Scientific researchers (and hopefully not wannabe arms dealers) at the University of California have worked out how to use a pair of drones and Wi-Fi to create an instant 3-D map of a building, contents and all. This is good for emergency workers and architects, and probably terrible for humanity when the machines rise up to kill us all.

The test that the researchers conducted involved two drones, one with a Wi-Fi transmitter and one with a receiver. By sending out a known set of radio waves and then listening for what came through, the researchers were able to build a relatively accurate 3-D map of a building.

You can see the result in the video above, and while it’s not a perfect map — it’s lacking definition around the edges — it’s better than nothing. The obvious application is for search-and-rescue in collapsed buildings or mines, where workers can use the drones to build up a picture of inside before sending any humans in.

Of course, the far more scary prospect is the drones gaining sentience and using the newfound ability to see through walls to hunt and kill their creators. The future is nothing if not impressive and slightly terrifying.

You can find the full research paper here, or watch the video above for a more brief understanding of the project.