As the BeeGees sang “Well, you can tell by the way I use my walk/I’m a member of the Muslim Brotherhood intent on wiping the two Great Satans from the earth and returning the power of the Caliphate to lands far and sundry.” It seems that NASA is using shadow analysis to follow humans from space. By using gait analysis, investigators can detect a specific walk regardless of how the subject is disguised.
By analysing the movements of human shadows in aerial and satellite footage, JPL engineer Adrian Stoica says it should be possible to identify people from the way they walk – a technique called gait analysis, whose power lies in the fact that a person’s walking style is very hard to disguise.
Instead of looking at a person directly the system watches their shadow and their specific up and down motions as they move through space. You can dress Bin Laden up like Big Bird but his tell-tale limp or nervous knee-buckle will always give him away. They do, however, mention that this process will be fairly difficult to perform from space as the resolution might be too low.