3D capture of historic costumes at Helston Museum, Cornwall

Sign reading "3D scanning project. Thanks to Cornwall Museum Partnership with funding from Arts Council England we are learning how to 3D scan our collection"In December 2017 I was asked by Helston Museum to train staff and volunteers in how to use photogrammetry to record their historic costume collection in 3D. The costume gallery had closed and become a much-needed storage area. They decided that online 3D models, and possibly through screens in the museum, would be an interesting and engaging way to present the costumes now in the museum stores. They could record and display many more than there has ever been physical gallery space for.

The best way to capture the costumes is, of course, to use a mannequin. This would allow the costume to be viewed in the way it would have been worn, and rotated and viewed from any angle, an advantage over traditional static photographs. They would use Sketchfab to display the results.

Helston Museum decided to try the project in a very public way. Training was conducted in their temporary exhibition space, with panels explaining what was going on to the public. Projectors were used to display the results, as they happened. Staff and myself were on-hand to answer any questions from the public.

Over the course of a week, I trained both permanent staff, the Director and Assistant Curator, as well as a group of volunteers. They were shown how to light the mannequins, how to photograph them for 3D photogrammetry, and how to process and clean the 3D data on one of the museum’s existing PCs.

A volunteer photographs the dressed mannequin from every angle to ensure good coverage for photogrammetry
A volunteer photographs the dressed mannequin from every angle to ensure good coverage for photogrammetry

Some volunteers were more interested in photography, others in costume handling, and others in data processing and editing. I worked with their strengths, and the museum now have a great team to take the project on themselves. I remain available for questions from the team, and hope to teach some more advanced methods as they gain experience and confidence with 3D digitisation.

Helston Museum are Cornwall’s first museum to create a Sketchfab account, where they will share the results of this ongoing project. Visit Helston Museum on Sketchfab.

 

Hendraburnick ‘Quoit’ – the most decorated stone in southern Britain?

hendraburnick-featured-image

Last year (2016) I was asked by Dr Andy Jones from Cornwall Archaeological Unit to record and study the surface of Hendraburnick Quoit on Bodmin Moor in Cornwall. The work, funded by Cornwall Archaeological Society, involved detailed 3D recording of the surface of the two stones that comprise the monument (which isn’t actually a quoit, more a ‘propped stone’). It was a complex task for which I used photogrammetry as the 3D scanning method. It involved careful planning and then taking many hundreds of high resolution photographs to guarantee coverage at an even resolution across all sides of both stones to enable careful study with millimetric levels of accuracy.

Our research was covered in the Telegraph who used the curioisty-grabbing headline “Ancient stone monuments may have been used for mysterious moonlit ceremonies, say archaeologists“. A full account of the project and our interpretation of the site can be found in the article Hendraburnick ‘Quoit’: recording and dating rock art in the west of Britain in Time & Mind – the “Journal of Archaeology, Consciousness and Culture”.

Analysis

After processing the 3D data I began the lengthy task of analysing the surfaces in great detail. Each potential feature was subjected to four checks using alternative methods, including virtual RTI and cross sections. I burnt a lot of midnight oil ensuring finding ‘cup marks’ and tracing the grooved lines that connect many of them together. I found 105 cup marks and 47 possible grooved lines connected or radiating from them, following the slope of the stone. This suggests that the lines were made in-situ rather than before the stone was moved in prehistory to its current location. This makes Hendraburnick Quoit the most known decorated or deliberately marked stone in southern Britain – possibly topping even Stonehenge in number of human-made features (152) on its surface.

The result was this plan:

Plan of cup marks on Hendraburnick propped stone
Cup marks on Hendraburnick propped stone

A very reduced resolution model of Hendraburnick can be viewed on Sketchfab, to aid understanding of the monument.

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.

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.

On Sketchfab and Cultural Heritage

Sketchfab screenshot

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.

 

Interactive 3D Models on Sketchfab

Publishing 3D models online used to be a pain. It always relied upon plugins, and the results could never be very detailed. Sketchfab has changed all of that, and made publishing beautifully detailed 3D models a breeze. You could use the analogy that Sketchfab is a kind of YouTube for 3D models. It is also a social network in that favourites, comments and forum discussions are all part of the system.

Whenever I can I will be publishing my models on Sketchfab, and when it’s not work in progress or for a client, I intend to enable downloads under a Creative Commons (CC BY 4.0) license.

Here’s a taster of Penzance Market Cross with a detail enhancement filter applied to it (think inverted chalk rubbing). You may need a fast broadband connection and fairly recent computer to have a smooth viewing experience of this model.

[sketchfab id=”6760debf8f17424c8f20579b910f4c2e” start=”0″ spin=”” controls=”1″]

 

Carwynnen Quoit

Earlier this year I was commissioned by Sustrust to digitally reconstruct the then-collapsed Carwynnen Quoit, a neolithic dolmen, using existing 3D laser scan data. This would be used to inform the physical reconstruction of the monument. I was also asked to investigate and report on a number of stones adjacent to the quoit which were thought to have been worked or decorated in antiquity.

The ‘rock art’ panels (a mixture of natural and hand-made lines, not necessarily as part of a single deliberate piece) were recorded in 3D using Structure from Motion (SfM) photogrammetry.

On summer solstice 2014, the capstone was lowered into place by crane in front of hundreds of spectators, marking an end to a four year project.

The graphical output that I produced was used on leaflets and publicity, as well as extracts from my report on the potential rock art. Below are some of those images, used with permission.

Carwynnen Quoit reconstructed from laser scan data, placed upon the excavation plan

Carwynnen Quoit reconstructed from laser scan data, placed upon the excavation plan

One of the images created for the analysis of the 'Coffin Stone' close to Carwynnen Quoit

One of the images created for the analysis of the 'Coffin Stone' close to Carwynnen Quoit

Visit the Giant’s Quoit website to find out more about the project.

The Mermaid of Zennor – a low-fi 3D scan

The Mermaid of Zennor. A render of the 3D model to show detail of the carving.

Illuminance (occlusion) render of the low-resolution 3D model of the Mermaid of Zennor

At the weekend I had the chance to visit the church of St Senara in Zennor, Cornwall. I spent some time looking at the wonderful medieval carving of the famous mermaid. Despite not having my Canon DSLR with me, I decided to take a series of photos with my iPhone 4S (8MP) with the view of trying to reconstruct a low-resolution 3D model using photogrammetry to see how well opportunistic captures might come out. After processing the data, I managed to extract reasonably detailed geometry, with just over a million vertices (points) after cleaning the data up (removing unwanted elements, removing stray points). A bit of processing and I was able to produce the above image to show some nice details on the carving. The mermaid looks quite different to my eye. Below is a render using a directional surface filter. The data is a very long way from being perfect, and I was unable to take any measurements to scale and check the accuracy of the geometry. However, the results are very usable for interpretative purposes, especially given the nature of how the underlying photos were captured – by hand on a 2.5 year old iPhone.

Render of the 3D model of the Mermaid of Zennor, using a directional material.

The following image is a ‘depth map’ of the Mermaid, where black is far and white is near. Can you see a hint of the Mermaid’s face? Scroll down to see an embedded 3D model (latest Firefox, Safari or Chrome browser recommended).

Depth map of the low-resolution 3D model of the Mermaid of Zennor

[iframe width=”100%” src=”http://studio.verold.com/projects/53a9836fc55d9602000007cd/embed”]

Reprocessing the St John the Evangelist data from Gulval

Since first posting about the images of the Four Evangelists found on the medieval cross-base at Gulval Church, I have been striving to produce clearer images of each saint for inclusion in a publication. The image will only ever be as good as the condition of the stone allows, but it is possible to wring a fair amount of detail from the monument through digital means.

The most difficult image of the Evangelists on the Gulval stone is St John. Depicted as half man, half eagle, his side of the cross base is damaged and worn, especially at the top. The details which I would like to further enhance are the eagle head, and the book he is holding in his hand. This is the only side where the lettering is far from clear, and many people remain to be convinced that there is indeed an “IH” (Iohan) carved on it at all.

As many archaeologists do, I have become rather obsessed with this image. When processing data of this nature one does have to be very careful in the interpretation, and not see what one wants to see. Part of my ‘therapy’, if you like, is to blog about the results as I go.

So, I have re-processed the photographs of the east side of the cross-base using the highest level of detail that my computers will allow, adding in some extra angles which I did not use in my initial images, to try and capture further detail at the sculpture’s head level. The processing took from about 7am until 6pm. After some tidying of the data (and a fair amount of quiet wishing that the computer wouldn’t crash), I produced a 1.7GB point cloud ready to inspect.

The use of false colour can be really useful, as it affects one’s perceptions of the data. Good for ‘getting your eye in’ to the data, and the shapes of the carving.

So without further ado, here are some renderings of St John with his Symbol’s head (the eagle). Can you spot any vertical lettering on his book? Fellow digital specialists please note that this is still rough data!

gulval2-east-ambient-occ-1024-128s-bw-hicontrast-ortho-high
High contrast ambient occlusion.
gulval2-east-ambient-occ-1024-128s-ortho-high
Greyscale ambient occlusion.
gulval2-east-ambient-occ-1024-128s-red-yellow-ortho-high
Ambient occlusion using red and yellow colouring
gulval2-east-ambient-occ-1024-128s-redwhite-ortho-high
Ambient occlusion using red and white colouring.