Powered by
JSPWiki v2.8.2
g2gp 17-01-2009
View PDF

Previous | Bibliography | Contents


Case Study 6: Symon's Castle Documentation#

Jeremy Huggett#

Symon's Castle is a 13th century AD timber and earthwork castle situated on the Welsh borders (see also Case Study 1). It was excavated in a series of one-month seasons from 1985 to 1994 by Dr Jeremy Huggett (University of Glasgow) and Dr Chris Arnold (then of University of Wales Aberystwyth) as a research and training excavation. The castle consists of two platforms separated by a ditch; the whole of the north-east platform (the 'bailey') was excavated, a section through the ditch, and the whole of the interior of the south-west platform (the 'motte') with sections through the stone-revetted clay bank on its perimeter.

As a result of the degraded nature of the soil, few archaeological contexts could be defined on any basis other than the relative density, distribution and nature of stone and artefacts alone. In the absence of distinct layers of soil over much of the excavated area, the removal of the deposits was carried out in a series of arbitrary spits. Individual context numbers were only assigned where layers and features were clearly defined (usually as a result of burning). Hence the recording of all non-artefactual material comprised a series of drawings on which the objective data were all stones larger than about 0.03m in their greatest dimension, with any apparent 'edges' in stones or soil highlighted. For any given area this record comprised a maximum of four drawings:

  • Plan 1: the visible and normally amorphous surface following the removal of the vegetation;
  • Plan 2: the pattern revealed following the removal of topsoil;
  • Plan 3: the distribution of stones lying directly on the subsoil or bedrock;
  • Plan 4: any stones which appeared to have been set into the subsoil by human agency.

All artefacts, including burnt clay and charcoal fragments, were recorded in three dimensions, and the importance of this for the subsequent identification of structures that had no earth-fast timbers is demonstrated in Case Study 1.

Digitisation of the plan data was carried out as part of the post-excavation phase. In the absence of a large-format scanner (although a bureau service could have been used), all the original A1 (approx.) field plans in pencil on permatrace were scanned in overlapping sections using an A3 scanner. To create stone plans, the scans were sharpened and converted to 2-bit black and white images which were automatically traced. These traces were subsequently imported, scaled, rotated and positioned on the site grid in AutoCAD 2000, along with the original grey-scale scans. The overlaps between traces were removed and the plans cleaned manually with reference to the underlying scanned images. To create individual context plans, the extents of contexts were manually digitised from the scaled and rotated and positioned grey-scale scans. A series of interpretative three-dimensional models were constructed on the basis of the excavated evidence (see Huggett and Chen 2000). An intra-site GIS was also constructed for analysis by importing the digitised stone and context plans, which had been saved in AutoCAD version 14 format for compatibility, into IDRISI and ArcView version 3.2.

The digital archive created by the Symon's Castle project is a research level archive and includes:

  • Project reports covering the stratigraphic sequence
  • CAD files
  • Layer-naming convention.

Project Documentation

Project NameSymon's Castle project.
Reference NumberNone.
Project PurposeExcavation of a 13th century AD timber and earthwork castle near Churchstoke, Powys. The project was directed by Dr C. Arnold and Dr J. Huggett over a 10 year period, on site for four weeks per year. The excavation was run as a training school for university students and other interested parties, and as a volunteer excavation. Although the site was largely undisturbed, the soil was very shallow and highly leached, requiring a modified recording procedure and full three-dimensional recording of artefacts.
Project KeywordsExcavation, Medieval, castle, motte and bailey, timber and earthwork.
SubjectTimber and earthwork castle, with stone-revetted clay rampart and timber palisades, timber buildings in interior.
Site Address Symon's Castle, Churchstoke, Powys.
Administrative AreaChurchstoke, Powys
CountryWales.
Spatial Coverage(OSGB) SO 285 933
SizeNot reported.
Duration1985-1994.
OriginatorDr J. Huggett, Department of Archaeology, University of Glasgow, Dr C. Arnold.
ClientNone.
BibliographyJ. Huggett and C. Arnold (1998) Symon's Castle[1]

C. Arnold and J. Huggett (in prep), Symon's Castle, Churchstoke, Powys: Excavations 1985-1994.

J. Huggett and Chen Guo-Yuan (2000) '3-D Interpretative Modelling of Archaeological Sites: A Computer Reconstruction of a Medieval Timber and Earthwork Castle' Internet Archaeology 8[2]
CopyrightDr J. Huggett and Dr C. Arnold

Layer-naming Convention

The project defined three layer-naming conventions, for the stone plans, the context plans and for three-dimensional models. Each convention is described below, with AutoCAD Colour Index (ACI) being used to define the colours used.

Convention:Stone plans
Layer NameDescription
BedrockLayer content: Extent of exposed bedrock
Source: Project files
Colour: Green (AutoCAD Colour Index 100)
Line type: Continuous
Exc_edgeLayer content: Edge of excavation
Source: Project files
Colour: Magenta (ACI 211)
Line type: Continuous
ScanLayer content: Links to original scanned images of stone plans
Source: Project files
Colour: Grey-green (ACI 54)
Line type: Continuous
aXbYLayer content: Stone plan where a = area of site (m=motte, b=bailey, t=terrace, d=ditch); X = plan level (1, 2, 3 etc.), b = sheet of plan X, Y = scanned element of sheet b
Source: Project files
Colour: White (ACI 249)
Line type: Continuous

Convention:Context plans
Layer nameDescription
BedrockLayer content: Extent of exposed bedrock
Source: Project files
Colour: Green (ACI 100)
Line type: Continuous
Exc_edgeLayer content: Edge of excavation
Source: Project files
Colour: Magenta (ACI 211)
Line type: Continuous
Context X
(X = context number)
Layer content: Context extent.
Source: Project files
Colour: Red (ACI 240)
Line type: Continuous

ConventionThree dimensional models
Layer nameDescription
TopographyLayer content: Surface mesh of topographic survey
Source: Project files
Colour: Green (ACI 84)
Line type: Continuous
PalisadeLayer content: Palisade posts
Source: Project files
Colour: Brown (ACI 14)
Line type: Continuous
PlanktimberLayer content: Palisade planking
Source: Project files
Colour: Yellow (ACI 50)
Line type: Continuous
RoadLayer content: Roadway on bailey to bridge
Source: Project files
Colour: Mustard (ACI 52)
Line type: Continuous
BridgeLayer content: Bridge between motte and bailey
Source: Project files
Colour: Gold (ACI 40)
Line type: Continuous

File-naming Convention

Each stone plan file is named by its area and plan level - hence Motte Plan 1, Motte Plan 2, Bailey Plan 1, etc. and standard file extensions. Each individual context plan file is named using the site context number and standard file extensions, e.g. 12345.dwg.

On-site Data Capture Documentation

Project NameSymon's Castle
Reference NumberNone
Survey TypePlanning
Survey PurposeStandard site planning on permatrace, employing 1m square drawing frames and hand tapes. All plans drawn to a scale of 1:20.
Duration1985-1994 (approx. 10 months in total)
SurveyorDr J. Huggett and Dr C. Arnold
Survey KeywordsHand measurement, level
InstrumentationLevel
CoverageEntire excavated area
Precision and AccuracyMeasurements to nearest centimetre, estimated accuracy ±5cm
Data Transfer FilesN/A

Project NameSymon's Castle
Reference NumberNone
Survey TypeTopographic survey
Survey PurposeApprox. 5000 spot heights measured across area of site at 1m intervals. Grid reconstructed in local areas using tapes anchored by permanent steel pins.
Duration1985-1986 (approx. 2 weeks in total)
SurveyorDr J. Huggett and Dr C. Arnold
Survey KeywordsHand measurement, level
InstrumentationLevel
CoverageEntire area of earthworks
Precision and AccuracyMeasurements to nearest centimetre, estimated accuracy ±10cm
Data Transfer FilesSymondem.img - IDRISI image format, heights in centimetres at one-metre intervals, 76 columns x 72 rows, 0 is null value Symon.asc - ASCII text format, heights in centimetres at one-metre intervals, 76 columns x 72 rows, 0 is null value.

Off-site Data Capture Documentation

Project NameSymon's Castle
Reference NumberN/A
Source NamePlans (stones)
Source ReferenceNone
Type of SourceDrawing
Source MediumPermatrace
PublisherNone
CopyrightDr J. Huggett and Dr C. Arnold
Scale1:20
Accuracy±5cm (estimated)
TechniquesScanning
EquipmentScanner = Umax Mirage IISE
SoftwareMagicScan 4.2
SoftwarePaintShop Pro 6.0
SoftwareRasterVect 5.2
ParametersScanner maximum resolution = 9800 dpi x 9800 dpi; scan resolution = 150 dpi;
filter used = sharpen
Post-processingOutlines sharpened (Image/Sharpen/Sharpen more) if needed and converted to 2-bit black and white images (Colours/Decrease Colour Depth/2 Colours). Software used: PaintShop Pro 6.0
Automatic ProcessingAuto-traced using centrelines with arc and circle recognition turned off. Software used: RasterVect 5.2
Control PointsSite grid fixed points on plans.
Data Precision and AccuracyTracing precision: 1.5 pixels, minimal length of line: 1 pixel. Resulting plans cleaned manually, though polylines representing the smallest stones (c. 5cm or less) were not closed.
Data FilesAutoCAD dxf/dwg, version 14

Project NameSymon's Castle
Reference NumberN/A
Source NamePlans (contexts)
Source ReferenceNone
Type of SourceDrawing
Source MediumPermatrace
PublisherNone
CopyrightDr J. Huggett and Dr C. Arnold
Scale1:20
Accuracy±5cm (estimated)
TechniquesDigitising
EquipmentDigitising tablet = A3 Summagraphics Summasketch III
SoftwareAutoCAD 2000
ParametersTablet claimed accuracy ±0.010 inches; resolution: 2540 lines per inch.
Post-processingN/A
Automatic ProcessingN/A
Control PointsSite grid fixed points on plans
Data Precision and AccuracyNot given
Data filesAutoCAD dwg, version 14

List of All Files

File NameDateCopyrightFormatContent
Motte Plan 1.dwg12/08/2001JWH/CJAdwg version 14Motte stone plan at Plan 1 stage
Motte Plan 2.dwg12/08/2001JWH/CJAdwg version 14Motte stone plan at Plan 2 stage
...
41.dwg20/01/2002JWH/CJAdwg version 14Extent of context 41
42.dwg20/01/2002JWH/CJAdwg version 14Extent of context 42

N.B. These details would be repeated for each file in the archive.

Documenting the CAD Models

Project NameSymon's Castle
Project Reference numberNone
Name of CAD ModelInterpretative reconstruction
CreatorChen Guo-Yuan and J. Huggett
CAD SoftwareAutoCAD 14
Files UsedSym_22.dwg (topographic surface)
Hall_1.dwg (version 1 of the hall)
Tower_2.dwg (version 2 of the tower)
Symlisp.lsp (AutoLISP programs for construction of timber palisades, wallwalks, roadway and bridge)
Layer Convention3D models layer convention with additional layers as follows:
Hallrftimber: Colour = brown (ACI 33); Line type = continuous (rooftimbers of hall)
Hallroof: Colour = gold (ACI 41); Line type = continuous (roof of hall)
Hallwall: Colour = red (ACI 10); Line type = continuous (walls of hall)
Hallwindow: Colour = maroon (ACI 242); Line type = continuous (windows/doorway of hall)
Towerroof: Colour = gold (ACI 41); Line type = continuous (roof of tower)
Towerstair: Colour = orange (ACI 30); Line type = continuous (stair within tower)
Towertimber: Colour = brown (ACI 42); Line type = continuous (timber framework of tower)
Towerwall: Colour = red/brown (ACI 12); Line type = continuous (planked walls of tower)

N.B. This documentation would be repeated for each model in the archive.


[1] http://www.gla.ac.uk/departments/archaeology/research/projects/symonscastle/
[2] http://intarch.ac.uk/journal/issue8/huggett_index.html


Previous | Bibliography | Contents