Inside Unmanned Systems provides actionable business intelligence to decision-makers and influencers operating within the global UAS community. Features include analysis of key technologies, policy/regulatory developments and new product design.
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70 unmanned systems inside April/May 2016 AIR MAPPING heritage- and conservation-related services to various clients, including drone-derived data collection and processing. Rauxloh, who himself holds a PhD in ar- chaeology, said MOLA was asked to f ly a small unmanned aircraft over the hillfort site in Au- gust 2015 with the aim of capturing detailed two- and three- dimensional data over a wide area. This was to provide both baseline data for research and management purposes and an immersive representation of the monument. The elongated shape of the site, some 800m long and 400m at its widest point, coupled with a strong wind blowing diagonally across it, required an clever f light plan to capture the imagery accurately, Rauxloh said. "Since the aircraft must f ly in a regular grid pattern, we needed to turn into the wind at the end of each leg. Equally, since the overlap between one image and the next image must be maintained around the magic 80% mark, and because that overlap is directly propor- tional to speed, we needed to keep a constant speed. We therefore f lew across the wind, since f lying directly into it would lead to great variation in speed on each leg of the survey." Nine ground control targets were laid out and their positions accurately recorded, and the f light was completed in about 30 minutes. The data was processed in Agisoft PhotoScan with the resultant detailed 2D orthomosaic and 3D model made available immediately to researchers via DroneLab (2D orthomosaic) and Sketchfab (3D model) web services (best viewed with the Chrome browser). Rauxloh said MOL A uses DJI hexa and quad copters, and is currently considering Lehmann Aviation fixed wing aircraft for lon- ger sorties. "Stability and affordability plus a broad user base are important, as is ease of use and good support from our suppliers." Because MOLA undertakes 'aerial work', i.e. for payment, the rules for them are different. "We have carried out commercial work in the UK and research f lights in Spain and Germany," said Rauxloh. "Different Federal Aviation Authorities do have different rules, and some are more draconian than others. In the UK, for example, UK Aviation Law re- quires an organization such as ours to hold a Permission for Aerial Work (PFAW) to allow them to provide a commercial service to cli- ents using small unmanned aircraft (SUAs)." Rauxloh said MOLA works with EuroUSC, which is a company that helps groups like MOL A achieve compliance w ith complex CA A reg ulations for commercial ser v ice providers. "Our Basic National UAS Certificate for Small Unmanned Aircraft (BNUC-S), which we obtain with the help of EuroUSC, is the preferred pilot qualif ication required by many national aviation authorities before a permission or exemption for aerial work may be granted," Rauxloh explained. "We currently have one qualified pilot at MOLA and two more in training," he added. THE NON- PROFIT MUSEUM OF LONDON ARCHAEOLOGY USES AGISOFT PHOTOSCAN to process the images it captures with its drone. The detailed 2D orthomosaic and 3D model aare then made available immediately to researchers via two web services: DroneLab for the 2D orthomosaics and Sketchfab for the 3D models. The team from the Catholic University of Louvain takes drone photos daily, which they use for mapping the archaeological site. Photo courtesy of Jan Driessen, the Catholic University of Louvain