The streets and buildings of Piercebridge,
a Roman town ©
Satellite images
Conventional photography is the mainstay of aerial archaeology, but there is tremendous potential for archaeological surveys in other, less familiar, remote sensing techniques.
A lot of interest is being focused on satellite imagery that can offer sub-metre resolutions (ie can show fine detail).
This means that most archaeological earthwork remains could be made visible, as could many cropmark sites, providing the imagery is captured at the right time of year, time of day, and in the right conditions. Satellite or airborne multispectral imaging of this kind, used a lot by geologists and environmental analysts, holds great potential for archaeology - but to date its use
has been limited.
'The system is so accurate that height differences of a few centimetres can be detected.'
Another exciting recent development is LIDAR (Light Detection and Ranging), which uses an airborne laser to measure the distance between the aircraft containing the equipment and the ground. This effectively produces
a high-resolution model of the landscape that the plane has flown over, which can be lit and viewed from any position.
This mapping technology is being deployed by a variety of organisations, such as The Environment Agency and the Unit for Landscape Modelling at Cambridge. The system is so accurate that height differences of a few centimetres can be detected, revealing the most subtle archaeological earthworks.
Yet another technique is that of thermal imaging, or Infrared Line Scanning technology, mainly in military use, which is also successful at detecting archaeology.
None of these techniques, however, is likely to replace conventional or digital photography in the immediate future.
