Impossible views: 3D scanning monuments in West Penwith, Cornwall

How can you make a solid, accurate record of an ancient monument for the archaeological record, whilst also making an accessible digital experience with novel ways to view the site highlighting its construction? We think that we’ve cracked it.

Penwith Landscape Partnership asked us to capture 3D scans of four monuments as part of the Ancient Penwith strand of the project. It was critical that these were accurate so that they could be used for future condition monitoring purposes. At the same time, some of the sites are reasonably difficult to access because of their remote location, sometimes on private property, rough ground, and difficult to access for anyone who needs mobility assistance. This was also an opportunity for the archaeological data to be repurposed into 3D models which can be explored on all manner of devices via the Sketchfab platform.

Using Augmented Reality apps such as the Sketchfab app, you can even stand underneath Lanyon Quoit from the comfort of your own home to look under the capstone or beam yourself into the middle of the sun-dappled Madron Baptistry and have a look around.

We have completed all four of the sites now –

The outputs from these 3D scans represent our philosophy well — curating is half knowledge generation, half communication. They provide an accurate record of the present condition of the structures as they stand today which facilitate study and learning. We can use this data to study their surfaces and look for details that are difficult to spot with the human eye during a site visit, such as inscriptions, tool marks, decorations, damage, and much more. The data can be used in the future as a comparator to check for (and quantify) damage or erosion.

An image of Lanyon Quoit with no colouring visible. This lays bare the surface of the stone with no distracting lichens or crystal formations visible. The date of the reconstruction of the quoit is picked out by a red box containing the letters "A D 1824".
Spotting the hard-to-spot – the date of Lanyon Quoit’s re-erection in 1824 is hard to spot with the naked eye, here it can be spotted more easily.

Using Augmented Reality apps such as the Sketchfab app, you can even stand underneath Lanyon Quoit from the comfort of your own home to look under the capstone or beam yourself into the middle of the sun-dappled Madron Baptistry and have a look around. Bosporthennis Beehive Hut is in the middle of the moor and was the most difficult to locate – we can now crawl through the small doorways, peer into the ‘cupboard’ and float above the monument to see the layout of the building and its later additions.

A black-and-white image looking down from the air onto the top of the capstone at Lanyon Quoit. This computer-generated image is akin to a rubbing done with chalk and paper. The darker areas are cut in to the stone - where our metaphorical chalk cannot get into the crevices - and the white areas are easily covered. Thus, the initials LN and JB (one above the other) can be easily spotted as they have been carved. These are highlighted by a red box on this image.
Spotted on the 3D model using filtering techniques (occlusion) – well-worn graffiti, possibly from the 19th or early 20th centuries.

Annotations on the 3D model allow us to highlight elements and attach notes to them. We can point out important details and provide a rich experience not possible in a physical visit.

Screenshot of a 3D model of Lanyon Quoit. Three upright stones on a rectangular bed of grass support a huge granite capstone. Three white numbers are visible on black backgrounds attached to several parts of the quoit. These can be clicked to read more information.
Three annotations visible on the 3D model of Lanyon Quoit. They may be clicked to read a short piece of text, or followed in sequence to create a tour-like experience.
Screenshot of a 3D model of Lanyon Quoit showing an annotation illustrating the hard-to-see reconstruction date carved into the monument. Three upright stones support a huge granite capstone. One of the upright stones has the numeral 1 (coloured white) in a circle of contrasting colour (black). When clicked, as shown here, a black box with white text reads "Reconstruction date - The date AD 1824 is carved into this upright. This marks the date that the quoit was reconstructed after collapsing in 1815".
When an annotation is clicked on Sketchfab, a short annotation can be read. It is possible to advance to the next annotation to create a tour.

Visualising the unseen

One of the specifications for this project was to provide an alternative to the visually-pleasing photo-real 3D views. A way for people to be able to appreciate how the monuments were constructed. After some experimentation with transparency, we opted to go ‘lo-fi’ and use the point clouds – our giant 3D dot-to-dot – to do this. By not using any ‘solid’ faces in the model and reducing the number of points visible (200 million measurements is beyond many computers and most portable devices), we could achieve this interesting alternative.

A view of Lanyon Quoit from above. The image is made from 1.8 million individual points, or dots, and can be seen through, as there is no computer generated surface.
Point cloud view of Lanyon Quoit from above. The position of each of the upright supporting stones can be easily seen.

In this example, looking at Lanyon Quoit from above, we can clearly see the alignment of the upright supporting stones.

This image of Madron Baptistry is made from 2 million individual points, or dots, and can be seen through, as there is no computer generated surface. The outline of the walls is clear, as well as the position of the altar and font.
Point cloud view of Madron Baptistry – from below

Point clouds aren’t new – they’ve been around since the earliest beginnings of 3D scanning in the 1980s, but they aren’t used very often for public display as they can be difficult to interpret. We thinned the dense cloud of 3D dots, made the dots larger, and coloured them with their appropriate counterpart from the real world. We think that this method provides a useful alternative to the traditional approach of photorealism.

Animation of the Madron Baptistry point cloud showing the font viewed from ‘inside’ the walls – an impossible view that can help to understand a building’s construction.

As you can see above, the point cloud of Madron Baptistry allows you to see the way the font in the lower right corner goes below ground. Exploring the model on Sketchfab you can see that the font ‘flares’ outwards and the base is sloping to keep the water in. All from an angle impossible in reality.

3D scanning can sometimes be a lengthy process. But with views like this, we weren’t complaining!

View over the two remaining capstones of Tregeseal Entrance Grave in the foreground. Green ferns and pink foxgloves cover the lower half of the image. In the background the houses, chapels and church tower in St Just are visible with its parapets, and the hazy sea is beyond.
View over the two remaining capstones of Tregeseal Entrance grave before clearance for 3D scanning. The town of St Just, the most south-westerly on the British mainland, can be seen in the background.

Explore more of the ancient Penwith landscape

Visit the Penwith Landscape Partnership channel on Sketchfab to explore the 3D models.

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