Final (final) tent post

by Alex Hern

Because I consider this to put the matter to bed:

Claims that nine in 10 tents at Occupy London remain empty overnight are based on “rubbish science”, a military scientist specialising in camouflaging soldiers against thermal imaging technology has told the Guardian.

He said: “They cannot make the assumption that they have made from those images. The way they are set up, you wouldn’t be able to tell if there’s anyone in the tent or not, especially if someone is sleeping in an insulated sleeping bag.”

A camera of this kind would very rarely be able to see “into” a tent, said the scientist, as tent materials are almost always opaque to thermal imaging. A photographer would only be able to detect internal activity if the tent fabric was itself re-radiating heat produced by a warm object behind it – and this in turn would only be possible if very specific camera settings were used.

But the scientist said: “The first thing I noticed when I saw those images was that the camera was on an auto setting.” In order for the images to be of any relevance, the photographer would have needed to manually adjust its settings, until the tents were clearly defined, in almost binary terms, against the background; and the figures of the occupiers walking around outside were completely over-exposed and apparently “white hot”, rather than a spectrum of colours.

The scientist also said that the kind of camera used – probably a hand-held FLIR thermal imager – was unlikely to be used by the police for surveillance. “Those sorts of cameras are usually used for inspections at close range,” he said, adding that customs officials only use such cameras at close quarters to look for stowaways. If police helicopters had scanned the camp they would have used much more sophisticated technology. “I’m not that interested in the story,” the scientist concluded. But he said: “I wanted to set the record straight because that’s just rubbish science.”

SCIENCE

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