ALBERT

Description: This data set consists of satellite based study of East Greenland in particular 260 km-long section of coastline between 66.3 and 68.4◦N, used to explore glacier change from 1985 to 2019. Imagery were downloaded from the USGS website EarthExplorer (U.S. Geological Survey USGS, 1995). We sought images with minimal cloud-cover that were gathered in July/August, when we expect surface snow cover to be at a minimum. We sourced imagery from Landsat-5 for the years 1985 and 1995, from Landsat-7 for the year 2005, and from Landsat-8 for the years 2015 and 2019 (all Landsat imagery courtesy of the U.S. Geological Survey). For each year for which we had data, composite images were generated. The data set consist of shape files of fronts of glaciers in 5-year intervals. Data set used in: Unravelling the long-term, locally-heterogenous response of Greenland glaciers observed in archival photography Michael A. Cooper, Paulina Lewińska, William A. P. Smith, Edwin R. Hancock, Julian A. Dowdeswell, and David M. Rippin, 2021

Description: This data set consists of 1930s, 1960s and 1980s orto-mosiac of East Greenland in particular 260 km-long section of coastline between 66.3 and 68.4◦N The archival orthophotomaps were produced with the use of Agisoft Metashape (Agisoft Metashape, 2020). We used 3 data sets: a) British Arctic Air Route Expedition (BAARE), aerial oblique images taken between July 1930 and August 1931. Photogrammetric reconnaissance was done with the use of two De Havilland DH.60 Moth planes with Gipsy 1 engines equipped for taking vertical and oblique photographs with Williamson P14 camera with a lens of known focal length of 2209.8 mm (7.25'), and 127 mm ×101.6 mm (5' ×4') glass plates with envelope adaptors for changing slides in daylight were used. For our study we used 73 images obtained during the summers of 1930 and 1931. The data set was obtained from Scott Polar Institute and is licensed by this organization. b) CORONA satellite mission, 1959-72, mostly consists of satellite stereo pair images. It was lead by the CIA and the U.S. Air Force, aimed at gathering spatial data for the creation of maps of vast remote areas for intelligence purposes. It was declassified in 1995. We used images taken on 24.09.1966. For this mission the KH-4M stereoscopic camera with 75% overlap was used. The KH-4A (Keyhole-4A) carried two J-1 (in earlier missions KH-3 cameras of 3.66 m resolution) panoramic cameras, with a focal length of 61 cm, and a ground resolution of 2.7 m to 7.6 m. The J-1 cameras were placed on an M (Mural) mount, one pointing 15° aft from the vertical and the other 15° forward. The minimal flight height was 180 km and the duration of each mission was 14-15 days. The panoramic cameras used work on the general principle that during the scanning process the lens and the scan arm moves while the film remains stationary. In this case the lens rotates around the second nodal point allowing the cylindrical focal plane to keep the image of distant objects sharp. As a result a 'bow-tie' shaped region is photographed and becomes compressed into a rectangular image. This effect creates significant panoramic image distortions. No additional meta data is available. The Corona data can currently be obtained (as digital high-resolution scans; 7 μm) from the EarthExplorer website (U.S. Geological Survey). c) Greenland 1:15000 scale, vertical aerial images. Mission was carried out between 1978-87 by the Geodetic Institute, the National Cadastre and Survey of Denmark, and the Danish Geodata Agency. A WILD RC10 camera with a nominal focal length of 87.72 mm was used to collect super-wide-angle photographs at planned flying heights of 13000 m. The images were captured on photographic film, in black and white and with 8 fiducial marks on each image. For our study we used 58 images obtained on 30th of July and 14th of August 1981. Data was obtained from Agency for Data Supply and Efficiency (SDFE). Since we did not have sufficient data to select the images with the best overlap or with the best light conditions, it was decided to use all the available images for this procedure. Initially we divided the 1930s data set into 5 regions for the production of 5 orthophotomaps. However, the 1960s and 1980s datasets were significantly different in terms of their extent and overlap. This forced us to divide our area into different sub-regions in order to produce mosaics of the same glaciers as covered by the 1930s images. For all of the images we found the corresponding areas on the ArcticDEM model and created GCPs on stable, non-ice covered bare ground, which we assume to be fixed over the time period covered. The GCP placement accuracy calculated during the processing of the mosaics was around 1 pixel and in 90% of cases was smaller than 0.8 pixel. The spatial accuracy in metres varied, but in most cases was less than 20 m, and did not exceed 15 m in the X and Y directions separately. This result can be considered satisfactory when taking into account the quality of the ground truth model, problems with the definition of the stable areas for GCPs, and the age and type of the archival images.

Description: Analyses of riverbed shape evolution are crucial for environmental protection and local water management. For narrow rivers located in forested, mountain areas, it is difficult to use remote sensing data used for large river regions. We performed a study of the Prądnik River, located in the Ojców National Park (ONP), Poland. A multitemporal analysis of various data sets was performed. Light detection and ranging (LiDAR)-based data and orthophotomaps were compared with classical survey methods, and 78 cross-sectional profiles were done via GNSS and tachymetry. In order to add an extra time step, the old maps of this region were gathered, and their content was compared with contemporary data. The analysis of remote sensing data suggests that they do not provide sufficient information on the state and changes of riverbanks, river course or river depth. LiDAR data sets do not show river bottoms, and, due to plant life, do not document riverbanks. The orthophotomaps, due to tree coverage and shades, cannot be used for tracking the whole river course. The quality of old maps allows only for general shape analysis over time. This paper shows that traditional survey methods provide sufficient accuracy for such analysis, and the resulted cross-sectional profiles can and should be used to validate other, remote sensing, data sets. We diagnosed problems with the inventory and monitoring of such objects and proposed methods to refine the data acquisition.

Description: The study is devoted to the uses of laser scanning in the field of engineering surveying. It is currently one of the main trends of research which is developed at the Department of Engineering Surveying and Civil Engineering at the Faculty of Mining Surveying and Environmental Engineering of AGH University of Science and Technology in Krakow. They mainly relate to the issues associated with tower and shell structures, infrastructure of rail routes, or development of digital elevation models for a wide range of applications. These issues often require the use of a variety of scanning techniques (stationary, mobile), but the differences also regard the planning of measurement stations and methods of merging point clouds. Significant differences appear during the analysis of point clouds, especially when modeling objects. Analysis of the selected parameters is already possible basing on ad hoc measurements carried out on a point cloud. However, only the construction of three-dimensional models provides complete information about the shape of structures, allows to perform the analysis in any place and reduces the amount of the stored data. Some structures can be modeled in the form of simple axes, sections, or solids, for others it becomes necessary to create sophisticated models of surfaces, depicting local deformations. The examples selected for the study allow to assess the scope of measurement and office work for a variety of uses related to the issue set forth in the title of this study. Additionally, the latest, forward-looking technology was presented - laser scanning performed from Unmanned Aerial Vehicles (drones). Currently, it is basically in the prototype phase, but it might be expected to make a significant progress in numerous applications in the field of engineering surveying.

Description: This research is focused on searching for frequency and noise characteristics for available GNSS (Global Navigation Satellite Systems). The authors illustrated frequency stability and noise characteristics for a selected set of data from four different GNSS systems. For this purpose, 30-s-interval clock corrections were used for the GPS weeks 1982–2034 (the entirety of 2018). Firstly, phase data (raw clock corrections) were preprocessed for shifts and removal of outliers; GLONASS and GPS satellites characterize a smaller number of outliers than BeiDou and Galileo clock products. Secondly, frequency and Hadamard deviation were calculated. This study concludes that the stability of GPS and Galileo is better than that of BDS (BeiDou Navigation Satellite System) and GLONASS. Regarding noise, the GPS, Galileo, and BDS clocks are affected by the random walk modulation noise (RWFM), flashing frequency modulation noise (FFM), and white frequency modulation noise (WFM), whereas the GLONASS clocks are mainly affected only by WFM.