The image above is an extract from a 3D animation of the Stonehenge landscape, created from LiDAR (Light Distance And Ranging) data which is produced by attaching a 3D laser scanner to an aircraft. A cloud of measurement points across the landscape is produced as the laser-beam is fired at the ground and measured when it is reflected back to the aircraft. Depending on how high the aircraft flies and how the raw data is processed, this typically results in a dataset of points spaced between 15cm and 2m apart, with a vertical tolerance of up to 20cm.
Much of the upstanding archaeology, from well-preserved barrows (burial mounds) to the subtle earthworks of prehistoric field systems, are clearly visible in the full animation.
The highly detailed terrain models which can be produced from this data are incredibly useful for identifying archaeological features, even those which can barely be seen with the naked eye. In addition to the spatial component of the data, the intensity of the reflected laser beam is also recorded and this can be used to identify buried features where they cause changes in the vegetation cover or soil moisture content and hence the amount of absorption and reflectance of the laser beam.