satellite photos

[entwined]

Yesterday evening, my wife and I were watching an episode of CSI (crime scene investigation?) and they showed a satellite shot of a girl being kidnapped and the face was recognizable as if the picture had been taken accross the room.

 

I explained to her that satellite photography was probably not quite that good and she said that it certainly is that good as they do it all the time on csi.......

 

Then I got to wondering.......this sort of thing is certainly not in my bag of tricks, so who really knows? Certainly not me.

 

Then I thought of you guys, and I figured that some of you just might know the current capability of satellite photography, so what is the story on this?

 

Anyone?

[Sayonara]

Most of the forensic and surveillance tech you see on CSI is exaggerated to ridiculous extents.

 

It's certainly possible that you could put a satellite in orbit with the technology to take recognisable images of faces. However the chances of such a satellite passing overhead on a clear day and taking photos of a kidnap which just happens to be ongoing within the insanely narrow viewing window are ridiculously small.

[Flashman]

Anyone who "really" knows probably isn't allowed to discuss it. However, last I heard, resolution from orbit was on the order of baseball sized objects, say 4 inches. There would be relatively huge problems getting much beyond this due to atmospheric instability and haze.

 

Now spyplanes have much less atmosphere to see through, and may be able to duck below high level cloud and haze and can read a license plate from 10s of thousands of feet and a few miles away. Let's say they've got about half an inch resolution.

 

But, if you want to get to a point of about quarter inch resolution that I figure would be minimum necessary for positive ID of someone, you'd need your basic UAV or a close-in photo-recon.

 

That is why the troops are playing with radio controlled planes in the Afghan mountains and they haven't just lasered Bin Laden from orbit.

 

Probably goes like this, satellite IDs area of suspicious activity, "spyplane" or recon confirms type of activity (can tell guns from sticks) and UAV will tell you who exactly is doing it...

[ParanoiA]

Yeah, but that part where they take someone's face and then do their "super duper search" where it finds the name, address, fresh picture, police record, employment record, blood type, family members, cell mates, all within fractions of a second in nicely presented frames is totally real...

[swansont]

The basic resolution is given by the diffraction limit given by Rayleigh's criterion.

 

[math]sin\theta = 1.22\frac{\lambda}{d}[/math] for a circular aperture

 

For a satellite 100 km up, to resolve dots 5 mm apart, that's 0.05 microradians; at 500 nm, that's a ~10 meter iris.

 

Resolution, and especially enhancement of resolution, is something with which TV shows take great liberties.

———

 

(I'm guessing it was NCIS rather than CSI)

[entwined]

That's about what I thought.

 

And yes, it was NCIS......she says.

[nitric]

yes it would be NCIS instead, no public CSI unit would have access to technology such as that, theoretically (Scientific America) it is possible to get 1/8 meter to 1/20 of a meter