I've fantasized about various versions of the following setup as a kid.
> Concentric rings of motion sensors surrounding home
> Smaller rings have the highest quality, but least sensors
> Outer rings have the cheapest, but most plentiful sensors.
> Divide up sensors into slices/sectors/wedges and give each one a separate brain box
> If sensors from two adjacent layers trigger , phone home
> Home box sits on roof or porch and contains a drone
> drone is sent to fly over the triggered sensors with a speaker and camera. It reads the local law that the trespasser is breaking, along with the sensor. It then audibly counts down from 15.
> If the drone locates something it recognizes as a person or animal, it will strobe a light at the target, film them, and wake the home owner(If the strobe light hadn't already).
> If nothing is found by the time the recording has ended, the drone will take a couple circuits of the house's perimeter and then return to charge without waking the home owner.