contour lines idea

[jon9uk]

Hi All,
Often contour lines leave you unsure of which way a slope is running, I have a simple remedy for this; if contour lines were two tone or had a rough side and a smooth side, it would be possible for each line to have a discernible high side and low side which you would instantly see when you looked at a map, and so you would gain much more information at first glance. At the moment you have to hunt down the altitude readings if you want to firmly establish which way a slope is running. I feel that my idea would make reading a map much more intuitive and wouldn't necessarily make the contour lines any wider, so it's all gain and no loss. The odd thing is though, I've got in touch with OS maps and the British Cartographic Society plus many more and no one is at all interested except for the North American Cartographic Society who very kindly invited me to come and give a talk at their conference, but for various reasons that's a bit tricky.
An additional benefit would be that bumps, on the contour line, say 100m apart, would help with reading distances, but that's really a secondary idea.
I've been told that if I want to get into a professional magazine I need to write a paper about it but it's hardly a complicated idea.
My grandfather was a cartographer during the war so I feel that this project sort of completes a circle for me.
If anyone could help or has a suggestion I would be very grateful, it seems a shame to drop the idea without it even seeing the light of day.

[Redrobes]

Hello and welcome to the guild.

I agree with your observation. At least on OS maps they always print the altitude of the contour line such that the text points the correct way up as you look up the hill but its often hard to find that reference in all the mess especially when there are built up areas since buildings and the contour lines are in the same colour.

The problem is that there can be a lot of contour lines. If you make them anything other than a very thin line then it can overwhelm a map. OS are very unlikely to change their style since its been in use for ages - a hundred years or so.

In the "Old Series" of OS maps the relief is done in a different way. There are many ways to show relief and most European maps show it very differently to OS which might be due to places like Austria having such high mountains so lots of lines is impractical.

It would be good if you can post an image showing a map with the style of contours that you have in mind and we can see exactly how you would represent them.

Another option is to mark the high point or low point with a mark that is different. Then at least you can follow the contour lines up/down the hill until you determine which was was the up direction.

I think its also true that 2D maps will be going out of fashion and use with the advent of mobile phones and other dynamic displays that can show 3D maps and present the relief in other methods that don't have the restriction of a 2D piece of paper.

[waldronate]

Something generally in the concept of Tanaka's illuminated contours ( https://mountaincartography.icaci.or.../kennelly1.pdf has some information ), except with shading direction and line width based on local slope angle and steepness rather than illumination from a fictitious light? I recommend trying a few maps to show this idea, maybe write up a paper with those maps plus the technique and submit it somewhere. Lots of conferences are looking for submissions, even (sometimes especially) for novelty elements.

I suspect that one of the reasons for apparent general disinterest from publishers is for practical reasons. You'd need at least two tightly-aligned process colors on the map or go with what amounts to a raster image and then halftoning or other process. Contour maps are cheap to print because they don't use a lot of ink or require a lot of colors. They are also well-understood by their user base and a new, potentially easy-to-misunderstand implementation might not be much of a seller. By the time that you're using multiple colors, a lot of publishers are more likely to go for existing hillshading variants of one form or another. It's not a high-margin business for the most part and they tend to be pretty conservative in what they publish.

Older (19th century or so) maps used something called hachures to show local slope and direction, with some attribute of the individual hachures (usually thickness, sometimes length) coding slope. You can arrange the hachures along contour lines or encode density of hachures to show various attributes. Because they generally where's precisely defined, they largely fell out of favor with contour maps as their replacement. Contour maps have the nice property that the steepest up/down local slope is always at right angles to the contour.

[worldbuilding pasta]

Also worth noting that fully enclosed pits aren't actually that common as topographic features, fluvial erosion will usually ensure all points on land have a downward slope to the sea in at least one direction, so for most cases the ambiguity just isn't much of an issue; it's usually obvious which way is downslope if you assume any closed loops represent peaks and any water features will be lower than their surroundings. And there are some conventions for showing the occasional exceptions when they occur, which is more economical (in terms of printing cost and whatnot but also visual clarity) than altering the appearance of all contours to account for them.