Table 2.

Summary of CCTV systems’ technical limitations in the application of morphological analysis.

General Limitations	Specific Limitations	Effects
Camera placement	Camera height above ground [21,48,49,99,100] Angle of incidence [21,48,49,100] Subject-to-camera distance [103,104,127]	Image composition affected—target size and screen/picture height [21,48,99] Reduction of observable facial features [21,48,49,100] Perspective distortion [103,104,127]
Camera specifications	Analogue or digital [82,115,116] Sensor size [99] Pixel count [48,99] Lens focal length [99]	Reduced image quality [21,48,99] Image distortion and artefacts [99]
Lighting conditions	Ambient lighting [99,107,108] Infrared vision [93,107,108]	Loss of facial detail [48,49] Shadows and overexposure form artificial boundaries and altered facial appearance [49,106] Optical distortions [99]
Image quality	Resolution [21,48] Pixelation [48,92] Noise/grain [99] Video compression [90] Color [48]	Low clarity [99,103] Reduced useable detail [21,48,82,90,92] Face matching ability reduced [21,48,90,125,129]
Data loss and corruption	Network infrastructure [41,72] Software [99] Hardware [41,99] Imminent weather [41] Power outages [41] Compression rate [90] Anti-forensic techniques [109,110,111,112]	Inconsistent network connection and coverage—transfer corruption [41] Partial or complete data loss [41] Data tampering and removal [109,110,111,112]