X-ray eyes in the sky: New method for 3-D through-wall imaging that utilizes drones and WiFi

[Jim__]

From phys.org ( https://phys.org/news/2017-06-x-ray-eyes-sky-method-d.html ) :

<excerpt>

Researchers at UC Santa Barbara professor Yasamin Mostofi's lab have given the first demonstration of three-dimensional imaging of objects through walls using ordinary wireless signal. The technique, which involves two drones working in tandem, could have a variety of applications, such as emergency search-and-rescue, archaeological discovery and structural monitoring.

"Our proposed approach has enabled unmanned aerial vehicles to image details through walls in 3D with only WiFi signals," said Mostofi, a professor of electrical and computer engineering at UCSB. "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."

…

In their experiment, two autonomous octocopters take off and fly outside an enclosed, four-sided brick house whose interior is unknown to the drones. While in flight, one copter continuously transmits a WiFi signal, the received power of which is measured by the other copter for the purpose of 3D imaging. After traversing a few proposed routes, the copters utilize the imaging methodology developed by the researchers to reveal the area behind the walls and generate 3D high-resolution images of the objects inside. The 3D image closely matches the actual area.

"High-resolution 3D imaging through walls, such as brick walls or concrete walls, is very challenging, and the main motivation for the proposed approach," said Chitra R. Karanam, the lead Ph.D. student on this project.

…

</excerpt>

[cstanleytech]

1. I wonder how long it takes for them to gather enough data to generate the image?

If not to long then I could see it being useful in search and rescue such as in areas prone to avalanche or collapsed buildings and mines.

[Igel]

2. Mines might be tough.

But burning buildings, both to find people and check structural integrity.

[Jim__]

3. The paper does talk a little bit about the number of measurements required.

I don’t think it gives time measurements, but the purpose of this technique is to handle time-critical applications. The full paper is available here: http://www.ece.ucsb.edu/~ymostofi/papers/IPSN17_KaranamMostofi.pdf . Here is the abstract:


<excerpt>
In this paper, we are interested in the 3D through-wall imaging of a
completely unknown area, using WiFi RSSI and Unmanned Aerial
Vehicles (UAVs) that move outside of the area of interest to collect
WiFi measurements. It is challenging to estimate a volume repre-
sented by an extremely high number of voxels with a small number
of measurements. Yet many applications are time-critical and/or
limited on resources, precluding extensive measurement collection.
In this paper, we then propose an approach based on Markov ran-
dom field modeling, loopy belief propagation, and sparse signal
processing for 3D imaging based on wireless power measurements.
Furthermore, we show how to design efficient aerial routes that are
informative for 3D imaging. Finally, we design and implement a
complete experimental testbed and show high-quality 3D robotic
through-wall imaging of unknown areas with less than 4% of mea-
surements.
</excerpt>