Geomatics

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Our specialists make use of the latest survey instruments to capture spatial data including Global Navigation Satellite Systems (GNSS), laser scanners (airborne, terrestrial and close range), total station theodolites (TST). We then use industry standard and open source Geographic Information Systems (GIS), Computer Aided Design (CAD) and specialist survey and data processing software to work with this data and data from external sources. Such work is facilitated by our top of the range geomatics workstations which have been custom built for dealing with massive and complex datasets and produce publication quality maps, figures, videos and interactive multimedia outputs.
 
For Case Studies click here
 
For more about our Geomatics services click on the links to the right or below.
 
Contact
Damien Campbell-Bell
d.campbell-bell@wessexarch.co.uk
03303 133450
 
For the full range of Geoservices click here
For the full range Wessex Archaeology Services click here
 

Airborne LiDAR

179 LiDAR profile through a Bronze Age barrow

Airborne LiDAR (Light Detection and Ranging), a type of airborne laser scanning (ALS), is a form of indirect data capture, whereby a laser beam is used to measure distances to points within the field of view of a laser scanner. The big difference between this and terrestrial laser scanning (TLS) is that the scanner is mounted in an aircraft pointing down towards the ground, typically capturing a 3D measurement every 10-200cm.
 
Airborne LiDAR is an excellent way of capturing surface data over entire landscapes. Wessex Archaeology work with data from archived data repositories (such as that managed by the Environment Agency) and also commission our own flights to capture new data.
 
ALS data can also be used to produce Digital Terrain Models (DTMs) and/or Digital Surface Models (DSMs); DTMs are usually bare-earth models with all extraneous surface features such as trees and buildings removed whereas DSMs comprise everything recorded by the laser scanner. Whilst the removal of trees and buildings is often useful, the algorithm used to do this can have adverse effects on upstanding archaeological features so it is important to choose the appropriate model for the task in hand.
 
These models can be used within Geographic Information Systems (GIS) for analysis and interpretation, allowing us to draw profiles across monuments and features, examine the slope or aspect of the ground surface, and conduct spatial analysis such as visual impact assessment. Advanced analytical techniques can be applied to enhance and visualise the 3D data which is then typically interpreted in a similar way to aerial photographs. TheDTM/DSMs can also be used within 3d modelling packages to produce rendered images and videos of landscapes. Approaches such as realistic and analytical lighting, archaeological reconstruction work and the inclusion of, modelled people and vegetation are used to help with interpretation and understanding.

180 Frame from a rendered animation of a virtual fly-through of the Stonehenge World Heritage Site LiDAR dataset

Terrestrial & Close Range Laser Scanning

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Laser Scanning is a form of indirect data capture that typically involves the use of a laser beam to measure distances to a series of three dimensional points on the surface of an object.. The term indirect indicates that the user does not choose which individual points to record, instead the resolution and area of interest are specified and the scanner fires enough laser beams to indiscriminately measure however many points are needed. This results in what is called a point cloud, a mass of 3D measurements.
 
Laser scanning is an ideal technique for a range of purposes from detailed recording of objects and architectural features to recording of buildings, complexes of buildings or entire landscapes or cityscapes. A number of types of laser scanner are available to suit different needs. The technique is particularly suited to archaeological work where there may not be obvious lines or points for a surveyor to record and what is really needed is a spread of measurements across a surface, for example the walls of a ruined castle or an earthwork.
 

Buildings, structures and landscapes

Terrestrial Laser Scanning (TLS) employs either a time of flight or a phase-offset method to establish distances and is often used to survey entire buildings and large engineered structures but can also be used to survey the ground surface ie for topographic survey. Data captured this way can be imported into Geographic Infomration Systems for detailed analysis to produce Digital Surface Models (DSMs) and contour plans. This makes it possible to draw profiles across surface features, to examine the slope or aspect of the ground surface and to conduct spatial analysis such as visual impact assessment.
 
Airborne Laser Scanning (ALS) techniques, including LiDAR, use similar methods but from an aerial viewpoint; more information on such techniques can be found here.
 

Objects and Artefacts

Close Range Laser Scanning (CRLS) uses very high resolution scanners to capture much smaller areas of data at very  high resolutions; right down to tens of microns. This is particularly useful for recording smaller objects or in-situ structures and features requiring very detailed surface analysis.
 

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Terrestrial laser scanning of buildings, structures and earthworks typically reduces time spent on site compared with more traditional direct survey methods., The big difference however is in the post-fieldwork stage. Having a detailed point cloud and other supporting information allows our archaeologists to make better informed decisions in order to produce a range of informative products such as elevation drawings or orthographic images. We are also able to return to a scan dataset many times in order to extract measurements for purposes which may not have been foreseen during fieldwork.
 
TLS is also suitable for monitoring purposes; to investigate and measure change over time. This may be to quantify the effects of natural erosion, damage to buildings and earthworks caused by people, animals or vehicles or it could be to assess the deformation of a historic structure over time.

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Guidance for metric survey projects including TLS is provided by the Metric Survey team at English Heritage and all our work is undertaken to their standards. Wessex Archaeology are also members of the Survey Association, a professional body for organisations undertaking survey work.
 
Contact us on 01722 326867 or
email p.baggaley@wessexarch.co.uk for further information.
 

Case Studies

Photographic recording

Photography is an essential tool for recording heritage as part of a broad range of projects. As well as using film photography, both 35mm and medium format, we make extensive use of a range of digital cameras including full-frame professional grade systems.

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We often use photography in conjunction with Mobile Geographic Information Systems (GIS) as part of walkover surveys and condition assessments to allow us to build up a digital photographic record and register as we go, including the location of each photograph. This also allows for integration into our database/GIS based reporting and analytical systems on return to the office.
 
High Dynamic Range (HDR) photography involves capturing a range of photographs from the same location with different exposure settings so as to capture a broader range of highlights and lowlights. A single image will typically contain some over- and under-exposed areas and the HDR technique allows a single composite image to be constructed which reduces or eliminates these extremes, allowing detail in darker and brighter areas to be seen in the same image.

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Rectified Photography is a method which combines direct data capture using Total Station Theodolites (TST) with photographic images, producing a scaled, orthographic image which as well as being a photographic record has the properties of a measured survey. This provides a visual record of the subject as well as the ability to measure distances within the image.
 
Panoramic Photography allows a seriesof imagesto be composited into one interactive view, often called a bubbleworld. A series of photographs are taken from a single location using a tripod and (optionally) with a special tripod head designed to reduce distortion between images as the camera is rotated around the scene. These images are then projected onto the inside of a virtual cylinder, sphere or cube so that when viewed from the camera position, they form a complete 360° scene.

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Measured Survey

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Measured Survey involves measuring distances and angles to produce 3D data and/or 2D plans and drawings of archaeological sites and structures. Wessex Archaeology typically use survey instruments for such work, for example Global Navigation Satellite Systems (GNSS) and/or Total Station Theodolites (TST).
 
The TST uses laser beams and an angle measuring device combined with a data logger all in one instrument. TST work is a form of direct data capture whereby the surveyor uses the instrument to measure specific points and lines on the subject. We use these to record buildings, structures and architectural details and on archaeological excavation sites to record precise locations of artefacts or skeletal remains.

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When working on buildings or structures, our surveyors typically use such instruments in conjunction with tablet computers to allow them to build a 3D wireframe model of the subject in real-time in the field, a highly efficient process which allows them to see their results as they go and  ensures high quality data is captured. From this 3D CAD drawing, we can then produce elevation drawings and interpretive figures such as phase plans showing the development of the building or structure through time.

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The GNSS uses satellites to calculate an exact position on the earth’s surface to within a centimetre, another form of direct data capture. GNSS covers a family of systems including GPS operated by the United States, GLONASS operated by Russia, Galileo operated by Europe and Compass operated by China. These instruments allow us to rapidly undertake topographic survey of earthworks and landscapes and are also used to locate TST surveys within the British National Grid coordinate system as used by the Ordnance Survey.
 
Both GNSS and TST are used for monitoring of archaeological assets, to measure any change over a period of time. This includes activities such as monitoring erosion over earthworks and monuments or deformation in a structure.

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Guidance for metric survey projects is provided by the Metric Survey team at English Heritage and all our work is undertaken to their standards. Wessex Archaeology are also members of the Survey Association, a professional body for organisations undertaking survey work.
 
Contact us on 01722 326867 or email p.baggaley@wessexarch.co.uk for further information.

Aerial Photography

Aerial Photography has been used for many years to identify and record archaeological sites. Depending on the lighting conditions, time of year and vegetation cover, it is possible to see a variety of archaeological features in aerial photographs including earthworks and even sub-surface features (as soil marks, crops marks or changes in vegetation).

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With the advent of Remote Sensing techniques including airborne LiDAR (Light Detection and Ranging) and CASI (Compact Airborne Spectrographic Imager), aerial photograph interpretation techniques have been applied to a much wider range of source images. Both these datasets and aerial photographs can be manipulated using Geographic Information Systems (GIS) to further enhance features of interest.
 
Guidance for the transcription of aerial photographs as part of archaeological survey projects is provided by the National Mapping Programme team at English Heritage and all our work is undertaken to their standards. Such work is often carried out as part of Historic Environment Record (HER) enhancement projects in order to add to the archaeological records held by local authorities.

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Historic Environment Record (HER) / Sites & Monuments Record (SMR) Audit and Enhancement

The National Monuments Record (NMR) runs a programme of HER Audits and Audit Reviews. These are carried out by the individual HERs following a specification produced by, and using a database supplied by, the NMR. A grant to carry out the audit is available from the NMR to cover 50% of the cost. The audits are wide ranging in scope covering the data, database, GIS, archives, resources (financial and staffing), website and services. Wessex Archaeology staff have considerable experience in working with a range of HER systems and situations and can assist with undertaking audits, particularly useful when internal resources are already overstretched.
 
Similarly, Wessex Archaeology can provide an HER enhancement service, either on a per project basis or on a longer term arrangement. Our staff have experience of working in SMR/HERs and are trained in the use of a variety of systems including the HBSMR software. By using Wessex Archaeology to create, enhance or maintain records, resources that would otherwise have been devoted to this task can be used elsewhere.
 

Geographic Information Systems (GIS)

Geographic Information Systems (GIS) are essentially database management systems (DBMS) capable of storing spatial information and which provide a map-based view of the data. Google Maps is a commonly used simple GIS platform but we also use a range of more specialised desktop and server-based applications for data capture, analysis and cartography.

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Much of our work now involves GIS including archaeological excavation and evaluation, desk-based assessments and transcription work with aerial photos and LiDAR. As most Historic Environment Records (HERs) also use GIS for the management of their heritage records, we also use GIS for HER enhancement work where we add to or enhance existing HER records. Our use of mobile GIS is invaluable here as it allows us to take HER information out into the field and, where necessary, capture new information.

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Where data does not exist in digital form, we can digitise points, lines and polygons from source plans and maps by georeferencing source material to a specified coordinate system such as the British National Grid, WGS84 or UTM zone. By attaching Global Navigation Satellite Systems (GNSS), we can use GIS to capture data in the field using mobile devices or on computers situated on boats for marine work.
 
GIS can also be used to undertake spatial analysis. This can include analysis of topographic survey data to quantify data quality or produce derived products such as hillshades, slope and/or aspect maps. Models of change can also be prepared using data from measured surveys including terrestrial laser scanning (TLS) and airborne laser scanning (ALS); depending on the scale, these can be used to monitor erosion and quantify impacts on a large scale, for example coastal erosion, or on a small scale, for example vehicular damage to earthworks. Spatial statistics can be used to investigate apparent patterns and correlations between features. Visual impact can be investigated using visibility analysis a method able to calculate the extent of potential visual intrusion and to inform an assessment of the effect this may have on archaeological sites and landscapes.
 
Maps and plans can be prepared to publication quality using GIS, including existing data or data captured for the purpose. Cartography is the discipline of conveying information using maps and our Graphics and Geomatics teams have considerable experience in producing high quality maps for archaeological purposes.

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GIS is a good way of publishing spatial information online and we regularly use Web Mapping Services (WMS), mobile GIS and platforms such as Google Maps to share our information with clients and the public, for example producing virtual tours of archaeological landscapes.
 
All our GIS and database work adheres to national heritage standards such as MIDAS Heritage and uses the National Monuments Record thesauri and the Inscription terminology lists maintained by the Forum on Information Standards in Heritage (FISH). This ensures our data is interoperable with other datasets and is fully compliant with English Heritage recommendations.

Mobile Geographic Information Systems

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Mobile Geographic Information Systems (GIS) allow us to take spatial data out into the field and (optionally) capture new spatial data. These systems comprise a mobile computer, either a tablet computer or PDA, running GIS software equipped with a Global Positioning Device (GPS) or Global Navigation Satellite System (GNSS) to provide a location. Depending on the needs of the project, these systems can provide <10m or 3-5m or <1m accuracy on the ground.
 
Being database driven, structured data can be used to determine the cartographic style and control data capture, ensuring standards can be enforced. These can either be national standards, for example for land use classifications, or client specific standards, based on agreed recording pro-forma. This makes data captured in this way ideal for subsequent analysis and reporting, the best solution for gathering monitoring information about archaeological sites (e.g. condition surveys) or for validating data produced by desk based assessments in the office or for walkover surveys aimed at locating potential new sites and monuments (eg as part of Rapid Coastal Zone Assessment Surveys).

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It is possible to take any spatial data out into the field this way including client supplied plans and maps, historic and modern Ordnance Survey maps, Historic Environment Record (HER) datasets or even LiDAR data, aerial photos and associated transcriptions.
 
Any data captured out in the field can then be loaded into our desk-based GIS and database applications ready for analysis and reporting, removing the need to enter data from paper-based recording forms.

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Using open platforms such as Google Maps, it is also possible to use mobile GIS to deliver interesting and informative content to the general public, for example as part of landscape tours and other outreach activities. In this way we can deliver rich GIS data to any mobile device, optionally equipped with GPS, including SmartPhones, iPads and tablet computers and using the internet can provide links to further sources of online information, either pre-existing resources such as online HER pages or Wikipedia pages, or we can create online resources for particular projects including rich multimedia (pictures, videos and interactive elements).
 

GIS Consultancy, advice & training

Getting the right advice at the right time is very important when commissioning projects which involve Geographic Information Systems (GIS). Wessex Archaeology’s Geomatics team have considerable experience in all aspects of GIS and survey and can provide consultancy services and/or contracting services to meet most heritage geomatics needs. Our team have experience working in all areas of the heritage sector including for national bodies such as English Heritage and the Ordnance Survey, local authorities, charitable bodies, education establishments and commercial companies. We have close links with university departments specialising in heritage computing and work closely with hardware and software manufacturers to get the most out of available technologies for heritage purposes.
 
Where there is a need for GIS components within a project, we can advise on and/or provide the necessary skills and services as a fully costed block for insertion into a larger project. For example, this might be as part of a MoRPHE compliant Project Outline/Design for an English Heritage funded project, a grant submission for funding from one of the UK Research Councils (for Higher Education establishments) or a Heritage Lottery Fund (HLF) bid.
 
Training is a key element in the successful use of GIS, especially so for the use of GIS in heritage contexts. GIS is an expansive discipline in its own right and the key to successful heritage use is to have training in the specific aspects of it that are directly relevant to heritage rather than generic GIS training courses which may cover some aspects in far too much detail yet not cover other important aspects in enough detail if at all. Our trainers have taught the use of GIS for heritage use in a variety of contexts including the commercial archaeology sector, providing GIS teaching within university archaeology departments at undergraduate and postgraduate levels and also providing GIS training for archaeologists working in Cultural Heritage Management contexts particularly those within Local Planning Authorities.
 

Polynomial Texture Mapping / Reflectance Transformation Imaging

Polynomial Texture Mapping, or PTM for short, is part of the family of technologies known as Reflectance Transformation Imaging (RTI). RTI approaches have for the last ten years been traditionally used to create interactive images of objects, whereby the user is presented with a photograph of an object whose illumination can be altered at will on screen. This 'interactive relighting' of objects can be incredibly powerful in revealing the detail of a surface. Because the technique captures the surface normal in addition to colour information, a variety of powerful filters can be used to enhance the surface, even removing colour information entirely. RTI techniques are being used within the cultural heritage sector to help read cuneiform tablets, illuminated manuscripts, interpret rock art, read eroded inscriptions, and examine glazes, to name but a few of its applications.
 
These techniques can also be used to investigate whole landscapes by transferring the technique to a virtual world. Using virtual objects captured using Airborne Laser Scanning (ALS), Terrestrial Laser Scanning (TLS) or Close Range Laser Scanning (CRLS) techniques, combined with virtual lights and virtual cameras, it is possible to generate the same sorts of interactive outputs as with real objects, lights and cameras.

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Case Studies

 

Multi-image photogrammetry

1345 Mesolithic handaxe on the Baltic seabed

Multi-image photogrammetry (or Structure from Motion) is an extremely versatile, rapid and cost-effective tool for recording and analysis of objects and surfaces. Although photogrammetry has been used for survey for over a century, recent advances in computing power and software have resulted in a technique able to produce results similar to those of laser scanning, under suitable conditions but with much lower overheads. Wessex Archaeology has been at the forefront of adoption and exploitation of the technique and now has a sector-leading capability in multi-image photogrammetric survey for heritage applications. Multi-Image Photogrammetry is a powerful method of capturing high-resolution 3D surfaces with complete texture with sub-centimetre accuracy.
 

1346 17th century stone carving of a ship

Wessex Archaeology has undertaken a wide range of photogrammetric surveys, including aerial and terrestrial topography, Historic Building Recording, underwater wreck survey and small finds recording. Our resources include high-end digital cameras, a comprehensive suite of professional photogrammetric software, a bank of dedicated geomatics workstations and a full range of 3D modelling software for producing high-quality stills, videos and reconstructions.
 
For the full range of geoservices click here
For the full range of coastal & marine services click here
 

Case Studies

 
 

BIM for Heritage

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In May 2011 the UK Government published its construction strategy, which aimed to reduce the CAPEX, OPEX and risk in public sector building projects by up to 20% by 2016. In order to achieve this it was mandated that by the 4th of April 2016 all centrally procured government projects would be working at BIM Level 2. This requires the use of 3D data, collaborative tools, clear documentation and strict contract control, all under a framework of industry standards. The hope was that this requirement would cause widespread adoption of Building Information Modelling (BIM) across the construction industry, leading to a more efficient, successful and stable industry. The clear benefits of BIM mean that it is now used by firms large and small throughout construction, whether working on public or private sector projects.
 

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BIM is far more than the use of certain software or 3D modelling; it is a project, data and resource management process with a greater level of integration than any other such tool. Just as it can improve the construction aspects of a project, it can also improve the heritage aspects. The principles of BIM can be applied to both built heritage and infrastructure projects to gain these benefits.
 
Wessex Archaeology have been investing in developing work flows for the application of BIM in a heritage context for a number of years and can respond to your BIM requirements. Apart from the use of COBie files, which do not support heritage data, Wessex Archaeology is fully BIM Level 2 compliant, and our understanding of BIM has led to processes designed specifically to meet our client’s needs across a range of projects. One of the key elements of a successful project is early engagement of all contractors and BIM puts this at its heart. Contacting us at the early stages of your project will allow us to deliver the maximum benefit of BIM and improve project outcomes.
 
If you would like more information on some of the ways BIM can be utilised in a heritage context you can read our four part article series in BIM Today magazine issues 3-6.
 
If you would like to discuss your BIM requirements, or join us for a lunchtime CPD session on BIM and heritage, please get in touch with our Geomatics team.
 
Damien Campbell-Bell                                   Chris Breeden
03303 133450                                            03303 133510
d.campbell-bell@wessexarch.co.uk              c.breeden@wessexarch.co.uk