Inconsistent and unacceptable probability of detection (PD) and false alarm rates (FAR) due to varying environmental conditions hamper buried object detection. A 4-month study evaluated the environmental parameters impacting standoff thermal infra-red (IR) detection of buried objects. Field observations were integrated into a model depicting the temporal and spatial thermal changes through a 1-week period utilizing a 15 minute time-step interval. The model illustrates the surface thermal observations obtained with a thermal IR camera contemporaneously with a 3-d presentation of subsurface soil temperatures obtained with 156 buried thermocouples. Precipitation events and subsequent soil moisture responses synchronized to the temperature data are also included in the model simulation. The simulation shows the temperature response of buried objects due to changes in incoming solar radiation, air/surface soil temperature changes, latent heat exchange between the objects and surrounding soil, and impacts due to precipitation/changes in soil moisture. Differences are noted between the thermal response of plastic and metal objects as well as depth of burial below the ground surface. Nearly identical environmental conditions on different days did not always elicit the same spatial thermal response.
Soil and meteorological conditions hamper improvised explosive device (IED)/mine detection yielding inconsistent and in some cases unacceptable probability of detection (PD) and false alarm rates (FAR). To assess and identify the environmental parameters impacting standoff thermal infrared (IR) utilization over varying temporal and spatial scales a three-month study evaluated the associated degree of variance. The lessons learned include; 1) the considerable spatial variance in surface soil temperatures at varying scales of observation, 2) spatial and temporal impact of buried objects on the thermal signature of soil, 3) identification of the environmental parameters impacting the thermal spatial and temporal temperature variance for disturbed and undisturbed soil, and 4) development of a data analysis technique taking into account temperature variance (ΔT) over time (Δς) as a approach to assess buried objects.