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Using unmanned aerial vehicles in recognizing terrain anomalies encountered in the gas pipeline right-of-way (row)

100%

Kozuba J. , Marcisz M. , Rzydzik S. , Paszkuta M.

tom z. 123

57--73

The objective of the undertaken research was to characterize and evaluate the impact of weather and lighting conditions on recording terrain anomalies in the photographs obtained during a UAV photogrammetric flight. The present work describes the use and capabilities of the UAV in the mapping of photo acquisition conditions similar to those performed during inspection flights with the use of a manned helicopter equipped with a hyperspectral camera, in the target range of visible light. The research was conducted in the southern part of Poland (between Gliwice and Katowice), where 7 routes were selected, differing from one another in terms of terrain anomalies (buildings, types of land areas, vehicles, vegetation). In the studies, which involved photogrammetric flights performed using a UAV, different seasons and times of day as well as changes in light intensity were taken into account. The flight specification was based on the main parameters with the following assumptions: taking only perpendicular (nadir) RGB photographs, flight altitude 120 m AGL, strip width 160 m, GSD ≤0.04 m and overlap ≥83%. The analysis of the photographic material obtained made it possible to correct the catalog of anomalies defined previously, since the recognition of some objects is very difficult, being usually below the orthophotomap resolution. When making and evaluating orthophotomaps, problems with mapping the shape of objects near the edges of the frame were found. When a 12 mm lens is used, these distortions are significant. It was decided that for the purpose of generating training data from orthophotomaps, only the fragments containing objects which shape would be mapped in accordance with the real one would be used. Thus, the effective width of orthophotomaps obtained from simulated flights will be approximately 100 m.

Diurnal variation of cloud cover over the Baltic Sea

100%

Paszkuta M. , Zapadka T. , Krężel A.

tom No. 64 (2)

299--311

Instantaneous cloud cover over the Baltic Sea, estimated from satellite information, may differ by as much as several dozen percent between the day and night. This difference may result from both weather conditions and different algorithms used for the day and night. The diurnal differences in cloudiness measured by proprietary and operational systems were analysed as part of research on marine environmental assessment and monitoring. An optimised algorithm for 2017 was presented and supplemented with information from radiation modelling. The study showed that, in general, the average values of daily changes in cloud cover over the sea depend on the season, which generally corresponds to the length of the day and contrasts with the amount of cloudiness. The results were compared with available online data that met the night and day detection criteria, the climate model, and the climate index. The averaged analysis of seasonal changes showed that similar values of the satellite estimates are higher than those obtained from the climate model and the lidar estimation. The satellite estimates from SatBaltic showed the lowest uncertainty. The diurnal cycle was confirmed by all analysed systems. These results may indicate common physical mechanisms and a methodological reason for the uncertainty of satellite-based data. The results clearly showed the existing diurnal difference in the amount of cloud cover over the Baltic Sea and indicated that this difference is not always explained by the physical properties of the atmosphere. The probable causes for these uncertainties were identified and diagnosed.