This DRI ranges calculator enables 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.
Upon completion of the calculation, using the final values, you will be able to search for the appropriate IR lens to meet your requirements.