Rochester Cathedral - A Virtual Tour

By Jacob Scott

What has become the Virtual Cathedral Project has been gathering pace for several years. I’ve been producing models of the Cathedral and its features to supplement our public interpretation programme since 2015. The project was given a new impetus with the onset of the COVID-19 lockdown, resulting in the new Rochester Cathedral Virtual Tour.

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Fig 1: Explore the cathedral in a growing collection of high-resolution 3D models

In March 2020, for the first time in living memory, the Cathedral was closed for public access. The furnishings and public interpretation were stowed and the doors locked for two months. Staff, volunteers and contractors were unable to access any of the site. As Operations Assistant, I was still accessing the Cathedral day to day to ‘mothball’ the building and its systems and stop the dust piling up too high. As Exhibition Assistant, I was aware that the 3D model collection was suddenly one of the few ways to ‘see’ the interior of the Cathedral and its features, and one of the only public interpretation elements that could continue during lockdown.

A crash course production of hundreds of models, together with the model collection that had been growing for some time, resulted in the launch of the Virtual Tour in May.

After the rush of production, there has been some time to consider what has been produced, and how we could use this new resource moving forward into the strange “new normal”. The primary aim is the culmination of a database cataloguing 3D models and collections of the Cathedral. All components are recorded and available for free viewing in high-resolution, from any angle, anywhere in the world. Many of the architectural elements and sculptural features are inaccessible or difficult to inspect from the cathedral floor.

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Fig 2: Head corbel model

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Fig 3: SfM modelling provides an inexpensive method of building recording with stunning detail

Public interpretation aside, these models serve as a valuable record of irreplaceable medieval art at risk of further weathering, damage or deterioration.

In 2013, two laser scan models were produced of artefacts during the planning phase of the Heritage Lottery funded Hidden Treasures, Fresh Expressions project to redevelop the cathedral crypt,

and other operational areas. One outcome being the high-resolution laser scan models of the fifteenth- century tomb of Lord and Lady Arundel, now covered by the construction of a large two-storey storage unit, and an eleventh- century door (the second oldest in the country). Due to its fragility, it has not been possible to place on public display.

These high-resolution models have set the benchmark for the later modelling work during the Virtual Cathedral Project, utilising the alternative technique of Structure- from-Motion (SfM) photography.

SfM produces models from a series of photographs taken from many angles. Software (in our case, Agisoft Metashape) produces models from the automatic identification and estimated relative ‘movement’ of identified common features within the photographs.

SfM allows archaeologists to record complex objects and contexts quickly and accurately, allowing items and collections to be viewed side-by-side, aiding comparative and typological analysis. A comprehensive database will provide a valuable conservation record. Damage and wear of stonework can be recorded and compared with conditions in the future to identify at-risk collections and features.

Excavations for archaeological investigation, maintenance and works can be a routine occurrence at Rochester Cathedral, as they are at many urban heritage sites.

Trenches and pits are excavated for services, repaving, conservation and investigatory works. SfM modelling can quickly and cost- effectively record trenches and holes for public interpretation, archaeological research or future maintenance and planning. It is not always possible for a professional archaeologist to be on site for the entire duration of utilities excavations. Still, the basic process of photography for SfM modelling can be described to contractors, on-site staff and volunteers.

An essential objective of the project is to develop a practical workflow for a volunteer group with low to medium technical ability and funding. Photographs have been taken with a consumer-end DSLR camera. However, the software is versatile enough to work with photographs from a modern smartphone, video footage, or drone photography. Objects and features are typically photographed from 20 to 40 camera locations, although this varies greatly depending on the size and shape of the object. The large models in the Virtual

Tour covering whole portions of the building, often requiring several hundred photos, a process made much easier by the temporarily empty building. Photographs have been processed to produce 3D models of widely variable scales and resolutions, and image files are retained for any future re- processing at higher resolutions.

Photography was carried out using ladders, cherry pickers, booms and scaffolding, reflecting the numerous challenges posed by these sites.

Works occasionally provide once-in- a-lifetime opportunities for close- up inspections. SfM produces a cost-effective, accessible record.

Repairs to the quire vaulting this summer have seen the east end of the Cathedral filled with two enormous scaffold towers providing access for close-up inspection and photography of the vaulting ribs.

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Fig 4: Quire boss reconstruction model

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Fig 5: Quire boss

Two bosses over the quire stalls were found to feature extensive fragmentary remains of their original c.1200 AD decoration.

All content is made freely available on the cathedral website, with donations encouraged. Visitors to the Virtual Tour webpage can also follow along with the Audio Tour narrated by Jools Holland, also with French, German, Spanish and Mandarin translations. We also offer a Family Tour suitable for all ages and a Reflective Tour with music and time for a thoughtful exploration, narrated by Dean Phillip Hesketh. A blog is available on the cathedral website with updates on the progress of the project and highlights from the growing collection of 3D models. You can also find out more about the project on the Rochester Cathedral Research Guild website.

Enormous thanks are extended to all the staff and volunteers for many months and years of expertise.

Especial thanks are reserved for Lesley Olley of Olley Design for the web, graphic design and getting the Virtual Tour online over lockdown.

Find out more about the techniques behind the project: rochestercathedralresearchguild. org/virtual-cathedral- project

Blog with highlights and updates on the project: rochestercathedral.org/ virtual-cathedral-project jacob.scott@rochestercathedral.org

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Fig 6: Quire scaffolding

1. | Kent Archaeological Society