Drones, or unmanned aerial vehicles, are useful tools for surveying historic buildings and structures, as well as assisting in diagnosing building failures. Drones can also be useful for archaeological research and of ruined buildings and their surrounding landscape. Drones are small, portable, and able to hover and operate in confined spaces, yet are powerful enough to carry DLSR still and HD/4K video cameras for survey work, as well as lidar and terrestrial scanners. For historic buildings and heritage sites, drones offer high-resolution imagery and data which can be used for monitoring, recording, presentation, interpretative display, surveying, and mapping.
The recent Drone and Tech Expo 10-12th March 2017 at the RDS presented a wide range of UAVs, and many systems already offer roof inspections, mapping and survey services. For historic buildings and archaeological monuments, drones are useful in two main areas – to understand and present the cultural values of the place, but can also be used to assist in inspecting their conditions. Images and video from drones can allow an initial inspection of a high level wall top or roof, and the capture of still and video images allows real-time and off-site consideration of the condition. There are however significant problems in making a judgement on the condition of a historic wall or high level feature from images alone. While detailed, they have severe limitations in determining whether the stability of historic structures. Unlike modern structures such as modern architecture and modern structures such as window power turbines where any deviation can be a red flag, historic structures are more complex and often exhibit a stress history and odd detailing, and it is usually essential to get ‘hands-on’ to evaluate its condition. However, as an initial step it can provide a useful guide and allow targeting of where closer access with a mobile aerial access platform is needed.
Drone imagery is also very useful for the presentation and interpretative display of historic buildings. The imagery can also be used to generate 3D surface models of landscape and buildings. The drone is simply an aerial platform, and data acquisition is most often performed by digital cameras. Larger octocopters mounting DSLRs offer exceptional imagery. However, entry level UAVs with limited payload can carry smaller compact cameras of GoPro Hero cameras. Photogrammetric processing of UAV imagery allow the generation of point clouds and polygonal meshes needed to generate Digital Surface Models to capture buildings and landscapes.
With the ability to rapidly generate on-demand, high-resolution spatial imagery, UAVs offer another tool to record and analyse historic buildings and archaeological sites.