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An idea: Cameras are deployed for a few different purposes. The more discrete functions you are trying to accomplish, the more cameras you need.

Example 1: Red light cameras. Only needed at specific intersections that have particular characteristics (high speed? high volume? not sure). The distribution of these probably maps more to physical space than population itself as the spacing of red lights is relatively independent of population.

Example 2: Cameras that are aimed at crime suppression. These will be unevenly distributed around a city depending on where crime happens. Looking at Chicago I see particular neighborhoods heavily blanketed in cameras, others very very sparsely. The distribution of this type of camera would be quite different than traffic-control cameras.

Example 3: Population monitoring cameras. I honestly don't know why China has so many cameras. Are these literally population surveillance cameras? These might be evenly distributed around a city to maximize coverage.

Some of the power law distribution you see might be a result of different cities applying cameras for 1, 2, 3, N different functions (each of which requires a different number of cameras).



A few years back I was mugged in Chicago at a busy intersection very close to a train station. Being the FOIA nerd I am, I submitted a FOIA request for the footage of the spot I was mugged at. It came back saying that no footage exists. Probing the investigator, I was told that the camera rotates randomly, and wasn't pointed in my direction. It's very difficult for me to think of Chicago's surveillance with any sort of charity, when they can't even do a single major intersection.

Fun fact: Chicago's city hall has a retention period of zero days on its cameras. Go figure.


> Chicago's city hall has a retention period of zero days on its cameras.

Does it mean that they have people watching the camera, warning the street police if they find anything, but do no recording?


That's my understanding, yes.


Given that it's Chicago, my understanding would be that the officer handling the FOIA request fed you a line, and they probably didn't even look at any recorded video to see if the camera was pointed in the correct direction.

Did you do a follow up request for whatever that camera actually recorded while you were getting mugged?




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