The Veiled Landscape
The Veiled Landscape project is part of the Miner2Major five-year landscape partnership, established to promote and safeguard the natural, built and cultural heritage of Sherwood Forest in Nottinghamshire. The partnership is led by Nottinghamshire County Council working alongside local and national partners, including the RSPB, Nottinghamshire Wildlife Trust, Inspire, and Newark and Sherwood District Council. Reclaim Heritage CIC were commissioned to process and analyse high resolution LiDAR data in advance of ground truthing events with volunteers in Sherwood Pines.
Sherwood Pines
Sherwood Pines is a forest park just outside Manfield that has been under the stewardship of Forestry England since 1925, at which time it was planted with pine trees in response to a wood shortage following the end of WWI.
Before its now distinctive coniferous woodland, the area was previously known as Clipstone Heath and comprised heathland and scrub woodland interspersed with small tree plantations and coverts. During WWI the heathland was transformed into Clipstone Camp training ground, which spanned much of the western part of Sherwood Pines and extended beyond to the north and west.
LiDAR
LiDAR (Light Detection and Ranging) is a method by which the range or distance of a surface can be measured by recording the time taken for a laser beam to be fired and returned to a receiver. Most often this is achieved aerially with lasers originating from aircraft targeting the ground to record relative heights, although ground-based terrestrial laser scanners are also used depending on the size and characteristics of the object being surveyed. As the laser beam travels towards the target the beam diverges to cover a larger area, meaning that more than one object may fall within its footprint and multiple returns are recorded, giving the height and intensity readings for vegetation and surface features in that location.
Extensive 1m resolution datasets already existed for Sherwood Forest thanks to the Environment Agency National LiDAR Programme, but for a more detailed study of archaeological remains greater resolution was required. An enhanced 0.16m resolution LiDAR survey was commissioned in early 2021.
Data visualisation
A typical Digital Terrain Model (DTM) can be viewed most simply as a range of colours or in grayscale format to give a sense of elevation. This technique allows for quick viewing of the data but often fails to pick out some of the more subtle topographical changes when dealing with large areas, leading to blurred images of little interpretive value.
LiDAR data visualisation should be determined primarily by the aims of the project. With this in mind, a method was required to process and visualise the entire study area to allow quick interpretations for use in field ground truthing.
The most widely used technique for this is the application of hillshades to the DTMs to enhance earthworks. Hillshades in their most simple form are simulations of light cast across terrain from one or multiple directions that create a shadow effect that enhances positive and negative features in a landscape.
It was decided that a combination of hillshades were required and, through trial and error, the Visualisation for Archaeological Topography (VAT) hillshade was settled upon as the one from which the most interpretative value could be extracted. Details of the hillshade settings are listed below and were applied using the Relief Visualisation Toolbox (RVT) in QGIS.
Find out more…
To learn more about the results of the ground-truthing survey, check out the fully illustrated report by clicking here.
Chris has also been busy presenting the findings at the Chartered Institute for Archaeologists Conference. Watch this video to see him explain the project and discuss some of the results and thoughts. about using high-resolution LiDAR.
To learn more and to see the lidar yourself, visit The Veiled Landscape, Miner2Major project page and Nottinghamshire Historic Environment Record.
