Coastal erosion monitoring at Skara Brae, Orkney

I have just returned to Edinburgh after an adventurous 4-day fieldwork trip to Skara Brae in Orkney, using laser scanning to determine the degree of coastal erosion on the Bay of Skaill around the neolithic settlement. To do that, a 3D survey of the site is conducted every 2 years and the data compared to determine the changes in the position and shape of the sand dunes forming the edge of the coast.

 

Due to limited time on site (and adverse weather conditions) 2 teams were working at the same time on the beach using the Leica P40 and C10 scanners and survey control using traverses and GPS. The C10 was used to scan the top of the dunes on the east of the village, in a traverse tying to scans along the beach (see photos).

 

The weather was not in our favour (low temperatures and high winds), but the work was completed in time. The data is being processed at the moment and the comparison with the 2014 scans will reveal the degree of erosion on the coastline.

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Edinburgh Castle Palace Scan2BIM

March was a very busy month for the Digital Documentation team. Much of our time has been spent laser scanning the Palace block at Edinburgh Castle for a scan-to-BIM case study by Historic Environment Scotland. The idea is to create an BIM or AIM (asset information model) of the Palace block to be used for the subsequent management of various aspects of the building’s function.

Laser scanning is the primary method of survey for the building fabric (architectural elements), but it will be supplemented by additional surveys. The laser scanning survey is guided by the Asset Information Requirements document, which specifies areas of interest/priority and required levels of detail per category. The goal is to achieve 100% coverage of both exterior and interior spaces.

According to the AIR document, some of the least “glamorous” areas of the building, such as boiler rooms, electrical cupboards, switch rooms, and attic spaces have a higher priority for the model than some of the high-profile exhibition areas for example. This means that a lot of our time on site has been spent crouching inside tiny cupboards and boiler rooms surrounded by pipes and cables. These areas tend to be confined spaces full of equipment, difficult to navigate (or even to set up the scanner) and usually need a lot of scans to get good coverage and avoid shadows or data voids. Although we do not have to scan every last surface inside a boiler room, the AIR document makes it clear that at least the general dimensions and position of all equipment will need to be visible in the resulting point cloud.

In this project, multiple scanners have been used. The Leica P40 produces clean, crisp data with considerably less noise over great distances, but is very difficult (or impossible) to set up inside any of those tight cramped spaces. Therefore, all the cupboards, boiler rooms, switch rooms, etc were scanned with a Faro Focus 3D, which has a much shorter range and produces noisy data, but is significantly smaller, a lot lighter, and can easily fit inside any of those spaces. The same scanner was used in the attics, which were accessible through a folding ladder and generally very tight spaces, difficult to navigate when carrying any sort of equipment. Using the Faro proved very successful in those areas (on a photographic tripod or sitting directly on the floor).

Laser scanning an attic at Edinburgh Castle Palace with a Faro Focus 3D. Ghostbusters uniform to be worn at all times, as per the risk assessment report. 

Registration of the data has been progressing along with the field work. More on that to follow very soon…