by Lucy Cockcroft
Last Updated: 12:50PM BST 04 Sep 2008
A computer programme has been developed to process the image of a shadow cast on the ground, and match it up with its owner. The technique, called gait analysis, works on the premise that it is extremely difficult to disguise your walking style.
Aerial shots alone give little away about a person's movements, but analysing the shadows they cast can - provided their walking pattern is on file.
Is that what is behind the airport scanners?
According to Dr Adrian Stoica of Nasa's Jet Propulsion Laboratory in California, which developed the shadow technology, video from space could provide enough data to confirm a suspect's identity.
Dr Stoica has created computer software that can seek out and recognise the shadows of individuals in aerial video footage, reports New Scientist magazine. It isolates moving shadows and uses data on the position of the sun and camera angle to 'correct' the shadows if they are foreshortened or elongated.
"... as long as it's a sunny day, the suspect is walking on flat ground, and not in a crowd." -- Webmaster of Wake the Flock Up
The technique, called gait analysis, works on the premise that it is extremely difficult to disguise your walking style.