The team from Orkney Research Centre for Archaeology were back on the island of Rousay two weeks ago to work with the Deutsches Archäologisches Institut Römisch-Germanische Kommission (DAI) and the University of the Highlands and Islands Archaeology Institute (UHI) on the largest geophysical survey ever undertaken on the island.
Once again, Frank Forrester, our work placement student from the University of Bradford, continues the story of the project..........
"Our first day, Dan Lee and I travelled to Rousay, meeting up with Jane Downs and Steve Davis of University College Dublin and going through the different sites of Rousay. before meeting the DAI team. The four team members of DAI where Knut Rassmann, Ruth Beusing, Johannes Kalmbach and Andreas Grundmann.
The team ventured out into the brilliant sunshine and travelled around the Rousay landscape, looking over the sites to be surveyed and finalising the overall approach. The UHI team then had to travel back to Kirkwall, while I stayed with the DAI team, helping them set up the surveying equipment.
The equipment itself was a 14 magnetometry system. Built on a carbon fibre frame, the 14 sensors where placed at the back-on wheels with high suspension. This frame was designed so that no metal from the quad bike, that pulled the system would interfere with the results. The cart had its own GPS attached, which was feeding back to a known base station point. This guaranteed the accuracy of the location of the cart, which in turn located the sites revealed from the survey.
Surveying started on the second day. An amazing 45 hectares were surveyed in a single day. The quadbike, allowed the team to be very moveable when surveying the fields, and yet still be fast enough to cover the large area detailed in the overall plan.
In the morning of the third day I had the chance to go through the results of the previous day. This was an amazing opportunity, as I had never seen magnetometry data on such a large scale. Being able to already pick out sites from the first set of data showed the importance of this survey and how much it can help understand the archaeology and landscape of Rousay.
Ruth and I went and collected some magnetic susceptibility data of the stone from around the area of the survey. These points included a field dyke, Midhowe Broch, Swandro, Broch farmstead and Skaill farmstead. This data was collected by using a probe sensor, first taking a measure from a control sample, then of the air around the different spots, of the stone itself and finally of the surrounding air again. This is to make sure that there is a clear measure between the stone measurement and the surrounding area.
Thursday the 19th April saw the start of the Gateway to the Atlantic: Rousay Workshop. We met the speakers and delegates at the ferry, before going on a fieldtrip of the island. This was followed by a late lunch before the start of the talks.
The second day of the workshop started with coffee at the Rousay community school, before moving into the talks. After lunch, and to stretch the legs after a long period of talks, the group went and saw some clearance sites on Rousay, as it is the only island of Orkney that was cleared. This small break was followed by a round table discussion and brainstorming session of possible future collaboration and projects. This workshop experience was incredible to see as the collaboration of all these different partners coming together is something I had never seen before. It showed me how projects can be formed between different organisations dealing with big questions."
The Orkney Research Centre for Archaeology (ORCA) team not only use the standard methods to survey archaeological sites, but also aerial drone photography and video.
This section of coast on the small island of Papa Westray in Orkney has experienced severe coastal erosion which has exposed significant archaeology. ORCA were commissioned by Historic Environment Scotland to complete a survey of the area around St Boniface's Church as part of a larger community archaeology project which will provide a baseline assessment of coastally eroding archaeology.
The drone video clip will form part of the baseline assessment and, together with the 3D models produced by Jim Bright and the ORCA team, gives the archaeologists a unique perspective on the structures eroding out of the cliff. The drone videos provide a very quick and cost effective method of assessing a coastline and in future may be used to create 3D models.
The coastline is eroding at an alarming rate at this point and has already receded 30cm in one year. The plan is to undertake further drone flights in subsequent years which will enable the team to assess the damage quickly and cost effectively. Using such technology also allows a client to examine a structure or remains remotely from a connected computer anywhere in the world.
The drone is operated under strict guidelines by a fully trained member of the ORCA team.
For more information on the 12th Century St Boniface's Church, cross slab and the Norse hogback grave stone see Canmore.
The Orkney Research Centre for Archaeology team are using a 3D modelling method that provides a rapid insight into the physical remains at any site under investigation.
The 3D model shown above was created by the ORCA team for the baseline assessment of coastal archaeology threatened for Historic Environment Scotland. Coastal erosion is one of the main threats to shoreline archaeology in the islands of Orkney.
The site at Munkerhoose is within a section of eroding coastline stretching over 80m in length. The exposed section is over nine meters wide and stepped in a series of narrow uneven terraces. This aspect is due in part to the excavation and back fill of the northern and central portion of the site in 1990. The most significant threat to the site is from high energy storms from the open ocean to the north and northwest.
The section is annotated and by clicking on each number on the 3D model above, the details of the coast at that point can be examined. You can also rotate the coastline model or zoom in using your mouse. Taking each point.....
Point 1 Dense Midden Deposits. The area with few stones is midden material - mainly domestic rubbish from the nearby structures. An excavation in 1990 identified several features within this area.
Point 2 The piled stones here are parts of an ancient structure. They have been protected from erosion by dumped material from the 1990 excavation.
Point 3 shows in detail the remains of a large Iron Age roundhouse excavated in 1990.
Wave action has had the most significant impact in the features within the lower section of the site, such as the point identified here, where soft deposits from below wall sections have been undermined and smaller pinning stones and wall cores washed out, leading to collapse or destabilisation.
Point 4 shows a roundhouse passageway. Erosion has exposed a structure not visible in 1990. This passageway could be internal, as part of this roundhouse structure, or external, between it and a separate structure to the south of the roundhouse.
Point 5 shows further structural remains which is another newly exposed structure, possibly another roundhouse; the sagging horizontal slabs are the floor. This area has suffered significantly from wave action.
The detail captured by the ORCA team in these 3D models provides a very cost effective method of providing baseline data which in turn enables everyone involved in the project to analyse, measure and compare erosion effects at different sites very quickly.
This pioneering approach to using 3D modelling has been used to some effect at the world renowned Ness of Brodgar excavation where multiple 3D models tracked the progress of the disassembly of the north wall of Structure One and enabled archaeologists working at the site to plan the excavation more rapidly than if field sketches were used.
In short the 3D team can collect the data and within days create a detailed model....for anyone to view anywhere on the planet - as long as they have an internet connection of course!
The creation of the 3D models above were in connection with the Community Archaeology Baseline Assessment Project completed for Historic Environment Scotland in March 2018. See ourprevious blog post for details of the overall project.
Archaeology is increasingly using technology to both shed new light on research questions and speed up processes in a drive to become more efficient. ORCA is investing in new technologies and the skills that people such as Jim Bright are now bringing to commercial archaeology.
Jim is a recent MSc graduate of the UHI Archaeology Institute who has developed photogrammetry and 3D modelling through his research at the world-renowned Neolithic excavation at the Ness of Brodgar and the equally important Iron Age dig at The Cairns, South Ronaldsay, Orkney.
Photogrammetry is a method by which a vast number of photographs can be converted into 3D computer models, which can then be viewed by anyone who possesses a computer and readily accessible social media platforms such as Sketchfab.
Following discussions with Pete Higgins, Senior Project Manager Orkney Research Centre for Archaeology, the ORCA team realised that Jim’s skills could be used in a commercial archaeology setting to offer clients a new resource and service. 3D modelling is a powerful resource, which can be used to aid client’s own public relations activity, but also, due to the accuracy inherent in the data collection methods, the technique is also used to record archaeologically important sites; replacing time consuming hand drawing– saving precious time on clients sites.
The main tools used are a camera, a Nikon D60 SLR and the software AgiSoft PhotoScan. The process of creating a good 3D model of a structure or item is a multi-phased one. Firstly Jim photographs the area around the object or area for modelling, making sure that the photographs overlap at every angle. Once all the photos had been taken they are uploaded into the software where each photo is checked, removing any blurry or unwanted areas using the masking tool. The alignment process can then begin, this is where the software takes millions of points in each photograph, compares them to the other photographs to identify the position and angle in which they were taken, and from this generate a base point cloud.
Once this is done, any potential errors or bad data can be removed by selecting certain parameters in the software before beginning the dense point cloud generation, where millions of points in a model are created as you can see in the two pictures below, the top image is of the whole model and the bottom one is zoomed right in so you can see all the points which make up the model.
When the dense point cloud has been made, the model is trimmed and tidied before creating the wireframe mesh, where the points are essentially joined up, and millions of triangles or faces are created ready for textures to be painted onto them. The texture file is made up of all the photographs taken to create the model which will then be wrapped around the mesh. The texture generation is the final process in the workflow of creating a 3D model.
That data’s geolocation coordinates are recorded using a total station theodolite (an electronic/optical instrument used for surveying and building construction). Once input, the ruler tool becomes available in the software, which allows the user to measure the 3D model down to the nearest millimetre.
The 3D models can be used as embedded images in presentations, press releases or social media have been used as an addition to the archaeological record of certain trenches, where models are created at different phases of excavation.
This blog has been created by Orkney Research Centre for Archaeology in beautiful Orkney. We aim to add features and news about our work on the islands and further afield on a regular basis.