Tracking Drone Flight Path Via Video, Using Cameras We Can Get

Calculating three-dimensional position from two-dimensional projections are literal textbook examples in geometry, but those examples are the “assume a spherical cow” type of simplifications. Applicable only in an ideal world where the projections are made with mathematically perfect cameras at precisely known locations with infinite resolution. Making things work in the real world is a lot harder. But not only have [Jingtong Li, Jesse Murray et al.] worked through the math of tracking a drone’s 3D flight from 2D video, they’ve released their MultiViewUnsynch software on GitHub so we can all play with it.

Instead of laboratory grade optical instruments, the cameras used in these experiments are available at our local consumer electronics store. A table in their paper Reconstruction of 3D Flight Trajectories from Ad-Hoc Camera Networks (arXiv:2003.04784) listed several Huawei cell phone cameras, a few Sony digital cameras, and a GoPro 3. Video cameras don’t need to be placed in any particular arrangement, because positions are calculated from their video footage. Correlating overlapping footage from dissimilar cameras is a challenge all in itself, since these cameras record at varying framerates ranging from 25 to 59.94 frames per second. Furthermore, these cameras all have rolling shutters, which adds an extra variable as scanlines in a frame are taken at slightly different times. This is not an easy problem.

There is a lot of interest in tracking drone flights, especially those flying where they are not welcome. And not everyone have the budget for high-end equipment or the permission to emit electromagnetic signals. MultiViewUnsynch is not quite there yet, as it tracks a single target and video files were processed afterwards. The eventual goal is to evolve this capability to track multiple targets on live video, and hopefully help reduce frustrating public embarrassments.

[IROS 2020 Presentation video (duration 14:45) requires free registration, available until at least Nov. 25th 2020.]

Watching The Watchers: Are You The Star Of An Encrypted Drone Video Stream?

Small aircraft with streaming video cameras are now widely available, for better or worse. Making eyes in the sky so accessible has resulted in interesting footage that would have been prohibitively expensive to capture a few years ago, but this new creative frontier also has a dark side when used to violate privacy. Those who are covering their tracks by encrypting their video transmission should know researchers at Ben-Gurion University of the Negev demonstrated such protection can be breached.

The BGU team proved that a side-channel analysis can be done against behavior common to video compression algorithms, as certain changes in video input would result in detectable bitrate changes to the output stream. By controlling a target’s visual appearance to trigger these changes, a correlating change in bandwidth consumption would reveal the target’s presence in an encrypted video stream.

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Radio Jamming Rifle Claimed To Disable Drones

[Battelle], an Ohio-based non-profit R&D firm has just unveiled a device they call the DroneDefender — a long-range anti-drone defense weapon. It almost sounds like they’ve brought the fictional drone hunter’s RF cannon to life. But does it really work?

According to the site, it uses radio frequency disruption to blast unwanted drones out of the sky. Cool concept, but does it actually work? Unlike the hackable MAVLink protocol used by Parrot AR, ArduPilot and a handful of other consumer drones, this weapon uses brute radio signal force to disable any(?) consumer drone.

There’s a video after the break demonstrating a simulated use of the technology, which leaves us a bit confused. They show the drone slowly landing all nicely after being “guided” down by the rifle. If the system is jamming both GPS and the 2.4 GHz control link, the behavior will all depend on the software loaded on the drone. Some will go to a fail-safe mode, which is low throttle or motor power off, assuming the pilot has set fail-safe. Others may attempt to loiter on IMU sensors only.

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