DRI Range Calculator

    Detection, Recognition & Identification (DRI) calculator

    This DRI ranges calculator enable one to easily estimate the maximum range that an object can be either detected, recognized or identified.

    It is important to note that these estimates are based solely on geometrical parameters – the target size, distance, lens focal length and camera detector pixel size. Signal level, detector sensitivity, atmospheric conditions and other factors are not considered!

    The calculations used here are based on the “Johnson Criteria”. According to the Johnson Criteria, the minimum resolution, pixels on target, required to achieve a 50% probability for an observer to discriminate an object are:

    Detection: an object is present – 2 pixels on target
    Recognition: discern the type of object, a human vs. a vehicle – 8 pixels on target
    Identification: discern specific objects, a man vs. a woman, a car model – 12.8 pixels on target

    Calculated DRI ranges are based on the following target size assumptions:

    The ranges calculated are based on a simplified analysis and are intended for comparative purposes only. Actual range performance of any lens may differ from those shown. The ranges displayed do not imply any warranty on expected performance.


    Detector pixel pitch


    Lens focal length