Comparison between laser scanning, single-image rectification and ground-penetrating radar technologies in forensic science

Abstract

The data provided by three different measurement instruments, terrestrial laser scanning, image measurement from rectified photographs and 3D ground-penetrating radar, are compared and analysed in this work. For this purpose, an experimental grave is prepared using human bone remains and a pig carcass.A comparison of the geometrical data collected from the bone remains using laser scanning and single-image rectification show an agreement better than 4% for bones longer than 75mm, which confirms the possibility of using the low cost image measurement technique for forensic purposes.The volume and weight of the pig carcass is also evaluated using the laser scanning data and a surface model fitted to the point cloud. The obtained result matches with the real data provided by the veterinarian. However, care must be taken to avoid the occlusions of the laser data, which could artificially increase the volume.The ground-penetrating radar survey clearly reveals the place where the pig is buried. The cross-sectional area is evaluated. The volume of the pig detected by GPR was determined and compared with the value obtained from the laser scanning. The results show a difference of about 25%.The ground-penetrating radar survey also shows some evidence of the cranium from the bone remains in the grave. However, the results are not clear, which demonstrates that the reliability of this technique decreases when the tissues of the cadaver are completely degraded.