This.

Also, how would the system search for its target? Without a fairly specific location in mind to find said terrorist, it'd be searching gait profiles for a long time. Even if it's as small as area as the City of San Diego, there are millions of people to sort through.

The other alternative would be to map all visible persons to have tabs on everyone all the time, but that's extremely creepy and would be difficult to maintain. If it couldn't penetrate buildings, people would disappear and reappear on the grid all the time.

If it COULD penetrate buildings, any operator would basically be seriously invading your privacy, as it could catch you in any location, including showers/etc.

What would be the procedure if you were spotted taking some controlled narcotic? While this is a minor crime, where is the line for punishment? There's a reason why the locator in your cell phone only activates when 911 is dialed, I couldn't see any way this would constitutional.

It couldn't work through non-transparent substances because it's watching your shadow, which is defined by the visible light arround it.

Jeeze man your getting way to deep. Its a tool, for example facial recognition software you see in movies. Except this is a point at a location and see if any shadows are recognized. Its not xray vision its just normal vision. Its not tracking every person on the planet. Its a human operated intel based tool.

Point click recognize.

Your just thinking way to advanced.

Gotta quote this for poor English.

Yea I know, I usually have to read my post a couple times through because of my poor english.

Yet, you clearly avoided his entire point, which I agree with. Volls is taking it to another level of complexity of which this really isn't.

I didn't "avoid" anything. I agree with him.

The sun isn't positionally static, so I'd assume it could use other light sources to a limited degree as well. /shrug

Also, a lot of my previous post was just idle speculation on how it would work.

Yes, but the device watching has to be able to see the absence of visible light that is the shadow.

Yeah, I just realized how incredibly stupid that thought process was. Posting at 4am or whatever for the win.

Edit: Okay, that was at 9pm. Nevermind, no excuses there, that was straight failure.

How is that failure? It is how the machine works.