Dynamic changes in land use, many of which are related to land abandonment, are taking place in many regions of the world. As a result, forest vegetation appears, which in part is a consequence of planned afforestation programs and in part has the characteristics of secondary forest succession. Monitoring of forest structure allows the range and dynamics of such changes to be identified. The aim of the study was to assess the usefulness of historical aerial photographs in the determination of forest structure. On the basis of such data, a point cloud was created which represented the forest structure in 1966. Subsequently, using airborne laser scanning data for the same area, corresponding datasets describing the situation in 2012 were created. Comparison of the two tall vegetation models made it possible to perform four analyses related to forest structure changes over a period of 46 years. The analyses were carried out in four areas in southern Poland. The analysis of the results confirmed that historical aerial photographs may be a valuable source in long-term analyses of changes in the range and height structure of areas containing tall vegetation.
The railway system in Poland is undergoing technological transformation. The development of the Polish railway system concerns not only high-speed trains but also infrastructure. The steel bridge is the most popular type of railway bridge in Poland. Most of them were built in the 1950s and 1960s. According to the recommendations in place in Western Europe, such railway bridges should be reviewed in terms of their fitness for use with modern high-speed trains. The modern technological revolution affects not only the railway, but also developments in displacement and deformation measurement techniques. New technologies provide more objective measurement results and accelerate results processing. They also facilitate the non-contact measurement of bridge structure stability. The authors investigated the vertical displacement of an old steel railway bridge in three different, specific case studies of terrestrial laser scanning data application. Then, the results of 3D data were compared with traditional land surveying results. The scientific results led to a conclusion that a strictly determined methodology of the measurement and analysis of a terrestrial laser scanner results supported by traditional land surveying techniques facilitates the determination of the vertical displacement of bridges with acceptable accuracy.
21 December 2017 in IOP Conference Series: Earth and Environmental Science
The aim of the study was to determine the mental workload of a harvester operator when working in late thinning and in windthrown stands of the same type and age, using eye movement patterns as an indicator. Eyeball movement variability was analysed using the eye tracking method. The mean duration of eyesight fixations in windthrown stands was shorter than in the control undamaged stands by about 20% (444 ms and 534 ms, respectively). The mean time of eyesight movements (saccades) in the windthrown stands was shorter than in the control undamaged stands by approx. 15%. The largest differences between the duration of saccades in the windthrown and control stands were observed between the cutting of trees and cutting logs off their root plates: the saccades were longer by about 20% when working in the control stands (49 ms) as compared to the windthrown stands (43 ms). Large differences in the duration of saccades between the windthrown area (42 ms) and the control area (47 ms) were also found when travelling between successive operation sites. In both types of stands, the shortest saccades were observed during processing: 39 ms. Summary durations of saccades observed during the processing of successive trees occurred in sequences showing repeated periods of variable eyeball activity, where longer saccades were followed by shorter ones. Documented more variability of eyesight activities of the harvester operator performing the operations of processing and moving is new standard of eye balls activities for the more taxing work conditions presented by windthrown stands.