Military sites — how this layer is made

What you are looking at

Each point is a military site — 230,814 of them worldwide, from OpenStreetMap, drawn as a dot sized by the footprint of the site and coloured by what kind of site it is.

Two selections make the layer: anything carrying the `military` tag, and anything tagged `landuse=military`. The second is needed because land set aside for armed forces usually carries no `military` tag at all, and it is a third of what is here.

Click any feature to see what OpenStreetMap records about it — whose forces hold it, and its website. Where it has a Wikipedia article, a short summary is fetched live and shown in your own language; and every feature links to the OpenStreetMap object it came from.

Everything on this map is already public. It is drawn from a public database of things people have recorded from survey, aerial imagery and published sources. Nothing here is derived from anything restricted.

What the colours mean

Bunker — 105,237 features, 45.6%. Nearly half the layer, and see the warning below.
Military land — 65,122, 28.2%. Land held by armed forces with nothing more specific recorded.
Base — barracks, bases and naval bases. 20,813, 9.0%
Training — training areas, ranges and danger areas. 10,874, 4.7%
Office — recruitment and administration. 8,574, 3.7%
Checkpoint — 7,722, 3.3%
Trench — 2,729, 1.2%, and see the second warning below.
Nuclear test site — where a device was detonated. 2,381, 1.0%
Airfield — 2,220, 1.0%
Not recorded — `military=yes` and a long thin tail. 5,142, 2.2%

A site that is both a barracks and military land is drawn as a barracks: the specific tag says what a place is, and the land use only says who holds it. About 27,000 features are both.

Bunkers: a map of mapping as much as a map of bunkers

Nearly half of this layer is bunkers, and their distribution has to be read carefully.

Counted crudely — `military=bunker` features inside a country's boundary, per million people:

France — 131.2 per million, 8,973 in total
Germany — 127.4 per million, 10,610
United Kingdom — 50.0 per million, 3,413
United States — 37.1 per million, 12,419
Australia — 6.7 per million, 177
Japan — 1.5 per million, 181
China — 1.0 per million, 1,379
Brazil, India, Indonesia — 0.1 per million each
Nigeria — none recorded

Germany's rate is about 910 times India's. No plausible reading of history makes that a true statement about how many fortifications exist. Two things are happening at once and this map cannot separate them: the Atlantic Wall and the Cold War did leave northern France and Germany covered in concrete, and those are the countries where enthusiasts have gone out and recorded each one. Most of the world's fortifications have never been mapped.

So the bunker colour is best read as "where bunkers have been catalogued". The same warning applies harder to trenches.

Military land is the honest half

`landuse=military`, per million people:

France — 54.8 per million, 3,745
United Kingdom — 26.3 per million, 1,799
United States — 25.9 per million, 8,661
Germany — 21.7 per million, 1,805
Australia — 19.4 per million, 515
Brazil — 11.1 per million, 2,387
China — 5.8 per million, 8,243
Japan — 4.7 per million, 587
Indonesia — 3.9 per million, 1,096
India — 1.7 per million, 2,353
Nigeria — 0.5 per million, 103

Germany against India is about 13 here — flatter than schools, and seventy times flatter than the same comparison for bunkers. Where a country has armed forces it has land for them, and that land gets mapped at a fairly even rate everywhere because it is large, obvious and visible from the air.

If you want the part of this layer least distorted by who does the mapping, that is the olive one.

Nine tenths of the trenches are missing

27,650 objects in OpenStreetMap carry `military=trench`. This map shows 2,729 of them.

The reason is a limitation of how HueMaps builds these layers rather than anything about the data: 24,964 trenches are mapped as lines, and this pipeline draws points and areas only. A trench is a linear thing, so mappers draw it as a line, and the line is dropped.

The trenches you can see are the minority that somebody drew as a closed shape or a point. They are real, and they are not representative — the great mapped trench systems of the Western Front are almost entirely lines and almost entirely absent here.

Linear features are a known gap on this site rather than an oversight, and they are not currently drawn on any layer.

Sizes here span nine orders of magnitude

The median traced footprint on this layer is 1,467 m² — a large building. The 99th percentile is 10,114,933 m² — ten square kilometres. The largest is the Central Test Range of the Russian Federation at 84,257 km², bigger than Ireland, with Woomera in South Australia close behind.

Those top features are administrative areas rather than installations, so the size scale is capped far below them. A very large shape on this map is a range, a danger area or a test site; a small dot is a structure.

29.0% of the layer has no footprint at all, and three quarters of those are bunkers. Untraced features are drawn at 140 m² — the median footprint of a traced bunker — rather than the layer median, because using the layer median would have drawn fifty thousand concrete boxes at ten times their real size.

Naming

33.2% carry a name, and it varies more by class than on any other layer here:

Nuclear test sites — 95.7% named
Airfields — 86.8%
Offices — 59.0%, training areas 51.3%
Military land — 44.3%
Bunkers — 23.1%, trenches 13.9%

The pattern is straightforward: documented places have names, and incidental structures do not.

An overlap worth knowing about

Military airfields carry `military=airfield` here and will also appear on the airports layer when that is published. That is intentional — an airfield is genuinely both, and a reader looking at aviation and a reader looking at defence should each find it.

Mapped, not modelled

Each feature is an object a mapper drew. Nothing here is modelled or estimated, and no defence register has been merged in — nor could one be. What is here is what people have chosen to record, which for this subject is a stronger caveat than for most.

Size

Each symbol is sized by the footprint of the feature, in square metres measured on the globe. Symbol area is proportional to that (radius to its square root).

Among the traced features, the median footprint is 1,467 m², the 90th percentile 278,213 m² and the 99th 10,114,933 m².

A picture of the present

Today's map, not a history — although a great deal of what is on it is historic, and some of it is a century old. OpenStreetMap is edited continuously; this copy is refreshed periodically. A base shown here may have closed, and a bunker generally outlives the war it was built for.

Source and licence

Back to the map