At the end of July we were commissioned by the Lake District National Park Authority to undertake topographic survey of the three large spoil tips at the extensive Greenside lead mining complex near Ullswater in the Lake District. Archaeologically the site is of national importance and is protected as a Scheduled Monument. Future management of the property necessitated the present detailed topographic survey in advance of engineering works to maintain the stability and structural integrity of the large spoil tips. The buildings beneath the spoil tips are currently used as hostel accommodation.
Normally such a detailed survey, requiring close contours for the extensive complex would take an inordinate amount of time to survey using traditional survey techniques such as Total Station or even differential GPS. Over the last few years we have been developing more rapid and cost-effective survey capability using various unmanned aerial vehicles (UAV) to photograph archaeological sites, which is combined with Agisoft software to create 3D models and contours of sites.
Part of the site was surveyed and excavated in 2003-4 in advance to engineering works on Spoil Tip 2 using traditional survey methods, but whilst that took a week or so to undertake the present UAV survey took a day of flying and setting in survey control to cover the entire mine complex.
The site was visualised in Agisoft as a digital terrain model in both solid form and also with the aerial photography draped over the top. The data from this model was used to create detailed contours of the earthworks at various scales which could then be used when drawing up the site.
The complete site was also output as a single flattened scaled composite image which was then annotated in the field to add in the finer detail of archaeological structures and provide hatchures to the topographic survey.
The finalised site drawings, contours and survey detail were then compiled into a single CAD drawing for the entire complex and figures created showing both the entire complex and detailed ones of specific features in the complex.