Remote sensing of volcanic terrains by terrestrial laser scanner: preliminary reflectance and RGB implications for studying Vesuvius crater (Italy)

Abstract

This work focuses on the use of terrestrial laser scanner (TLS) in the characterization of volcanic\renvironments. A TLS survey of the Vesuvius crater (Somma-Vesuvius volcano, Italy) allows the construction\rof an accurate, georeferenced digital model of different sectors of the crater. In each sector, the intensity is\rcomputed for each point as the ratio between the emitted amplitude and the received one, normalized to the\rmaximum signal, providing the radiometric information. Moreover, the RGB colours of the observed surfaces\rcan be captured by means of a calibrated camera mounted on the TLS instrument. In this way, multi-band\rinformation is given, since a long range TLS operates in the near infrared band. The reflectance and RGB\rdata are compared in order to verify if they are independent enough to be complementary for model analysis\rand inspection. Results show that the integration of RGB and intensity data can fully characterize this\rvolcanic environment. The collected data are able to discriminate different volcanic deposits and to detect\rtheir stratigraphic features. In addition, our results shed light on the spatial extension of landslides and on\rthe dimensions of rock fall/flow deposits affecting the inner walls of the crater. The remotely acquired TLS\rinformation from the Vesuvius crater is compared with that from a sedimentary terrain (coal-shale quarry) to\rdetect possible similarities/differences between these two geological environments.