What does IFOV describe?

• A. The angle between the outer edges of the scene
• B. What a single pixel sees measured in MRAD
• C. The total field of view
• D. The camera's spectral range

Answer: (B)

IFOV describes the angular size of the scene that a single pixel (detector element) sees. It’s the per-pixel field of view, expressed in milliradians (MRAD). This is different from the overall field of view, which is the entire scene the camera can image, and from the spectral range, which is the wavelengths the sensor detects. The practical importance is that IFOV links to ground sample distance: ground distance per pixel ≈ distance to target × IFOV (in radians). For example, at 1,000 meters distance, an IFOV of 0.25 milliradians yields about 0.25 meters per pixel on the ground. A smaller IFOV means higher resolution because each pixel covers a smaller ground area. IFOV is determined by the pixel size and the lens focal length (roughly IFOV ≈ pixel size / focal length, in radians).