“…In previous studies, the walking velocities using different postures were usually measured with a professional set of cameras and/or electromyography (EMG) equipment [ 27 , 28 , 34 , 35 , 48 ]. These methods either require more than ten fixed cameras at the test site [ 9 , 20 , 34 , 35 , 38 , 40 , 48 , 49 , 50 , 51 , 52 ], or a self-developed equipment set with attached cameras [ 27 , 28 , 32 , 33 , 53 ]. However, this kind of method may not be functional when the cameras are covered by the smoke of a fire event, and thus may only be used under experimental conditions without vision impediment.…”