Questions · Cameras
How far does a camera's infrared really reach?
A good deal less than the box says, because the range the manufacturer publishes is measured against a white wall in an enclosed corridor, and in a yard there is no wall to send the light back. Infrared works by reflection: it lights, it bounces off something and it comes back to the sensor. If what is in front is open ground, wet tarmac or grass, a large part of that light never comes back.
There are two more effects that spoil the sums. Dark clothing absorbs infrared and the person comes out as a silhouette with no detail; and whatever is very close to the camera —a branch, the sunshield itself, the rain— bounces back so much light that the sensor closes down and what is behind disappears. It is the same effect as driving with your main beam on in fog.
So over large outdoor areas, the unit's own infrared is used for the first stretch and beyond that it is solved with separate lighting, infrared or white, put somewhere else and not stuck next to the lens. Lighting from a point other than where the camera is gives shadows and depth, and a face with shadow is recognised far better than a flat one.
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A written answer is enough to decide whether it interests you. To know whether it works at your site you have to see it on a real scene, with the image as it is and, on top of it, what the system understands from it. That is on the IRIS Neural website, which is the group's product.