JPH02251986A - Map drawing method - Google Patents

Abstract

PURPOSE:To display an enlarged map automatically without registering detailed maps of the whole Japan on a CD-ROM, etc., by converting the scale of map data of another scale reduction level with a large scale reduction rate, generating the map of a contiguous area and scrolling and displaying the map according to the movement of a vehicle. CONSTITUTION:This method is equipped with a means 6b which checks whether or not there is map data on the contiguous area, a means 6d which converts the scale of existent map data, a map generating means 7a and a map scrolling means 7d. Then it is checked whether or not there is map data of current display scale reduction level as to the area adjoining to the area where the current is currently present and when not, the scale of the map data of another scale reduction level with the large scale reduction rate is converted and the data obtained by the scale reduction conversion is used to generate the map of the contiguous area of the current display scale reduction level, thereby scrolling and displaying the map according to the movement of the vehicle. Consequently, even when the detailed maps of the whole Japanese are not registered on the CD-ROM, etc., an enlarged map can be displayed automatically without any map absence at a border part.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a map drawing method for automobile navigation, and particularly to a map drawing method for scrolling and displaying a map according to the movement of a car.

<Prior Art> There is an automobile navigation system that uses a CD-ROM as a storage means for storing map data. Such an automobile navigation system is a CD-ROM.
In addition to storing a large amount of map data, a display device and a position measuring device for measuring the current position of the vehicle are installed, and a mark (location cursor) indicating the current position of the vehicle is fixedly displayed at a fixed position on the display screen. At the same time, map data corresponding to the vehicle position is read from the CD-ROM, a map is drawn on the display screen, and the map is scrolled and displayed in accordance with the movement of the vehicle.

To scroll the map, select mXn (for example, 3X3) in advance.
As shown in FIG. 8, two adjacent map images M1 are developed (stored) in a first video RAM (VRAM), and map data is read out from the VRAM according to the movement of the vehicle. to scroll the map on the display screen.

The above scroll display process is performed until the vehicle enters the adjacent area, and when the vehicle enters the adjacent area, the 3x3 adjacent map data is read out and a new map image MP2 for 9 screens is created.
is generated and stored in the second VRAM. From then on, the 2nd VRA
A map image is read out from the specified window of M and scroll-displayed on the CRT. Then, each time a new area is entered, 3×3 map images are stored alternately in the first and second VRAMs, and the VRAM from which the map images are read is switched to continuously scroll and display the map.

<Problems to be Solved by the Invention> The map data stored on the CD-ROM has a hierarchical structure of several levels, from map data for each predetermined area to detailed maps that describe the area in detail.

However, detailed map data by hierarchy is not stored for all areas. 1 Some map data may be missing depending on the importance or area. 0 For example, all areas have maps with a scale of 1:50,000. Data exists, but 1:25,000 map data only exists in urban areas.

For this reason, when a vehicle is in an urban area and a 1:25,000 scale map is used for scrolling display, the vehicle moves and there is no 1:25,000 scale map data. When approaching a rural area, the 1/25,000 scale map image MP3 (9th
The shaded area in the figure) cannot be prepared in the VRAM, and as the vehicle moves, there will be areas where the map is not displayed on the display screen (see the area shown by narrow intervals in Figure 9) (referred to as map missing). .

If this map is missing, the entire map will not be displayed.
The function as an awkward renavigator is impaired. Therefore, the driver operates the reduction key to display the map in a reduced size, but in this case, the enlarged map at the boundary between the city and the countryside cannot be used.

From the above, the purpose of the present invention is to provide detailed maps of all of Japan on CD-
To provide a map display method capable of automatically displaying an enlarged map without missing the map at the border without registering it in a ROM or the like.

Means for Solving the Problems> The above problems are solved in the present invention by a means for checking whether map data of an adjacent area exists, a means for converting the scale of the existing map data if it does not exist, and a map generating means. and a map scrolling means.

For the area adjacent to the area to which the vehicle currently belongs, it is checked whether map data at the currently displayed scale level exists, and if it does not exist, the map data at another scale level with a larger scale is converted and the scale is changed. A map of the adjacent area at the current display scale level is generated using the data obtained by the conversion, and the map is scrolled and displayed as the vehicle moves.

<Example> 1st rJi! i is a block configuration diagram of an automobile navigation system that can realize the present invention.

In the figure, 1 is a CD-RO that serves as a map data storage means.
It is M. , :(7) The map data stored in the CD-ROM 1 has a hierarchical structure of view sets A, B, and C. Here, view set A is map data for one screen at a certain reference scale (for example, 1/50,000 scale), and view set B is map data for enlarging and displaying 1/4 of the area displayed in view set A ( View set C is map data for one screen (with a scale of 1:25,000), and view set C is map data for one screen to further enlarge and display a quarter of the area displayed in view set B. , each view set Ai,
The relationship between the ranges displayed on one screen by Bi and Ci is as shown in FIGS. 2(a) to (Q). Note that if we pay attention to view set A (see FIG. 2(a)), view set A to A4. A, ~A, is a view set A,
This is the adjacent map data of the area displayed by B□～
B4 becomes the enlarged map data. Also, view set B engineering (
Referring to FIG. 2(b)), view set A5 is the reduced map data, and C1, C2, C6, and C6 are the enlarged map data.

FIG. 3 is a structural diagram of view sets stored in the CD-ROMI, including a pointer Pu to the upper view set, a pointer Pd to the lower view set, and pointers Pnl to Pn8. to the IIgB contact view set. It has unit data (map data) UND, etc.

Therefore, in the relationship among view sets Ai, Bi, and Ci, as shown in FIG.
d specifies the start address of the view set Bi,
View set C by pointer Pd of view set Bi
The start address of view set Bi is specified by the pointer Pu of view set Ci, and the start address of view set Ai is specified by the pointer Pu of view set Bi. Note that if the lower view set does not exist, the pointer Pd will be a specific value (for example, all 1), and the view set A
Allotopic management information is provided corresponding to the area displayed by i, and the top address of the view set Ai is specified by the allotopic management information.

Returning to Figure 1, 2 is the map search and enlargement of the CD-ROM.
An operation section 3 includes various keys such as reduction, etc., and 3 is an azimuth sensor for detecting absolute azimuth, including a geomagnetic sensor and a steering sensor. Reference numeral 4 denotes a movement amount sensor, which includes a vehicle speed sensor that detects travel distance, a transmission sensor that detects forward and backward movement, and the like. 5 is a CPU for position calculation, and direction sensor 3. The current position of one's own vehicle is calculated from each value input from the movement amount sensor 4.

6 is a navigation processing unit, and a position calculation CPU 5
Based on the vehicle position and display scale level input from
(1) An entry/read address generation unit 6a that generates a VRAM image read address and (2) determines whether the vehicle has entered an adjacent area, and a map related to the adjacent area when the vehicle enters the adjacent area. Data is CD-R
A map data presence/absence detection unit 6b that checks whether it exists in OMI, a reading/storage unit 6c that reads and stores map data from CD-ROMI, and converts the scale of map data as appropriate depending on the presence or absence of adjacent map data. Alternatively, it includes a scale converter 6d that outputs without converting. The memory section of the reading/storage section 6C stores map data for a total of nine areas including adjacent areas read from the CD-ROMI, in other words, map data for nine screens.

7 is a display device, and a CRT controller 7a
, first and second video RAM (VRAM) 7b, 7c
, a readout control unit 7d, a cathode ray tube (CRT) 7a, etc., and displays a desired map and cursor on the CRT, and scrolls the map in accordance with the movement of the vehicle.

FIG. 5 is a flowchart of map drawing processing according to the present invention, and FIGS. 6 and 7 are explanatory diagrams of map display according to the present invention.

If the map is to be displayed at a scale of 1/25,000, and if a car is located in an area according to the map data BS (see Figure 6), then the reading/storage unit 6c will display information about the area. Map data B1 to B9 of 3x3 areas in the center
is read from the CD-ROMI and input to the display device 7.

The CRT controller 7a generates nine screens worth of map images MPI (see FIG. 6) using these map data B to B, and stores the map images in the first VRAM 7b.

In parallel with the above, the entry signal/read address generation section 6a
determines which VRAM to read the image from and outputs it, and also determines the position of the VRAM window (image reading area) WD so that the cursor indicating the vehicle surface position is displayed in the center of the screen, and reads the address. It is input to the control section 7d.

The read control unit 7d reads the specified VRAM (first VRAM).
A map image is read out from a specified window of the RAM 7b in synchronization with raster scanning and displayed on the CRT 7e. Thereafter, the map is scrolled by moving the position of the window WD according to the movement of the vehicle. ...Step 1
01 The above scroll display process is performed until the vehicle enters the adjacent area (step 102), and when the vehicle enters the adjacent area, the map data presence/absence detection unit 6b detects that the 3×3 adjacent map data adjacent to the entered area is on the CD. - Check whether it is stored in the ROMI (step 103), and if it is stored, notify the reading/storage section 6C of this fact.

As a result, the reading/storage unit 6c reads 3×3 adjacent map data from the CD-ROMI (step 104).
input to the display device 7 without scaling, and 9
Generate a new map image MP2 for the screen and store it in the second VRAM.
7c (step 105).

Further, the approach signal/read address generation unit 6a generates a second VR so that a cursor indicating the vehicle position is displayed at the center of the screen.
The position of the window WD of the AM 7c is determined and its address is input to the readout control unit 7d. Thereafter, the readout control unit 7d reads out the map image from the designated window of the designated second VRAM 7c in synchronization with the raster scan, and scrolls and displays it on the CRT 7a (step 109).
.

From then on, each time you enter a new area, the data will be stored in the first and second VRAMs.
3×3 map images are stored alternately, and the VRAM from which the map images are read is switched to continuously scroll and display the map.

The above is a case where all adjacent map data at the current display level exists, but if even one does not exist, step 1
03 becomes No.

If No, the reading/storage unit 6c reads the upper view set Ai tr of each adjacent area where no adjacent map data exists.
The data is read from the cD-ROM (step 106), scaled by the scale converter 6d, that is, the dimension value is doubled (step 107), and the obtained scaled data is input to the display device 7.

The CRT controller 7a generates a map image based on the input scale conversion data, stores a predetermined map image portion in a predetermined area of the VRAM that is not currently involved in the display by overriding, Generate map images from all scale conversion data and sequentially store them in VRAM
If the map image is overridden to a predetermined area, the map image of the portion indicated by diagonal lines upward to the right in FIG. 7 will be stored in the VRAM.

Thereafter, the CRT controller 7a generates an image (see the downward diagonal line in FIG. 7) using the map data for the area where the adjacent map data exists, and stores it in a predetermined area of the VRAM. This means that the level images are stored in the VRAM without gaps (step 108).

In parallel with the above, the entry signal/read address generation section 6
a determines the position of the VRAM window WD so that the cursor CSR indicating the vehicle position is displayed in the center of the screen;
The address is input to the read control section 7d. The readout control unit 7d reads out the map image from the designated window of the designated VRAM in synchronization with the raster scan.
Scroll display is performed on RT 15 (step 109).

Thereafter, each time the user enters a new area, the above process is repeated and the map is scrolled and displayed.

<Effects of the Invention> According to the present invention, it is checked whether map data exists at the currently displayed scale level of an area adjacent to the area to which the vehicle currently belongs, and if it does not exist, map data at another scale level with a larger scale factor is displayed. Scale the map data, generate a map of the adjacent area at the display scale level using the data obtained by the scale conversion,
The map is configured to scroll according to the movement of the vehicle, so the map can be automatically enlarged at the boundary between cities and rural areas without having to register a detailed map of Japan on a CD-ROM, etc. Maps can be displayed.

[Brief explanation of drawings]

Figure 1 shows an automobile navigation system that can realize the present invention.
A block diagram of the system; Figure 2 is an explanatory diagram of the hierarchical structure of map data; Figures 3 and 4 are explanatory diagrams of the case where map data is stored hierarchically on a CD-ROM; Figure 5 is an illustration of the present invention. FIG. 6 and FIG. 7 are explanatory diagrams of map display according to the present invention, FIG. 8 is an explanatory diagram of map d-scroll display, and FIG. 9 is an explanatory diagram of conventional problems. ...CD-ROM, ...CPU for position calculation, a.. Approach signal/read address generation section b.. Map data presence/absence detection section, C.. Read/storage section, d.. Scale conversion section, a.. CRT controller 7b -- 1st VRAM 7c... 2nd VRAM 7d... Readout control unit Patent originator

Claims (1)

[Claims] In a map drawing method for automobile navigation, in which a mark indicating the current position of the vehicle is fixedly displayed at a fixed position on the display screen, and a map image is scrolled and displayed as the vehicle moves, an area adjacent to the area to which the vehicle currently belongs is used. Check whether map data exists at the currently displayed scale level, and if it does not exist, scale the map data at another scale level with a larger scale ratio, and use the data obtained by scaling to change the scale to the current display scale. A map drawing method for automobile navigation characterized by generating a map of an area adjacent to a level and scrolling the map according to the movement of a vehicle.