Archaeological applications of multi/hyper-spectral data – challenges and potential Anthony Beck – School of Computing, University of Leeds, Leeds, LS2 9JT, UK. arb@comp.leeds.ac.uk Pre-print Abstract Multi/hyper-spectral sensors offer immense potential as archaeological prospection tools. The sensors are sensitive to emitted or reflected radiation over different areas (wavelengths) of the electromagnetic spectrum. Their two major advantages are that they have the potential to detect archaeological sites and monuments (henceforth archaeological residues) that are undetectable in the visible wavelengths and that they may extend the window of opportunity for their detection. For example, localised crop stress and vigour variations, which underpin crop-mark formation, are sometimes better expressed in the near-infrared than in the visible. In addition, multi/hyper- spectral data collected from different platforms (aerial and satellite) under different conditions can be used to generate ancillary themes that aid interpretation (e.g. soil, geology and land-use layers) and are important for ‘Total Archaeology’. However, multi/hyper-spectral sensors are relatively expensive and require systematic surveys under ‘appropriate conditions’ in order to be successful. It is this latter point which is critical: there is a poor understanding of the spatial, environmental and seasonal contrast dynamics that determine an ‘appropriate condition’ and therefore whether features of archaeological interest can be detected. Introduction In the UK, the practice of using remote sensing techniques for detecting archaeological sites and visualizing archaeological landscapes has traditionally been based on low altitude aerial photography using film emulsions sensitive at optical and sometimes near-infrared wavelengths. In the 1920s O. G. S. Crawford, the archaeological officer of the British Ordnance Survey, demonstrated that archaeological structures could be identified from shadow, soil and crop markings on panchromatic aerial photography (see Figure 1). Since that time, both oblique and vertical aerial photographs have been used extensively for archaeological reconnaissance and mapping all over the world (Bewley, 2000; Donoghue, 1999). Early aerial photographers helped to refine the instruments and establish methods that are still in use today. Crawford in particular established methods of site classification and wrote about the effects of weather, season, soil moisture and crop type on photographic return (Crawford, 1923; Crawford, 1928; Crawford, 1929). Today, these aerial approaches are accepted as a cost-effective, non-invasive technique for the reconnaissance and survey of monuments.