"Now!" John's voice boomed from high above, breaking their chitchat. "Listen up! The cannons need to register your biometric signatures, your voices and your physical features. I need you all to go outside the walls. One by one, you're going to move and speak loudly when I give the signal."
"Why didn't you just let us do that down here before you went up?" Luke called out, sounding confused. Regardless, he and the others began running through the massive gate to the area outside. John had chosen the starting point near the main gate for this very reason.
"The sensors are modified for long-range targeting!" John shouted back. "They need to register your profiles from this specific height and distance. If I calibrate them at ground level, the parallax error will be too high, and the system might mistake you for a breaching enemy in the heat of battle!"
