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T H E B U I L D I N G C O N S E R VAT I O N D I R E C T O R Y 2 0 1 6

T W E N T Y T H I R D E D I T I O N

1

PROFESS IONAL SERV I CES

and incremental process which, after

much consideration, was felt to represent

the most effective use of resources.

In summary, the objectives of the exercise

were to:

• capture comprehensive survey imagery of

the castle internally and externally, and (at

little additional expenditure) the wider site

• provide corrected base-level survey data

for the castle and site in digital format

• digitally model the superstructure of

the castle internally and externally.

Once the digital modelling phase was

complete, the digital model would be used to:

• carry out a comprehensive moisture-

mapping exercise relating interior

and exterior thermal imagery

• act as a framework for representing/

overlaying the evidence from both past

and current analytical recording exercises

• permit the mapping of the history of

secondary (post-Lutyens) repairs

• form a resource base for other purposes

such as future recording or archaeological

works, and act as a basis for the cumulative

and/or more general mapping of the

evolutionary history of the castle

• provide information for

interpretative representation

• form the basis of a building information

model as a management tool for

the proposed works and for the

future management of the site.

The challenges of the site

The principal challenge for any works at

the castle is the inaccessibility of much

of its precipitous crag-top location. This

had hitherto precluded comprehensive

survey – accurate architectural survey

during major works in the mid-1990s had

only extended to the accessible areas of the

superstructure. The present project required

all-embracing survey coverage, which also

necessitated accurate modelling of the partly

vegetation-obscured rock-faces below the

castle’s walls in advance of stabilisation.

Another difficulty for more conventional

survey was the extreme irregularity of the

structure overall, its labyrinthine passages

and its curious internal geometry.

Data capture

The new survey involved data capture by

means of laser-scanning and high-resolution

digital photography, the latter taken both

manually and by means of a UAV (Figure 4).

Each technique was applied as appropriate so

that comprehensive coverage was achieved

of all areas. The efficiency of the exterior

coverage by the UAV also permitted entire

coverage of the topography of the field

and foreshore areas surrounding the site,

data which will be retained for ongoing

management of the site.

Creating the modelled imagery

The captured image data was registered

and combined to create a single model

(Figure 5). Point-cloud imagery was overlain

with the photographic to produce high-

resolution orthographic projections.

These were then digitised by hand to

overlay a stone-by-stone level of detail

and further corrected by hand on site.

Applications

Having achieved this level of dimensionally-

accurate base survey detail, the imagery

was then used as a basis for layering-on

various categories of qualitative information:

architectural data, condition-related

information, archaeological recording and

analytical observations.

The archaeological data from recording

works carried out by the author on the

north elevation during works in 1996 was

digitised and integrated onto the model as an

analytical layer. Analytical mapping included

the plotting of areas of repairs subsequent

to the early 20th century works of Sir Edwin

Lutyens, much of which involved the use of

inappropriate materials, particularly cement

and (internally) various proprietary products.

Thermal imagery is to be overlain on

the model both externally and internally to

attempt to map the routes of moisture ingress

into the superstructure. Drainage and water

run-off systems will be similarly plotted and

modelled in order to better understand the

complexities of the site.

The resulting model will also be a

powerful interpretative tool on which will be

plotted the analytical history of the castle, its

phases and evolution. When this information

is cross-correlated with the detailed historical

records for the site it will be possible to model

the structure at fixed points in its evolution

over its 500-year existence. This information

will be made accessible to the visiting public

on site as the work progresses, and will also be

accessible as a web-based resource.

Acknowledgements

The author would like to thank John and David

McCreadie, and David Connolly of CHC

Heritage for their assistance in the preparation

of this article, and the National Trust (North

Region) for permission to use material relating

to Lindisfarne Castle.

Further Information

Chartered Institute for Archaeologists

www.archaeologists.net

Historic England, ‘Surveying and

Recording Heritage’, 2015

(http://bc-url.com/recording-heritage

)

TOM ADDYMAN

MA FSA FSA(Scot) MCIfA is

the founder of Addyman Archaeology and a

partner at Simpson and Brown Architects (see

www.simpsonandbrown.co.uk/archaeology)

.

Figure 6 The north elevation of Lindisfarne Castle: hand-recorded imagery from a survey in 1996 was digitised and merged with the digital survey carried out in 2015 to

show analytical information and phases of construction and repair.