Gait analysis by satellite


Here’s a new project in the surveillance race: gait analysis by using satellites that can identify people’s shadows. NASA’s Jet Propulsion Laboratory in Pasadena, California are working on developing this technique that should be a next step in fighting terrorism. ‘Normal’ gait analysis is done by CCTV (closed circuit television). Where camera’s must film people from a more or less horizontal angle to recognize their face or their way of walking, this technology can recognize people from a vertical angle, relying on people’s unique shadow patterns for analysis and identification.

Although the technology is still in its infancy (successful tests apparently have only been done by filming from the 6th flour of a building) it can be seen as a next step in what Crang & Graham have described as the “technophiliac fantasy” which dreams about “perfect technological omniscience against the new challenges of asymmetric warfare as ushering in a new world of ‘clean’ war”.


Different about this new type of surveillance is the aspect of visibility (or better: the lack of it). CCTV surveillance can to a certain extend be made visible (e.g. Bits of Freedom‘s Spot the Cam; Surveillance Camera Players in New York City). This new type of satellite surveillance however would be totally invisible. This raises the question how Situationists projects and/or locative media projects could possibly expose this kind of invisible surveillance?

A related aspect is the way surveillance comes into being. You can often spot CCTV cameras or at least you know they are there. This imposes self-surveillance (the true force of modern surveillance according to Foucault). It is important to know that the watchdog is there all the time and occasionally be reminded of this. But with satellites we simply wouldn’t know whether we are being watched or not. Many people will not even know this technology is operating when they walk the streets. Blissful ignorance or a lamentable lack of ‘surveillance capital’?

Ideas and projects like this could only be developed in a sunny place such as California. UK citizens (and the Dutch for that matter) who fear the “spy in the sky” may feel their climate to have at least one advantage when it comes to this. And for the truly paranoid the motto might become: bring your umbrella, it’s going to be a sunny day.

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  1. Plenty of people already avoid spy satellite surveillance e.g. military forces, smugglers, terrorists etc. – the low earth orbits are entirely predictable, simply a matter of physics and observation. All the relevant information is available on the internet compiled by amateur astronomers. e.g.

    Attempting to take detailed photos, let alone perform “gait analysis” from geostationary satellites i.e. from a distance of about 37,000 kilometres, is never going to happen.

    Changing your gait enough to confuse these algorithms, can be as simple as changing your shoes.

    Gait analysis is first being tried out on urban CCTV cameras networks, rather than via satellites, and, like other biometric technologies, it is hugely inaccurate and prone to false positives and false negatives.

    There have been research projects for real time video “suspicious behavior” analysis (e.g. dwell time or loitering near parked cars), and attempts at detecting “stabbing” or “kicking” motions.

Michiel de Lange

Michiel de Lange (1976) is an Assistant Professor in New Media Studies at Utrecht University, researching mobile media and urban culture and identity. He is the co-founder of The Mobile City, an independent research group founded in 2007 that investigates the influence of digital media technologies on urban life and the implications for urban design and policy. Michiel is trained as a cultural anthropologist, and holds a PhD in philosophy (2010) with a dissertation about mobile media technologies and urban identities. He collaborated in a locative media art & science project ( He worked for  Kennisland, a Dutch think-tank that aims to strengthen the knowledge-based society. Here he worked on several projects at the intersection of ICTs and the city, e.g. co-organizing the Creative Capital conference. He also volunteered and worked for Cybersoek, a computer neighborhood center in Amsterdam. He is advisor e-culture at Mediafonds.
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