Hyperspectral techniques and GIS for archaeological investigation

Abstract

Aerial photos, both in colour and in black and white, have always been very important tools in archaeological surveys. Sensors, called hyperspectral, were available on the market for some years: they are able to expand the research beyond the visible area of the electromagnetic spectrum as far as the thermal infrared too. The use of these sensors, at first restricted to the applications in the traditional fields of Remote Sensing (such as, for instance, Botany, Agronomy, Geology, Hydrology), was spreading, in recent years, to some sectors, such as archaeological surveys, which were unexplored before. The presence of structures and hollows in the top subsurface is likely to cause variations in humidity in the surface. These variations affect both vegetation, and some physical features of the ground such as thermal conductivity and capacity. Especially in the first hours of day, you can notice thermal anomalies due to different evaporation. The exam of these anomalies, carried out by the use of techniques of digital processing of images in the spectrum bands particularly sensitive to the abovementioned indicators, enables the photointerpreter to determine possible signs of underground structures of archaeological interest. The application of the remote sensing in archaeology allows to acquire, with rapidity, a lot of information connected to the territory; that's the reason why, together with the development of sensors, came out the necessity to take advantage from the potentialities offered by the GIS to manage, process and file the spatial dates acquired with the remote sensing techniques. In this work, in fact, the results produced with the image processing technique were implemented in a GIS and were overlaid on the historical and contemporary maps and on the DEM in order to produce, for each study area, a Prediction map of archaeological finds.