Individuazione di coperture in cemento-amianto e del loro deterioramento da immagini iperspettrali

In this proceedings are shown the results of a research project about the mapping of asbestos cement roof sheets in the municipalities of Biassono, Lissone, Monza, Muggio? and Seregno (MB) above an area of about 65 km2. The study was performed using hyperspectral images collected on the 5th July 2013 with the aerial MIVIS (Multispectral Infrared and Visible Imaging Spectrometer) sensor that acquires data in 102 channels in the spectral interval between the visible and the thermal infrared regions. Furthermore, field measurements were performed with a portable spectroradiometer Fieldspec FR (ASD, USA) on roofing with different deterioration status, with the aim of investigating their spectral characteristics. The geometrical and the atmospheric corrections were followed by an automatic classification with the SAM (Spectral Angle Mapper) algorithm using a training set selected on the basis of orthophotos and of information about asbestos cement roof provided by the municipalities. Field measurements allowed to define a spectral index related to the albedo of asbestos cement sheets and to the presence on their surface of mosses and lichens that was used to distinguish deteriorated and preserved roofs through the aerial images. This approach allowed to suggest different priorities in removal to the municipalities, that is imposed in the PRAL (Lombardy Region Asbestos Plan) since 2005, which also set among the strategic objectives the removal of asbestos from the regional territory by ten years after the plan approval. Data on asbestos roofing sheets were handled in a GIS (Geographic Information System) to supply the municipalities with the cadastral references of each property that has to be restored.