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National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Využití pozemní fotogrammetrie pro inventarizaci lesních porostů
 Řezba, Martin
The purpose of this thesis is to evaluate utilization of terrestrial and aerial photogrammetry in the forest inventory process. It describes and analyzes data collection and processing in Agisoft PhotoScan and ArcGIS software, with the use of automatically calculated tree parameters from a photogrammetric point cloud obtained by imaging the inside of the forest stand in combination with an imagery from air using unmanned aerial vehicle (UAV). Individual trees were identified and modelled using an algorithm, next cuts at the breast height were created from the photogrammetric cloud and finally diameter in breast (DBH) was calculated for each tree as well as the tree height was assigned to the position of each tree stem. The error of the diameter estimation was observed to be 3,3 cm root mean square error (RMSE) and the height estimation error was 1,3 m. Apart from the mentioned accuracy, the main advantage of the proposed work is shorter time demand for field measurement; we could complete both inventories of 1 hectare forest stand in less than 2 h of field work.
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Analýza a optimalizace inventarizačních metod v podmínkách tropického deštného lesa v peruánské Amazonii
 Němec, Petr
The submitted work compares results of two forest inventories conducted on the plot of 200 ha within the forestry concession in the tropical rainforest in the Peruvian Amazon. First inventory conducted in 2007 used for field data collection the common method with tapes and mechanical compasses. The second inventory conducted in 2008 used a set of electronic devices, consisting of a field computer, laser rangefinder, electronic compass, a GPS unit and a specialized software Field-Map. In both inventories the positions of all trees with a dbh bigger or equal 400 mm were mapped and following attributes were recorded: position, species, total height, trunk height and dbh. Significant differences were discovered between both methods and the inadequacies were described. The results from the comparison study show that the method conducted using electronic devices is faster and more exact in measurement of tree attributes and in navigation on the plot. However, nor use of this method encompassed to map all the trees and that is why the distance sampling method for population density estimation was used for completion of inventory results. The population map of big trees was created and used for inventory simulations using circular and belt plots of different size and different density with the aim to find most suitable variants. Results of simulated inventories were evaluated regarding their accuracy and time expenses and the variants suitable for use in the zone were suggested.
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