Modelli tematici 3D della copertura del suolo a partire da DTM e immagini telerilevate ad alta risoluzione WorldView-2

The integration of thematic layers and DTM (Digital Terrain Model) becomes possible to achieve 3D models that can contextually display the variability of both the morphology and territorial and / or environmental components. WorldView-2 high resolution images, presenting a reduced size of the pixels on the ground (0.5 m in panchromatic and 2 m in multispectral) and a high spectral resolution (with 8 bands in the portion of the electromagnetic spectrum between wavelengths 400 nm and 1040 nm) allow the creation of very detailed maps of land cover. The simultaneous availability of DTM with appropriate cell size transforms these thematic layers in digital 3D models with high resolution. This paper is aimed to test positional and thematic accuracies that can be achieved in the construction of 3D models of land cover using WorldView-2 images. Phlegraean area (in Campania region, Italy), characterized by particular morphological configuration, mainly due to the presence of craters and volcanic cones, is considered. The dataset is firstly orthorectified, using rational polynomial functions, and then processed using supervised classification (Maximum Likelihood method) to identify several homogenous classes. The indices derived by confusion matrix (Producer Accuracy, User Accuracy, Overall Accuracy, Cohen Index) permit to check the thematic accuracy. DTM is derived from technical maps (at 1:5.000 scale) and used as the basis for 3D models of land cover.