Maximum Distance To Identify Faces With Ptzs?

If you need to identify the intruder in court, you are going to need a fairly detailed image, like 60ppf in ideal lighting conditions. See our identfication vs detection tutorial on that.

The next issue is how 'far' a speeddome can optically zoom and deliver that level. Roughly speaking you are looking at ~100 meters. See our 'How Far Can a PTZ See?' tutorial.

That implies putting a speeddome every ~200 meters.

However, this presumes no low light / night time issues. Unless this perimeter is very well lit or you do not care about night time monitoring, this is going to be a big problem as it will significantly cut down how far you can identify a person.

Finally, as a point of reference, if you only needed to detect a person and verify that one was there, the PTZs could cover ~6 greater range - a huge distance. This is mainly noted to emphasize how much of a tradeoff exists in requiring identification.

If you are willing to forgo a speeddome and use a pan / tilt positioner instead, there are some more possibilities that might get you far longer range with identification. See our recent discussion on 'Viewing a Person's Face 3000 meters away'. While that is not terribly realistic, you should be able to get to 500 meters with a specialized solution which could decrease the total number of cameras used by 5x (though each camera will be significantly more expensive).