Requirements for CCTV Cameras
The primary requirements for installation and characteristics of CCTV cameras in your FindFace-based face recognition system are the following:
For correct face detection in a video stream, mount the camera so that the face of each individual entering the monitored area surely appears in the camera field of view.
The vertical tilt angle of the camera should not exceed 15°. The vertical tilt is a deviation of the camera’s optical axis from the horizontal plane, positioned at the face center’s level for an average height person (160 cm).
The horizontal deflection angle should not exceed 30°. The horizontal deflection is a deviation of the camera’s optical axis from the motion vector of the main flow of objects subject to recognition.
The minimum pixel density required for identification is 500 pixels/m (roughly corresponds to a face width of 80 pixels).
Select such a focal length of the camera’s lenses that provides the required pixel density at a predetermined distance to the recognition objects. The picture below demonstrates how to calculate the focal length subject to the distance between the camera and recognition objects. Estimating the focal length for a particular camera requires either calculators or a methodology provided by the camera manufacturer.
The exposure must be adjusted so that the face images are sharp (“in focus”), non-blurred, and evenly lit (not overlit or too dark).
For imperfect lighting conditions such as flare, too bright or too dim illumination, choose cameras with WDR hardware (Wide Dynamic Range) or other technologies that provide compensation for backlight and low illumination. Consider BLC, HLC, DNR, high optical sensitivity, Smart infrared backlight, AGC, and such.
Video compression: most video formats and codecs that FFmpeg can decode.
Video stream delivery protocols: RTSP, HTTP.
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