Imaging the Tintagel early medieval inscribed slate

English Heritage have just announced the important and rare discovery of an early medieval stone inscribed with writing, dating from the 7th century.  I was called in by Cornwall Archaeological Unit, who discovered the stone in the summer of 2017, to help enhance the inscriptions.

Some of the writing is very faint, and so rather than the usual technique of using 3D capture (close range laser scanning or photogrammetry), I opted to use Reflectance Transformation Imaging (RTI) to obtain our best chance of reading all of the letters.

The results were fantastic, and I was lucky enough to be perhaps the first to read some personal names from 1,300 years ago, as I processed the data from my home office.

There have been many calls via Twitter to see more of the enhanced images, so here they are (released under a Creative Commons attribution non-commercial license) with thanks to Professor Michelle Brown who conducted the interpretation and final transcription.

Enhanced image of the inscription
tito
vi.ri. duo
Æ(D A?) fili 
Enhanced version of the inscription
bue dic
tu Δ/D A

There’s a great article on the Guardian which describes the Tintagel excavations and the significance of the discovery in more detail.

Recording St Piran’s Oratory – 3D model and animation

I have now completed my recent work on St Piran’s Oratory on behalf of St Piran Trust and Cornwall Archaeological Unit. It was a challenging task requiring a huge amount of computer resources and time, with colleagues at Archaeovision helping when my computer broke down, but I am pleased with the results.

Here is a short animation of St Piran’s Oratory, digitally freed from its concrete walls:

Here is an interactive model which you can zoom, turn, and inspect:

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And here is an interactive 3D model of the complete Oratory structure with the concrete walls we see today:

[sketchfab id=”b360da3fe0ca4deda9d6d8b03e2cb4cf” start=”0″ spin=”” controls=”1″]

We must now wait for the final report by CAU (to which this data contributes) to better understand the building and its phasing. Watch this space.

It’s All About The Photos

It’s been a busy time for me recently, with much of my recent work focussing upon historic photographs and photogrammetry.

I have been working with the Morrab Library in Penzance to build a digitisation facility so that they may begin, with a volunteer workforce, to scan their wonderful collection of historic photographs. There are about 12,000 photos in the collection, ranging from 19th century glass plate negatives, to recent prints covering the whole of Cornwall. I have collated their Microsoft Works databases (one for each collection) into a single database, undertaken a data cleaning exercise, and mapped fields into Dublin Core metadata element set. The entire database was then imported into Omeka which is running on a local web server. I have tweaked Omeka and the environment in which it runs so that large TIFF files (up to 1GB) can be uploaded, with JPEG derivatives being created, the original TIFF being stored on a different server (separate from Omeka, with dual redundant disks and external backup) with the original filename (the photo’s accession number) being preserved. You can’t be too careful.

Whilst it isn’t designed out of the box to be a cataloguing tool, Omeka is doing exactly what we need. The user interface is well-designed and sufficiently easy for some elderly people to grasp quickly. The customisation to store unaltered original scans on an abstraction layer works well. Automatic database backups are also placed on the same server.

I have also begun working for an organisation called Azook, where I am the Project Officer for a project called MemoryFish. It will collect unpublished historic photos, films and recordings from private collections, documenting the history of the fishing industry in Cornwall. The initial areas are Falmouth, Newlyn and Newquay, and photos will be published on cornishmemory.com.

Then there’s the digital archaeology. I have been working for Cornwall Archaeological Unit and St Piran Trust on the recording of the now fully excavated St Piran’s Oratory. With the help of colleagues at Archaeovision we have processed a point cloud consisting of nearly 300 million points. This project is ongoing, but here is a taster of the work in progress.

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And in other news, in December 2014 I walked into a hairdressers and came out with short hair. It’s the shortest I’ve worn it since I was 17. Here’s the evidence.

Tom with short hair
Tom with short hair

And I’ve retired my famous trademark brown velvet jacket, replacing it with…. an almost identical copy. Some things should never change!

Recording St Piran’s Oratory

For the last couple of weeks, and on St Piran’s Day itself, I have been helping out with the Uncovering St Piran’s Oratory project. Organised by St Piran Trust and run by Cornwall Council Historic Environment Service the project aims to uncover as much of the (potentially) early medieval structure to assess and record its condition.

Following a 15-year-campaign, the St Piran Trust plans to unearth and conserve St Piran’s Oratory, believed to be amongst the oldest Christian buildings on mainland Britain. The site has been of central importance to Cornish people for over 1,400 years as a place of worship and pilgrimage, and as a focus for cultural expression. Today, many hundreds of people gather at the site annually to mark St Piran’s Day. The saint’s flag (which features in a stained-glass window installed in Westminster Abbey in 1888) – a white cross on a black field, is flown the length and breadth of Cornwall.

The scheduled ancient monument is a listed building and was buried in 1980, for “its own protection”. Since then expert opinion has shifted, amid calls for it to be uncovered and conserved in a more sympathetic way.

The Oratory and associated protective concrete structure from 1910 are protected as a Scheduled Ancient Monument. Unfortunately in 1980 as part of the burial programme, the concrete roof was removed – or so we thought. During this year’s excavation we found that part of the roof structure, badly damaged and sitting at an angle, had been left where it fell and simply buried. It has been decided that the pile of broken concrete needs to be removed to safely continue with the project.

Concrete at St Piran's Oratory

I have been commissioned to record concrete remains in-situ using photogrammetry to complement more traditional recording. I undertook the photography aspect of photogrammetric recording on St Piran’s Day (5th March 2014) and am now processing the point clouds. This will result in a highly detailed model of the concrete remains, which include a buttress, part of the reinforced concrete curved roof, and the hollow mundic blocks used to construct the walls.

From a technical point of view it is proving to be a challenge. There is no uniformity to the concrete remains – it is full of overhangs, pockets and voids. The photographic capture strategy was tough to work out, and 16GB of RAW images were taken after careful cleaning of the concrete by trowel, hand shovel, bucket and brush. I have covered as many angles as was safe and practical to do so.

I will be delivering the point cloud and a series of orthographic views to the client.

Once the concrete has been removed, it is hoped to expose more of the Oratory, and I will be able to record the medieval structure in the same manner.

In the meantime, I have the opportunity to get out in the open air and dig, which I love.

The are plenty of photos on the open Facebook group Uncovering St Piran’s Oratory. You can also see a 3D model of the excavation as it stood on St Piran’s Day 2014.

Announcing Archaeovision

Archaeovision logo

I am delighted to announce that I am now a consultant for Archaeovision, a pan-EU group of experts in the field of archaeological computing.

Here’s a summary of what Archaeovision is about:

Archaeovision offers innovative solutions to a wealth of problems in the heritage sectors.

We can 3D scan your objects, survey your building, investigate and enhance surface details – from microwear on teeth to coins and monumental inscriptions, build 3D reconstructions of objects and even whole landscapes.

If that wasn’t enough, we can also build you modern, accessible websites for your institution or collection.

I will still be working freelance for smaller local projects. However, Archaeovision will allow me to take on larger projects with a group of fantastic and experienced archaeologists who have overlapping and complementary skills.

If it needs to be 3D scanned, recorded, photographed at huge resolutions, have hidden details enhanced, or transmitted via the internet, we can do it.

Visit http://archaeovision.eu to find out more.

A Medieval Discovery at Gulval Church, Cornwall

Gulval Cross-BaseJust to the left of the south porch of Gulval Church, near Penzance in Cornwall, lies a large block of granite. I first came across it on a visit to the churchyard in 2012. However, it really piqued my interest a couple of months ago after reading a short report in Newsletter 132 of the Cornwall Archaeological Society. The article, entitled ‘An unusual stone at Gulval Church‘, by Professor Mick Aston, Teresa Hall, Professor Rosemary Cramp, Ann Preston-Jones and Andrew Langdon, highlighted that the block was a medieval cross-base, and was decorated on all four sides. Aside from the south, pictured here, the images on the other sides were very difficult to see at all. Ann and Andrew visited the stone at night “armed with car batteries, a mirror, two spotlights, a tripod, head torches, and a camera” to capture raking light photos of the decorations to see if controlled shadows could be used to interpret the decorations.

The results were good, producing a set of shadowy atmospheric photos of each side. Professor Cramp began to interpret the scenes from these photos but noted that, while useful, the photos only provided a single fixed view, and she had not seen the cross-base with her own eyes. It was thus difficult to say for sure what was depicted on this rough stone.

It was shortly after receiving the newsletter that I also heard the sad news of Mick Aston’s death. Doubtless that Mick would have had a continued interest in the cross-base, and given that I only live a few miles from the church I became determined to use the tools available to me to record the cross-base and see if I could help with the interpretation.

On 8 June 2013 I visited Gulval Church and recorded in high resolution 3D each side of the cross-base using a photogrammetric approach. Taking a series of over a hundred overlapping 18 megapixel scale photos at a fixed focal length, I covered the whole block.  It was quite a tricky subject to tackle, as there is very limited clearance between the cross-base and two of the church walls.

Over the next few weeks, I began to process the images into 3D point clouds, and from there to solid 3D meshes. Afterwards, I subjected each side to a series of techniques which I have used to analyse prehistoric rock art and inscriptions in the past. The results were fantastic.

What is depicted on the cross-base?

Thanks to this analysis, I believe that we now know what is shown on the cross-base at Gulval. The existing interpretations, as laid out in the CAS Newsletter, didn’t match up with what I have found. The computer-generated images, shown below (and may others that I have created using false colour representations of depth), have been able to provide a slightly clearer representation of the granite carvings, and, I believe, help perceive them in a different way. I can now see many of the details in the original photos now that I know what I am looking for.

Rather than sit on this discovery for ages until everything is just right, I have decided to post my initial findings here. It does not represent a full description of the findings and condition of the cross-base and its imagery, and it builds upon the work already done.

Firstly, I must thank my friend, Nick Ford, for putting me onto the iconography – I believe that he spotted what was depicted in the first image I showed to him straight away, and knew what the others would reveal. It led to an exciting evening searching for comparative images, and further enhancing them. And without the original report in CAS Newsletter 132 (now online) I wouldn’t have got this point at all.

The cross-base depicts the four Evangelists, Matthew, Mark, Luke and John, as the four living creatures described in Ezekiel 10:14 and Rev 4:6-7

Revelation 4:6-7

New International Version (NIV)

6 Also in front of the throne there was what looked like a sea of glass, clear as crystal.

In the center, around the throne, were four living creatures, and they were covered with eyes, in front and in back. 7 The first living creature was like a lion, the second was like an ox, the third had a face like a man, the fourth was like a flying eagle.

The Gulval Four Evangelists

The south side of the stone depicts St Matthew. He is symbolised as a winged man or an angel, and depicted here with a halo, holding a book (Gospels or Book of Life?) with “MT” inscribed on it. The lower part is damaged. This image shows the details picked out using an ambient occlusion filter.

On the west, facing outwards, is St Mark. He is shown kneeling, with haloed lion head. His book, held in his left hand, has “M” on it. It is possible that he is giving the sign of benediction with his right. The folds of his robes are nicely visible.

On the north, facing the church proper, is Luke, depicted here seated with haloed calf head . His book, held in a rather large left hand, has “LS” on it (Lucas). Luke is mainly depicted as an ox, but it isn’t unknown for him to be shown as a calf.

On the east, facing the porch wall, perhaps the most badly eroded of them all, is St John, depicted as the eagle. His robes, especially the folds around his legs, are clearly visible.  It is difficult to discern the presence of any halo. He is holding a book in his right hand, with what looks to be an “H” on it (not easily visible in this image – only range-colouring a very small area shows this). It would be very neat if it said “IH” – Iohan, but archaeology isn’t always a neat discipline. Further work needs to be done here.

We must remember that the stone block onto which these images are carved is a course Lands End granite. Some of the quartz crystals are several centimeters long – fine detail just isn’t possible – and granite can crumble when exposed to the elements.

A Tetramorphic Cross-Base?

So there we have it. Starting on the south side of the stone, if you run the sequence clockwise (South, West, North, East), runs the familiar sequence of Matthew, Mark, Luke and John. Matthew, the best preserved of all, was positioned facing outwards, and the shield-like shape of the carving has, according to some, become thought to be a coat of arms. Now that we know what is really shown here, perhaps we can even call it a tetramorphic cross base, bringing together the symbols of the Four Evangelists together into a single object. One thing is for certain, however, and that is a lot more work needs to be done on the Gulval cross-base, in terms of research, verification, and recording techniques. Reflectance Transformation Imaging (RTI) will certainly be the next approach for further enhancing the panels. Comparative examples need to be sought.

This could have a big impact upon our understanding of Gulval, and indeed have ramifications on how we understand the history of this part of Cornwall in the early Middle Ages.

The authors of the original article in the CAS Newsletter have had copies of the images and my findings in advance of this blog post. Luckily, when I sent my findings to Ann Preston-Jones, she was pleased, as she felt that these were the Evangelists, but lacked firm evidence to back it up. I trust that my arguments, and the images above, will help to win around any doubters.

I have been asked to add the finished images of the Evangelists to the forthcoming Corpus of Early Cornish Sculpture, to which I am honoured to be able to make a contribution. The vicar of Gulval Church is adding the images to his parish newsletter. Who knows, even a sermon may come of it!

Further images and information will be added to subsequent blog posts, and linked from here, so do bookmark this page and check back from time to time.

And now for the plug!

As an independent archaeologist, I am of course pleased to offer my professional services. Please contact me with any enquiries.

Below is a series of images of St John (Eagle) from the east side of the cross-base. The 3D data has been filtered in a number of ways to extract the detail of the carving.

East elevation of a medieval cross base at Gulval, Penzance, depicting St John the Evangelist as an eagle (see Rev 4:6-7 & Ezekiel 10:14). Captured using photogrammetric methods and processed using different filters to interpret the carving.

Armour Heritage

Armour Heritage
Armour Heritage
Armour Heritage website

My good friend Rob Armour Chelu has recently set up a new archaeology consultancy, Armour Heritage. One of Rob’s many specialisms is archaeological advice for renewable energy schemes whose developments may impact upon the historic environment.

I have set up the bones (if you’ll pardon the appalling pun) of Rob’s archaeology website, and have chosen to use a simple Content Management System (CMS) which enables him to build the rest of the site himself. I am also advising upon Search Engine Optimisation (SEO) and listing on Google Places for Business.

If you need a website, I can help you. Please contact me for further information.