Tuesday, June 16, 2009

No, the government isn't watching you

When writing about conspiracy theories a few weeks ago I mentioned that one of the characteristics of conspiracy theorists and their proponents is that they often rely on or assume the existence of technology that is far in excess of current capabilities or they get their ideas of the capabilities of available technology from television or cinema - in other words, they are way off the mark.

One thing in particular they often take as granted is the government's ability to track personal movements or individuals by remote sensing - usually via the all seeing eye in the sky. This form of surveillance is well entrenched in popular culture now, from novels, television and movies to crap annoying songs ("There are Cameras in the sky, Lasers in our Living rooms").

This post is my two pence worth of poking a hole in the myth perpetuated by popular culture that the government can use satellites, aircraft mounted cameras or CCTV to keep track of individuals on a daily or regular basis.

Digital cameras as CCTV

Take a look at your own digital camera pictures and videos. What size are they in terms of megabytes when stored on your computer? I have a 4 minute 25 seconds video with sound taken by a 6 mega pixel camera. It has a file size of 91.8MB. That's 265 seconds of video. There are 86,400 seconds in a day. Which means approximately 326 of my videos. Which would mean a storage space of just over 29GB for the whole day (if anyone sees a hole in the maths , let me know).

29GB, for one camera, for a whole day's worth of video. Now, let's assume that your average digital security camera is much worse quality and has no sound, so let's halve that number and call it 14GB for one camera for one day. That is still approximately 5 terabytes of data for one camera for one year. Well, maybe the camera is stop motion or motion activated so isn't recording constantly. Hell, let's make the storage space needed a fifth of that of my original home movie. So just 1 terabyte of data per year. For one camera. A 2002 study estimated (and the study has been criticised for its methodology - but it is often cited by the "We Are Being Watched" crowd) estimated that there were 4,200,000 CCTV cameras in the UK. In New York City alone in 1998 there were estimated to be 3,000 known CCTV cameras watching the city streets.

All this adds up, to use the technical term, to a shitload of data. For the UK alone that would be 4,101.5 petabytes of data per year. Who exactly is looking through all of this for you.

But it doesn't have to be a person doing the watching your "We Are Being Watched" (WABW - pronounced wabwer, it has a suitably childish ring to it) proponent will proclaim - facial recognition software. Saw it on CSI so they did.

Well, now you should retort "And how does facial recognition software work with the back of someone's head?" See, the WABW thinks that your face is the only part of you that a camera ever sees. There are never any obstructions in the way. Cameras only ever see faces, and complete or only partially obstructed ones at that. How, precisely, does one write a program to extrapolate and then recognise accurate facial features for an individual from a slightly above, behind and to the left shot of a bald spot and an ear? The commercial remote sensing industry uses automated systems to analyse and classify imagery and it still needs human input and it is still not as accurate as the Mark I eyeball with a reasonably intelligent human operator behind it - and that is for identifying relatively simple things like ground cover and usage, nevermind distinguishing one fat round face with two eyes from another fat round face with two eyes from 200 feet away in an image containing hundreds of fat round faces with two eyes all facing the camera at different angles.

On top of that problem, just exactly how many types of 'ultra fast supercomputers that don't yet exist ' does the UK government (for instance) have in order to sift through the data from 4.2 million cameras to distinguish 1 face from the other 61,113,204 potentially recorded faces everyday (and that's just the population of the UK by the way, doesn't include visitors). And these computers do this so quickly that the task can be performed regularly or even daily?

Oh, and since most of the cameras being operated in the UK (as the favoured example of the surveillance society) are not even government owned, how does the government even get hold of the data from them?

And storage? Don't even get me started on the storage. OK, do. Where is this data stored? For how long? Data compression we hear. As long as they need it we hear. Well, see, here's another problem your WABW hasn't thought about. When you compress images you lose information contained within the image, and in some cases uncompressing can result in even more distortion. It doesn't matter how good your compression system is, that's what happens. There are mathematical ways to compensate for this but they are complicated, not 100% accurate in relation to the original image and they can be time consuming. This is something the commercial remote sensing industry deals with on a daily basis. Yet apparently the government has a perfect compression system that loses no data and that no-one knows about, and a bottomless vault to store all of this in for as long as they need it.


Video Cameras as CCTV

But, as always, there's more. Not every camera is digital - video tape is still widely used because it is cheap and reusable without stumping up the cash for a nice computer system. So here's a little maths I prepared earlier.

T160 tape has a length of 1,075 feet and record time of 225 minutes.
4.2 million cameras in the UK
24 hours = 1440 minutes
1440 / 225= 6.4 tapes per day for one camera
1075 * 6.4 = 6,880 feet of tape for one camera for one day
6,880 * 4.2 million = approx 28,896,000,000 feet of tape a day for all cameras in the UK
5,472,727.2727 miles of tape a day

Now, these figures assume every camera to be a video camera, which isn't the case. So let's be massively generous and assume that figure is now down to only a quarter of the UK's CCTV cameras being video tape - still 1,368,181.8 miles of tape a day. That's 7,224,000,000 feet a day. Or 6,720,000 tapes a day. Where the hell is the British government storing nearly 7 million videotapes a day?

Quality of the imagery

So far all we have talked about is the sheer volume of data and how to store it and this creates enough problems for the WABW, we haven't even looked at data quality yet.

Anyone who has ever seen a CCTV still or video excerpt from Crimestoppers in the UK or America's Most Wanted in the USA knows that basically, the majority of CCTV footage is useless. The cameras are very poor, so the imagery is very poor. Good cameras cost a lot. But we are supposed to believe that crap original images from crap cameras can be compressed, uncompressed and then enhanced to get an image that facial recognition software can then use to identify a face from? Oh right, they do it on CSI. Well guess what? CSI is wrong (and increasingly rubbish to boot). Enhancing an image doesn't work like it does in Blade Runner (which is wrong but awesome). Zooming in to an image does not increase its sharpness or clarity if the sharpness and clarity were never there at that level of resolution.


Currently, the satellite with the best resolution commercially available is GeoEye 1, which is operated by GeoEye. It has a resolution of 41cm in panchromatic imagery and 1.65 metres in the spectral bands equivalent to red, green, blue and near-infrared (and no, infrared does not let you see through things) on the electromagnetic spectrum. GeoEye 2, when it is launched, will have a resolution of about 25cm. GeoEye 1 orbits the Earth at a height of 425 miles. It will flyover the same area on the Earth's surface about once every 8.3 days.

Now, that resolution is awesome. That means that when you display an image taken by GeoEye 1 at it's maximum resolution, one pixel is equivalent to 40cm on the ground. But that is the commercially available data. We know the military gets better resolution, we just don't know how much better. Say that the military gets the unrealistic resolution of 10cm - one pixel is 10cm. Sounds awesome right? Sounds like Big Brother is watching you, right? Well, yes an no. It is awesome.

How wide is your face? Mine is roughly 15cm wide. Oh dear. Ever tried enhancing an image so that you can see one pixel from the original resolution and identify what that pixel is? I have, don't waste your time. In digital imagery terms, one face would be roughly one pixel at 10cm resolution. That one pixel then has to store all of the spectral information about your face - all of the many colours that make up your skin tone and facial definition. Trust me, it won't be very accurate. You'll have a largely pink blob and nothing else.

That is, of course, if you happen to be looking up at the exact time in the 8.3 day cycle when GeoEye 1 passes directly over your head. And you would have to be outside of course. And there would have to be no cloud cover. And nothing else between your curiously and randomly upturned face and the camera. GeoEye 1 passes over the Equator at about 10:30am everyday if you want to try.

"Directly over your head" is important. An image is distorted the further from nadir it is (that's the point directly below the camera when an image is recorded), and GeoEye 1 takes a swath of images 15km wide when it passes overhead. That's a lot of image to find you in, especially if you are at the edges where distortion is greatest. And if you aren't looking up instead of a pink blob for your face there will be a blob of similar colour to whatever your hair colour is. No, the government can't track you via images from a satellite.


So, what about images taken from lower flying aircraft? The resolution will certainly be better. Your face could certainly be recognisable. You might not even have to be looking up, cameras could record your image from an angle. However, how easy do you think it is too do this in a crowded city? And don't you think you'd notice the black helicopters following you around (Hollywood stereotypes remember). It takes a lot of time, money and effort to plan a remote sensing mission - and that is when you know the target location, required flight height, speed and time of day as well as track (all of which can affect settings for the camera and the type of film you need to use). Can the black helicopter crew tracking you know this? Do you always stay at the same speed and height as you move around every day?

So, in the end

What makes you so bloody important?

I know it pokes a massive hole in your ego dear conspiracy theorist - but the government really isn't watching you via cameras in the sky.

There are far easier ways than that.

1 comment:

  1. Don't forget...battery life.

    I realize that much of the installations claimed could have power routed to the camera, for example cameras in streetlights. But while data can be routed wirelessly pretty easily, powering cameras that are hidden or placed in places where power is not available requires a battery. A camera eats through a battery easily. I dont have the numbers off hand, but there is a reason your digital camera dies in 60 minutes.

    There are solutions, like charging a big battery during the day by a solar cell, but you lose half a day of recording and you can only record at night.

    Anyway, regardless of the specifics there are many cases where battery life woudl also be an issue.