A fisheye camera uses an ultra-wide lens to cover a full room or a 180- or 360-degree view from one position. The image is curved and is dewarped in software to give a natural view. Wide coverage costs resolution per subject, so a fisheye is best for overview rather than identification.
One camera covering an entire room is an attractive idea. The trade is that each person in the frame occupies a small part of the sensor.
Coverage and dewarping
The lens compresses a hemisphere onto the sensor, so straight lines curve. Software flattens the image, or presents several virtual views from one feed. A 360-degree view from a ceiling mount sees everything below it, which suits a sales floor or a stockroom.
Where a fisheye earns its place
Use it where the question is what happened in a space, not who a person is. Add a fixed or PTZ camera for identification at the entrance. Keep the camera close to the area of interest, because distant subjects lose detail quickly at the edges of the frame.
Related:Commercial security camera systemsGlossary: PTZ camera systems