[PD] 4 cameras for tracking people in a space

[ronni montoya]

HI, I been working on interactive installations for public spaces
usually i put one camera in the roof pointing to the floor, i always
have the problem that i  need to have the camera 6 or 7 meters in the
roof to track 4 * 4 meters space aproximately and thats a very big
limitation since there are a lot of spaces that doesnt allow to put a
camera 7 meters up.
The thing is that i went to a conference where a guy explained he used
4 cameras to track people in a space instead of just one  and you dont
need to have a high roof .
I would like to know if somebody know this technique for tracking
people in spaces with 4 cameras ?


thanks


R.