LoMaps: Display contour lines in feet.

Taras D shared this idea 2 weeks ago
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The world works in the metric system, except the USA. It would be useful if LoMaps could display contour lines in feet.

I propose LoMaps contain data for displaying contour lines in metric (meter) and imperial (feet). The map's theme could offer the choice of which set of contours to display.

Perhaps this new feature (dual-system contours) would be limited to LoMaps produced for the USA. I believe there's little interest to display contours in feet elsewhere in the world.


The current workaround is to use Dynamic Altitude to "spot-check" elevation in feet.


However, displaying contour lines in feet would be better.

Comments (3)



thank yo for idea...I checked our current possibilities and it seems that would be possible to prepare map with contour lines in feet. However I don't like the idea to duplicate data for all maps because 5 - 30% of map size is due to the contour lines. The idea to create contour lines in feet only for USA sounds better for me but it has also weakness - the border areas. On the border (for example USA - Canada) would be inconsistent/broken lines. I'll discuss it with the rest of the team.

BTW: do you know if is there another country where are feet used for elevation?

Thank you



First I wish to thank you for just discussing this idea! I don't imagine many people outside of the USA are interested in maps with contour lines in feet (except maybe as a novelty item)! However, in the USA, topographic maps with contours in meters are baffling to its citizens because they measure distances in miles and feet.

I believe only the USA, Myanmar, and Liberia officially use the English/Imperial system of measurement (miles, feet, pounds, gallons, ounces, etc). However, some countries use the metric system officially yet continue to use the Imperial system unofficially.


For example, in Canada most everything is in the metric system yet we post prices for certain foods in both dollars per kilo and per pound. We also sell certain building materials in Imperial units. However, our maps are metric.

In contrast, our southern neighbour, the USA, does not use the metric system (except in scientific research) and its maps are published in miles and feet. https://viewer.nationalmap.gov/basic/

I realize adding imperial contour data to USA LoMaps will cause their file size to grow. The alternative would be to have Locus Map dynamically recalculate contour lines (using elevation data). That would require creating an entirely new capability for Locus Map. The feature would require significant computing time, to recalculate the position of contours in feet, and the end-result would probably be a very sluggish map. I think it's better to calculate the imperial contour data up-front, when the map is created, and store it within the map. Locus Map only needs to allow the user to choose metric or imperial contour lines using the map's theme.

Regarding the border areas, between the USA and Canada and Mexico, maybe it won't be a problem. Canada and Mexico LoMaps will not have imperial contour data. So if you're viewing a northern state like Vermont (bordering on the province of Québec in Canada), Vermont's imperial contour lines end at or just beyond the border. No contour lines will be visible on the Québec side of the border because the map theme is set to display imperial contours (and there will be none within the Québec LoMap, only metric contours).

The only way to show seamless contour lines running across the USA-Canada border will be to choose metric contour lines. Then the contours will display for both the USA and Canada (and Mexico). I think that's a fair compromise.



thank you for information about imperial units. I know that for example in UK are used imperial units but contour lines on topo maps are in meters.

The dynamic recalculation on the device isn't possible or better it's complicated on mobile devices. The only way (that I can imagine) are different maps for countries with metric or imperial system.

Canada and Mexico LoMaps will not have imperial contour data - you're right and this is the complication I mentioned. LoMaps always overlap the country border for a couple kilometers (due to another limitation) and it can happen that imperial contour lines will appear in country with metric system. But I guess that it isn't such problem.