Geomatics Examples

The following case studies showcase various geomatics techniques as used on project by Wessex Archaeology. Geomatics techniques are often used as an element within a broader project and these case studies focus solely on the geomatics elements rather than the overall project.
 
For a full list of Geomatics services click here.

Tamworth Castle: survey enhancement

Introduction

Tamworth Castle is a Grade I Listed Building now housing a museum. Originating as a late 11th century motte and bailey castle it has undergone several phases of repair and expansion. The castle is sited in the Pleasure Grounds close to the town centre of Tamworth and is a popular tourist attraction.
 
Wessex Archaeology were commissioned by Tamworth Borough Council to undertake an enhancement project of an existing metric survey of Tamworth Council. The existing survey was undertaken by NGM Surveys Ltd and provided architectural style outputs comprising elevation drawings and plans. Whilst being of the highest quality, these were of limited use for archaeological work as architectural drawings typically do not contain enough detail of the historic fabric; only the outlines of major features such as walls, doors and windows are included with no representation of the stonework itself. Our job was to produce stone by stone drawn elevations of the castle to the highest level specified in the English Heritage Metric Survey Guidelines.
 

A tricky proposition

The original specification to enhance the existing survey with the requisite level of detail suggested the use of photogrammetric techniques but it was quickly realised that to capture the necessary photography and survey control for such work would be unfeasible. As the original survey drawings were based on a point cloud created by terrestrial laser scanning (TLS) techniques, Wessex Archaeology suggested reusing this existing scan data to create stone by stone drawings of all faces of the castle, based on our experience with similar projects.
 
Existing scan data was limited in that it was captured using a phase scanner which captured no colour information. Drawing individual stones from the scan data alone was in many cases impossible, even using advanced visualisation techniques to enhance the surface detail as much as possible. The limited access available to scan the external walls meant that a very short standoff was necessary and the combination of scanning from positions close to the walls combined with protruding features such as windows meant that there were considerable areas of shadow (i.e. no data) on the upper surfaces of the walls. The oblique angle onto the upper surfaces of the walls also resulted in a much lower point density on these upper surfaces (laser scanners have a fixed angular precision so the laser beams are fired at fixed angular intervals resulting in a variable density of points on the subject depending on how far away the subject is and the angle of incidence of the laser beam onto the surface).

The sheer volume of TLS data posed issues for data processing, manipulation and visualisation. Comprising over 1.4 billion individual measurements, the dataset is certainly one of the larger datasets produced as part of a heritage project.

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A novel solution

It was looking like a complete resurvey would be necessary to meet the project specifications but any survey would suffer from many of the same problems due to the shape and position of the castle walls. Photogrammetry would be too costly and rectified photography would not work due to the curved surfaces of the walls. After a bit of lateral thinking, a combination approach was opted for which would use the existing point cloud to provide a metric framework but supported by a photographic survey to provide the additional detail required to allow stone by stone drawn elevations to be produced.
 
Traditional photogrammetry involves very carefully controlled photography and survey control but recent developments in survey software now provide a means to integrate any photography, even historic photography, with any survey control, including laser scan data. Our solution was therefore to undertake a photographic survey to provide a visual record and combine this with the TLS data to allow us to produce stone by stone elevation drawings. In addition to photographs taken from ground and from vantage points on the castle, photographs were taken from elevated positions using specialist kite and pole based systems to provide a good record of the upper surfaces of the structure.

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The drawing up process then used the TLS data and the photographic record combined to produce a 3D wireframe model with each stone drawn using the visual detail from the photographs, metric data being provided by the TLS data. Orthographic views onto this model then formed the basis for scale drawings of each elevation.
 
Working with the data was less than straightforward given its sheer volume. Thankfully, our dedicated GIS/Survey custom built workstations are designed for this kind of work and whilst standard laptops and PCs floundered, the specialist workstations were able to manipulate, process and visualise the data easily.
 

A combination approach

In addition to the drawn elevations, the causeway leading to the castle needed to be recorded. Unfortunately, this was not surveyed as part of the original TLS survey. As such, there was no metric framework to allow us to use the same methodology as was applied to the rest of the castle. Instead, rectified photography was used to provide a visual record that can also be used for measurement.
 
Also, a set of orthoimages produced directly from the TLS data were produced. These look very much like photographs, albeit black and white in this case as the TLS data contained no colour information.
 

Conclusions

With the right set of skills and tools, a great deal is possible, even with existing data that may not have been captured to ideal specifications. This is the first time the technique of combining TLS data with photography in this way to produce detailed stone by stone elevation drawings has been applied on this scale and the methodology developed for this project is a very good and cost effective alternative to photogrammetry.
 
This project exemplifies the complexity of many archaeological survey projects; rarely is survey in the heritage sector straightforward and a team comprising geomatics and archaeological specialists is often better placed to make the right survey decisions to get to the desired outcome.
 

Acknowledgements

Tamworth Borough Council – client.
 
Bill Blake Heritage Documentation – kite and pole based photography.
 
NGM Surveys Ltd – original survey work including TLS data capture.
 

Sandsfoot Castle; metric & photographic survey

Sandsfoot Castle is a Henrican Castle built during the 16th Century on a cliff overlooking Portland Harbour, Dorset. Together with Portland Castle, it provided defence of the harbour and surrounding roads, protecting shipping and preventing invasion. It is a Grade II* Listed Building and a Scheduled Ancient Monument.
 
Wessex Archaeology were commissioned by Weymouth and Portland Borough Council to undertake recording and survey work to contribute to a Conservation Management Plan as part of a Heritage Lottery Fund bid to improve access to the ruinous remains of Sandsfoot Castle. After consultation with the client, a combination of techniques were deployed including terrestrial laser scanning (TLS), rectified photography and panoramic photography.

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Producing a 3D record

As with most TLS projects, the fieldwork was undertaken in a very short space of time, with photographic survey work being undertaken simultaneously. This was particularly important as the interior of the castle is a hazardous place with the potential for falling masonry. Laser scanning was undertaken using the latest Leica C10 instrument capable of recording up to 50,000 3D measurements per second. In addition to allowing the surfaces of the castle to be recorded to around 2mm precision, the C10 captures full colour information resulting in a coloured point cloud.
 
Survey control for the TLS component was implemented using a closed loop traverse with Total Station Theodolite (TST) instruments, a commonly used surveying technique to ensure unavoidable error introduced by the tolerances of the survey instruments around the survey control network is minimised and quantified. The survey control network was then related to the British National Grid coordinate system using Global Navigation Satellite System (GNSS) to ensure that every point in the TLS data is within the standard Ordnance Survey coordinate system.
 
The TLS data was then used to produce a series of orthographic images and was also used to produce elevation drawings of each elevation of the castle. Stone by stone elevation drawings were required and this was facilitated by having a high resolution, coloured point cloud to work with.
 
It was also necessary to understand the nature of the levels inside the castle and immediately around the castle to help with any design proposals to enhance visitor access. To facilitate this, the TLS data was imported into a Geographic Information System (GIS) where a Digital Surface Model (DSM) of the ground surface could be produced. This DSM was then used in conjunction with the photographic record to interpret the observed remains inside the castle and to provide accurate height measurements across the ground surface and on the remaining archaeological deposits. The GIS was then used to produce illustrative plans of the interpretations and height data as a grid of levels plus contour lines.
 

A complementary photographic record

In addition to the TLS component of the project, rectified photography was used to produce a visual record of each elevation, both the internal and external elevations. This was particularly challenging for the seaward side as the only available vantage point to take photographs from was the beach at low tide, resulting in photographs taken looking up at the castle atop the cliff. Survey control for this element of the project was provided using Total Station Theodolite (TST) instruments.

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Panoramic photography was also used to create interactive bubbleworlds suitable not only to view and investigate the castle and its surroundings as part of the overall record, but with a view to using them to create online resources for the public to interact with and find out more about the castle. Each panorama involved capturing a series of photographs from a single location with an equal angular separation between them. A special tripod head was used to ensure the camera rotated around the focal point of the camera, reducing distortion to a minimum. These photographs were then stitched together using specialist software to produce the final product and an index provided as a Keyhole Mark-up Language (KML) file for use in Google Earth or Google Maps or any other GIS platform.
 

Conclusions

TLS is an ideal technique for rapidly surveying potentially dangerous structures such as ruins due to the reduced time spent on site. The TLS data, when captured in colour, provides a good visual record as well as being highly metrically accurate.
 
Photographic techniques, particularly panoramic photography provides an excellent user experience for the visualisation of heritage sites and furthermore can be used as the basis for engaging outreach materials aimed at the general public.
 

Acknowledgements

Weymouth & Portland Borough Council – client
 
Friends of Rodwell Trail & Sandsfoot Gardens
 
Heritage Lottery Fund

Wakehurst Place: measured survey

Related info
Read a blog post about our survey work at Wakehurst Place.
The Wakehurst Place Estate consists of c.200ha of land situated one mile to the north-west of the village of Ardingly in the High Weald of West Sussex. The property was bequeathed to the National Trust in 1964, and since 1984 has been administered by the Board of Trustees of the Royal Botanic Gardens, Kew. The Wakehurst Place Mansion is a Grade I listed building and the Stable Block is listed Grade II*, while an area of c.40ha of their associated parkland and gardens are Registered, Grade II*.
 
Wessex Archaeology were commissioned by the National Trust to undertake a Historic Buildings and Structures Survey, part of which was measured survey of the mansion, stable block and walled garden. The measured survey outputs would then be used as the basis for subsequent analytical and descriptive records of the structures.
 

Interior survey

Floor plans, a long section and two cross sections of the mansion were surveyed using Total Station Theodolite (TST) and a laser measuring device linked to a tablet PC running AutoCAD. This enabled the surveyor to build a 3D model in CAD directly on site, a highly efficient means of producing the required drawings.
 
Survey control was implemented using a closed loop traverse around the building, a commonly used surveying technique to ensure unavoidable error introduced by the tolerances of the survey instruments around the survey control network is minimised and quantified.
 

Exterior survey

The external elevations of the mansion in particular are complex, with numerous projecting gables and projections. This would have made an approach such as rectified photography very complicated indeed. Instead, terrestrial laser scanning (TLS) was used to record all the external faces of the buildings and structures, including accessible parts of the roofscape.
 

Drawing up

Both the internal and external elements of the measured survey were placed in a common coordinate system (British National Grid) using Global Navigation Satellite Systems (GNSS); this allowed them to be integrated to produce elevation drawings suitable for the subsequent interpretive stages of the project.

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Conclusions

A combination of digital techniques can be deployed to undertake measured survey works to national standards most efficiently; choosing the right tools for the job in hand can reduce overall project costs whilst maintaining the highest standards of product. In this case, the use of TLS to record the external elevations was the most appropriate technique and not only resulted in drawn elevations as per the specification but provided a detailed point cloud suitable for other purposes including visualisation.
 

Acknowledgements

National Trust - client

Stonehenge & Avebury World Heritage Site Condition Survey

The Stonehenge & Avebury World Heritage Site comprises two discreet areas centred on the world famous henge monuments. Whilst being geographically separated by some 20km, both regions are characterised by the proliferation of prehistoric archaeological sites, notably from the Neolithic and Bronze Age but with sites of all periods as well.
 
Wessex Archaeology undertook a pioneering condition survey in 2001 for the Stonehenge part of the World Heritage Site, utilising a mobile Geographic Information System (GIS) equipped with Global Positioning Systems (GPS) for field data capture, supported by an extensive digital photographic record.
 
In 2010, Wessex Archaeology were commissioned by English Heritage to undertake the periodic resurvey for both the Stonehenge part of the World Heritage Site and also the Avebury part plus measured survey of the upstanding earthworks across both parts of the World Heritage Site.
 

Data driven monitoring

The approach taken is based around the idea of being data driven ie field observations are made which are then validated and used to make detailed assessments and management recommendations. This is a very different approach from simply making assertions whilst out in the field which are then collated and reported on as the former allows for very fine grained analysis and evidence based assertion whereas the latter is very much implicit and dependence on the expertise and consistency of the field team.
 
Wessex Archaeology routinely deploy mobile GIS for such projects to facilitate the gathering of robust, standardised field data in a rapid fashion. In the hands of expert field teams, data gathered is systematic and consistent and compliant with national and client specific standards, able to be analysed immediately on return to the office without the need for manual data entry of recording forms. For this project, terminology was derived from the Inscription wordlists maintained by the Forum for Information Standards in Heritage (FISH), making it compatible with other datasets using these national standards and suitable to feed into larger monitoring programmes such as Heritage at Risk.
 
This system is the best way of recording and analysing monitoring information in a rigorous and robust manner.
 

Field Recording & post fieldwork analysis and reporting

Mobile computers running GIS and equipped with GPS are used to capture spatially referenced assessments so every single piece of data gathered can be related to a real-world location using the British National Grid. Importantly, every observation is supported by photographic records, again all of which are spatially referenced. The structured data gathered can be loaded into desktop GIS back at the office as fieldwork progresses providing feedback for the field teams. Database Management Systems (DBMS) and GIS are then used to validate, analyse and report on the data, removing the need for the majority of manual data handling and thus freeing up valuable time for archaeologically important issues. Maps and plans can be produced directly from the GIS to visually present results and indicate change.
 

Measured survey

In addition to the condition assessment, the height of earthworks was to be accurately recorded. Wessex Archaeology decided that our survey grade Global Navigation Satellite Systems (GNSS) would be the best solution for this task and furthermore, whilst the field teams were deployed, capturing extra measurements would not significantly increase the time take to complete the survey. As such, transects of points across earthworks were recorded.
 
This data was again loaded into GIS back in the office and used to produce a series of over 1000 maplets for surveyed sites, each of which showing a location plan of the site and surveyed transect plus a profile graph of the height data.
 

Conclusions

The use of mobile GIS for recording data in the field allows for more robust, data driven survey methodologies. Assertions and recommendations are all based on observations made in the field then validated and anlysed, supported by evidence. Data handling time is reduced providing the most efficient way of monitoring archaeological sites and landscapes.

Stonehenge Carvings: Research & Development

The world famous megalithic structure known as Stonehenge dates back to the Bronze Age with earlier phases dating back even further into prehistory.
 
In the middle Bronze Age, activities at Stonehenge included marking and carving some of the stones with depictions of bronze flanged axes and a daggers. In more recent times, names have been carved, including, allegedly, the famous 17th/18th century architect, Sir Christopher Wren.
 
Wessex Archaeology in conjunction with Archaeoptics and the English Heritage Centre for Archaeology were able to investigate the carvings using Terrestrial Laser Scanning (TLS) as part of research and development into the use of laser scanners for archaeological recording in 2002-3 before the technique had become widely adopted.
 

Fine surface detail

This project required very high resolution data capture in order to examine the surfaces of the stones and at that time, the majority of laser scanners could not achieve anywhere near the resolution required. As such, a type of scanner called a triangulating laser scanner was used as these systems are capable of recording much finer detail than time-of-flight based systems, including pulsed and phase systems; The carvings themselves are only a fraction of a millimetre deep in places so any scanner used must be able to record with a suitably high degree of precision.
 
The combination of very fine resolution data, specialist software and the skilled team at Wessex Archaeology and Archaeoptics paved the way for some very interesting and ground-breaking discoveries as well as demonstrating the capacity of the technology for such work.
 

Conclusions

Using the right type of scanner for the job in hand is very important. Some record in colour, some don’t; some are only accurate to a few millimetres whilst others are accurate to tens of microns, some have much longer or shorted ranges, some function as survey instruments whilst other function more like cameras. Wessex Archaeology have experience with all types of systems so would always deploy a suitable scanner or other technique depending on the needs of the project.
 
 

Tidworth Garrison: building recording

Tidworth Garrison Barracks were primarily developed in the last decade of the 19th and first decade of the 20th centuries.
 
In advance of redevelopment, Wessex Archaeology were commissioned by Aspire Defence to undertake recording of the barracks at Tidworth.
 

Recording an entire complex of buildings

Due to the scale of the task in hand a combination approach was used which involved an initial photographic survey of every external and internal elevation of every building plus a measured survey using Terrestrial Laser Scanning (TLS). Selected buildings were then recorded using direct survey techniques, specifically measured survey using Total Station Theodolites (TST) linked to CAD systems.
 
This combination approach provided a complete 3D record of all the buildings, captured using TLS, supported by a complete photographic record and detailed drawings of specific buildings of interest.
 
At the time (2007), this was one of the larger TLS projects undertaken for heritage purposes, covering an area of 0.75 km2 including 37 buildings and resulting an a point cloud containing 25 billion 3D measurements, over 18Gb of survey data. Due to the scale of the survey work, the laser scanning was undertaken at relatively low resolution (10-25mm) which was why detailed recording of specific buildings using direct survey techniques was also applied.
 

Conclusions

TLS is particularly effective for recording large scale complexes of buildings where other methods such as rectified photography or direct survey techniques would have been unfeasible in a short timescale. Massive volumes of data can be produced but Wessex Archaeology have a range of specialist tools and considerable experience in dealing with such large datasets to produce a range of products from TLS data.

Chapperton Down: archaeological topographic survey & monitoring

The field system of Chapperton Down lies within the Salisbury Plain Training Area on Salisbury Plain and is a Scheduled Ancient Monument. The aim of the periodic resurvey is to monitor any erosion and damage to the upstanding earthworks to assist in the ongoing management of the site.
 
Wessex Archaeology were commissioned by Landmarc Support Services to undertake the original baseline survey then undertake periodic repeat surveys to assess any change.
 

A progression of methodologies

The original baseline topographic survey was undertaken in 2005 using direct survey techniques, namely the use of a survey grade Global Navigation Satellite System (GNSS) capable of recording to centimetric precision. The speed with which data could be captured using the GNSS as opposed to the use of a Total Station Theodolite (TST) had significant advantages due to restricted access to the site.
 
Fieldwork involved walking transects across the site at fixed intervals to gather height information as well as surveying breaks of slope and any specific impacts observed. This data was then imported into a Geographic Information System (GIS) for analysis and reporting involving the creation of a Digital Terrain Model (DTM) for the site.
 
The first resurvey in 2007 repeated this methodology but also included some comparative work using the GIS to look for change between the resurvey and the baseline data. The GIS is an ideal tool for undertaking surface difference analysis and producing maps to illustrate the situation as observed on the ground.
 
In 2009, the resurvey was undertaken using Terrestrial Laser Scanning (TLS) which allowed much more surface detail to be captured. Fieldwork time was reduced considerably, a significant benefit given the restricted access to the military land.
 

Conclusions

TLS is not just used for recording buildings and upstanding earthworks, it can provide a rapid and high quality technique for undertaking topographic survey across wider areas of landscape. When compared to other suitable methods such as GNSS or TST, it can provide equivalent or better quality of data in terms of accuracy, with much higher resolution and reduced fieldwork time.
 

South East Rapid Coastal Zone Assessment Survey

Rapid Coastal Zone Assessment Surveys (RCZAS) are being coordinated by English Heritage in response to the potential effects of natural coastal change and coastal management schemes. By late 2010, surveys were complete or underway in all parts of the country with the south-west peninsula due to start soon.
 
Wessex Archaeology were commissioned by English Heritage to undertake Phase I  (desk based component) of the south-east project covering an area from Kent to the New Forest.
 

A wealth of existing information

To undertake the desk-based assessment phase of the project, data was sourced and collated from a wide variety of sources including all the numerous Sites and Monuments Records and Historic Environment Records in the study areas. Additional data included modern and historic Ordnance Survey maps, aerial photography, LiDAR data and extracts from the National Monuments Record. The sheer volume of data required careful planning for with appropriate management strategies in place. All this data was accessioned and processed to be stored and used through a Geographic Information System (GIS).
 

Creating new information

A comprehensive aerial photograph transcription element formed a major part of the project. After training at the National Monuments Record (NMR) by the English Heritage National Mapping Programme team, the aerial photograph collection was loaned to Wessex Archaeology and the transcription process began apace. Unlike most NMP type projects were data is either entered into the database system at the NMR or kept as a separate dataset requiring import or re-entry, an important element of this project was to create records suitable for direct inclusion in the SMRs and HERs within the study areas. As such, the HER/SMR systems were replicated at Wessex Archaeology’s offices with all data being entered straight into a working copy of each HER/SMR database. This involved not only working to NMP standards for the transcription work but to each set of standards for each of the destination HER/SMR databases. This approach will, however, dramatically improve the ease with which data output from the project can be reincorporates into the local and national archaeological records, overall a more efficient process for such HER/SMR enhancement type projects.
 

Conclusions

Whilst the data flow within the project, to/from HER/SMRs and the NMR involves considerable investment in IT infrastructure and requires skilled project team members supported by geomatics specialists, approaches such as this bring significant long term benefits through ease of integration of data output by the project when it comes to project completion and handover, especially for large projects.
 
Wessex Archaeology has a team of trained aerial photograph interpreters, HER/SMR systems experts and GIS specialists capable of undertaking complex projects such as this.
 

Wiltshire Sites and Monuments Record: SMR Enhancement

Wiltshire Sites and Monuments Record (SMR) is maintained by the Archaeology team at Wiltshire Council and provides a record of archaeological sites, monuments, activities and sources of information. Every piece of archaeological fieldwork in Wiltshire results in a report which is lodged with the SMR and is ultimately catalogued and indexed to inform subsequent planning and policy decisions and also to support research projects. The volume of reports submitted and the work involved in accessioning and creating new SMR records from paper based reports has, over time, resulted in a backlog of reports waiting to be accessioned.
 
Wessex Archaeology undertake a considerable amount of work in Wiltshire and it was recognised that a cost effective way of reducing the backlog would be to commission Wessex Archaeology to process some of these reports creating new SMR records and enhancing existing ones. 
 

Enhancing the record

Two projects were undertaken following an initial pilot study. Using digital data from Wessex Archaeology’s archives, our team were embedded for the duration of the projects within the archaeology team at the Wiltshire and Swindon History Centre in Chippenham. This allowed them to work directly with the live SMR database and to import and create new records as needed with the support of the archaeology staff. This also facilitated the QA process as records created or amended could easily be checked by the Wiltshire Council Archaeology team.
 

Conclusions

Whilst in many cases it is possible to undertake enhancement work remotely from our offices, it is also possible to deploy Wessex Archaeology specialists to work within the Sites and Monuments Record or Historic Environment Record. The use of external contractors can be a cost effective way of adding to or enhancing the archaeological record.

Avebury World Heritage Site GIS

The henge and surrounding landscape at Avebury forms one half of the Stonehenge & Avebury World Heritage Site.
 
Upcoming projects at Avebury and ongoing management of the World Heritage Site required a spatial database of relevant information to be collated. Wiltshire Council commissioned Wessex Archaeology to collate data and to implement a Geographic Information System (GIS) to support these functions.
 

Building an enabling tool

The project involved building upon the Avebury part of the Stonehenge & Avebury World Heritage Site GIS created by English Heritage in the 1990’s. In order to support the requirements of the Stonehenge & Avebury World Heritage Site Revised Research Framework project and also the needs of the Avebury World Heritage Site Coordinator,  it was necessary to update the WHS GIS to reflect recent boundary changes in the WHS and to add new data for an extension to the study area to the east. This required spatial data in CAD format and descriptive information as tables of text, both supplied by Wiltshire Council Sites and Monuments Record, to be processed and turned into data suitable for use in GIS using the same structure as the WHS GIS. Other GIS layers such as those published by English Heritage and English Nature were refreshed and new datasets created for or by the Avebury Archaeological and Historical Research Group (AAHRG) and Wiltshire Council were added.
 
Basic training in the use of the data within GIS was also provided as part of the package.
 

Conclusions

The use of GIS to support specific projects and ongoing management tasks at World Heritage Sites is highly beneficial. Having access to data and indices to other data accessible via a map based view is a powerful management tool, particularly where the ongoing results of management activities can be incorporated.
 

North Kent Coast Rapid Coastal Zone Survey

Rapid Coastal Zone Assessment Surveys (RCZAS) are being coordinated by English Heritage in response to the potential effects of natural coastal change and coastal management schemes. By late 2010, surveys were complete or underway in all parts of the country with the south-west peninsula due to start soon.
 
Wessex Archaeology were commissioned by Kent County Council to undertake both Phase I (desk-based assessment) and Phase II (field survey) of this Rapid Coastal Zone Assessment.
 

An integrated solution

A working copy of the Kent Sites and Monuments Record (SMR) Database Management System (DBMS) and Geographic Information System (GIS) for the study area was set up in the offices of Wessex Archaeology and used for the desk based assessment work. This data was then downloaded onto mobile GIS for the fieldwork stage, allowing new records to be created in the field using the same data structure as the SMR. Records created and/or amended in the field were then loaded back into the working copy of the SMR ready for further assessment, SMR enhancement and reporting.
 

Conclusions

By setting up a working copy of the SMR for the project, then using mobile GIS to take data out into the field for data capture and validation purposes, the data flow from the SMR through the project and back to the SMR was streamlined. This meant less time was spent handling data and more time could be spent focussing on the archaeological work in hand.
 
A robust integrated approach such as this also facilitates quality assurance and reintegration of the data output back into the local archaeological record.

St John's church, Bemerton

St. Johns Church is a Victorian Grade II* Listed Building in the village of Bemerton just to the west of Salisbury. The church was designed by T.H. Wyatt and built 1859-61 with a restoration undertaken in 1896 by C.E. Ponting; many of the original fixtures and fittings are still in place and also worthy of note are the capitals on the columns, each of which is very finely carved to individually unique designs. The church also features a rather lovely lych gate which serves as the village war memorial. The church is currently the focus of a community driven plan to convert it into a community centre whilst retaining space for worship.

323 Interior view of the church, rendered from the point cloud data

324 Section drawing through the church, north-south

Wessex Archaeology were commissioned by Bemerton Community and Paul Stevens Architecture (the project architects) to undertake a metric survey of the church to assist with planning and designing the new community space and also to provide a record of the structure as it stands. We used Terrestrial Laser Scanning (TLS) to record the interior and exterior of the church as well as the interior of the tower and the lych gate.
 
From this laser scan point cloud, we then created a set of orthographic images, images which look like photographs but are also scaled and contain no perspective distortion, making them suitable for measuring from. A set of traditional internal section drawings were also created through the church, capturing the long and short internal elevations. A number of animations of the data were also prepared for use by the community when talking about the proposals; these were also shown at the Remembrance Day commemorations, the lych gate being the village war memorial.
 
The laser scan data is also ideally suited to form the basis for any more detailed heritage recording that may be required as part of the proposals. Wessex Archaeology have already demonstrated on other projects such as Tamworth Castle how the combination of digital photography and laser scan data can be used to produce very detailed record drawings of heritage structures. The scan data can also be used as the metric framework for rectified photography as was undertaken at Sandsfoot Castle.
 
More information is available from salisburychurch.net and the Bemerton Community Saving St John's blog.

325 Orthographic view of the exterior of the church

Acknowledgements

Bemerton Community (client)
 
Paul Stevens Architecture (client)