How to do people detection from bird eye view?

1. Why do people use a bird's eye view?
2. What is a bird's eye view an example of?

Why do people use a bird's eye view?

This shot can be used to give an overall establishing shot of a scene, or to emphasise the smallness or insignificance of the subjects. These shots are normally used for battle scenes or establishing where the character is.

What is a bird's eye view an example of?

a broad view of a situation.