A new system by University of California, Santa Barbara researchers Yasamin Mostofi and Chitra R. Karanam uses two drones, a massive Wi-Fi antenna, and a little interpolation to literally see through solid walls. The system is two-fold. The one drone blasts Wi-Fi through the structure and another picks up the signal. Then, working in tandem, the two drones fly around the solid structure until it maps the differences in wave strength at different points. Using this information the researchers have been able to create 3D model of a closed building.
In the video below you can see the drones idly flying around a brick structure. They cannot see inside. As the waves penetrate the brick they change as they pass through other structures behind the wall. After a few passes the drones start mapping the entire structure in high resolution.
"Our proposed approach has enabled unmanned aerial vehicles to image details through walls in 3D with only WiFi signals,” said Mostofi. "This approach utilizes only WiFi RSSI measurements, does not require any prior measurements in the area of interest and does not need objects to move to be imaged."
The team was first able to create 2D models of objects using this technique but quickly graduated to 3D models. The system uses off-the-shelf devices including a simple Wi-Fi router and a Google Tango tablet. It also uses a Raspberry Pi and Wi-Fi card for the receiver. Drones talk to each other and act autonomously.
While you're not going to get a Predator-like view of living things through walls - yet - this project does have a lot of potential for indoor mapping and emergency situations when you need to know what's inside a building without breaching the door. The researchers even expect some interesting archeological applications as well.