A Low Cost Approach to Disturbed Soil Detection Using Low Altitude Digital Imagery from an Unmanned Aerial Vehicle

Abstract

Until recently, clandestine burial investigations relied upon witness statements to determine target search areas of soil and vegetation disturbance. Due to this, remote sensing technologies are increasingly used to detect fresh clandestine graves. However, despite the increased capabilities of remote sensing, clandestine burial searches remain resourcefully intensive as the police have little access to the technology when it is required. In contrast to this, Unmanned Aerial Vehicle (UAV) technology is increasingly popular amongst law enforcement worldwide. As such, this paper explores the use of digital imagery collected from a low cost UAV for the aided detection of disturbed soil sites indicative of fresh clandestine graves. This is done by assessing the unaltered UAV video output using image processing tools to detect sites of disturbance, therefore highlighting previously unrecognised capabilities of police UAVs. This preliminary investigation provides a low cost rapid approach to detecting fresh clandestine graves, further supporting the use of UAV technology by UK police.

Drone aerial imagery for the simulation of a neonate burial based on the geoforensic search strategy (GSS)

“…Our contribution to an actual search using aerial imagery is different from those who precede us [12,13] in that we placed the use of drone technology within the context of the Geoforensic Search Strategy to provide a basis for understanding ground conditions in and beyond the immediate area of interest (Control Site Survey Area). Subsequently, there was a more detailed focus on the survey locations (Focussed Survey Area and Location 3), using desk study combined with drone image analysis.…”

“…Their site and imagery comprised a 1 × 1 m purpose-dug simulated shallow grave (from their Figure 2, approximately 10-20 cm deep) to create a ground disturbance in clay-rich soil outside of Chester, Cheshire. Parrott et al [13] used image processing to despeckle and enhance visible light photographs as opposed to NIR, but Parrott et al [13] do not definitively state how long after their ground disturbance was made that they obtained drone imagery, but do state that at the time of the overflights, the vegetation had…”

“…partly recovered. Critically for this work, the Evers & Masters [12] and Parrott et al [13] work were primarily focused on the efficacy of the drone-based survey method, as opposed to our approach which is to integrate primary and processed aerial imagery with an understanding of the overall solid/drift geology and topography (part of the GSS), with attendant controls on vegetational variations and digital elevation modeling using photogrammetry.…”

“…” They conclude that NIR is useful and that further work using NDVI, as trialed here, would add to their work. Parrott et al [13] used very similar equipment as Evers & Masters, with a GoPro camera mounted on a DJI Flame Wheel drone. Their site and imagery comprised a 1 × 1 m purpose‐dug simulated shallow grave (from their Figure 2, approximately 10–20 cm deep) to create a ground disturbance in clay‐rich soil outside of Chester, Cheshire.…”

“…Their site and imagery comprised a 1 × 1 m purpose‐dug simulated shallow grave (from their Figure 2, approximately 10–20 cm deep) to create a ground disturbance in clay‐rich soil outside of Chester, Cheshire. Parrott et al [13] used image processing to despeckle and enhance visible light photographs as opposed to NIR, but Parrott et al [13] do not definitively state how long after their ground disturbance was made that they obtained drone imagery, but do state that at the time of the overflights, the vegetation had partly recovered. Critically for this work, the Evers & Masters [12] and Parrott et al [13] work were primarily focused on the efficacy of the drone‐based survey method, as opposed to our approach which is to integrate primary and processed aerial imagery with an understanding of the overall solid/drift geology and topography (part of the GSS), with attendant controls on vegetational variations and digital elevation modeling using photogrammetry.…”