JP2705116B2 - How to display map information - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a map information display method applicable to, for example, an automobile navigation system.

[Conventional technology]

In a self-contained navigation system, map data is stored on a CD-ROM, and the map data is displayed on a CRT display device. Map information is recorded as vector data. Conventionally, map information of a plurality of levels of detail has been recorded, and a user has selectively displayed a map of a desired level of detail on a CRT display device. Unlike this method, it has been considered that a map with an arbitrary level of detail is displayed by enlarging or reducing the map information of a predetermined level of detail. The enlargement or reduction is performed by a process of multiplying the coordinate data by a magnification.

On the other hand, in the map, markers such as × and □ are added to the line in order to represent other railway lines, road types, and the like other than the line.

[Problems to be solved by the invention]

Conventionally, there has been a problem that the interval between the markers changes according to the magnification with the enlargement or reduction, and the display becomes difficult to see. This problem occurs because the coordinate data of the marker position is recorded on the CD-ROM.

Therefore, an object of the present invention is to provide a method of displaying map information in which the distance between markers does not change when the image is enlarged or reduced.

[Means for solving the problem]

According to the present invention, a drawing processor forms straight line data and marker data based on input vector data, writes the straight line data and marker data to a graphic memory, and uses a map data based on image data read from the graphic memory. In a map information display method in which information is displayed on a display device, the drawing processor sequentially forms data of a plurality of points forming a straight line using vector data, and forms the straight line by the data of the plurality of points. Marker data to be attached is formed, and by controlling the write address when writing the marker to the graphic memory, the interval between the markers is set to the same interval set by the program regardless of the display scale. This is a map display method.

[Action]

The map information displayed on the CRT display device is formed by a drawing processor from vector data, and is stored in a graphic RAM.
Is stored in The image data read from the graphic RAM is converted into an analog image signal, supplied to a CRT display device, and displayed on a map. Markers such as x, □, and * are formed by program processing in the drawing processor. In the drawing processor, the marker is formed as a set of a plurality of points. The interval between the markers is controlled by specifying an interval included in the vector data. Therefore, even when the magnification changes, the interval between the markers is controlled to be constant.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a map display system to which the present invention can be applied. 1 is a host processor, 2 is a drawing processor, and 3 is a graphic RAM. Although not shown, the host processor 11 reads out vector data stored in a CD-ROM or the like and supplies the vector data to the drawing processor 2.
The drawing processor 2 forms line segment data and marker data from the vector data, supplies these data and addresses to the graphic RAM 3, and writes the data to the graphic RAM 3, as described later. graphic
The image data sequentially read from the RAM 3 is stored in the D / A converter 4.
, And is supplied to the CRT display 5 to display map information on the CRT display 5.

As shown in FIG. 2, the vector data for displaying the line segment includes coordinate data including data at the beginning of the line segment (x1, y2) and data at the end of the line segment (x2, y2). ing. The curve is represented as a continuation of a plurality of line segments. The vector data from the host processor 1 usually includes a set of coordinate data indicating the start and end positions of each of a plurality of line segments. Data indicating the type of display (toll road, national road, railway, river, etc.) is added as vector data. The type of display determines in advance what line segment (solid line, broken line, line thickness, marker type, marker interval, etc.) is to be displayed.

In the drawing processor 2, data to be written into the graphic RAM 3 is formed in accordance with the flowchart shown in FIG.

First, a predetermined value is set in the step counter (step). This predetermined value is set in the host processor 1
Is included in the vector data from. In the next step, coordinate data is input, and a change (slope) of a straight line is calculated from the data at the start and the data at the end (step). The coordinate data is changed in accordance with the enlargement or reduction magnification.

In the data write (step), the drawing processor 2
Is formed in the graphic RAM 3. In the next step, the address is changed. This change is a process in which a change is added to the previously obtained coordinate data. It is determined in the step whether the changed address is the end coordinate data. In the case of the end coordinate data, the process of forming the drawing data ends.

When the changed address has not reached the end coordinate data, the step counter is decremented by 1, ie, decremented (step). Then, it is checked whether the content of the counter is 0 or negative (step). When the value of the step counter is not 0, return to the step,
The address (coordinate data) is changed. When the value of the step counter is 0, the step counter is set again (step). The process returns to the step data write operation.

Actually, the display data is written to the graphic RAM 3 at the data write (step) stage, and the display data interval is determined by the value initially set in the step counter. For example, the interval between points when displaying a dotted line is determined by the step counter.
In the case of the solid line, the value of the step counter is set to 1 or 0, and data at points at the minimum interval is formed.

Marker display data is generated by generating a marker indicated by vector data at the data write stage. The markers are formed with types and intervals according to the data included in the vector data. For example, 5
The program is controlled at the data write stage so as to add a □ marker to each point.

4 to 7 are diagrams for explaining the generation of a marker. In FIG. 4, P indicates the center coordinates to which a marker is to be added. A cross-shaped marker can be formed by sequentially forming point data at positions having an offset Δ on the upper, lower, left and right sides of the center coordinates. In addition, as shown in FIG. 5, by forming four points having an offset Δ at the top, bottom, left, and right with respect to the center coordinate P, a square marker can be formed. By forming both the markers in FIGS. 4 and 5, the marker shown in FIG. 6 can be formed. Further, a marker as shown in FIG. 7 can be formed by adding a point in an oblique direction to the marker shown in FIG. In addition to these markers, a marker having a desired shape can be formed by a program.

〔The invention's effect〕

In the present invention, unlike storing coordinate data of a marker in a memory such as a CD-ROM, data of a marker added to a line segment is formed by a processor, and the interval between the markers at this time is independent of the magnification. By doing so, even when the map is enlarged or reduced, the markers are displayed at regular intervals, making the map easier to see.

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of a map display system to which the present invention can be applied, FIG. 2 is a schematic diagram used for describing coordinate data, FIG. 3 is a flowchart used for describing one embodiment of the present invention, and FIG. FIGS. 5, 5, 6, and 7 are schematic diagrams showing some examples of a method of forming a marker. Explanation of main reference numerals in drawings 1: host processor, 2: drawing processor, 3: graphic RAM, 5: CRT display.

Claims (1)

(57) [Claims] 1. A drawing processor forms straight line data and marker data based on input vector data, writes the straight line data and marker data into a graphic memory, and reads an image read from the graphic memory. In a map information display method in which map information is displayed on a display device by data, the drawing processor sequentially forms data of a plurality of points forming a straight line using the vector data,
The data of a plurality of points forms the data of the marker attached to the straight line, and by controlling the write address when writing the marker in the graphic memory, the marker interval is designated by the program regardless of the display scale. A map display method characterized in that the intervals are set at equal intervals.