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Spy satellites could analyse shadows from space to help identify terrorists - Telegraph
Spy satellites could analyse shadows from space to help identify terrorists
Spy satellites could soon be able to identify a person from space, by analysing the way their shadow moves.
By Lucy Cockcroft
Last Updated: 9:42AM 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.
It could be used to monitor known criminals and suspected terrorists, such as Osama Bin Laden, using satellites or spy planes.
There has been an explosion in satellite imagery and technology in recent years, but it is still virtually impossible to recognise people from pictures taken from orbit. Images from high-altitude aircraft and spacecraft only ever the tops of their heads.
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.
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.
However, critics say there are doubts that images taken in orbit will be sharp enough to be used as identification. There are also concerns that weather and visibility will affect the quality.
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.
Dr Stoica, who presented his research at a security conference in Edinburgh, said the software then applies regular gait analysis to the corrected images.
The technique is still at the earliest stages of development, and it could be many years before it is used by military, police and intelligence services.
The technology is already here.Subs are being tracked by satellites whose sensors watch out for the minute surface trails of a sub's wake.