IDK but that's how they did it and they also factored in your electrical consumption for grow lamps.I have a good friend that works San Diego Sheriff's dept. on their drug interdiction task force. What you just described is almost impossible without other factors. You simply aren't allowed in this country to survey an area like that with no PC.
this is ohio you can get locked up for a joint but the guy in the car next to you is workin his 10th DWI.