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Potentials of the hyperspectral remote sensing - Aisa Eagle system and future perspectives
Lukeš, Petr ; Hanuš, Jan ; Kaplan, Věroslav ; Zemek, František
Since 2004 the Global Change Research Centre (CVGZ) operates a hyperspectral airborne imaging system AISA Eagle. A basic introduction to hyperspectral remote sensing and its potential applications in science as well as for commercial and military uses are presented, followed by a description of the system together with an overview of the key data pre-processing steps. The application of a rapidly developing technology, hyperspectral remote sensing, is presented within the field of quantitative remote sensing of plant health status. Finally, the future development of hyperspectral remote sensing at the CVGZ is outlined.
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Individual tree crowns delineation using local maxima approach and seeded region growing technique
Novotný, Jan ; Hanuš, Jan ; Lukeš, Petr ; Kaplan, Věroslav
Remote sensing applications in forestry can profit from a rapid development of optical sensors. Applied algorithms should be suited to the new properties of the data (very high resolution and wide spectral range). Segmentation of the image into objects is an important task in forestry applications of optical remote sensing. Segmentation of individual tree crowns involves two parts — detection and delineation phase. Local maxima approach and seeded region growing technique are presented as the key concepts. Furthermore improvements, namely histogram equalization and Voronoi diagram, are incorporated. Two datasets were processed and results of the segmentation are presented. Hyperspectral data with spatial resolution of 0.8m were found as a suitable for segmentation process with 84% and 78% accuracy of detection phase and 64% and 52% accuracy in delineation phase respectively. Finally discussion of recommended settings in the algorithm is presented.
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The effect of elevated air CO2 concentration on water regime and transpiration of Norway spruce
Valouch, Ludvík ; Pokorný, Radek ; Tomášková, Ivana
Under the elevated CO2 air concentration, changes in physiological processes and morphology were evident in relatively short time. Direct measurement via heat pulse method proved reduction of specific sap flux throw the stem in the first year of cultivation in elevated CO2. SSF in both treatments was comparable in the next tree years. During the sixth year of fumigation, higher transpiration rate in trees growing under elevated CO2 was recorded. It was implication of larger bearing leaf area, larger conducting vessels area on the in crosscut stems section and larger root absorbed area. Continuously sap flow measuring of sun and shaded part of the crown was found that SSF of higher crown part was higher in both treatments. Average hydraulic conductance soil-leaf (GTsa) was 1,4 times higher in sunny part of the crown than estimated for the whole crown in ambient treatment A (ambient [CO2] concentration). Difference in hydraulic conductance between the upper and lower crown part of the E treatment (doubled [CO2] concentration of A treatment) was not so pronounced.
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