Potential of the Ads40 Aerial Scanner for Archaeological Prospection in Rheinau, Switzerland

The goal of this research is to test an empirical line radiometric calibration of airborne digital scanner ADS40 data from Leica Geosystems, for remote sensing applications in general and to demonstrate the potential of ADS40 data for archaeological prospection in detail. In this study we present the first results of multitemporal flight campaigns with two different generations of ADS40 sensor head systems and simultaneous ‘traditional’ oblique airborne photo flights over the archaeological test site Rheinau in northern Switzerland. In a first flight campaign in July 2006 the ADS40 of the Swiss Federal Office of Topography (swisstopo), a first generation SH40 camera head, was used. A second flight campaign in September was carried out with the ADS40 sensor, operated by the manufacturer Leica, with the new second-generation SH52 head. Spectral signatures of several ground targets were taken in parallel with a field spectrometer and a field survey was carried out. The ADS40 data sets were geometrically corrected with respect to national map sheets. A radiometric calibration of the spectral bands was applied with an empirical line approach, including the ground spectra. Archaeological interpretations of both ADS40 data sets and of oblique aerial images were compared. The visible structures are predominantly old house-forms with cavities and fosses, historic soil withdrawals, remaining structures from agriculture treatments, historic harbour facilities and refilled riverbeds from the Neolithicum until today. The visibility of the archaeological structures in ADS40 data and oblique photos was compared. It was shown, that thanks to the higher radiometric performance of ADS40, additional elements were detectable. ADS40 data is shown to be a good choice for archaeological prospection. Every three years, a complete nationwide coverage of Switzerland with 25cm ground sampling distance will be flown operationally by swisstopo, a perfect alternative or even substitute in aerial archaeological prospection with traditional aerial image survey.