The RFID chip / GPS locator inside matches up against data for the camera operators. I imagine when a family and camera operators data "matches" that indicates

The RFID chip / GPS locator inside matches up against data for the camera operators. I imagine when a family and camera operators data "matches" that indicates they stood still for a picture and I'm sure DIsney tries to find every opportunity like that to display those images to the visitors as a chance for them to purchase memories they hardly realized they were making during a picture they didn't realize they were taking. All in all I think it's really really amazing what they are capable of doing.