DOI: 10.1594/pangaea.956223
title: 53 orthomosaics processed from Unoccupied Aerial Vehicle (UAV) image data of lake shorelines sampled during a field campaign in Central and Eastern Yakutia, Siberia in 2021 (RU-Land_2021_Yakutia)

description: During the RU-Land_2021_Yakutia summer field campaign in August and September 2021 in the Verkhoyansk Mountain Range in Eastern Yakutia and in the Central Yakutian Lowland, multispectral drone-based images were acquired over 53 selected lakes to analyse the vegetation and shallow lake waters along shores and to record the current lake shorelines. The images were taken in the course of further investigations of the lakes during that summer expedition. Baisheva et al. (2022) gives an overview of the lakes studied and the corresponding hydrochemistry. In addition, we published datasets including water isotope data of the lake (Stieg et al. 2022) and vegetation surveys of the lakeshores (Stieg et al. 2022).This dataset includes the orthomosaics (in raw data format (DN), and for the good-quality acquisitions normalised to surface reflectance) and the processing reports of the 53 sampled lakes. The event list gives an overview of the relevant lake information, which can be found here: https://doi.pangaea.de/10.1594/PANGAEA.955723 We used a consumer-grade, lightweight Unoccupied Aerial Vehicle (UAV) set up in combination with a D-RTK Station (GNSS antenna). The multispectral images were taken by a DJI Phantom 4 quadcopter UAV including an imaging system with one Red-Green-Blue RGB sensor and five spectral channels, able to capture both colour and narrow band images (5 bands: Blue, Green, Red, Red-edge, Near-infrared).A standardized flight plan was used to capture the shoreline of the lakes whenever possible using the DJI GS Pro app. If a preliminary route planning was not possible due to non-high-resolution map material or external circumstances (limited view, wind, rain), it was flown manually. For both flight procedures, multispectral images were taken automatically every 2 seconds. Speed was set to 4 m/s and altitude above ground level to circa 55 - 60 m.The produced UAV images were processed to construct the orthoimages using the software Agisoft Metashape Professional, version: 1.7.5. build 13229 (64 bit). Orthoimages are geometrically corrected images that are georeferenced to the topography (the relief) and vegetation (the top-of-canopy elevation). The orthomosaics were constructed from the multiple overlapping pictures from different camera viewpoints which make it possible to create a photogrammetric point cloud reconstruction and constructing the orthomosaics using structure from motion/multi-view stereo (SfM-MVS) techniques. There was no preselection of the images before the processing. Regular settings of the software were used, the processing parameters are listed in the individual processing report of each orthomosaic. The Micasense DLS2 illumination-sensor data, measured in parallel during each acquisition, was used to normalize the Digital Number (DN) of the orthomosaics to surface reflectance.
description: All data were collected and processed by scientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), Germany, the University of Potsdam, Germany, Technische Universität Berlin (TUB), Germany and the North-Eastern Federal University of Yakutsk (NEFU), Russia.