|Tagging:||contour=int (representing height above sea level)|
|Applies to:||way, area|
|Rendered as:||thin brown line|
Add contour lines representing height above or below sea level. Perhaps at ten meter (height) intervals like on an ordnance survey map.
It is a useful piece of scientific and geographical data. Uses: People planning walks or bike rides could avoid tiring inclines. Route planning algorithms could even take this into account. It could be used if ever a visualisation program wished to implement a 3D view.
I think a simple contour=number is the simplest way. An alternative would be to tag them as natural=contour then add a separate height=number value to them. Though to me that seems unnecessary.
Circular way. It's not really an area because a contour defines a line not the area inside the line.
A thin brown line is how it displays on most maps. The heights should not appear on every line (that would be cluttered) but every few lines depending on the zoom level. Alternatively of course the view could be 3D.
Contours page, for the many automated methods of generating these