JPH06294663A - Map display processing method for mobile navigation system - Google Patents

Abstract

PURPOSE:To provide a map display processing method for a mobile navigation system in which processing time can be shortened at the time of switching the scale of a map without increasing the capacity of a video memory. CONSTITUTION:Upon detecting stoppage of vehicle (Step S1) a part of map data for a predetermined range of area including the vehicle is read out at a scale different from that of the displayed map from a CD-ROM and then it is developed on a video memory (Step S2). When switching of map scale is requested (Step S3), residual map data of different scale is read out from the CD-ROM and developed on the video memory (Step S4). A map around the vehicle position is then displayed based on the map data of new scale.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a map display processing method in an in-vehicle navigation system, and more particularly to a map display processing method capable of switching the scale of a display map centered on the current position (vehicle position) of a vehicle. Is.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a configuration example of a vehicle-mounted navigation system. In the figure, an ECU (Electronic Control Uni
t) 1 includes various sensors such as a vehicle speed sensor 2, an azimuth sensor 3 and a GPS receiver 4, an operation unit 5 for externally inputting information such as a scale of a map to be displayed, and map data from a CD-ROM 6. The CD driver 7 for reading and the graphic display controller 10 for displaying a map on the display 9 based on the map data temporarily stored in the video memory 8 are connected.

In the vehicle-mounted navigation system having the above-mentioned structure, when the system is powered on, the ECU 1 firstly gives a moving distance, a traveling direction, a longitude / latitude, etc. given by various sensors such as the vehicle speed sensor 2, the direction sensor 3 and the GPS receiver 4. The vehicle position is detected on the basis of each information of 1., the CD-ROM 6 is searched through the CD-ROM 6 for the map data of a certain area including the vehicle position, the map data is developed, and the map data is expanded to the video. It is temporarily stored in the memory 8. On the other hand, the graphic display controller 10 reads the map data stored in the video memory 8 and displays a map based on this map data on the display 9. Further, the graphic display controller 10 has two functions, a function of displaying the current map data read from the video memory 8 and a function of displaying the traveling locus and other information, and the display data by both functions are superposed. It is configured so as to perform one display screen.

Focusing on the map display processing, the conventional map display processing method will be described below roughly divided into three modes. First, in the initial state, after the start-up or after the map scale switching operation, the own vehicle position is set as the center of the screen, and the map data for 9 screens including this screen and its 8 adjacent screens is
It is read from the D-ROM 6, edited, and stored in the video memory 8. After that, as shown in FIG.
Display a map of the central screen centering on the vehicle position 9
The corresponding map data is addressed to be read from the video memory 8 for display above.

When the vehicle is traveling, based on the vehicle position calculated according to the traveling, as shown in FIG. 4B, a map for one screen centering on the vehicle position is displayed in the map for nine screens. 9. Address video memory 8 for display on screen 9. This display process is repeated, for example, every time the vehicle travels a certain distance. At this time,
As shown in FIG. 4C, a threshold area indicated by a chain line is set for the vehicle position on the map for nine screens.
When the vehicle position exceeds this threshold area,
Map data for 3 adjacent screen areas (hatched areas in the figure) in the direction of travel is newly read from the CD-ROM 6, the map data for the 3 screen areas on the opposite side is discarded, and a new 9-screen map is created. The process of storing the data in the video memory 8 is performed.

When the vehicle is stopped, no processing relating to map display is performed unless there is an operation request from the outside. Also,
When stopped due to a signal waiting or the like, the driver may perform a map scale switching operation for enlarging the map displayed on the display 9 in order to confirm the geography around the current position. When this map scale switching operation is performed, the map data for 9 screens of the specified scale is read again from the CD-ROM 6 and expanded in the video memory 8, and then one screen centered on the vehicle position is loaded. The map data is read from the video memory 8 and a map based on the read map data is displayed on the display 9. Regarding the change of the map scale, the driver tends to perform the scale switching operation within a limited time, such as when the vehicle is stopped such as waiting for a signal.

[0007]

However, in the above-described conventional map display processing method, when there is a map scale switching operation, the map data for 9 screens of the designated scale is read from the CD-ROM 6 when the map scale switching operation is performed. Since the map data was loaded into the video memory 8 and the necessary map data was read from the video memory 8 and displayed on the screen, it takes time to read the map data from the CD-ROM 6 in particular. There is a problem that it takes a very long time to display the map after the scale switching operation. On the other hand, in order to reduce the processing time, a method of always expanding the map data of different scales in advance on the video memory 8 together with the map data of 9 screens of the scale map being displayed can be considered. In this case, the capacity of the video memory 8 increases and the price of the entire system becomes expensive.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle-mounted device capable of reducing the processing speed when switching map scales without increasing the capacity of the video memory. It is an object to provide a map display processing method in a navigation system.

[0009]

A map display processing method according to the present invention includes a storage medium storing map data of a plurality of scale maps, a video memory, and a predetermined range including a current location of a vehicle while recognizing the current location of the vehicle. A system control unit that reads and expands regional map data from a storage medium and temporarily stores it in the video memory, and a display that displays a map including the current location of the vehicle on the screen based on the map data stored in the video memory. In a vehicle-mounted navigation system including a control unit, map data read from a storage medium is expanded into map data of an area including the current location of the vehicle and a plurality of areas around the area, and the map data of the plurality of areas is stored in a video memory. Map data for a plurality of areas stored in the video memory, with a map centered on the current location of the vehicle stored corresponding to a plurality of areas With screen display based monitors stopping of a traveling vehicle, when detecting the stop of the vehicle,
An area corresponding to the display screen out of a plurality of areas of the video memory and a vehicle which are different scales from the display screen and read and expand a part of the different scale map data of a certain area including the current location of the vehicle from the storage medium. When the scale switching request is made, the rest of the map data of the different scale is read from the storage medium and expanded, and stored in the remaining area of the video memory. A map centering on the current position of the vehicle is displayed based on the new scale map data stored in the rear video memory.

[0010]

When the stop of the running vehicle is detected, a part of the different scale map data of a certain area including the current location of the vehicle is read from the storage medium and expanded regardless of the map scale switching request. It is stored in advance in a region other than a region corresponding to the display screen and a partial region in the traveling direction of the vehicle among a plurality of regions of the video memory. Then, if there is a map scale switching request, the rest of the different scale map data is read and expanded from the storage medium and stored in the remaining area of the video memory, and the current position of the vehicle is calculated based on the new scale map data. Display the main map. In this way, by reading a part of the different scale map data from the storage medium and storing it in the video memory in advance before the map scale switching request is issued, when the map scale switching request is issued, the remaining different scales are changed. Only the map data need be read from the storage medium and stored in the video memory, and the amount of newly read data can be small, so that the processing speed at the time of switching the map scale can be shortened.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, a configuration example of an in-vehicle navigation system to which the map display processing method according to the present invention is applied will be described in more detail with reference to the block diagram of FIG.
In FIG. 2, the ECU 1 is provided with a vehicle speed sensor 2 for outputting information according to the speed of the vehicle, a direction sensor 3 for outputting information according to the traveling direction of the vehicle, and longitude / latitude information indicating the absolute position of the vehicle from the artificial satellite. Various sensors such as a GPS receiver 4 for receiving information, an operation unit 5 for externally inputting information such as the scale of a map to be displayed, and a storage medium such as a CD-
A CD driver 7 for reading map data from the ROM 6,
A graphic display controller 10 that displays a map on a display 9 such as a CRT based on map data temporarily stored in a video memory 8 including a VRAM (Video Random Access Memory) is connected.

The CD-ROM 6 stores in advance map data of a plurality of reduced scale maps, and this map data is composed of road data, place name data, river data, facility data, and the like. The storage medium for storing the map data is not limited to the CD-ROM, and other storage medium such as an IC card can be used. The ECU 1 is composed of a microcomputer, and is based on various information such as the moving distance of the vehicle, the traveling direction and the longitude / latitude from various sensors such as the vehicle speed sensor 2, the azimuth sensor 3 and the GPS receiver 4 and the like. While recognizing the (vehicle position), map data of a certain area including the own vehicle position is read from the CD-ROM 6 via the CD driver 7, expanded, and temporarily stored in the video memory 8. The ECU 1 also constantly monitors changes in the acceleration of the vehicle based on the output of the vehicle speed sensor 2 and performs processing such as detecting that the running vehicle has stopped from the changes in the acceleration.

In the vehicle-mounted navigation system having the above structure, in the initial state, the vehicle position is set to the center of the screen as shown in FIG.
This screen (a ₅ ) and eight adjacent screens (a _{1 to} a ₄ , a ₆
9a map data for 9 screens including a ₉ ) are read from the CD-ROM 6, expanded in 9 areas of the video memory 8 and temporarily stored, and the central screen (a ₅ ) centering on the vehicle position is displayed. The process of displaying the map on the display 9 is performed. Further, when the vehicle is traveling, based on the own vehicle position calculated according to the traveling, as shown by a broken line in FIG. 3, one screen worth of map data a ₅ , centered at the own vehicle position in the map for nine screens, Processing for sequentially expanding a ₂₁ , a ₃₁ , and a ₆₁ is performed.

Next, the map display processing method according to the present invention executed when switching the map scale will be described with reference to the flowchart of FIG. It should be noted that this routine is executed every predetermined cycle or every predetermined traveling distance while the vehicle is traveling. The map scale switching request is input through the operation unit 5, and the switching operation is generally performed when the vehicle is stopped such as waiting for a signal. While the vehicle is traveling, the vehicle stop is constantly monitored on the basis of the output of the vehicle speed sensor 2 (step S1). When the vehicle enters the stopped state from the traveling state, a map of a scale different from the map currently displayed on the display 9 is displayed. (For example, enlarged map)
Then, a part of the different scale map data of a certain area including the vehicle position is read from the CD-ROM 6 and the video memory 8
It is expanded and stored (step S2).

Here, a part of the different scale map data means a region excluding a region corresponding to the display screen and a partial region in the traveling direction of the vehicle. In this example, a region for 9 screens shown in FIG. It is map data corresponding to areas a ₁ , a ₄ , a _{7 to} a ₉ of 5 screens. A part of this different scale map data is stored in each corresponding area of the video memory 8 in place of the map data of the scale up to that point. Next, it is monitored whether or not there is a map scale switching request (step S3), and when there is a scale switching request, the remaining different scale map data is recorded on the CD-R.
It is read from the OM6, expanded on the video memory 8 and stored (step S4).

Here, the remaining different scale map data means the area a ₂ of 4 screens out of the area of 9 screens shown in FIG.
It is map data corresponding to a ₃ , a ₅ , and a ₆ , and is stored in each corresponding area of the video memory 8 in place of the map data of the scale up to that point. Next, the address of the video memory 8 is calculated so that the vehicle position (current position) is displayed in the center of the screen on the display 9 (step S5), and the calculation result is set as the screen display start address (step S6). ), Based on this screen display start address, new scale map data is read from the video memory 8 and a map based on this is displayed on the display 9 together with the vehicle position mark (step S7).

As described above, when the running vehicle stops, a part of the map data of a scale different from the map being displayed, in this example, 5 screens of map data is previously recorded on the CD-R.
By reading from the OM 6 and expanding it on the video memory 8, only the remaining different scale map data, that is, the map data for 4 screens in this example, is stored in the CD-
Since it only needs to be read from the ROM 6 and expanded on the video memory 8, it takes time to access, for example, a CD-ROM.
Even when 6 is used as a storage medium for map data, the processing speed of reading, developing and displaying map data at the time of switching map scales can be shortened.

After the map scale switching operation, when the vehicle shifts from the stopped state to the running state, the map display process is continued based on the new scale map data stored in the video memory 8 by the above-mentioned process. Will be seen. In addition, when the map scale switching operation is performed in a stopped state before the start of vehicle traveling, 9
It takes time because the process of reading the new scale map data for the screen from the CD-ROM 6 and expanding it on the video memory 8 is performed. Since there is plenty of room, there will be no problem in practical use.

[0019]

As described above in detail, according to the present invention, when the vehicle shifts from the running state to the stopped state, a part of the map data of a scale different from the map being displayed is stored in advance in the storage medium. Since the map data is loaded from the storage medium and expanded in the video memory, only the remaining map data of different scales needs to be loaded from the storage medium and expanded in the video memory during the map scale switching operation. Since the amount of data to be newly read is small, it is possible to reduce the processing speed of reading, developing and displaying map data from the storage medium.

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing procedure of a map display processing method according to the present invention.

FIG. 2 is a block diagram showing a configuration example of an in-vehicle navigation system to which the map display processing method according to the present invention is applied.

FIG. 3 is a map development view at the time of map scale switching operation.

FIG. 4 is a map development view at each stage of map display.

[Explanation of symbols]

 1 ECU 2 Vehicle speed sensor 3 Direction sensor 4 GPS receiver 6 CD-ROM 8 Video memory 9 Display 10 Graphic display controller

Claims (1)

[Claims] 1. A storage medium storing map data of a plurality of reduced-scale maps, a video memory, and while recognizing the current location of a vehicle, map data of a certain area including the current location is read and expanded from the storage medium. In-vehicle navigation system including a system control unit for temporarily storing in the video memory and a display control unit for displaying a map including the current location of the vehicle on the screen based on the map data stored in the video memory. Developing the map data read from the storage medium into map data of an area including the current location of the vehicle and a plurality of areas around the area, and storing the map data of the plurality of areas in correspondence with the plurality of areas of the video memory. A map centering on the current location of the vehicle based on the map data of a plurality of regions stored in the video memory. This is a display processing method that monitors the stopping of a moving vehicle and detects a stop of the vehicle, and then a part of the different scale map data of a certain range including the current location of the vehicle at a different scale from the display screen is displayed. When read and expanded from the storage medium and stored in advance in a region other than a region corresponding to the display screen and a partial region in the traveling direction of the vehicle of the plurality of regions of the video memory, when a scale switching request is made, The rest of the different scale map data is read and expanded from the storage medium and stored in the remaining area of the video memory, after which the current position of the vehicle is centered based on the new scale map data stored in the video memory. A map display processing method, characterized by displaying a map.