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ŠUMARSKI LIST 9-10/2014 str. 51     <-- 51 -->        PDF

to be taken into account due to the availability of the imagery for this research project.
The satellite imagery consists of an 8-band multispectral image with resolution of approximately 2 meters and a panchromatic image with 0.5 m resolution (Tab. 1). They contained only basic radiometric and sensor correction, which means that they were not projected onto a plane using map projection (level 1B). Metadata with information on the satellite orbit, camera properties and rational polynomial coefficients (RPC) were supplied by the image provider. The panchromatic and multispectral images were first orthorectified using RPC and an accurate laser scanning digital surface model (with 1 m resolution). The orthoimages were generated only where the laser scanning digital surface model (DSM) was available. Then to maintain the high spatial resolution of the panchromatic images and the high spectral resolution of multispectral images, they were combined into a pansharpened image with a resolution of 1 m using the modified Intensity-Hue-Saturation (IHS) method (Švab and Oštir, 2006). The pansharpened image was then used for classification.
2.3. Tree data – Podaci o drveću
The tree data for tree species classification were obtained from a virtual network of circular 2000 m2 plots in a 100 x 100 meter grid in the forest. On each of the 332 plots, a coniferous and a deciduous tree were recorded. Only dominant and co-dominant trees were selected to maximize the sunlit parts of the crowns and to be distinguishable from surrounding trees on images.
A field manual (Fig. 3) for each plot was prepared for locating each plot in the field. It contained a section of the true orthophoto image, DCM and a digital model of terrain (DMT) derived from laser scanning data. DCM shows stand canopy model and DMT shows a detailed ground relief model. Plots were located using the LEICA one 10 GNSS receiver with interchangeably displayed true orthophoto,