The detection of humans on the images obtained from six 360-degree cameras is performed by a single embedded computer. The detection range depends on numerous factors: the size of a person in the frame, whether the person's full height is viewable, the lightning, the background, or whether there are other objects partially covering the person. Nevertheless, in the most general case, the detection range on the robots' current models is around 40-50 meters. The image from each camera is analyzed with the frequency of several frames per second, which is sufficient for robust operation of the system.
In order to increase the human detection distance, for example when patrolling along chain-link fences, a potential threat can be localized at farther distances using a PTZ camera. This camera can detect a human at the distance of about 200 m. The camera works in scanning mode. It performs a 360-degree surveillance, rotating smoothly around its vertical axis. The PTZ camera image is processed by an additional dedicated Jetson TX2 supercomputer, that analyzes the high-definition video stream at 25 frames per second. The scanning detection mode can be suspended, allowing the PTZ camera to follow a specific object.