IR Thermography for the Detection of Buried Objects: A Short Review

Sub-surface buried objects, such landmines and archaeological artefacts, and the surrounding environment constitute a complex system with variable characteristics. As a consequence, the detection and recognition of these objects may be extremely difficult. IR thermography, which is widely employed in the detection of discontinuities in materials and structures, would be in principle suitable also for this kind of application. The issue in this case appears to be the presence of excessive levels of background noise, whose modelling is difficult, in that it results from a number of factors e.g., moisture content, presence of vegetation, and variation of solar radiation at topsoil level. In recent years, a number of studies have tried to overcome these limitations and improve the reliability of this method, using filtering and automatic pattern recognition techniques, specific for the detection of buried objects. This work is aimed at revising and commenting the most recent experiences in this application of IR thermography. In particular, the possibility of combined use of IR thermography with other techniques, in particular ground probing radar (GPR), and high frequency electromagnetic techniques are discussed, in order to improve the reliability of buried objects detection by fusion of data obtained from different sensors.