the scale after change is acquired from map data having a scale larger than the scale, and the map is enlarged and drawn using the map data. Display device.
The map data acquisition means is a map capable of drawing a map in the same range as the currently displayed map from the map data stored in the map database when a map scale change operation is accepted by the operation accepting means. The map display device according to claim 1, wherein the map display device acquires a plurality of map data which are data and are different in scale from the map data used for drawing the currently displayed map.
When a plurality of map data having different scales are acquired by the map data acquisition means, the map data cache means stores a plurality of map data in the internal memory, and when the map data is stored in the internal memory, the map data cache means has a detailed scale for data indicating the same point. The map display device according to claim 1, wherein the map display device is excluded from the map data.
An operation reception processing step in which the operation reception means receives a user operation, and a map in which the map data acquisition means stores a plurality of map data having different scales when a map scroll operation is received in the operation reception processing step. From the database, obtain map data that can draw a wider range of maps than the currently displayed map, and that has the same scale as the map data used to draw the currently displayed map. Map data that can draw a map in the same range as the currently displayed map when the map scroll operation is not accepted in the reception processing step, and is used for drawing the currently displayed map A map data acquisition processing step for acquiring a plurality of map data having different scales, and a map data cache means for acquiring the map data. A map data cache processing step for storing the map data acquired in the processing step in an internal memory; and a map drawing processing step in which the map drawing means draws a map using the map data stored in the internal memory. Map display method.