I was kindly invited to present at a CPD session on introducing Structure-from-Motion photogrammetry to beginners at this years CIfA Conference, by the Graphic Archaeology Group. It was a great opportunity to network, catch up with colleagues and hear about exciting new research using the technique, plus all of the advice and tips for using SFM were valuable not just to beginners but to anyone who’s using the method for recording archaeology and heritage! I shared my learning experiences from my time with Historic England, in addition to covering some of the interesting findings we made in my research reports (click here for link) and also gave a brief sneak preview of my PhD plan.
The session on managing World Heritage was also particularly insightful, as the three wonderful brochs I’m researching are all on the UK’s tentative WHS list!
26th-30th September. After an epic drive down south (in 7 and a half hours!) I arrived in Penzance with David and Fiona from Historic England’s Geospatial Imaging team, for a week of surveying Iron Age courtyard houses, unique to the Lands End peninsula and the Isles of Scilly, on the famous site of Chysauster. The houses all had a central open courtyard area, with several rooms attached. More information on the site can be found on English Heritage’s webpage: http://www.english-heritage.org.uk/visit/places/chysauster-ancient-village/.
The layouts of these very impressive structures are very complex – there’s even a semi-detached house! So they were quite challenging to record, but armed with plan drawings and context sheets, we sucessfully laser scanned three of the houses with the most upstanding, exposed stonework and took photographs for SFM photogrammetry, as a record of their current condition.
The weather also took a turn for the dramatic, and I was very thankful for my wellies as torrential downpours and sweeping mists arrived at the start of the survey. On a clear day, the views from the village are spectacular – you can see all the way to Penzance and the coast beyond, but then the fog was thick, I could barely see past the walls of the house I was recording!
Luckily, the sun was out on the last day of the survey, and we ended with a site visit to another Iron Age village site, called Carn Euny, to see the fogou (an underground passageway with a large, central chamber). Chysauster also has a fogou, but this has been sealed up for safety. The purpose of these structures is not clear, but the main theories suggest they were either storage areas, places of refuge in times of warfare, or special religious places.
The week before last, Historic England welcomed a visit from our Historic Environment Scotland (HES) colleague, Sofia Antonopoulou. We had a packed schedule for her to visit some of the sites that the Geospatial Imaging team has previously surveyed around North Yorkshire, including Clifford’s Tower, Rievaulx Abbey and Mount Grace Priory.
We also photographed artefacts in the care of English Heritage’s North Territory store at Helmsley, for SfM photogrammetry. The object in question is a curious little 19th century wooden box, that had been decorated with wax seals taken from medieval stamps that had originated from Fountains Abbey. I’m in the process of generating the 3D models at the moment, so it’ll be really interesting to see how Photoscan copes in processing all of the slight details in each seal design, which range from the personal seal of an abbot’s signet ring to depictions of the Virgin and Child.
We also returned to Bellman Park in Clitheroe, six months after the team’s first survey of the area, to collect the next epoch of laser scans at this Heritage at Risk site. The grass had really shot up since December, but we managed to scan the entire structure in a day.
We rounded off the week with a trip further south, to the Natural History Museum (NHM) and their science department, to see how their researchers are using scanning electron microscopes to gather imagery of microscopic features for SfM photogrammetry and other visual techniques for research, such as producing CT scans. Overall it’s been a very hectic but enjoyable week!
This Tuesday I presented the finished 3D models of three scheduled standing crosses in Leek town centre to the West Midlands Historic England office and Staffordshire Historic Environment Record. I’m pleased to say I can share the results on my blog, via Sketchfab, so click on the links below to open them:
May has been a very busy month for me – I’ve been attending and presenting at conferences up and down the country, so I’m catching up with my blogging this week with some of the geospatial industry conferences I attended a couple of weeks ago.
ESRI UK 2016
I went to ESRI UK 2016 on 17th May to find out about the latest developments from the company behind ArcGIS, and how they are bringing SfM photogrammetry and laser scanning into their platforms. It’s interesting to see how many programmes are moving into cloud-based formats, and the process of displaying and editing GIS data is being streamlined in their WebGIS. It will be interesting to trial the capabilities of Drone2Map – ESRI’s own SfM processing software to generate DTMs, currently on beta.
Geo Business 2016
I travelled back down to London two weeks ago to attend Geo Business – a major conference and geomatics expo, showcasing the latest new technologies and innovations for the geospatial sector. The conference was a great insight into how all of the techniques I am being trained in at Historic England can be used in different disciplines and industries other than in heritage.
I saw some very exciting demonstrations of new handheld mobile mapping solutions, and new software for the processing of laser scan data to a very high resolution (I must state I do not endorse any particular manufacturer of such equipment!). All in all, it was fascinating to find out the latest developments in these industries, and I’ll definitely be attending next year to see what new technologies are going to appear…
This post is about one particular use of laser scanner point clouds collected in the field. After several scans are acquired and are correctly georeferenced, using a total station, GPS or other systems, plan and elevation drawings of the scanned features can be drawn in CAD. Using the Bentley Pointools plugin for AutoCAD 3D, it is possible to display sections through the scan data in the vertical or horizonal plane (x and y axes). This appears onscreen as a thin line of the point cloud, which can be traced as polylines to generate CAD drawings of building plans and elevations, with details of faces and sections where necessary.
The great advantage of using this techique is that the onsite data acquisition is far faster than taking measurements by hand, and the data can be later exported back in the office. So it was that I worked with laser scan point clouds (scanned using the Faro Focus 3D) and a photogrammetric 3D model (processed in Photoscan) of the Monk’s Oven and Pump House at Calder Abbey , a site I have never visited, in order to produce elevation and plan drawings using CAD. Special thanks to David Andrews for his patient tuition in this!
These are the plans and elevations of the Pump House that I drew, with additional corrections and editing by David. (All images and drawings: copyright Historic England).
Earlier this week I travelled to photograph and laser scan a series of scheduled ancient monuments in the historic market town of Leek, in Staffordshire. Two Anglo-Saxon stone crosses stand outside St Edward the Confessor Parish Church, both with surviving carved decorations and one bearing a runic inscription – I’m hoping the 3D data we’ve gathered will be able to help identify what is written!
It was fascinating to hear of the local stories that are attached to these stones. Passersby were keen to point out the circular dent marks on the rounded shaft cross, which were allegedly caused by gunshots from Bonnie Prince Charlie’s soldiers as he passed through the town, with the cross being used as target practice.
We also recorded the late medieval market cross, sited in the town square. Quite a challenge as it is over 5 metres tall! Luckily we used an extendable tripod for laser scanning, using the Faro Focus 3D. For the photography, we attached the DSLR to a mast, and operated the camera remotely using a Camranger synced to my phone – very useful to make sure the shots were correct.
It was great to see how many people were interested in the work we were doing. It’s important to collect this data as a permanent record of these monuments’ current condition, as they are so exposed to the elements, their detailed carvings are slowly being worn away over time. The data will eventually be held in Historic England’s archives, once I have generated the 3D models and investigated the stones some more. I’ve already noticed some carvings and writing on the very top of the market cross, that’s impossible to spot by eye on site as it is so high up! This really highlights how valuable geospatial imaging techniques are to capturing such details, so we can record and study them in future.