High-resolution UAS LiDAR digital surface model and multispectral orthomosaic of Bjørndalen, Svalbard (July 2024)

This dataset contains a LiDAR-derived digital surface model (DSM) and a multispectral orthomosaic (OM) covering a 140 ha High Arctic study area in Bjørndalen, Svalbard. These datasets are provided as GeoTIFF files with a spatial resolution of 1 m. Both datasets were collected during a field work campaign at the peak of the vegetation season (13.-17.07.2024) using a Trinity Pro (Quantum-Systems GmbH, Gilching, Germany) fixed-wing uncrewed aerial system (UAS) capable of vertical take-off and landing. The DSM and OM both have a spatial extent of (15°17'27.058", 78°12'32.842" : 15°21'0.882", 78°13'31.408") and are provided in EPSG:25833 (ETRS89 / UTM zone 33N). Digital surface model The DSM was created using data collected with a Qube 240 LiDAR sensor (Quantum-Systems GmbH, Gilching, Germany) acquired on 16.07.2024 at a flight altitude of 100 m (terrain following, average leg altitude) with 50% side overlap. The resulting LiDAR point cloud had a point density of about 94 points/m$^2$. The LiDAR point cloud was processed using post-processing kinematic (PPK) GNSS data from the ETPOS CORS network (Kartverket, Norway). We used Emlid Studio (version 1.9) to convert the GNSS observations to RINEX and subsequently created the smoothed best estimate of trajectory in Applanix POSPac UAV (version 9.0). Using YellowScan CloudStation (version 2403.0.1), we corrected the trajectory of the UAS, performed georeferencing, and created the DSM. The original resolution of the DSM was 10 cm per pixel, which we resampled to a resolution of 1 m per pixel using mean aggregation. The DSM (width: 1344, height: 1823) consists of one band: Elevation: surface elevation in meters above mean sea level (min. value: 1.98 m, max. value: 111.11 m). The DSM represents the elevation of the uppermost surface detected by the LiDAR sensor, including vegetation, rocks and other surface objects. Given the High Arctic environment of the study area, where woody vegetation and tall shrubs are absent, the difference between the DSM a a bare earth-elevation model is expected to be minimal across most of the landscape. Multispectral orthomosaic The OM was created using images taken with a MicaSense AltumPT multispectral sensor (EagleNXT, Allen, TX, USA) and is a composite of three flights (13.-17.07.2024) at a flight altitude of 100 m (terrain following, average leg altitude) with 78% forward and 80% side overlap. The resulting ground sampling distance was about 2.1 cm. The multispectral images were processed in Agisoft Metashape (version 1.8.4) using a Structure-from-Motion workflow. The data was pre-processed by performing reflectance calibration with images of a calibrated reflectance panel (MicaSense CRP 2) and data from a downwelling light sensor (MicaSense DLS 2). Alignment between the OM and DSM was ensured through the use of manual reference points using additional orthomosaics created from multispectral data collected with a DJI Mavic 3M and processed using a PPK workflow. The original resolution of the OM was 5 cm per pixel, which we resampled to a resolution of 1 m per pixel using mean aggregation. The OM (width: 1344, height: 1823) consists of five bands: Red: reflectance for wavelengths $668 nm \pm 7 nm$ Green: reflectance for wavelengths $560 nm \pm 13.5 nm$ Blue: reflectance for wavelengths $475 nm \pm 16 nm$ Red edge: reflectance for wavelengths $717 nm \pm 6 nm$ Near-infrared: reflectance for wavelengths $842 \pm 28.5 nm$