Cawthorn Camps

 Cawthorn Camps, Yorkshire, is a well-preserved earthwork site, largely of Roman date, which is situated on the southern edge of the North York Moors. The ongoing research project at Cawthorn is a joint initiative between the North York Moors National Park and English Heritage, the main aims being to improve academic understanding of the site and produce a revised management plan. The programme of research began in 1998 and, in addition to the air photographic work, has included geophysical survey, detailed metric earthwork survey and two seasons of excavations by archaeologists under the direction of Dr Pete Wilson from the Centre for Archaeology at Fort Cumberland.

The air photographic work at Cawthorn involved using digital photogrammetry to produce a plan of the earthworks at scale 1:500 and to a precision of ±10cm. This image shows the final hachured plan. Photogrammetry uses stereo imagery to obtain very accurate 3D measurements of the subject. The level of detail visible on the stereo images was such that individual tree stumps and rabbit holes could be seen; archaeological features of as little as 10cm in height have been identified and recorded.

 One of the benefits of using digital photogrammetry is the ability to manipulate the imagery to provide further products, for example Digital Elevation Models (DEMs), orthophotographs and perspective views. This image is a perspective view of part of the site produced through the photogrammetric software using the DEM. Lighting and colour balance of the resulting image can also be changed in order to highlight features of interest to best advantage.

This composite image shows an extract of the rectified 1993 photograph located in the centre of the eastern fort. A second identical image is overlaid with the air photo interpretative plan. The features shown in red and green were recorded from the photogrammetric stereo models. Those shown in yellow were transcribed from the 1993 photographs either because they were not visible on the stereo models, or the features were showing in more detail. Features depicted in dark blue, light blue or purple are all probable trenches or spoil heaps resulting from the 1920s excavations; those in purple were identified only from the 1993 photos. The magenta rectangle outlines one of the trenches opened in 2000 by Dr Pete Wilson of the Centre for Archaeology.

The conclusions of the air photographic study for Cawthorn are documented in a report (Stone, Aerial Survey Report Series AER/8/2002). They also from part of an article, currently in preparation, which will combine the overall findings of the research project.

The images used on this page are copyright English Heritage unless specified otherwise. For further details of any photographs or other images and for copies of these, or the plans and reports related to the project please contact the NMR English Heritage's public archive.

For further information on a project or any other aspect of the work of the Aerial Survey team please contact us at: AerialSurvey@english-heritage.org.uk.