I’m still here doing my landscape archaeology thing. but now we have nice shiny drones to help us out too. I will post some links to some of my photos soon.
As part of my work at Oxford Archaeology North I’ve recently been practicing (under supervision) flying and surveying with our UAV drones at various archaeological sites in the region. This is in advance of qualifying for a BNUC-S™ pilot qualification to get a Permission for Aerial Work for undertaking commercial projects.
The end of September saw community excavations undertaken at Quay Meadow, in Lancaster. It is located north-west of the Roman fort which is partially extant within Vicarage Fields, and is just below Lancaster Castle. The excavations were undertaken by Lancaster and District Heritage Group in tandem with a wider project aimed at trying to understand the heritage and archaeology of the area which is conducted by Beyond the Castle.
The three excavated trenches were located over interesting anomalies identified in an earlier geophysical survey of Quay Meadow previously undertaken by OANorth. The preliminary results of the excavations suggest evidence for a Roman road heading down towards the original Roman quayside, and what was initially identified as possibly being a post-medieval/modern structure in the geophysics actually turned out to be wall foundations of several Roman buildings found just below the topsoil. There is clearly much much more that Lancaster and District Heritage Group can get their teeth into in future years.
In practice the UAV survey was relatively simple for this site as all we wanted was a general plan view of all of the trenches and detailed post-excavation surveys of each individual trench, which we then created from the photogrammetry in Agisoft PhotoScan. We also created contours of the surrounding topography but this was not as spectacular as earlier results undertaken on the earthworks in Vicarage Fields to the south-east of the site.
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.
Jamie returned to Blelham Tarn last weekend to undertake aerial survey on the site of the bloomery as no excavation was taking place. He used his octocopter, one of two UAV we have at the company, to take multiple vertical images across the site. The north-western half of the site was covered in trees but the main area of the bloomery mound/platform where the four trenches were opened up was surveyed in full. From the photographs taken we were able to process them in Agisoft to create three outputs which will be really useful in trying to get an understanding of the subtle topography and earthworks for this site. First we have a flattened aerial plan view of the visible parts of the site which can be overlain on the survey data I took last week.
Then we have the 3D contour model of the detailed topography of the site which we can spin around, zoom in and out of, and pick up fine detail from. The screenshot above shows the model with the photo layer draped on, the one below shows it as the solid 3D generated model. Again from these we can pick up subtle details of the site and surrounding topography, and also see the trenches, spoil heaps and turf stacks!
Finally we can create close contours from the 3D model (these here are at 10cm intervals) which are overlain on the rough survey data we took last week – open the image below and zoom it to have a look. We found that the contours were very detailed for this particular site and were (obviously) better than ones generated from LiDAR data for the region, which at 1m accuracy really didn’t show much of the earthworks themselves, and were also offset slightly from the survey data. We have found that the Agisoft contours are better at depicting earthworks of discrete complex sites, whereas the LiDAR contours at 1m resolution are fine for broader areas and showing the surrounding natural topography.
I will use all of this information tomorrow when we go back out to site with the volunteers to finish off and do annotated hatchure drawings of the bloomery.
This time last year we battled through the snow and ice on our journey over to survey a small cairnfield located on the North York Moors near Whitby. The report for this particular project has just been posted online to the OA Library and you can download it here. Did it really snow so late last year? I just can’t contemplate anything other than rain rain rain at the moment, but luckily (and selfishly) I’m still indoors writing up reports.
We undertook at topographic survey to record all of the surviving earthworks located on a small plot of rough pasture by the farmstead of Eden House, which is near the village of Hutton Mulgrave, on what was once part of Barnby Moor. The 4.66 hectare area of the cairnfield is statutorily protected as a Scheduled Monument, and as part of an ongoing management plan for it further detailed recording was needed. You can find a description of the monument here.
The survey was completed using a combination of photogrammetry and GPS survey. The photogrammetry was undertaken using photographs taken from a small UAV helicopter that were used to generate a metrically accurate model of the surface of the study area, including all surface features that were not obscured by vegetation. Some features were obscured, and so in addition a ground topographic survey was undertaken to record the more subtle features by GPS survey.
The survey presents a thorough record of all the archaeological structures and components identified in the form of a detailed measured plan, profiles across the putative deer park boundary, digital photography and an outline site gazetteer.
Earlier in the year we were commissioned by Paul Frodsham of the North Pennines AONB under the guise of the Heritage Lottery funded Altogether Archaeology project to undertake two types of photogrammetric survey at Long Meg and Her Daughters stone circle located in the Eden Valley, near Penrith, Cumbria. This was part of a wider community project to develop an understanding of this exceptionally important monument and provide detailed surveys and geophysical investigation of the monument.
The work was undertaken in March 2013 and this post is concerned with the first part of our input into the investigation, which was producing a detailed aerial photographic plan of the site using a quadcopter UAV (Unmanned Aerial Vehicle).
This method uses aerial photographs taken from a small electrically powered model helicopter (UAV) which has the ability to carry a light weight camera and has the advantage that it can take photographs from much lower altitudes than can legally be achieved with a light aircraft. Survey control was introduced to the photographs by the placement of survey control targets across the site which were located by means of a survey grade GPS.The photogrammetric processing was undertaken using Agisoft software that provides detailed modelling using the overlap of up to 150 photographs, and creates a very detailed DTM (Digital Terrain Model) across the site. The photographs were then digitally draped over the model to create an accurate 3D model of the ground surface.
The primary output, however, was an accurate flat two dimensional image which can be used to generate accurate plans of surface archaeological features and contours across the extent of the site (at the top of the post). However, the 3D model can also be output as a tool to visualise the site from any perspective and can be viewed in more recent versions of Adobe Acrobat as a 3D pdf file.
Many thanks should go to all of the Altogether Archaeology volunteers who turned up in the cold weather to work on site during the project.
A training weekend was undertaken on the first weekend in September supervised by myself and Gemma Stewart, the Northumberland National Park Community Archaeologist, to survey a stone row alignment located on the open moorland at Standingstone Rigg, near Simonburn, Northumberland.
The project was funded through Northumberland National Park to enable volunteers to undertake practical archaeological projects within the National Park. The aim of the project was to provide appropriate professional supervision and training in order to build the capacity of local groups to actively research little studied or poorly understood elements of the archaeology of the National Park.
The survey falls under the wider umbrella of the Heritage Lottery Funded Altogether Archaeology Project, a multi-period community archaeology project being undertaken to record archaeological sites in the North Pennines AONB and beyond.
The field survey aimed to build upon preliminary survey work carried out in 2012 by Phil and Anne Bowyer, and train volunteers in various survey techniques to create a series of detailed plans of key features associated with the stone row.
The stone row was surveyed using a combination of a theodolite and disto technology to create a manual measured plan of the stones and a differential GPS to record surrounding structures and archaeological features. All upstanding and recumbent stones from the row were measured, described and photographed.
Preliminary results of the survey revealed a slightly sinuous NNE/SSW double alignment of both upstanding and recumbent stones that ran upslope over the crest of a ridgeline and down the other side, adjacent to one, or possibly two funerary cairns on the crest of the ridge. The stones have packing stones surrounding them and in the centre of the alignment it is often just the packing stones that survive as the standing stones have been removed for building a nearby sheepfold. The size of the stones does seem to follow the broad pattern of larger examples nearer the crest of the ridge in the north end of the alignment, and it is clear that the sandstone bedrock has been hewn and cleaved up along natural bedding planes often immediately adjacent to where the stones now stand.
The southern end of the stone row continues as an alignment of ten pits surviving as part-filled sunken features before it probably disappears into a boggy area to the south. The double stone row is a prehistoric monument usually dating from the later Neolithic or Bronze Age, and this example is a very rare, if not unique surviving example from Northumberland. In the British Isles sinuous double stone rows which meander across open moorland countryside are more typically associated with the Dartmoor area.
These types of monuments are often found in association with other features such as funerary cairns, which is also possibly the case at our example, but so far I have not been able to identify any other stone rows associated with an extant pit alignment.
When the bad weather abated the week after the survey weekend, my manager Jamie Quartermaine returned to site with Gemma and Phil to survey it using his Hexacopter. This is a small remote-controlled helicopter that can be used (in light winds) to take aerial photography of archaeological sites. The data was processed in Agisoft software to create both a composite photograph of the stone row and a 3D model of the site.
Hopefully when the final results of the project are published the weekend training exercise will have added significantly to our knowledge of the prehistory of Northumberland National Park, and it will have given local volunteers practical skills for recording further monuments in this landscape in the hinterland north of Hadrian’s Wall.
Particular thanks are due to Gemma Stewart for making the project possible, Phil and Anne Bowyer who have been doing so much background work to understand the archaeology of the surrounding landscape (forthcoming Ravensheugh Crags blog post), and the volunteers from Altogether Archaeology and members of Tynedale Archaeology Group who braved the inclement weather. Thanks are also due to the tenant farmer at Great Lonbrough farm and the Nunwick Estates. A special mention should also be given to Stan Beckensall who braved the rain on the Sunday to help survey the stones.