So I am in the process of creating some motion actived software that will be used in public. The sensors detect when a person is close and lights up to offer them something. My question is what is legal to do in a case like this? With the motion sensors can I legally have them turn on when someone is close? If its on a vending machine can I offer different selections based on peoples height and weight? Also do I need to inform people with a sign saying that the detector is recording them?