What are aerial maps actually used for? The technology has obviously come a long way since those tacky photos one used to get sold from time to time in the 80s, showing one’s house and neighbourhood from the air – but what is it used to do?
One of the primary uses of aerial maps, simply enough, is to provide a basis for producing the paper maps we’re all familiar with. Aerial photography and surveying allows cartographers to check, recheck and confirm the data they hold for map generation. It also allows for primary map generation, in which the aerial image actually becomes the basis for the map itself. Aerial imaging is also used to check the correct scale of a paper map.
Aerial imaging is required by law for certain undertakings – notably new builds and extensions. All planning permission applications must be supported by at least two scales of aerial maps – one showing the immediate site in detail and the other showing the site in relation to its wider surroundings. These two maps together (one is called the location plan and the other one is called the site plan) allow the relevant local authority to determine what kind of effects the proposed build or extension might have on the whole neighbourhood, as well as the immediate site itself.
For wider planning purposes, aerial imaging is used in a variety of extremely technical ways to support or reject location proposals for new construction. It’s now possible to generate aerial maps by means other than straight photography – in particular, by commissioning LiDAR (Light Detection And Ranging) images of an area. LiDAR shows actual ground topography, rather than tree lines or other forms of hazing: which means the maps it generates can be relied upon to provide an accuracy regarding the real elevation and terrain of an area far greater than any previous technology. Costly abortions are far fewer, now that LiDAR generated aerial images are being used by town planners and construction companies.
Historical and geological surveys are benefitting from aerial maps in ways they have never done before – again, thanks to the quality and varied technology associated with the imaging. Industry cooperation hasn’t hurt, either: organisations like Britain’s legendary Get Mapping tend to form spokes in a larger cartographic wheel, where technology and data are shared to guarantee a universally accurate set of maps.
It’s even possible to chart recent topographical and civic developments using the overhead maps generated by these alliances of institutions and organisations: Britain, for example, is the subject of an ongoing mapping project, whereby an almost constant series of aerial maps are being produced and electronically stitched together in order to provide a living, up to the minute record of the topographic, geographic and civic aspects of the island.