Herding Hogbacks Into Sketchfab

by Roger Lang, PhD research student at the Archaeology Department at Durham University

I’m Roger Lang, a PhD research student in the Archaeology Department at Durham University. I began using 3D at the start of the last decade, working as a freelance for the ACE-funded Culture Street website. One of my first projects involved making a 3D model of a Viking Age cross shaft in a Lancashire churchyard that surprisingly illustrated episodes from a Norse saga. I used the 3D image to make a short object biography.

My research is focussed on using photogrammetry and film to foster public understanding and aid academic study. This case study focuses on an unexpected discovery…

In 1867, the local builder hired to renovate the church of St Thomas in Brompton-in-Allertonshire, North Yorkshire, ensured the contract gave him ownership of any parts of the old building uncovered during the work. As it happened, his medieval predecessors had used 26 items of Viking-Age stone sculpture as foundation material beneath the chancel. The finds included the remains of 11 of the earliest Viking-Age ‘hogback’ grave-markers, carved to resemble Viking long houses with tiled roofs and giant bears at each end.

The parish could only afford to purchase 14 of the pieces from their presumably smug new owner. The remaining dozen were bought by Durham Cathedral and today form part of the major collection of Early Medieval artefacts in their museum.

Reuniting these sculptures in a virtual Sketchfab collection seemed an obvious subject for my research. In terms of public engagement, anything with the label ‘Viking’ has a head start in attracting attention and for academics, the ability to explore the entire collection from any angle and to control the direction of lighting seemed a clear benefit.

Pitching the idea to the Yorkshire Church and the Durham Cathedral, resulted in enthusiastic approval, and Year 5 children from Brompton Community Primary School took the photographs used to make the models of the three cross shaft fragments embedded in the exterior walls of the church.

The only significant challenge has been to capture all the necessary shots. The visitor experience in the Durham Cathedral Museum is excellent; the sculptures well-displayed, with interactive interpretation screens and well-informed friendly staff on hand, but many of the pieces have a restricted view of one of their sides. And two of the cross heads are displayed on tall columns giving the view from which they were intended to be seen, but with obvious problems for photography. (I assumed the early 15th century Monks’ Dormitory would be a No-Fly Zone).

There were similar issues at the church. The three complete hogbacks cemented in place near where they were found, are herded tightly together. I’m sure they appreciate the company, and they make a neat group, but only one of the six long sides is easily photographed.

It took a while to solve these problems. Photographing the cross-heads in the museum just needed a telephoto zoom lens - focal length set at 109 mm (!) according to the exif data. Telephoto zooms are not usually recommended for photogrammetry because of the danger of the zoom length getting accidentally changed during the shoot and the lack of depth of field in a telephoto shot; but the results proved adequate.

Photographing close to surfaces in confined spaces required using a wide angle lens (Sigma 24mm f3.5) on a small mirrorless full-frame camera (Lumix S5). Though this lens can focus as near as 10 cm from the subject, four of the hogbacks remained paparazzi-phobic. Luckily two of these had the same design on both long sides. By taking the model from Agisoft Metashape into Blender, it was possible to split it cleanly down the centre using a Generate-Boolean modifier, duplicate the good side of the model, flip it along the x axis and merge the two halves. The result gives a rough idea of what the sculpture looks like in the round. I confess to this in the description of the models (Brompton 16 and 24). 

Just one side could be included of Brompton 18, and Brompton 22 is rather a mess - badly damaged when it was reused as infill, and badly damaged by me a thousand years later (albeit virtually). It is missing a large bite out of the far side of the model which emerged from Metashape impersonating a  banana, and needed to be wrenched back into shape in Blender.  

Still, the bulk of the pieces seem to have worked out well-enough: skfb.ly/oSypV.

Sketchfab is the only place where one of them can be seen. Brompton 12 is in storage due to its fragile condition. Museum staff enabled me to photograph both its sides and combining the chunks has resulted in probably the cleanest of all the models.

The description for each object contains a link to its entry in The Corpus of Anglo-Saxon Stone Sculpture, Durham University’s massive project to identify, record and publish in a consistent format, all the English stone sculpture dating from the 7th to the 11th centuries. 

At the time of writing, the Parish Council are awaiting approval of funding to implement their plans to move their stones to a museum-quality display in St Thomas’s Church. So there could well be a chance to improve on some of the models.

Future developments with the Brompton work will include making video spins for the Durham Museum, and creating a film to explain more about hogbacks.

Other areas in my research are the assemblage of the English Sigurd and Fafnir stones (Sketchfab collection) a similar group picturing Wayland the Flying Smith, and a cleverly-cut Viking graffito of Ragnarök - again from deepest Yorkshire.

Many thanks to Marie-Thérèse Mayne of Durham Cathedral Museum and Rev. Jonathan Cooper of St Thomas’ Church, Brompton.

P.S. if hogbacks were new to you, you may not know about the awesome Early-Medieval Pictish stones excellently recorded by Douglas Ledingham and Hamish Fenton.

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