I want to count how many people every day visits our store. In store has two entrances. Second entrance is not used often. Entrance gate is about 1.5m wide. I plan to attach some device to Raspberry Pi. What is best method to count people flow? I know that i can use laser. Witch is better and precise method? I also want to make counter electronic stuff myself :), not to buy already made device. Thanks.
Edit: looks like question is more like: what type of sensor i need to count visitors?