What is a FishEye / Fisheye Camera?
Fisheye or Fish Eye cameras almost all have a single internal digital camera or sensor and the panoramic “magic” is done by a lens through common optics. In this case, these Fisheye cameras through software are capable of interpreting the image to later "unfold" it and achieve flat images.
There are other models that have more internal cameras and in which the optical lens is not essential since each camera is pointed toward different axes so that it can be reconstructed as a 360º image with software.
What Do You Need A Fisheye Camera For?
Fisheye 360 ​​vision applications are especially good for small spaces where you want to monitor the entire area with video surveillance. Its "range" to see at long distances is short, but its ability to show details is very good and it can give a 180 or 360º view.
In confined spaces, if you want to see every corner of a room, with "Bala" / "Bullet" type cameras you would need at least 2 cameras, but a single Fisheye could monitor an entire area:
Example of Fisheye camera view: