Hi!
In an application, I have to determine whether someone have passed between 2 points placed 300m to 500m appart. The situation is of outdoor type. I have many ideas but i do not know which one is best. Kindly tell me what do you think.
1, Using Infra-red beam broken type.
2, Using camera to capture image and then process it.
3, Ultra-sonic type. (how it will perform in outdoor with long distance detection).
4, Can I use Radar type thing which can scan area with RF and show image as small as few meters in height.
5, Use some sort of Capacitance detection to detect if insulator changes between to metal pieces.

Any other Ideas will be helpful.
Thanks!