what sensor can be used to detect trespassers for an intelligent street lamp system ?

im planning to do an intelligent street lamp and want to know about sensors that can be used in it.

bwrussell5 years ago
I assume these alights are out but if someone comes near you want them to turn on? Use an IR detector. If the surrounding air is cool enough it should be able to detect a warm body in its field of vision. Pressure sensors under the ground could work as could laser IR trip wires (like prevent your garage door from closing with something in the way).
Intelligent streetlights: I think I've seen this meme before.

The usual trick is to put video cameras and microphones in them, then feed all that data back to some central location where the overseers can monitor the feeds and intervene when necessary, and this can be done, in part,  by way of output devices like speakers and screens.

http://www.infowars.com/new-street-lights-to-have-homeland-security-applications/

So, um... what kind of "trespassers", or activity constituting trespass,  are you looking for anyway? 
rickharris5 years ago
For sensing what?

Microwave - approaching objects
Ultra sonic - approaching objects
Capacitive - touch
Sound - how close objects are, touch, mechanical vibration

electrical field distortion
inclination - to see if anyone had bent the post
Vibration - earthquake detection


Your question is FAR too vague and by the looks you should start with some research into different types of sensors in general.