human location detection

i want to detect the location of human in a particular field of view using arduino....which sensor should i use for that

A PIR passive infer red sensor like they use in burgler alarms.

but will it tell the location of the human

pramraika:
but will it tell the location of the human

Do you mean will it discriminate between a dog, or bear then no. There is no sensor that will.
It will also not give any location information just if there is some movement in the sensors field.

Can you be more specific about what you want this sensor to do and not do.

Use a guard dog. Name him "Arduino".

pramraika:
i want to detect the location of human in a particular field of view using arduino....which sensor should i use for that

Maybe a video camera, and a PC to perform the image processing you'll need to recognise the presence and location of a human?