JPH0829187A - On-board navigation apparatus - Google Patents

Abstract

PURPOSE:To easily grasp where a vehicle is running when going out to the outskirts from an urban area while displaying a map on a large reduced scale. CONSTITUTION:A map image-drawing part 12 reads out map data of various reduced scales including a position of a vehicle from a CD-ROM 1 to a buffer memory 11 based on data of the position of the vehicle detected by a GPS receiver 2. A data amount-detecting part 15 detects an amount of map data of a reduced scale to be displayed among the data read into the memory 11, and a reduced scale-changing/setting part 17 judges whether the detected amount of data is smaller than a fixed reference value. When the amount is less than the reference value, the reduced scale is changed to a one-step smaller scale. When the amount is not smaller than the reference value, the reduced scale is not changed. The map image-drawing part 12 draws, together with a mark indicating the position of the vehicle, a map image including the position of the vehicle at a video RAM 13 with the use of the map data of the reduced scale among the map data in the memory 11. An image-converting part 14 reads the image of the video RAM 13, converting to a predetermined video signal and outputting to a display device 4. The image is thus displayed on a screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted navigation device, and more particularly to a CD-R storing map data by scale.
The present invention relates to a vehicle-mounted navigation device in which a map image around a vehicle position is drawn together with a vehicle position mark by using map data of a certain scale read out from map data storage means such as an OM and an IC memory card and displayed on the display means. .

[0002]

2. Description of the Related Art An on-vehicle navigation device is a vehicle position detecting device such as a CD-ROM storing map data, a map data storing device such as an IC memory card, a display device, a GPS receiver or the like for detecting the current position of the vehicle. Have
The map data including the current position of the vehicle is read from a CD-ROM or the like, a map image is drawn based on the map data,
In addition to displaying it on the display screen, fix the vehicle position mark (location cursor) at a fixed position on the display screen (for example, the center of the screen), scroll the map image according to the movement of the vehicle, or fix the map image on the screen. By moving and displaying the vehicle position mark, it is possible to see at a glance where the vehicle is currently traveling.

Maps stored in a CD-ROM or the like are 1/1000, 1/50000, 1/25000 in order of decreasing scale.
, 1/12500, etc. are divided into an appropriate size of longitude width and latitude width according to the scale level, and roads and the like are indicated by a coordinate set of vertices (nodes) expressed in longitude and latitude. In addition,
A road is composed of two or more nodes, and a part connecting two nodes is called a link. The map data includes
(1) Road list, node table, intersection node list, map matching including intersection netlist, road layer for route search, (2) background layer for displaying roads, buildings, rivers, etc. on the map screen , (3)
It is composed of administrative division names such as municipalities, road names, characters such as building names, and character / symbol layers for displaying map symbols and the like.

[0004]

By the way, for example, when a driver travels from an urban area to the suburbs while displaying an image based on 1/12500 map data with a large scale, the driver is not aware of the geography of the suburbs. On the other hand, in the suburbs, the administrative area is wide and there are few roads and buildings, so the screen is displayed with a low information density as shown in Fig. 5, and it is difficult to know where the vehicle is currently traveling. There was a problem that became. In view of the above, an object of the present invention is to provide a vehicle-mounted navigation device capable of easily recognizing where a vehicle is currently traveling when leaving a suburb from an urban area while displaying a large-scale map. is there.

[0005]

According to the present invention, there is provided the above-mentioned object, a map data storage means for storing map data for each scale, a vehicle position detection means for detecting a vehicle position and a vehicle direction, and a map data storage means. It should be displayed on the screen in a vehicle-mounted navigation device equipped with map image drawing means for drawing a map image around the vehicle position together with the vehicle position mark using the map data of a certain scale read from An information amount detecting means for detecting the information amount of the scale map data, and a scale changing setting means for changing the scale to a small scale when the information amount detected by the information amount detecting means is below a certain level are provided, and the map image The drawing means is achieved by drawing the map image using the map data of the scale changed and set by the scale changing means.

[0006]

According to the present invention, the information amount of the map data to be displayed on the screen is detected, and when the detected information amount is below a certain level, the scale is changed to a small scale, and the map of the changed scale is set. Draw a map image using the data. As a result, when a map image is displayed using a large-scale map data and the suburbs are moved from the urban area to the suburbs, the amount of information in the map data in the suburbs is reduced, so that a wide range automatically based on the small-scale map data Since it switches to a map image,
Since many roads, administrative division names, road names, etc. are displayed on the screen, it becomes easy to grasp where the current location is from these information.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram of a vehicle-mounted navigation device according to an embodiment of the present invention. In the figure, 1 is a CD-ROM storing map data composed of road layers, background layers, character / symbol layers, etc., according to scale, 2 is a GPS receiver for detecting the vehicle position and vehicle direction by satellite navigation, 3 Reference numeral 4 denotes a display device for displaying a map image including the current position of the vehicle together with a vehicle position mark and the like.

Reference numeral 10 denotes a navigation controller having a microcomputer configuration, which draws a map image centering on the vehicle position together with the vehicle position mark using the map data stored in the CD-ROM 1 and displays it on the display device 4.
Reference numeral 11 is a buffer memory for storing map data read from the CD-ROM 1, 12 is a vehicle position, and the map data of the scale changed and set by a scale change setting unit to be described later is used to face north including the vehicle position. 3 is a map image drawing unit that draws the map image with the vehicle position mark. When the map image drawing unit 12 draws a map image, the map data of various scales around the vehicle position are collected together in a CD-RO.
The data is read from M1 to the buffer memory 11. Reference numeral 13 is a video RAM that stores the image drawn by the map image drawing unit 12, and 14 is a display device that reads the image stored in the video RAM 13 and converts it into a predetermined video signal.
Is a video conversion unit for outputting to.

Reference numeral 15 denotes an information amount detecting section for detecting the information amount of the map data of the scale of the map image to be displayed on the screen, out of the map data read out to the buffer memory 11. In the case of this embodiment, the information amount detection unit 15 extracts the data for displaying the road from the background layer of the map data of the scale changed and set by the scale change setting unit, and the total extension length of the road on the screen. L is calculated in cm units, data for displaying characters is taken out from the character / symbol layer, and the number A of items of character information on the screen and the total number B of characters are calculated. Then, according to the following formula, each of L, A, and B is multiplied by an appropriate weighting coefficient a, b, and c (a to c are fixed values) and then added, and the total amount of different types of information of L, A, and B is added. Find P. P = a.L + b.A + c.B (1) However, in this embodiment, a = 1/4 and b = c = 1.
For example, in the case of FIG. 2, the information amount P is about 15.

Reference numeral 16 is an operation for enlarging / reducing a map on the operation unit 3.
A scale registration unit for registering the scale D designated by the user,
Reference numeral 17 is a scale change setting unit, which is detected by the information amount detection unit 15.
The map image displayed on the screen is reduced based on the information amount P
The scale D'is changed from the scale D registered in the scale registration unit 16.
Set. Specifically, the map scale D'to be displayed on the screen.
The amount of information P of the map data is a predetermined reference value P_C1Is below
Change D'to one step smaller,
The amount of information P of the map data of the scale D'of the map to be displayed is
Constant reference value P_C2When it is above, increase D'one step
Change and set. However, within the range of D'≤D, P_C1When
P_C2Is a predetermined constant value, P _C1<P_C2connection of
There is.

FIG. 3 is a flowchart showing the operation of the navigation controller 10, and FIG. 4 is an explanatory diagram of a screen display example.
Hereinafter, these figures will be described. When the power is turned on, the GPS receiver 2 periodically moves the vehicle position by satellite navigation,
Detects the direction of the vehicle. On the other hand, after turning on the power of the navigation controller 10, the scale registration unit 16 and the scale change setting unit 17 initialize D = 1/12500 and D ′ = 1/12500 (step 101 in FIG. 3), and then the GPS receiver 2 The vehicle position data and the vehicle direction data are input from the CD-ROM 1 and the map image drawing unit 12 reads the map data of various scales including the vehicle position from the CD-ROM 1 into the buffer memory 11 (steps 102 and 103).

Then, the information amount detecting section 15 uses the buffer memo.
Read the map data of reduced scale D'stored in R11
The total amount P of information is calculated according to the equation (1) (step 10
4). Then, the scale change setting unit 17 displays the map data of the scale D '.
Information amount P of data is a reference value P_C1, P_C2Compare with size
(Steps 105, 106). P ≦ P_C1When D'is 1 step
After changing the floor to a smaller size (step 107),
Return to page 104, P> P _C2Then, until D '≠ D
If there is a condition (YES in step 108), set D '
After changing the setting by one step (step 109),
Return to step 104. And P_c1<P <P_c2Became
By the way (NO at both steps 105 and 106)
The diagram image drawing unit 12 stores the reduction image stored in the buffer memory 11.
The vehicle position is stored in the video RAM 13 using the map data of the shaku D '.
Draw one screen of map image with north facing upwards
The vehicle azimuth direction at the location corresponding to the vehicle position on the map image.
Draw a vehicle position mark pointing at (step 11
0). The image of the video RAM 13 is converted by the image conversion unit 14.
Displayed after being read out and converted into a predetermined video signal
It is output to the device 4 (step 111).

After step 111, the navigation controller 10 checks whether or not the scale registration unit 16 has performed a map enlargement / reduction operation on the operation unit 3 (step 11).
2) If NO, the vehicle position data and the vehicle direction data are input from the GPS receiver 2 (step 113). Then, the map image drawing unit 12 checks that the vehicle position has changed (step 114). If it has not changed, the process returns to step 112, and if it has changed, the processing from step 103 onward is repeated.

Since the vehicle started traveling in an urban area where the administrative division is narrow and there are many roads and buildings, when the amount of information P is larger than P _C1 even at the initially set scale of D '= 1/12500. Is a 1/12500 scale map image. After that, when the amount of information P fell below P _C1 because it was in the suburbs, D'is reduced by one step to 1/25000, and if P _C1 <P <P _{C2 at} this scale, a map image of a scale of 1/25000 is displayed. Switches. Therefore, even in the suburbs where the administrative division is large and there are few roads and buildings, a relatively wide range of map images is displayed, so many roads, administrative division names, road names, etc. are displayed on the screen. , It becomes easier to know where the current location is from these information (see FIG. 4). In this respect,
Conventionally, the scale of the map image remains at 1/12500 even in the suburbs, so the screen is displayed with a low information density, making it difficult to know where you are currently driving. (See FIG. 5).

Since the vehicle entered the urban area again while the map image at a scale of 1/25000 was displayed, the information amount P was P.
_When it exceeds _C2 , D'is increased by 1 step to 1/12500, and at this scale, if P _C1 <P <P _C2 , the screen is 1/500 of the original size.
Switch to a map image at a scale of 12500. Therefore, the information on the screen will not be overcrowded and the map will not be difficult to see.

When the user performs an operation to change the scale of the map, the scale registration unit 16 of the navigation controller 10 changes the scale D according to the operation (step 11).
5) Further, the scale change setting unit 17 sets D '← D (step 116). For example, when the reduction operation is performed in the state of D = 1/12500, D = D '= 1/25000. Therefore, after that, a map image with a scale of 1/25000 or less is displayed on the screen.

In the above-described embodiment, the information amount of the scale map data to be displayed on the screen is detected from the total length of road on the screen, the number of character items, and the total number of characters by using the equation (1). However, the total data amount of the scale map data to be displayed on the screen may be directly used as the information amount of the map data.

[0018]

As described above, according to the present invention, the information amount of the map data to be displayed on the screen is detected, and when the detected information amount is below a certain level, the scale is changed to a small scale and the change is set. Since it is configured to draw the map image using the map data of a reduced scale, the amount of information of the map data is small in the suburbs when going out from the city to the suburbs while displaying the map image using the map data of a large scale. Therefore, since it automatically switches to a wide range of map images based on small scale map data, many roads, administrative division names, road names, etc. will be displayed on the screen, and from this information the current location will be displayed. It becomes easy to understand where is.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a vehicle-mounted navigation device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a method of detecting the amount of information.

FIG. 3 is a flowchart showing the operation of the navigation controller.

FIG. 4 is an explanatory diagram showing a screen display example.

FIG. 5 is an explanatory diagram showing a conventional screen display example while traveling in the suburbs.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CD-ROM 2 GPS receiver 3 Operation part 4 Display device 10 Navigation controller 11 Buffer memory 12 Map image drawing part 13 Video RAM 14 Video conversion part 15 Information amount detection part 16 Scale registration part 17 Scale change setting part

Claims (1)

[Claims] 1. A vehicle using map data storage means for storing map data for each scale, vehicle position detection means for detecting a vehicle position and a vehicle direction, and map data of a certain scale read from the map data storage means. In a vehicle-mounted navigation device equipped with a map image drawing means for drawing a map image around a position together with a vehicle position mark and displaying the screen on a display means, an information amount detection for detecting an information amount of map data of a scale to be displayed on the screen Means and a scale change setting means for changing and setting the scale to a small scale when the amount of information detected by the information amount detecting means is below a certain level, and the map image drawing means is provided with the scale set by the scale changing means. An in-vehicle navigation device characterized in that a map image is drawn using map data.