RANGE PERFORMANCE

Detection, Recognition, and Identification (DRI) are terms we hear daily. This paper will explain the standards that have been set in place by The Night Vision Thermal Imaging Systems Performance Model, also referred to as the Johnston criteria, the universal standard for measuring thermal cameras.

What is it?

DRI is a universally accepted set of standards providing a means of measuring the distance whereby a thermal sensor can produce an image of a specific target. This tool was developed by the US Army and takes into consideration many different criterion such as noise, array size, optical blur, lens depletion, aperture, atmospheric depletion, detector pitch and many more.

Detection

Detection means that you will be able to see the target, however it will be little more than a spec. Specifically it means that the target is visible on at least two pixels, and that there is a good chance that the target is actually something of suspicion. Recognition Contrary to what you might think, recognition does not mean that you can recognize an individual. Recognition simply means that you are able to recognize an object’s class (is it a human or a car, is it a truck or a tank, etc).

 Identification

Identification of an object means that you are able to differentiate between objects. For example, being able to identify the type of vehicle not just its class. Putting it all together

If we ignore the effects of the atmosphere, normal recognition would be 25% of the detection and identification would be 12.5% of the detection range. Weather is almost never ideal so in reality these percentages are almost always reduced.

It’s all in the pixels…

As you can see the terms detection, recognition, and identification can be extremely misleading, especially to end users and the public who do not have a military or electro-optics background. The terms detection, recognition, and identification do not relate to performance, but rather are calculated based on their pixel counts. To put this in perspective, our high-res thermal sensors have a resolution of 640×480 which is over 300,000 pixels. Human “detection” only requires 3.6 of those pixels and “identification” only requires 230 pixels, which is an extraordinarily small amount on the screen that can easily go unnoticed by the human eye. In fact, if this page were the size of your video feed, the area required for a human detection rating would be equivalent to the size of this rectangle: Even when magnified, the amount of detail visible at the detection, recognition and identification distances is not as high as one might expect, as seen in the chart below.

 Industry Standard DRI Requirements

 Detection Recognition Identification Human

3.6 pixels by 1 pixel (Something is there)

13 pixels by 5 pixels (A person is there)

28.8 pixels by 8 pixels (The person looks like a soldier)

Vehicle

2.8 pixels by 1 pixel (Something is there)

13 pixels by 5 pixels (A vehicle is there)

28.8 pixels by 8 pixels (The vehicle may be a humvee)

Boat

4.5 pixels by 1 pixel (Something is there)

18 pixels by 2 pixels (Some kind of boat is there)

36 pixels by 4 pixels (The boat is a small inflatatble boat)

“Ideal Conditions”

Another thing that is often not mentioned is that these ratings are based on what is termed “ideal conditions” which rarely happen in the real world. The average environmental application will get 25% less than the distance that the thermal camera is rated for and in extreme conditions can be less than 10% of the rated distance. We wrote this white paper to give end-users the ability to understand the actual performance they can expect from these ratings. In addition to thermal imagers, Infiniti also offers active IR, SWIR, and visible sensors. We do not limit our clients to anyone technology; rather we custom build solutions that work for our customers.

Other considerations

Another often overlooked aspect is that these ratings are based on “ideal conditions” which rarely happen in the real world. In reality, the average application will get 25% less than the rated distance and in extreme conditions can be 90% less. We wrote this white paper to give end users the ability to understand the actual performance they can expect from their thermal cameras. In addition to thermal imaging, Infiniti also offers active IR, SWIR, and visible sensors. We do not limit our customers to any one technology; rather we custom build solutions that typically use multiple sensors depending on the project. The examples below are DRI calculations for three of our popular camera systems. Keep in mind that we have many other lens options available, and we excel at designing customized systems to suit specific needs.

Human DRI Examples: 715mm Viper 27,000m 6,800m 3,400m 275mm

Sigma 7,000m 1780m 890m 75mm

Phoenix 2440m 620m 310m

Vehicle DRI Examples: 715mm Viper 45,000m 11,400m 5,700m 275mm

Sigma 18,000m 4500m 2250m 75mm

Phoenix 7,300m 1900m 950m detection recognition identification