JP3561131B2 - Map scroll method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a map scrolling method in a navigation device, and more particularly to a map scrolling method for displaying a map around a vehicle position or a map around a cursor position on a screen and scrolling the map in a designated direction by a scroll operation.
[0002]
[Prior art]
2. Description of the Related Art A navigation device that guides a vehicle so that a driver can easily reach a desired destination detects a position of the vehicle and uses a map recording medium (e.g., a CD-ROM or a DVD disk) to detect a position around the vehicle. The map data is read, the map image is drawn on the display screen, and the vehicle position mark is drawn so as to overlap a predetermined position on the map image. Then, as the vehicle position changes due to the movement of the vehicle, the vehicle position mark on the screen is moved, or the vehicle position mark is fixed at a predetermined position such as the center of the screen and the map is scrolled. Map information around the location can be understood at a glance.
[0003]
Such a navigation device has a route guidance function of searching for a guidance route from a departure place to a destination, displaying the guidance route on a map, and performing intersection guidance (enlarged intersection view, arrow indication of traveling direction). . When a departure point and a destination are input, the guidance route control unit of the navigation device automatically determines an optimal guidance route, and continuously stores nodes (coordinates and longitudes) constituting the guidance route in the guidance route memory. At the time of actual traveling, a search is made for a guidance route included in the map display area of the screen from the node sequence stored in the guidance route memory, and the guidance route is displayed so as to be distinguishable from other roads, and the approach route is displayed. When the vehicle is within a predetermined distance from the middle intersection, an intersection guide map (an enlarged view of the intersection and an arrow indicating the traveling direction at the intersection) is displayed, which road should be traveled, and which direction should be taken at the intersection. You can see it. When the vehicle deviates from the guidance route (off-route), the guidance route from the current vehicle position to the destination is recalculated to update the guidance route.
[0004]
The navigation device has a function of scrolling a map by operating a joystick key. Such a map scroll function can be used, for example, when inputting a destination with a cursor or when registering a point such as a home. By the way, in the conventional map scrolling method, as shown in FIG. 7A, a map image of an area larger than an area displayed on a display screen is previously drawn and stored in a VRAM (map drawn area), and a joystick of a joystick is used. When the scroll direction is designated by the operation, the map is cut out while moving the map cutout range (window) WD in the VRAM in the direction, and the map is scrolled by displaying the map on the display screen. Then, as shown in FIG. 7B, when the map image reaches an area that is not stored in the VRAM (map non-drawing area), a map image in the scroll direction area is newly drawn and stored in the VRAM. The map scroll is performed by performing the above processing.
[0005]
[Problems to be solved by the invention]
However, in map scrolling, it is necessary to draw a map in the scroll direction, and if the drawing is not completed, fine map scrolling cannot be performed. For this reason, conventionally, the map is stopped until drawing is completed and scrolled after drawing, but there is a problem that map scrolling is intermittent. In addition, recently, there is a problem that the amount of map information is large and it takes time to draw a map, and the stop time becomes long.
Therefore, if the map is scrolled without stopping, the portion where the map is not drawn is seen and unsightly, and the effect as the map scroll is reduced. Therefore, there is a method of slowing down the scrolling speed so as not to stop and not to see the undrawn portion. However, this method is too slow and is inconvenient.
In addition, drawing of characters and the like is stopped at the time of scrolling, and scrolling is performed by drawing only roads. However, such a scrolling method has a problem that it is unclear which area map is being displayed and is inconvenient to use.
As described above, an object of the present invention is to enable high-speed continuous map scrolling and to enable scrolling without omission of a map.
[0006]
[Means for Solving the Problems]
According to the present invention, there is provided a map scrolling method for a navigation device that displays a map around a vehicle position or a map around a cursor position on a screen and scrolls the map in a designated direction by a scroll operation. ) Except during scrolling, a map image is generated at a predetermined first resolution and stored in the VRAM, and a map image around the own vehicle position or a map image around the cursor position is cut out from the VRAM, and the screen image is screened at the first resolution. (2 ) When scrolling, generate a map image with a second resolution lower than the first resolution and a wider area than in the case of the first resolution , store the map image in the VRAM, and move the cursor by scrolling. A map scroller that moves the position, cuts out a map image around the cursor position from the VRAM, and displays it on the screen at the second resolution. It is achieved by the method.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
(A) The principle of the present invention When the resolution of a map image stored in a VRAM is reduced, the area that can be stored in a VRAM of the same size increases. FIG. 1A shows a case where a straight line L is linearly interpolated at a first resolution (see a black circle) and a case where a straight line L is interpolated at a half of the first resolution (a second resolution) (see a white circle). is there. When the interpolation points (black circles) of the first resolution are stored in the VRAM, the result is as shown in FIG. 1B. When the interpolation points (white circles) of the second resolution are stored in the VRAM, as shown in FIG. 1 (c). Become. That is, if the resolution is reduced to 地 図, the maps in the same area can be stored in a サ イ ズ VRAM. In other words, if the resolution is halved, a map of four times the area can be stored in a VRAM of the same size. However, if the resolution is reduced to １ ／, the resolution is also displayed to に も on the display screen. Therefore, a rough map is drawn on the display screen as indicated by the white circle point in FIG.
As described above, if the resolution at the time of map scrolling is halved, the map size that can be stored in the VRAM is quadrupled, and four times faster map scrolling can be performed than the conventional scrolling method without changing the resolution. Become.
[0008]
FIG. 2 is an explanatory diagram of a map size and a window size that can be stored in a VRAM when a map is drawn and scrolled at a resolution of １ ／ the resolution at the time of normal map display. , (B) show the case of scrolling. At the time of scrolling, as described with reference to FIG. 1, a map image of an area four times as large as that in a normal state can be stored. In addition, the size of the window WD corresponding to one screen is １ ／ of the size at normal time.
As described above, if the map reading speed from the VRAM is the same in FIGS. 2A and 2B, a map in an area four times as large as that in the normal state can be read during scrolling. That is, if the resolution is scrolled down to 1/2, the map can be scrolled at four times the speed as compared with the case where the resolution is not changed. Although the image quality is reduced, such a reduction in image quality does not cause any problem during scrolling.
As described above, according to the present invention, at the time of scrolling, a map image is generated at a resolution lower than the normal resolution, the contents of the VRAM are stored / updated, the cursor position is moved by the scroll operation, and the map around the cursor position is moved from the VRAM. The image is cut out and displayed on the screen at the low resolution. This enables high-speed, continuous map scrolling.
[0009]
(B) Configuration of Navigation Control Device FIG. 3 is a configuration diagram of the navigation control device, 1 is a navigation control device, 2 is a remote controller, 3 is a display device, 4 is a recording medium for storing map information, for example, a CD-ROM, 6 is a GPS receiver, 7 is a multi-beam antenna, 8 is a self-contained navigation sensor, and 9 is an audio unit. The self-contained navigation sensor 8 includes a relative azimuth sensor (angle sensor) 8a such as a vibrating gyroscope that detects a vehicle rotation angle, and a distance sensor 8b that generates one pulse for each predetermined traveling distance.
In the navigation control device 1, reference numeral 11 denotes a map readout control unit. {Circle around (1)} When a map scroll operation or a map selection operation is performed with a joystick key, a map reduction / enlargement key, or the like, the cursor position (the latitude and longitude position at the center of the screen) is changed. In addition to the calculation, (2) predetermined map information is read from the CD-ROM 4 based on the position of the vehicle (normal time) or the position of the cursor (during scrolling).
[0010]
Reference numeral 12 denotes a map buffer for storing map information read from the CD-ROM. In the map buffer, plural pieces of map information (multiple units) around the own vehicle position or the cursor position are read and stored so that the map can be scrolled. Reference numeral 13 denotes a map drawing unit which generates a map image using map information stored in a map buffer, 14 denotes a VRAM for storing the map image, and 15 denotes a screen center position (own vehicle position or cursor position). A map cutout control unit that changes the position (window position) of one screen cut out from the VRAM 14 and scrolls and displays the map according to the movement of the vehicle position or the movement of the cursor.
[0011]
Reference numeral 16 denotes an intersection guide unit, which generates and outputs an enlarged image of an intersection for guiding a vehicle to a destination and guides the traveling direction at the intersection by voice. Reference numeral 17 denotes a remote control unit that receives a signal corresponding to an operation of the remote controller and instructs each unit, 18 denotes a GPS data storage unit that stores GPS data from a GPS receiver, and 19 denotes a position of the own vehicle based on an output of a self-contained navigation sensor. (Estimated vehicle position), a vehicle position / azimuth calculation unit for calculating the vehicle azimuth, 20 is a map matching control unit, and a predetermined traveling is performed using the map information read from the map buffer 12, the estimated vehicle position, and the vehicle azimuth. A map matching process by the projection method is performed for each distance (for example, 10 m) to correct the position of the own vehicle on the traveling road.
[0012]
Reference numeral 21 denotes a guidance route control unit, which performs (1) calculation processing of the guidance route to the input destination, and (2) guidance when the vehicle deviates from the guidance route (off route) from the current vehicle position to the destination. A unit that performs route recalculation processing, etc., 22 is a guidance route memory that stores guidance routes, and 23 is a guidance route drawing unit. Reference numeral 24 denotes an operation screen generating unit for displaying various menu screens (operation screens), 25 denotes a mark generating unit for outputting various marks such as a vehicle mark and a cursor when displaying a map screen, and 26 denotes an image synthesizing unit.
[0013]
(C) Scroll control FIG. 4 is a block diagram of the present invention in which a map drawing system is extracted from FIG. 3, and the same parts as those in FIG. 3 are denoted by the same reference numerals. FIG. 5 is a flowchart of the scroll control according to the present invention, and FIG.
If the scrolling is not being performed by the joystick key operation, the map is displayed at the normal resolution, and the map is scroll-displayed as the vehicle travels (steps 101 and 102). In this state, when scrolling by operating the joystick key provided on the remote controller is started, the map readout control unit 11 reads out the map data over a wide area around the cursor position, stores the map data in the map buffer 12, and displays “Scrolling , And also notifies the map extraction control unit 15 of "being scrolled" and the cursor position (screen center position). As a result, the map drawing unit 13 generates a map image with the resolution reduced to １ ／ and draws the map image on the VRAM 14 (step 103). An image of the minute (window) is cut out and input to the display device 3 (step 104). Since the display device 3 is instructed by the map reading control unit 11 to reduce the resolution to １ ／, the map is displayed with the resolution of the input image reduced to （(step 105).
[0014]
The map reading control unit 11 checks whether the window WD has reached an adjacent area map generation line BL set in advance around the outer periphery of the VRAM as shown in FIG. 6A (step 106). If not, it is checked whether the map scrolling operation has been completed (step 107). If the scrolling operation has not been completed, the processing from step 104 onward is repeated. That is, the map readout control unit 11 calculates the cursor position according to the scroll speed and notifies the map cutout control unit 15, and the map cutout control unit 15 reads an image for the next one screen from the VRAM 14 based on the cursor center position. The image is cut out and input to the display device 3, and the display device 3 displays the map at a resolution of 1/2. As described above, the map is scrolled.
[0015]
Thereafter, if the map scrolling continues and the window WD reaches the adjacent area map generation line BL in step 106, the map reading control unit 11 converts the map data of the adjacent area in the scroll direction (the hatched area in FIG. 6A) into a map. The data is read from the recording medium 4 and stored in the map buffer 12. As a result, the map drawing unit 13 generates a map image at a resolution of 1/2 using the map data of the adjacent area, and stores the map image in the VRAM 14 (FIG. 6B) (step 107).
After that, the map scroll is performed by repeating the processing of step 107 and thereafter. When the scroll operation is completed, the map reading control unit 11 notifies the map drawing unit 13, the map cutout control unit 15, and the display device 3 of the scroll end. Thereby, the map drawing unit 13 restores the resolution to generate a map image and stores the generated map image in the VRAM 14. The map cutout control unit 15 reads an image for one screen around the cursor position at the window size of the original resolution and displays it. Upon input to device 3, the display device displays the map at the original resolution (step 108).
[0016]
The above is the case where the resolution is reduced to 時 に at the time of scrolling, but the resolution is not limited to ２. In the above description, one VRAM is provided. However, two VRAMs may be provided to perform scroll control. When there are two VRAMs, a map image with a reduced resolution can be drawn in another VRAM prior to scrolling. In this way, if a scroll operation is performed with the joystick key, the map image is immediately displayed. Scrolling can be started.
As described above, the present invention has been described with reference to the embodiments. However, the present invention can be variously modified in accordance with the gist of the present invention described in the claims, and the present invention does not exclude these.
[0017]
【The invention's effect】
According to the present invention, a map image is generated at a predetermined first resolution except during scrolling and stored in the VRAM, and a map image around the own vehicle position or a map image around the cursor position is cut out from the VRAM. The screen image is displayed on the screen at the first resolution. At the time of scrolling, a map image having a second resolution lower than the first resolution and a wider area than that of the first resolution is generated, stored in the VRAM, and scrolled. The cursor position is moved by the operation, and a map image around the cursor position is cut out from the VRAM and displayed on the screen at the second resolution, so that high-speed continuous map scrolling is possible, and Scroll without omission of map is possible.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the size of an area that can be stored in a VRAM when the resolution is changed.
FIG. 2 is an explanatory diagram of a map size and a window size that can be stored in a VRAM in a normal state and a scroll state.
FIG. 3 is a configuration diagram of a navigation device.
FIG. 4 is a configuration diagram of a drawing system of the present invention.
FIG. 5 is a flowchart of a scroll control process of the present invention.
FIG. 6 is an explanatory diagram of timing of generation of an adjacent map.
FIG. 7 is an explanatory view of a conventional map scroll.
[Explanation of symbols]
3 Display device 4 Map recording medium 11 Map readout control unit 12 Map buffer 13 Map drawing unit 14 VRAM
15. Map cutout control unit

Claims (1)

A map scrolling method for a navigation device that displays a map around a vehicle position or a map around a cursor position on a screen and scrolls the map in a designated direction by a scroll operation.
Except during scrolling, a map image is generated at a predetermined first resolution and stored in the VRAM, and a map image around the own vehicle position or a map image around the cursor position is cut out from the VRAM and displayed on the screen at the first resolution. Display,
At the time of scrolling, a map image having a second resolution lower than the first resolution and wider than that of the first resolution is generated and stored in a VRAM, and a cursor position is moved by a scroll operation to move the cursor position. A map image around the cursor position is cut out and displayed on the screen at the second resolution.

Images