Near-Infrared Aerial Crop Mark Archaeology: From its Historical Use to Current Digital Implementations

Abstract

Even though most archaeologists are aware of the crop mark phenomenon and its possible archaeological nature, the information on its occurrence and specific character is, in most cases, obtained by imaging in the visible spectrum. After the Second World War, the occasional use of near-infrared (NIR) sensitive emulsions attributed this kind of invisible imaging with a great potential. However, archaeological NIR imaging always remained restricted due to several reasons not, at least, its complicated workflow and uncertain results. This article wants to delve deeper into the subject, looking at the conventional film-based approach of NIR aerial reconnaissance and its historical use in archaeological crop mark research, after which a current straightforward digital approach will be outlined. By explaining the spectral properties of plants and using examples of recently acquired NIR imagery in comparison with visible frames, it should become clear why the detection and interpretation of crop marks can benefit from low-cost digital NIR imaging in certain situations.

Ground Survey to Aerial Survey:Methods and Best Practices in Systematic Archaeological Explorations and Excavations

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Aerial Mapping and Multi-Sensors Approaches From Remote Sensing Applied to the Roman Archaeological Heritage

“…This permitting us to obtain a radiation between 700 to 1000 nm., with the radiation being absent or very low, between 300 and 700 nm. This type of sensor has already been applied in aircraft by Verhoeven (2008;2012).…”

Complex Archaeological Prospection Using Combination of Non-destructive Techniques

“…The NIR camera was used during flight surveys because NIR images are successfully used in archaeology thanks to its sensitivity to vegetation conditions. (Verhoeven, 2012). The position and altitude of six Ground Control Points (GCPs) were surveyed by GNSS receiver (Fig.2) …”