HMS Colossus Diver Interpretation

I have just completed a project creating an interactive diver interpretation for the wreck of HMS Colossus with marine archaeologist Kevin Camidge. Commissioned by Historic England, we have created a mobile-friendly website where divers and non-divers alike can explore the wreck. It is situated south of the island of Samson on the Isles of Scilly, and sank in 1798.

As the Colossus is in relatively shallow waters, it is a popular and accessible location for diving. A physical dive trail already exists; concrete stations around the site on the seabed with tethered and numbered buoys and an accompanying guide. To help divers plan a visit, and to provide non-divers with a sense of what the site is like, we have created an "interactive plan". Utilising Sketchfab, visitors can explore a simplified model of the wreck via computers, tablets and smartphones, tapping the dive stations to explore different locations in more detail, as well as viewing "diver-eye" videos of the site itself.

We opted to create a simplified 3D plan based on the archaeological survey, clearly indicating in bold colours the different components of the wreck, rather than adopt a photorealistic approach. The wreck itself is a mass of seaweed and sand-covered dark wood which can be difficult for the layperson to interpret.

Explore the wreck of HMS Colossus - dive in literally or virtually!

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Point Cloud Penzance - the town in 3D

Using 3D data (LiDAR) collected by the Environment Agency through the Government Open Data initiative I have created an interactive 3D model of the town centre of Penzance, Cornwall.

It's a very detailed model, with a measurement point every 50cm or so across the entire town. There are 12.9 million vertices (points) in this model.

You may need a reasonably modern computer for the model to work correctly, but give it a try. Use your left mouse button to rotate the model, right-hand button to pan, and the scroll wheel (or equivalent gesture) to zoom.

View this model directly on Sketchfab, where you can try full-screen mode.

If you get too close to buildings you may notice that you can see the 'points' that the model is made from. In the future technology will allow agencies to collect much more accurate and dense data, and faster computers will allow us to view more detailed models. Until then - enjoy!

LiDAR data is extremely useful to archaeologists to identify features in the landscape. This is my primary use of such data. In the future data like this will be useful for understanding how our towns have changed. This model is presented here for a bit of fun, and to demonstrate the many uses that this kind of data can have.

Penzance LiDAR

Penzance LiDAR with Ambient Occlusion to show streets and features more clearly.

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3D Printed Replica of the Mermaid of Zennor

In August 2015 I was commissioned by National Maritime Museum Cornwall to produce a 3D printed replica of the late medieval bench end in the church of St Senara in Zennor. It depicts a mermaid, which is famously known as the Mermaid of Zennor. This has, along with another medieval bench end, been incorporated into a seat called the "Mermaid Chair". The replica was for an exhibition entitled "Mermaids: Women at Sea" highlighting the achievements of female sailors. Naturally, people would expect to also see a mermaid - a legendary woman of the sea - as part of the display.

The concept was to produce a half-size replica, which would be mounted upon a large photograph of the church interior. The 3D print would be positioned exactly over the portion of the photo occupied by the original - a collage of 2D and 3D. Visitors would be encouraged to touch the exhibit - something that should not be encouraged with the original medieval frieze.

Before any work was undertaken, we sought permission from the churchwardens. They were keen to hear about the capture methods and learn more about the exhibition, and kindly gave us the go-ahead.

I used photogrammetry - a form of 3D capture that uses photographs - to capture the entire bench-end. Using natural light only a tripod was necessary to compensate for the long exposure times. Before commencing the capture I planned my visit with advice from the churchwarden, when there would be no direct sunlight pouring in through the stained glass. This is essential for correct colour capture, pretty as that may have looked.

There were many challenges with the capture in-situ in the church. Aside from technical challenges, St Senara is a well-visited church, and everyone wanted to see the mermaid. And to find out what I was doing. So it took a little longer than I had hoped, as it is always good to explain what's going on to curious visitors, but the results turned out very well indeed.

The resulting model consisted of tens of millions of measurement points which were used to create a highly accurate and 'watertight' 3D model. Given that the rear of the mermaid bench-end would be fixed to a display panel, the model was altered to create a smooth plane on the reverse to aid mounting. After preparing the model for 3D printing (checking the model for errors that could confuse a 3D printer) the data was sent to ThinkSee3D for printing. The resulting replica would be half actual size (182mm x 380mm x 20mm) - full size (370mm x 755mm x 40mm) would have been prohibitively expensive and would need to be printed in two parts then glued together. It would be printed in full colour using a solid gypsum-based resin.

After some small test prints and experiments with colour, and a coat of varnish to replicate the finish of the real medieval wood, the finished 3D replica of the Mermaid of Zennor was ready. Museum staff mounted the print carefully over one of my photos - the result was rather effective!

3D printed replica of the Mermaid of Zennor medieval bench end mounted over a photograph of the real bench in the church of St Senara.

3D printed replica of the Mermaid of Zennor medieval bench end mounted over a photograph of the real bench in the church of St Senara.

Since the Mermaids exhibition ended at NMMC, the 3D printed replica has gone on show in the "All Monsters Great and Small" exhibition at the Royal Cornwall Museum.

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On Sketchfab and Cultural Heritage

When I first started out with learning 3D visualisation techniques and software back in 2001 I longed for a way to share my models online. In the early days there was VRML and other, proprietary, methods (Superscape, Shockwave 3D, etc) but these required either big browser plugins with limited capabilities or in the case of VRML, very low polygon (simple) models. My 100,000 polygon reconstruction of the Tudor palace at Oatlands which I built from archaeological and contemporary visual evidence was never going to make it online back then.

Without providing a history of the technology used to present 3D models online - I've probably tried most methods through the years - we now have a splendid service called Sketchfab. I'm certain that someone has used the YouTube analogy here. Putting video online used to be hard until YouTube and the many similar services that came and went. Now you can open a Sketchfab account, upload your models, edit how you'd like them to initially appear, and share your links or embed them in your website or social media timeline. There are many sophisticated tools to change how your model appears, from its textures, to the environment and lighting, background photo, visual effects, and interactive annotations.

In the world of cultural heritage Sketchfab opens up a whole range of possibilities. Annotations allow numbered points to be attached to geometry and through the use of Markdown, those annotations can include embedded photos and hyperlinks.

Here we see a model of Hoa Hakananai'a from the British Museum's Sketchfab account (3D capture by my colleagues at Archaeovision) with annotations to explain some of the carvings on the statue.

I'm currently working on an interactive plan of a shipwreck where annotations contain links and are used as the launch to pages with further information. It's a really nice way to explore it without, or indeed before, any diving.

Sketchfab also contains a really good user community, including a dedicated cultural heritage group.

There's always room for improvement. I'd love to see a point-to-point measuring tool, and I hope that the download facility one day allows for charging for models - that way people who can't afford to give away their content can perhaps earn a bit of income, which could be good for freelancers and for Sketchfab via a commission model.

Other than that, Sketchfab is pretty amazing. Go and sign up - it's free.

Here's a lovely statue-menhir from the island of St Martins on the Isles of Scilly that I scanned in 2015. Sketchfab's now ubiquity allows models to be embedded within WordPress by just pasting the link into a new line in the editor. Very handy.

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Animal Headed Saints

Today sees the release of the January/February 2016 edition of British Archaeology. It features an article by Prof Michelle Brown and I on the early medieval cross-base at Gulval Church and its unusual depictions of the Four Evangelists.

Whilst my copy of the magazine has yet to be delivered the story has been picked up by Discovery News in a piece entitled "Medieval Monument Depicts Animal-Headed Saints". Use the arrow buttons or square page buttons to navigate through the story.

Findings also suggest that people from the U.K. at this time were traveling to the Middle East, and vice versa, negating a prior belief that contact between this region and the U.K. was interrupted from about the end of the Roman Empire in the West in 476 A.D. to the start of the Medieval Crusades in 1095 A.D.

Subscribe to British Archaeology and find out about the latest issue.

Read about my initial discovery in my post "A Medieval Discovery at Gulval Church, Cornwall". The British Archaeology and Discovery stories cover subsequent research with Michelle.

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