The LiDAR is, in simple terms, an image of the ground surface with most of the vegetation stripped away. The contours of the landscape are shown clearly, enabling you to see the gradient of hills and valleys and to pick out the streams which wriggle their way through them. Man-made features, such as buildings, roads and railway tracks, show up well.
LiDAR uses lasers to measure the difference in height of the ground surface. It cannot reveal archaeology under the ground unless the buried remains are causing the ground surface to rise.
Irregular brown areas on the image are where the lasers have been unable to penetrate. This often happens where evergreens grow - large holly trees, stands of young conifer and patches of rhododendron. Lakes and ponds can also appear brown, although sometimes they are the same colour as the surrounds, but look completely even. Gorse makes the LiDAR look 'lumpy' and lack detail.
LiDAR is especially good for finding archaeological features in woodland, where they are hidden by trees in normal aerial photos. It can show very subtle features which are invisible on the ground. Features in lines, such as banks and ditches, show clearly. Using LiDAR images and our specially-developed toolkits, you can discover more about the archaeology of the Weald Forest Ridge.
LiDAR images work best when printed out at A3. At this size you can see both the overall shape of the landscape and the individual features more clearly. Always look at the LiDAR print with north at the top as turning it upside-down will make valleys look like ridges and mounds look like hollows.