Small unmanned aerial model accuracy for photogrammetrical fluvial bathymetric survey

Fluvial systems offer a challenging and varied environment for topographic survey, displaying a rapidly varying morphology, vegetation assemblage and degree of submergence. Traditionally theodolite or GPS based systems have been used to capture cross-section and breakline based topographic data which has subsequently been interpolated. Advances in survey technology has resulted in an improved ability to capture larger volumes of information with infrared terrestrial and aerial LiDAR systems capturing high density (<0.02 m) point data across terrestrial surfaces. The rise of Structure from Motion (SfM) photogrammetry, coupled with small unmanned aerial vehicles (sUAV), has potential to record elevation data at reach scale sub decimetre density. The approach has the additional advantage over LiDAR of seeing through clear water to capture bed detail, whilst also generating ortho-rectified photographic mosaics of the survey reach. However, data accuracy has yet to be comprehensively assessed. Here we present a survey protocol for sUAV deployment and provide a reach scale comparison between a theodolite and SfM sUAV survey on the River Sprint, Kendal, the River Ehen at Egremont, England and the Afon Elwy, at Llanfair Talhaiarn, Wales. Comparative analysis between theodolite survey and SfM suggest similar accuracy and precision across terrestrial surfaces with error lowest over solid surfaces, increasing with vegetation complexity. Submerged SfM data, captured bed levels generally to within ±0.25 m with only a weak relationship recorded between error and flow depth. Significantly, associated error when linked to channel D50 highlights the ability of unmanned aerial vehicles to capture accurate fluvial data across a range of river biotopes and depths to 2.4 m

Global wealth disparities drive adherence to COVID-safe pathways in head and neck cancer surgery

Peer reviewe

From long-term savings to instant mortgages: financial demonstration and the role of interaction in markets

Accounts of the crisis have privileged 'high finance' innovations whereas retail banks constantly experimented with how they sell (new) products to consumers. I examine the case of product innovation at a home savings bank in Hungary during the pre-crisis credit boom. Turned from offering state-subsidized long-term savings-and-loans to promoting instant mortgages. Based on ethnographic observations of the bank's Direct Selling Organization, I trace the bank's shift from state-subsidized long-term savings-and-loans to instant mortgages, to problems with demonstrating the qualities of financial products, even ostensibly prudent ones. Drawing on concepts of scientific demonstration and proof, I compare how financial advisors explained the plan to consumers before and after it was combined with mortgages: first they drew the funds by hand, later they adopted software-generated scenarios. I suggest that as sellers perform products interactively with clients, consumers' needs appear. Thus, when organized differently, financial demonstrations yield different consumers-with-preferences. Based on this interactional perspective, I find that consumer finance is an 'economy of qualities' where preferences and product properties stabilize through consultation, and where "social" embedding can enable "economic" calculations. Based on this interactional perspective, I examine US and UK proposals for consumer financial protection