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Originally Posted by Lodesman  Umm, satellites look down - to read your license plates they would have to be mounted to the roof of your car and the letters would need to be half a metre (1 1/2 ft) tall. And the sky needs to be clear. I don't know of any computer sophisticated enough to do what you suggest - perhaps you or your fellow conspiracy theorists have proof otherwise?? An awful lot of our (taxpayers) money goes to SARSAT, Coast Guards, RCCs, etc. These are staffed by dedicated professionals, and they have the latest and best technology available to provide search and rescue services, free to all mariners in distress. The governments are not all bad.
Kevin |
Yes, satellites do look down. However, satellites are also quite capable of taking off-nadir images at angles between 10 and 35 degrees. Today, top notch commercial earth imaging satellites are capable of 0.41-meter panchromatic resolution. You can imagine what order of higher resolution military satellites are capable. It’s like GPS - for commercial use it’s accurate between 3 and 5 meters. For military use it’s accurate down to a few centimetres. So, no, the characters would not have to be 1 ½ feet tall at all.
Further, the sky does not have to be clear. Imaging satellites are capable of also collecting high resolution pan-sharpened multispectral imagery, meaning near-infrared, infrared and even radar data. Based on whether the images are panchromatic or multispectral, they can collect between 700.000 and 350.000 square kilometres of imagery every day. That’s a lot of data.
In order to process it, despite it sounding like a conspiracy theory to you, computers are used. Imagine that! And they do not process the image as such. They process the digital data directly, employing highly developed algorithms to find what they’re looking for.
Digital image processing is the only practical technology for
So you may have never heard of it but digital signal processing (
DSP) was first developed in the 60’s and has been used increasingly ever since. You can forget the pictures of military types gathered around large tables loaded with photographs, pipes clenched between their teeth, peering at them intently through large magnifying glasses.
Anyway, photographing licence plates is so retro anyway. Anyone wanting to keep track of you (or me) can do so by using that cute little mobile phone we have a way of taking with us wherever we go, either legally or illegally. It all just depends on the definition of “legally”. Some places, it doesn’t have much meaning any more.
In the final analysis, there is hardly a spot on earth which is not carefully monitored daily by satellite, either for commercial or military purposes. What I was trying to express in my short rant last night was the frustration of knowing that the resources and the capability are there in place but not being put fully to use, in order to also save lives.
If you have Google Earth, crank it up and go to 2.28’33.27 N – 101.50’44.77 E, adjust your viewing height to approximately 1000 ft. and tell me what you see. Even taking Google’s crummy resolution into account, you’ll recognize that its more than enough to locate a 53 foot yacht.
You can be sure that vessel is on somebody’s digital image, dutifully taken during today’s flyby.