Using Wi-Fi, drones will be able to see what is hidden from their "eyes."
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Three years ago, scientists from the University of California in Santa Barbara (UCSB) used ground robots to obtain two-dimensional images of objects hidden behind brick walls using Wi-Fi. Now, using tandem unmanned aerial vehicles, they received 3D images of similar objects. Ultimately, the technology can be used in search and rescue operations, archaeological excavations and in many other cases.
 
Under the guidance of Professor Yasamin Mostofi, a team of researchers from UCSB used a pair of autonomous aircraft equipped with Wi-Fi transceivers.
 
The drones flew along the synchronous routes from opposite sides of the cubic brick structure. One of the drones continuously transmitted a Wi-Fi signal, and the other measured the strength of this signal after it passed through the bricks. Analyzing changes in signal power, the computer program determined the size and shape of objects hidden inside the structure, as they violated the integrity of the signal. However, the technology does not require preliminary measurements of the area under test.
 https://youtu.be/THu3ZvAHI9A
While the ground robots managed to get only 2D images, the ability of the drones to fly in different directions allowed analyzing objects from different angles. As a result, scientists received 3D images hidden inside the brick cube construction.