Mapping the Past to Safeguard the Future

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MAPPING THE PAST TO SAFEGUARD THE FUTURE

Geospatial technology supplier, 3D Laser Mapping, recently released a detailed 3D map of Newark Castle in Nottinghamshire, UK. Here, business development director Mark Brown tells LiDAR News about the project and explains why the mapping of heritage sites is crucial.

Last month marked the 800th anniversary of the death of ‘Bad King John’. Portrayed as the greedy tax obsessed lion in the Disney cartoon Robin Hood, King John ruled England from the 6th of April 1199 until his death on 19th of October 1216.

In some quarters, King John has been dubbed as the ‘most evil monarch in British history’, and after contracting dysentery on his travels he painfully made his way as far as Newark Castle where, after a large feast, he died aged just 49.

Newark Castle lies just ten miles from the 3D Laser Mapping offices, so to mark the anniversary of King John’s death, we decided to take an in-depth look at the historic landmark with our multi-platform mapping system, ROBIN.

Newark Castle stands on the banks of the River Trent and is inaccessible by foot on one side. Using ROBIN, attached to a backpack, our team performed a 360° scan of the castle in under 15 minutes. The process proved to be much quicker than using terrestrial laser scanners, as these type of scans can take around a day and a half, with multiple set ups required to capture the same amount of data

The results gathered were extremely interesting, from the detail of the original mullioned windows to lost and damaged bricks on the ramparts. With survey-grade mobile systems now available, mobile scanning can achieve accuracies of around 10-20mm. It’s this kind of attention to detail that makes systems such as ROBIN ideal for documenting the intricacies of historical heritage.

The following video shows an elevated animation of the resulting pointcloud created by ROBIN.

Looking in-depth at heritage sites such as Newark Castle allows for closer inspection of architectural details, as well as the potential to maintain – and even rebuild – an exact replica of the building in the event that the structure is damaged beyond repair.

ROBIN is unique in its field, as it provides a multi-purpose all round system, integrating a 360° field of view laser scanner, 12 MP camera, two GNSS antennas, inertial navigation system, touchscreen control unit and three mounting systems. The ROBIN package also includes complete capture and post-processing software so users can gather data quickly and accurately.

The benefits of LiDAR in archaeological documentation were first recognised at a NATO symposium in Poland in 2000. Following a survey of the River Wharfe in Yorkshire, a Roman fort was discovered – previously thought to have been destroyed many years prior.

This finding led to Historic England engaging with the Environment Agency’s Geomatics Group to conduct an aerial LiDAR survey of World Heritage Site, Stonehenge, which produced a highly detailed terrain model that allowed for the study and identification of archaeological features, which otherwise may have gone unnoticed. Several new sites were discovered in the investigation and the scan also provided a map of much greater accuracy than previously recorded.

Other recent findings include the discovery of a network of medieval cities buried beneath the floor of the forest close to Siem Reap in Cambodia. A number of ancient sites have also been uncovered in Honduras and more has been learnt about Cannock Chase in Staffordshire and its involvement in The Great War. All these discoveries used the latest in LiDAR technology.

Almost all cultural heritage projects require the recording of dimensions, position and form to allow for documentation and analysis. Laser scanning allows for the detailed retrospective study of buildings and artefacts, giving conservation experts the ability to spot changes and erosion over a period of time by comparing repeated scans. Project managers can also plan restorative works more easily when they have access to an accurate 3D scan of the project.

Despite recent accomplishments made in the application of LiDAR in archaeological projects, it is yet to see extensive use within the industry. Sadly, there are several obstacles preventing the technology being more widely used.

Technological innovation comes at a cost, which can prohibit the use of certain equipment, especially in the not-for-profit sector. To perform effective scans of remote areas can also involve the use of planes or helicopters, especially where vegetation is dense and impenetrable. Often, external grants or funding are applied to help pay for specific projects, though collaboration between stakeholders and interested parties can help to raise funds or provide resources. We’ve seen this with larger scale applications, such as Cannock Chase where Staffordshire County Council worked with Historic England to deliver the project in the form of a grant from the Heritage Lottery Fund.

Even though scans, and scanners in particular, can be an expensive acquisition, the data collected allows for the examination of a large area, in detail, with the ability to zoom in to specific areas of interest. This has proven to be an invaluable way of referencing scale pre and post excavation, with mobile systems cutting the time spent scanning even further.

As shown at Newark Castle, vast amounts of data can be collected in minutes if the mapping system is moving. Some figures show that scans of this type proved to be over 80 per cent faster than if using terrestrial laser scanners. When factoring in the cost of human resources and time, the increased speed and practicalities of mobile mapping systems can suddenly become a game changer. With the cost of LiDAR systems dropping and the technology becoming more commonly used in other industries, there are many more opportunities for collaboration between the private and non-profit sectors.

Following a two-year project by the School of Civil Engineering and Geosciences at Newcastle University, professional guidance to cover 3D laser scanning for archaeology and architecture has now been developed. The project sought to provide information to guardians of national heritage such as local authorities, archaeologists and architects, to facilitate the use of LiDAR scanning for documentation and preservation.

Historic England has since released two publications, including ‘3D Laser Scanning for Heritage’, which builds on the guidance notes from Newcastle University. This provides a general overview, including the decision-making process, the accuracy required, and time and access restrictions. These pointers help people understand how best to capture the data, and how it can be used and archived.

Another publication, ‘The Light Fantastic’, focuses on Airborne Laser Scanning (ALS) for archaeological surveys, helping those in charge of historical documentation decide whether LiDAR data can help them achieve their research aims.

It’s encouraging to see the archaeological sector begin to embrace LiDAR technology, and the recent discoveries and published captured data has no doubt caused wide excitement in the industry and beyond.

For more details on 3D Laser Mapping and ROBIN visit www.3dlasermapping.com/robin.

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