Abstract: A method comprises: instructing a leader drone in a drone swarm to move to a first position; instructing a first follower drone in the drone swarm to move to a second position; instructing a first camera of the leader drone to record, while the leader drone is in the first position, a first video of an object; instructing a second camera of the first follower drone to record, while the first follower drone is in the second position, a second video of the object; wirelessly receiving the first video from the leader drone; wirelessly receiving the second video from the first follower drone; stitching together the first video and the second video to obtain a master video; and performing motion capture on the master video to obtain motion data of the object.

Abstract: A flame detector arranged to detect flames includes a non-microphonic infra-red sensor having a broad band frequency response. To maximize the sensitivity to radiation from flames in the 4.3 .mu.m solar absorption band a narrow band optical interference filer, transmissive in the band 4.54 .mu.m to 4.38 .mu.m is chosen such that the integrated solar energy transmitted thereby is less than an alarm threshold.A further filter prevents re-radiated heat from the filter reaching the sensor. Another filter prevents radiation of wavelengths less than 4.38 .mu.m from reaching the other filters to reduce heating thereof and also to provide a series of filters to stop direct broad band transmission to the sensor through pin holes in the filters. A signal processor detects flames by virtue of the flame flicker frequencies and includes provision for compensating for the effects of low frequency components on the amplitude of radiation produced by flames.