Detection, Recognition, and Identification (DRI) are guidelines that have been set in place by The Night Vision Thermal Imaging Systems Performance Model, also referred to as the Johnson criteria. They are a universally accepted set of standards developed by the US Army to provide a means of measuring the distance whereby a thermal sensor can produce an image of a specific target.
Identification of an object means that you are able to differentiate between objects. For example, this person looks like a tall woman wearing a dress, that person looks like a soldier.
For a complete explanation of DRI measurements and what to expect from them, please see our Whitepaper on DRI: Thermal Distance Ratings Explained.