GB2351837A

GB2351837A - Contour maps made easier

Info

Publication number: GB2351837A
Application number: GB9915907A
Authority: GB
Inventors: Stephen Pepper
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-07-08
Filing date: 1999-07-08
Publication date: 2001-01-10
Also published as: GB9915907D0

Abstract

The introduction of a simple system on contour maps to indicate whether crossing two adjacent contour lines involves going uphill, downhill or staying level, without the need of following each contour line to another area of the map which has the contour lines labelled with their height in relation to sea level. The system uses symbols such as equilateral triangles, positioned along each contour with the apex of each triangle pointing in the direction of an adjacent higher contour line. Figure 1 shows a simplified contour map with a footpath connecting points A and B. The dotted lines from the 10 cm prior art square to the 10 x 2 cm rectangle illustrate the map users task of following the contour lines to be crossed to another area of the map which has the contour lines labelled. Figure 2 is as Figure 1 but has the proposed invention added with small triangles pointing uphill and thus making it easy for the map user to know whether the route is continuously up; continuously down; or a mixture of up and down.

Description

2351837 CONIOUR MARS MADE EASIER This invention relates to making contour

maps easier to read.

The introduction of a simple system on contour maps to indicate whether crossing two adjacent contour lines involves going uphill, downhill or staying level, without the need of following each contour line to another area of the map which has the contour lines labelled with their height in relation to sea level.

Contour maps, such as the Ordnance Survey maps in the UX, are well established. They typically have lines drawn connecting points at the same height above (or below) sea level in steps of 1 Om and often depict each 50m contour with a darker line. At various areas of the map the absolute height of each contour line is shown, but these areas can be quite distant from the area of interest.

The map user wanting to travel from one particular point to another can read the map and consider the possible routes to see whether they involve crossing many contour lines and how close they are to each other which will give a good indication of the terrain. However, to know whether a route involves going continuously up; continuously down; or a mixture of up and down; the map user must follow the contours, sometimes over quite long distances, and through text or other markings on the map to an area which labels the height of the contour in relation to sea level. This can be difficult, particularly in adverse field conditions.

The proposed invention is to introduce symbols on contoured maps, such as small, but legible, equilateral triangles along each contour line at approximately 1 cm intervals which have the base on the contour line and the opposite apex pointing in the direction of the adjacent higher contour line.

If the contour line follows, or is close to following, a ridge and the two adjacent contour lines are either the same height or lower, then no triangles would be shown.

If the contour line follows, or is close to following, the bottom of a valley and the two adjacent contour lines were both higher, then triangles would be shown on both sides of the contour fine, slightly offset to each other.

The map user would now readily see that a possible route involved a continuous climb; a continuous descent or a mixture of climbing and descending. It would no longer be necessary to follow the contour lines from the area of interest to wherever they happened to be labelled.

If the absolute height above sea level is of interest to the map user, then only one contour line need be followed to its label and it is then easy to calculate the absolute height at any point on the proposed route by simple addition and subtraction.

It is the principle of the invention that is essential, not the detail of the execution and the labelling convention chosen. My proposal is equilateral triangles with sides of 1.5 mm shown in the same colour as the contour line at approximately 1 cm centres with their base on the contour line and their opposite apex pointing up-hill. Other conventions could be adopted and a variation on this theme may be more appropriate for ocean charts and other applications.

Figure 1 shows a simplified typical contour map with a footpath connecting points A and B. The map user has to follow the contour lines to another area of the map where their height in relation to sea level is labelled. On an actual map this could necessitate following the contour line through text and other markings on the map and can he extremely difficult in adverse field conditions. In Figure 1 this is illustrated by the dotted lines connecting the 10 cm x 10 cm square to the 10 cm x 2 cm rectangle which represents another part of the map.

Figure 2 is as Figure 1 but with the proposed invention added. The small triangles always point uphill and the contour line with the double offset triangles readily shows that this contour is at, or near, the bottom of a valley and it is uphill from this contour to both the adjacent contours. The unmarked contour line readily reflects that this is at, or near, a ridge and both adjacent contours are lower. The map user can now easily see that as he leaves A he will descend 2 x 10 m then ascend 3 x 10 m and finally descend 10 m as he arrives at B. If the absolute height above sea level is required, this can be read as in Figure 1 but only one contour would need to be followed to its label and then simple addition and subtraction applied.

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Claims

1. The introduction of a simple system on contour maps to indicate whether crossing two adjacent contour lines involves going uphill, downhill or staying level, without the need of following each contour line to another area of the map which has the contour lines labelled,with their height in relation to sea level.

2. The proposed invention, as claimed in Claim 1, makes contour maps much easier to read, especially in adverse field conditions.

3. The absolute height of a contour line relative to sea level can be determined by following one contour line to another area of the map where it is labelled. Once the value of one contour line is known, the height relative to sea level of other relevant contours can be easily calculated by simple addition or subtraction using the proposed symbols to readily recognise which are increasing height and which are decreasing height.

4. The proposed invention will make a contour which is following a ridge, or close to following a ridge, readily identifiable as it will be one of very few contours with none of the proposed symbols on it.

5. The proposed invention will make a contour which is following the bottom of a valley, or close to following the bottom of a valley, readily identifiable as it will be one of very few contours with the proposed symbols on both sides of the contour line.

6. The proposed invention is also applicable to ocean charts or any other form of contour map-