Drones with laser equipment join forensic science to solve crimes

Drones with laser equipment join forensic science to solve crimes

The drones equipped with lidars have already helped archaeologists discover traces of human activity thousands of years ago. We all know that it is a drone and its different models, but what is a LIDAR ?, the LIDAR (an acronym of the Light Detection and Ranging or Laser Imaging Detection and Ranging) is an optical remote sensing technique that uses light laser to obtain a dense sample of the surface of the earth producing exact measurements of x, y, z. It is mainly used in laser aerial mapping applications, this system produces mass point cloud datasets that can be managed, visualized, analyzed and shared using various software developed for this purpose since an active optical sensor transmits laser beams towards a target while it moves through specific topography routes. The reflection of the target's laser is detected and analyzed by the receivers in the sensor. These receivers record the precise time from when the laser pulse left the system to when it returned to calculate the distance between the sensor and the target. Combined with positional information (GPS and INS), these distance measurements are transformed into measurements of real three-dimensional points of the reflector objective in the object's space within the georeferenced x, y, z coordinates along with the time of emission and reception of the object. laser, scan angle, GPS position and INS information.

Taking advantage of this technique, a multidisciplinary team in Australia wants to use this technology to solve cases of murdered people who were buried in densely wooded areas. The results have been published in Forensic Science Research and are promising as laser pulses travel through gaps in the forest canopy to offer a view of the trees, as well as anything buried in the ground beneath them. To test this theory, at the Victorian Institute of Forensic Medicine in Melbourne they buried donated bodies for scientific purposes in a dense forest area of ​​20,000 square meters. The corpses were placed in three types of tombs to simulate different crimes: one with a single body, another with three and a larger grave with six bodies. Three empty tombs were excavated as controls.
Then, the Scout Aerial company then flew drones equipped with lidar equipment over the area without knowing any detail about the burials, the company used an algorithm to digitally remove vegetation from the resulting images and reveal the ground beneath. This allowed him to detect changes in both the surface and underground, which allowed him to successfully identify five of the six tombs. Although the technique could recognize the largest tomb under certain conditions; unfortunately, he failed to detect the tomb with a single body, so the process still requires refinement, since the Lidar captures all the alterations of the soil and there is not yet a method developed to distinguish the tombs of human bodies from those of animals, or even changes in the soil due to other causes.

But this new procedure proves to be very valuable since the search for an area, whether wooded or not, requires many resources, especially when researchers do not know exactly where to look. Drones with lidars can reduce a large area of ​​search with a rough terrain to some places of interest, currently a LIDAR team costs between 60 thousand and 200 thousand dollars, although without doubt the price of carrying out massive searches with traditional systems is much more expensive than the use of these technologies. The most recent success of the lidar has been to find the South African city of Kweneng, lost for more than 200 years. The discovery was made only a few weeks ago.

Gabriel Bazzolo