Scott Urquhart is a geophysicist and president of the engineering company Zonge. He teamed up with University of Arizona professor Moe Momayez on a project called Helios.
It doesn't involve cameras or fences or enforcement agents. It involves cable. Fiber optic cable, specifically, that is buried a short distance below the ground and can sense exactly what's going on up above. Helios sends laser pulses from the cable up to the surface and then detects variations in the pulse it receives back. Urquhart and Momayez say it's incredibly sensitive and can detect the difference between a car, a person, a dog, a horse, whatever is going on up there.
They say that since the program uses standard fiber optic cable, it would be relatively affordable to stretch it out over long distances and would be more reliable and comprehensive than cameras.