3D capture

Medieval Priories, Medieval Stones, Historic Photos, and Deep Dreaming

This week has been a busy week. Last Sunday I volunteered for the Tywardreath Priory open day as part of the Festival of British Archaeology. I am one of the archaeologists on the team in the early planning stages of a community archaeology project. It aims to search for, research, and excavate the site of Tywardreath Priory, a Benedictine priory established in the second half of the 11th century. We know the rough area where the priory ought to be, but very little is known for certain.

The open day was very successful, with over 100 visitors to the farm in the village. My role was to explain something of the history and wider landscape context of the site, and to demonstrate LiDAR data to show how the estuary had silted up, cutting off the Priory’s access to the sea.

Tom Goskar demonstrating LiDAR and landscape archaeology at the Tywardreath Priory open day. Photo by Josh Taylor.

Tom Goskar demonstrating LiDAR and landscape archaeology at the Tywardreath Priory open day. Photo by Josh Taylor.

I also showed some 3D captures of decorated medieval stonework taken from the Priory and now situated in the nearby churchyard, and how we can enhance the data to show the decorations more clearly.

For the first half of the week I have switched gear to working with historic photos. I looked at the wonderful glass lantern slides of an excavation at Magor Farm near Redruth in Cornwall during the 1930s held at the Morrab Library in Penzance. They have a fantastic archaeology collection which they hope to digitise later this year if a funding application is successful, which I will be helping with if all goes well.

Being a self-employed archaeologist it pays to widen your horizons to gain work. I’ve been honing my web technology skills and am building a website to host a collection of over 25,000 historic photos, films and audio recordings from around Cornwall. It’s going to be a great resource, complete with ways to get data out of the site in interesting ways. Lots of archaeologists are going to find it useful for desk-based research, not to mention local historians and societies.

And today, the Day of Archaeology itself, has seen me mainly writing and researching. I have an article deadline coming up for my work on 3D capture and enhancement of early medieval sculpture at Gulval near Penzance which I am co-writing with Prof. Michelle Brown an expert in early medieval manuscripts.

Earlier in the day I had a phone call from Prof. Charles Thomas to discuss some work we have done recently on the early medieval ‘Ignioc Stone’ at St Clement near Truro. We’re using 3D techniques to try to see if the accepted transcription of the inscription is correct and to see if the data can help us understand better how this tall stone was reshaped and repurposed.

As a distraction amidst writing and planning a trip to London next week to visit the Society of Antiquaries library, I have been playing with Google’s Deep Dream neural network visualisation (or perhaps, hallucination) engine. It shares some code used by Google Photos to identify the content of photographs (in itself interesting for curators of historic photographs) and produces very strange results as it recursively tries to identify then display what it ‘sees’. A riot of colourful psychedelic nonsense, or an exercise in the study of perception applicable to shamanism, hallucinogenic states and rock art? You choose. For fun, here’s one of the trilithons at Stonehenge like you’ve never seen before.

Stonehenge trilithon visualised with the Google Deep Dream neural art network.

Stonehenge trilithon visualised with the Google Deep Dream neural art network.

Enhancing worn inscriptions and the Day of Archaeology 2012

My name is Tom Goskar and I am one of the organisers of the Day of Archaeology, as well as being a freelance archaeologist who specialises in applying digital techniques to different aspects of the discipline. My day today has been rather mixed, but predictably involved being at the proverbial digital coalface of archaeology in two aspects.

At 8am I checked my email to catch up with the behind-the-scenes talk between the eight organisers of the Day of Archaeology, and log into this website to begin moderating the posts that were by then flowing thick and fast. By 11am I had been on a Google Hangout with Pat and Jess, and we had re-jigged the homepage to make it easier to explore, as well as temporarily excluding posts from last year to highlight the new contributions. It looked much better afterwards. I have been dipping into the website on and off all day, making sure that posts looked good, and expanding and linking the occasional acronym to help readers know what they are. The DoA moderators have been hard at work in the engine room!

In between, for a personal project I have been processing 3D data from a medieval cross close to where I live, here in Penzance, Cornwall, as well as helping to refurbish a soon-to-be-open digital arts space in the town centre.

The Penzance Market Cross, made in the 11th century, is decorated and has many inscriptions. These are very eroded and most people do not notice them. Unless you happen to see the stone in just the right glancing sunlight, the sides of the cross appear to just have some panels of dots and a few lines, not much else. Nothing could be farther from the truth. Using photogrammetric techniques, I have been examining the cross to see if how well 3D capture techniques can enhance the inscriptions and decorations, with the aim of comparing my results with drawings made using traditional techniques (rubbings, chalking, torchlit photos).

In the spirit of the Day of Archaeology, below is a working illustration showing the north east elevation of the Market Cross, which I produced for this blog post. In the centre of the image is the cross as the casual visitor may see it. To the left, the colour information has been removed (which can sometimes be distracting), leaving the shape of the stone artificially coloured grey, with a virtual light source moved to show some of the decoration. To the right, a Radiance Scaling shader has been applied, which colours concavities and convexities to help reveal details on the stone.

Penzance Market Cross

Penzance Market Cross, captured in 3D with photogrammetry, and enhanced using digital filters.


As you can see from the Radiance Scaling image to the right, there is definitely more going on than first meets the eye. The figure in the second panel from the top is clearly visible, as are the letters and glyphs in the lower two panels. As I type, I am processing a mesh with a much higher level of detail, and look forward to the results which will be ready in the early hours of tomorrow morning. Comparing the results to the accepted interpretations made by Professor Charles Thomas will be interesting, whether they differ or help to confirm what we already know.

So, my Day of Archaeology has been a busy and varying one, and it’s not over yet. Time to publish this post, and return to the list of posts to publish some more from around the globe, so that we can all show to the world what archaeologists really get up to in our own words. I hope that it helps people today and in the future to understand just how exciting and relevant archaeology is to us all.

You can follow my archaeology musings over at my blog Past Thinking.