This is an article on the comparison between Image Intensification and Thermal Capability produced by TNVC, which we are republishing with their consent. It’s a rather lengthy piece but worth the jump.

The term “night vision” actually covers two technologies: Image Intensification and Thermal. These two technologies have undergone significant development over the past 25 years and made tremendous leaps in the past 15 throughout the Global War on Terror. They have provided unprecedented advantages to the warfighter on the battlefield and law enforcement professionals in their never ending struggles to keep this country safe. And like most technologies born on the battlefield, tactical eventually becomes practical. With the rising popularity of nighttime hog and predator hunting in the United States, more and more hunters are finding themselves shopping for night vision gear. Night Vision Hunting has become the fastest growing segment of the hunting market and many hunters are asking: “what type of device is best for me?” The law enforcement community is asking itself these same questions as many agencies are finding a need to better equip themselves at night in order to keep the streets safe.

With the sudden surge in night vision popularity among professional end users and sportsmen, it is important to understand the differences in the technologies offered on the market. Often times, the capability requirements of both end user groups overlap. To this end, we wanted to put forth an education primer on the general performance capabilities of image intensifiers and thermal devices. Please note that there are many different brands, makes, models, etc. available. We are well aware (and you should be too) that the performance range can vary greatly depending on the device. This article is not going to get into a brand vs. brand or model vs. model battle. The intent is to provide general information that can be extrapolated over most night vision devices on the capabilities of the various technologies. This discussion is aimed at providing end users with an idea of which type of device will be most beneficial for their mission.

Let’s begin by discussing the differences between the two types of night vision.

Image Intensifiers are more commonly referred to simply as “night vision.” For the remainder of the article, I will refer to image intensifiers as “night vision.” Night Vision uses a powered image intensifier tube to produce a light-amplified image to the user. The tube literally amplifies existing ambient light to produce a bright, detail-rich image. Traditional night vision produces a green image to the viewer. Green is the most visible color to the human eye. We can see more shades of green than any other color in the visible light spectrum. As such, the green phosphor screen in the image tube presents the most hues and shades to the user, allowing him/her to best resolve the image in detail and depth. This is an important positive capability in that night vision users can see into the dark and gain positive identification of their surroundings and targets. Since night vision is simply allowing you to see in the dark, it is completely possible to achieve positive identification of faces, clothing, animals, etc. This is perhaps the most important aspect of night vision. Since night vision devices are mostly used in conjunction with a firearm, the ability to achieve 100% Positive Identification (PID) is critical before taking a shot. Night vision will allow the user to read signs as well. Another important aspect of night vision is that it allows for easier depth perception while moving. Because the tube is amplifying existing ambient light, shadows and terrain undulation can be more easily identified. This helps night vision users to gauge distance using terrestrial association. The key benefit to night vision is its identification capability.

However, despite the benefits of night vision, it is not a perfect tool. Like our eyes, we are susceptible to being fooled by camouflage. Nature has the ability to camouflage people, animals, and objects simply by placing foliage in front of them. Sometimes, possible targets will go out of their way to camouflage themselves in the terrain. Bad guys can wear camouflage clothing and attach foliage to their person. Animals often have natural camouflage in their coats. The same camouflage that works for a person or animal during the day will work just as well, if not better, through night vision (after all, the image is the same as normal, but now being presented in a single color palette). Night vision may also be slightly harder to use during inclement weather conditions such as rain, snow, fog, and smoke. Another, more obvious, deficiency in night vision is that it only works at night. However, we have to remember that night vision requires some amount of ambient light to function. Today’s Gen3 tubes can do much more with much less light, we still need to have some illumination to gather. If you take a brand new Gen3 device into an absolute pitch black environment, you will not have any image. At that point, an external infrared illuminator is required.

Thermal imagers work differently than night vision. Rather than amplifying the existing light in an image, thermal uses a special detector that senses infrared energy. Infrared energy is produced by everything in the world, whether natural or man-made, and increases as its heat rises or it produces friction. So essentially, thermal imagers detect heat, providing a starkly contrasted image where heat-producing targets and objects will light up against their cooler surroundings. This trait makes thermal imagers ideal for detecting targets in the user’s environment. The most obvious use for thermal devices is easy detection of targets in the field. The warmer an object is, the brighter it will appear in the thermal device. An animal or person that is hiding among foliage will more easily be spotted against the landscape since the user is not depending on the shading and tones of the target for detection. Detection is the most important aspect of thermal imagers. These devices will allow users to quickly detect the presence of a possible target against a wide range of landscapes. Thermal imagers can also be useful in tracking blood trails and, depending on the time lapse; foot prints. This can be useful in finding suspects or animals. Thermal is also capable of seeing through light rain, snow, fog, and smoke. Another positive trait for thermal devices is that they can be used during the day. Night vision will eventually become damaged when exposed to too much light for extended periods of time. Thermal devices can operate regardless of the ambient light present. This includes high noon or absolute pitch black. Though, thermal devices do tend to work better at night because the ambient environment will have cooled down, increasing target contrast.

While thermal devices excel at detection, they are not as useful for identification. It is possible to get a decent level of identification capability out of a thermal if it is a high resolution system (such as 640×480). However, facial recognition and PID is not generally possible. Thermal is also incapable of reading text printed on a flat surface. This is most easily demonstrated by looking at a sign or a garment. If the letters are raised or have a different finish than the rest of the surface, it may be possible to make out the graphic, but you will not get nearly the legibility of night vision. Positive Identification is perhaps the biggest drawback to using thermal. Obviously, the higher resolution systems will be able to resolve more detail in an image. However even they are going to be lacking in the ability to clearly identify someone’s face or one type of animal from the next. From a professional standpoint, this means that identifying an armed suspect from an armed officer is going to be more difficult. For hunters, it can make it more difficult to tell the difference between a coyote and dog. Though, we can surmise differences in our thermal targets by observing their movement and behavior, it is important to remember that we are most often dealing with firearms in conjunction with these devices. Once the trigger is squeezed, the possible outcome is the loss of a life. The consequences of mistaking a calf for a hog can be a $13,000 bill from the ranch owner. The consequences of mistaking a good guy for a bad guy can mean life in prison. And the consequences of mistaking someone’s dog for a coyote can mean the dog’s owner hunting you down. The issue is exacerbated at distance since electronic zoom cuts the image resolution every time. Thermal imagers are also incapable of seeing through glass. Because of this, their lenses are made from an expensive material called germanium. But this limitation can be detrimental to surveillance operations, or if a hunter wants to observe the field from his/her vehicle cab. One last thing to consider with thermal imagers is the video frame rate. Thermal imagers are active systems that provide the user a video on an OLED screen to view through the eyepiece. So unlike night vision, a user does not look “through” thermal and see the world. Real time video runs at 60 Hz and some thermal devices display at this frame rate. But, most thermal units run at 30 Hz. This means that the video image you observe can experience some slight clipping during fast movements.

Again, the above information is a simplistic overview or the characteristics and pros/cons of night vision and thermal imagers. Depending on the device you possess, some of the characteristics can vary. Now that we have established a baseline idea of the capabilities present in these devices, let’s take a look at how they are applied to some practical scenarios.

**DISCLAIMER**

We chose to bias these videos towards the first-responder market. We felt they would best display the capabilities of the various night vision devices in different environments and could be easily juxtaposed across the hunting and military markets as well. No live firearms were used in the production of these videos. Also please note that filming through night vision devices is incredibly hard to do because the focus of the night vision device and the camera are not always in perfect sync. We did our best to provide as accurate a representation as possible.

SCENARIO 1

This video is shot through a law enforcement officer’s point of view. It represents the aftermath of a foot chase where the fleeing suspect would have thrown away evidence in hopes of not being caught with it on his person. The suspect is in custody and we must now search the area where the object was tossed in an effort to recover it for evidence.

In the first part of the video, we show the officer using a time-honored tool found on every peace officer’s duty belt: the flashlight. Most of the time, individual patrol officers are not going to have access to night vision equipment, so they have to make do. During the flashlight sweep, we can see a ton of detail. As the officer walks along the brush line, he sweeps the light over the foliage. But at this distance, the light splash is almost too bright against the leaves, causing a whiteout. This hinders the officer’s ability to see detail and the outer spill of the light beam must be used. In fact, the light almost shows too much detail, effectively camouflaging the object in question. If we were to extrapolate this scenario into a full-on search, it could easily be surmised that the officer(s) would be out there all night, searching a long stretch of brush to find whatever was discarded by the suspect.

The next part of the video shows the same scenario through a night vision monocular. In this case, the night vision helps the officer see a larger area lit up. But, the dense foliage still provides a challenge to the officer trying to find the discarded evidence. As mentioned earlier, the same camouflage that works during the day is going to be just as effective at night. Another issue we see is the focal length. Night vision devices focus on a fixed focal plane and must be manually adjusted to refocus up close. Users want to generally achieve a baseline focus where objects will be nice and crisp from about 10 yards out to infinity. But, night vision will not automatically refocus when trying to observe things up close and must be done manually. This can be challenging during a search like this where the focal plane constantly changes. A long sweep of the area yields little result and can be especially difficult it the officer is unsure of exactly what he is looking for.

The final section of the video shows the search while using a thermal device. The first thing you will notice is that the detail seems to be way less than the night vision and flashlight segments. This is because thermal will generally have a harder time differentiating between cooler objects. You can also see that the undulation in terrain as the officer walks up to the brush line, is more difficult to ascertain and can make land navigation more difficult when using a thermal device. But in terms of accomplishing the mission (finding the discarded evidence), the thermal device seems to win the night. As the officer walks up to the brush line, the heat signature of the discarded item is almost immediately visible through the dense foliage. The heat from the suspect’s body was transferred to the object and it is still warm enough to be visible to the thermal device after 15 minutes. The discarded evidence turns out to be a pistol. On a side note: thermal, like night vision, must be manually focused for up close detail during observation. While the point of this particular exercise was to find the evidence, you will notice that there is a distinct lack of detail up close when the gun was recovered because the thermal device was not refocused during the pick-up.

In the first scenario, thermal is the clear choice due to its awesome detection capability when compared to the other viewing methods.

SCENARIO 2

This video shows the point of view of a SWAT marksman responding to a hostage situation at a local business park. The armed suspect is using a hostage as a human shield in the front atrium as he communicates with the on-scene hostage negotiator. The officer is given orders to hold on the target, but must be ready to take a crisis shot on the suspect if negotiations break down and the hostage is thought to be in immanent danger.

We first see the officer’s view through a standard day scope. As we can see, the darkened atrium presents an almost impossible view. Movement can be seen through the building’s glass door, but without lighting, it is impossible to decipher what we are looking at. The officer cannot determine who the hostage is from the suspect. Everything is in complete shadow making a crisis shot impossible and putting the hostage in danger. It’s not until the suspect makes the hostage open the door that the outside lights provide enough illumination to take a clear shot. However, if the suspect closes the door again, the officer will be back in the proverbial dark. Clearly, the use of a standard rifle scope in this situation would not only put the hostage’s life in jeopardy, but it perfectly illustrates the handicap created when a responding law enforcement agency lacks night vision capability.

In the second part of the video, we see the same situation played out through a dedicated 4X night vision weapon scope. Here, we can easily see into the darkened building and make out both the suspect and his hostage. We can see that the suspect has a semi-automatic pistol held to the hostage’s head and is standing behind him. In fact, the night vision image allows for clear identification of the suspect and his hostage. The officer not only knows where to shoot, if required, but he knows who the suspect is. We can easily determine that the suspect is an adult male with short hair and a larger build. We can see that the hostage is also an adult male with short hair, a beard, and an athletic build. We can even see when the suspect and hostage are speaking (or in the case of this role-play, we can see when they are laughing because the “suspect” is yelling out crazy stuff). When the door is opened, the outside lights create a slight bloom on the two individuals, but the level of detail and identification capability does not change. In a situation like this, night vision is giving the officer a commanding edge.

In the final segment of this video, we observe the same situation through a thermal weapon scope. While the building is clearly seen to include the columns, lights, paint on the parking lot, we are faced with a show-stopping problem: thermal does not see through glass. While the hostage negotiator is talking with the suspect, the marksman has absolutely no way of observing the situation, rendering him unable to take a critical shot should the need arise. It is not until the suspect forces the hostage to open the glass door that we can even see that anyone is there. When the pair are finally exposed, the officer is given enough data to see who is who and that there is a pistol to the hostage’s head. But, the thermal unit does not provide any facial detail. In this circumstance, the thermal scope is set to no magnification in an effort to retain as much resolution as possible. Resolution is critical in this situation because the officer may have to take a shot within a fraction of an inch. If he were to use the electronic zoom, he would lose resolution and hinder his ability to identify the critical shot.

The night vision weapon scope is the clear winner in this scenario. The standard day scope renders the marksman impotent to affect any type of resolution to the situation and the thermal scope was arguably a liability. Yes, the suspect and hostage became more clearly visible when the door was opened. But, without a green light to take the shot, the pair could just as easily go back inside the atrium, placing the officer in the same situation again.

SCENARIO 3

The third scenario simulates recorded surveillance video of a known drug deal/bad-guy meet location behind a local strip mall. The officers have set up in a concealed location to film this corner where criminal activity is often committed by gang members according local residents. The hope is that the police department can identify the drug dealers/trouble-makers and start building cases against them. However, PID must be achieved in order for evidence to be admissible in court.

The video starts out through a thermal imager. We can clearly see four subjects gathered in conversation at the back corner of this L-shaped strip mall. The overall height and build of the subjects can be identified as well as their clothing type. It can be confirmed that we are observing four grown males. All are wearing short sleeve shirts while two are in shorts and flip-flops and two are in pants and shoes. Ball caps can be seen on all of them. We can clearly see the subjects loitering about, talking and interacting with small electronic devices. The detail level is quite good overall. We can see that the shortest subject has a beard that gets longer at the chin and the suspect facing the camera also has facial hair. However, it is impossible to identify the faces of the subjects or their ethnicity. We can certainly see other details such as the fact that the subject facing the camera is wearing cargo pants and seems to be chewing gum. When one of the subjects motions to something in the distance, causing the closest subject to turn around, we can clearly see that he is wearing glasses and has a beard.

The second half of the video shows the same group of subjects through night vision. Again, we can immediately recognize four grown males as well as their height and build. We can see that they are all light-skinned; possibly White or Hispanic. While the ethnicity cannot be clearly ascertained, it is possible to rule out that we are observing Black males or darker-skinned individuals. Clothing can be identified as two subjects wearing pants, two wearing shorts, and all wearing ball caps. Printed shirt graphics can also be seen as well as the overall brightness/tones of the shirts. This information could be useful if a crime is committed during the surveillance and the observing officers need to provide an immediate description of the suspects to other officers. One of the main things to note is that facial features can be recognized enough to identify individuals.

Both thermal and night vision provided a good nighttime surveillance tool. The location was quite dark with any surrounding light sources facing away from the scene. Regular video surveillance would have been impossible. Depending on the mission, thermal or night vision could make an effective tool for monitoring individuals or areas. For a business or personal security system, thermal will definitely provide good data and allow users to recognize prominent features on individuals. Night vision provided this same data, but allowed the individuals to be identified. For professional use, this is an important point. Law enforcement officers need to make a case and be able to prove everything in court beyond a reasonable doubt. Warfighters need to identify subjects while working up target packages. But, civilian property owners may just need to see that there are people who shouldn’t be there, doing things they shouldn’t be doing. In that case, either technology will suffice in the dark. This particular scenario showed a video from a good vantage point where the four subjects could be clearly seen. Obviously, this is not always going to be the case during a surveillance operation. The thermal device being used was a 19mm 640×480 1X monocular. The night vision device was a Gen3 monocular.

SCENARIO 4

In this scenario, we are put into the shoes of a law enforcement officer providing perimeter security at the back of a commercial business that is a front for selling drugs, during a raid. An undercover officer is inside. As the assault element makes entry at the front of the building, we see two individuals go running out the back. The inner perimeter officer has a few seconds to determine what to do. Are they both suspects? Is one a suspect and the other a cop? As the two subjects run, we jump to the point of view of one of the outer perimeter officers who witnesses the same two subjects run through a gate into a residential yard. These situations can develop rapidly and radio communications can sometimes become garbled or confused. Usually, officers have very little time to process the situation and make a decision when use of force is called for.

At the start of the video, we are looking through a thermal imager and we see the first subject burst through the door, turn, and run away from the camera. We can ascertain a decent amount of information. We can see that he is male, athletic build, wearing shorts, T-shirt, and flip-flops. He appears to have some facial hair and is armed with a pistol. The subject appears to be trying to get away without regard to who or what may be in his immediate environment. The second subject follows close behind the first. We can see that he is male, larger build, does not have facial hair, and is wearing a short sleeve shirt and pants. This subject is also armed with a pistol. We can also see that his behavior is different than the first subject. While the first guy immediately came running out the door and took off away from the camera, the second guy has his gun at a low ready and takes a quick glance forward before running in the same direction as the first. What does this tell us? The inner perimeter officer has a couple seconds to decide whether or not to engage the first, second, or both subjects. Neither subject’s face can be clearly identified through thermal, nor can their clothing. The first subject is probably a fleeing suspect based on his behavior. But, is the second guy a fleeing suspect or a fellow officer giving chase? After all, the raid is being carried out by officers not in traditional uniform… The second guy seems to exhibit some more professional gun handling behavior. But at the same time, there are many bad guys out there with firearms and tactical training today. Either way, the inner perimeter officer does not have enough data to engage these subjects with force.

From here, we switch to the view of one of the outer perimeter officers. The two subjects ran down the alley, away from the first officer’s position, went through a gate, and entered a residential yard. The outer perimeter officer and his K9 observe the first subject running through the gate with the second right behind him. The first guy turns and both subjects draw down on each other. What do we do? At this point, it can be safely assumed that one of the subjects is a cop and the other is a bad guy. But the situation is more complex than we see on the surface. At first, we would think that the guy being chased is the bad guy. But, as an outer perimeter officer, we know that there was an undercover officer inside the building. At the onset of the raid, he was going to run so as to not blow his cover. But, was his cover compromised anyway and he is being chased by one of the suspects who knows he is going to get caught, but is intent on killing this “traitor” before he goes down? Everything is happening in a split second and the outer perimeter officer is about to watch two individuals, one of them cop, engage each other at close range. His heart is beating through his chest and the blood is rushing in his ears. The damn frogs in the pond behind him won’t shut up either. With the stress level through the roof, he doesn’t have 100% PID on either subject to make a shot.

In the second half of the video, we see the same scenario play out through night vision. The inner perimeter officer can immediately see the same details visible in the thermal video: grown male subject with facial hair in T-shirt, shorts, flip-flops, and armed with a pistol comes bursting out the back and takes off down the alley. The second subject is following close on his heels. He wears a short sleeve shirt, pants, has no facial hair, and is also armed with a pistol. The differences start when we see that both subject’s facial details are visible and identifiable. The inner perimeter officer can get a quick glimpse of the faces and get an idea of who is who. But, as the second subject rounds the corner after the first, “POLICE” is clearly printed on the back of his shirt.

As the chase continues into the residential yard, the outer perimeter officer can clearly the see the same details as the two subjects draw down on each other. Now, this split second decision is able to be made because it is clear who the suspect is. The outer perimeter officer can engage the suspect and help to save his buddy’s life.

While it is pretty obvious that officers equipped with night vision devices would be better off in this scenario, there are other factors we should acknowledge. These videos show great clarity and contrast of thermal devices. The subjects seem to literally pop out of their environments. It is incredibly easy for someone equipped with thermal to follow these subjects. The night vision devices allowed the officer to identify the subjects, but the detection limitations start to show. Notice how the first subject started to blend into the tree line as he ran away from the inner perimeter officer. While night vision provided more depth to the image, the light sources behind the tree line started to make it more difficult to follow the subjects. This can again be seen in the residential yard. When the first subject spins to engage the second, he is standing with a house and foliage behind him. This helps to conceal him slightly. While he can be seen, he is not popping out of the camera as he does when viewed through the thermal imager. This is a complex scenario that shows benefits and deficiencies of both technologies. Night vision edges out thermal in this case, due to its identification capability, but it is not without its shortcomings.

SCENARIO 5

Here, we see another surveillance video that simulates a drug/contraband buy. We show two different takes on this scene. The first one has the suspect enter the truck on the driver’s side. Another subject approaches the driver’s side shortly after and some sort of transaction appears to take place. The second take on this scene shows a subject entering the truck on the passenger side. A transaction appears to take place, the subject exits the vehicle, and leaves.

As we saw earlier, thermal imagers do not see through glass. So, vehicle surveillance becomes almost impossible to conduct. The video starts out with the suspected dealer entering the truck. It is impossible to determine if he is alone in the vehicle. Once he enters the cab, he is completely obscured from view. We watch as the second subject approaches the vehicle. We can see that he is wearing a T-shirt, shorts, flip-flops and hat. His beard can be identified as well. Beyond that, there is no other facial recognition. A transaction of some sort appears to take place where the outside subject hands something to the guy inside the truck and takes something in return before leaving. As observers, we are completely blind as to what is happening inside the truck through the thermal device. In fact, we cannot even be sure that the first subject who initially entered the truck is the same one interacting with the second suspect who later approaches because we do not know if anyone else is in the vehicle.

Next, we see the same scene play out through night vision. As the suspected dealer approaches the truck, we are able to get clear facial recognition. However, one of the deficiencies in night vision becomes immediately apparent when he unlocks the truck and enters: halo bloom. The headlights and mirror lights are activated when the truck is unlocked and the scene is almost completely bloomed out for a few seconds. A lot of the bloom is actually exacerbated by the camera that is recording through the night vision goggle. If we were to be looking through the night vision device with a naked eye, we would still see some bloom, but not as bad as what a camera adds. Nonetheless, this issue with night vision must be taken into consideration when filming through night vision for evidence. Once the suspect is in the truck, the lights are turned off and we can clearly see into the cab. We know that he is alone in the vehicle and we can still clearly identify him. We watch as he talks on his cell phone. Later, we see the other subject approach the truck. His face is also identifiable, though there is some extra light from off camera, which is somewhat washing out his face. We are able to see the transaction take place as the driver reaches for something under the dash or in the center console. The object is handed to the outside subject and the exchange is complete. At this point, we have evidence that the original subject that entered the vehicle was the only one in the truck and carried out the exchange with the suspected buyer.

In the next take, we watch a subject approach the truck from the passenger side, through a thermal device. Again, we can make out his clothing and build, but we cannot get detail from his face. He enters the passenger side of the cab and completely disappears from view. The subject stays in the truck for a little while and then exits and walks away. He is not visible again until he is out of the truck. At this point, we have no idea what transpired in the truck, let alone have anything we can build a case on.

Next, we see the same scene play out through night vision. We watch the subject approach the truck which already is being occupied by a male driver, clearly seen through the windshield. As the subject enters the passenger side of the truck, we are again blinded in the video by the excess camera bloom created by white light sources. Again, this is not typical when viewing auto-gated Gen3 tubes with the naked eye, but is a factor you must contend with when filming. In the vehicle, we can clearly see interaction between the two subjects. An exchange appears to have been made and the first subject exits the vehicle with something in his hand and walks away.

This set of videos makes it quite apparent that thermal imagers are not ideal for vehicle surveillance. While filming through night vision has its drawbacks in bloom created by the camera from light sources, it is still the clear choice when one needs to see through glass.

Night vision and thermal imagers are incredible tools that offer undeniable advantages to professionals and amateurs alike when operating in the darkness. However, there is no magic device that will offer a perfect solution for every situation. Like everything else, you must choose the right tool for the right job. The scenarios above were designed to provide overall examples of situations that today’s professional could find himself in. The scenarios were meant to illustrate the capabilities and deficiencies found in these technologies to aid you determining which one is best for your mission. While these videos focused more on the professional end-user, it is easy to look at the data and juxtapose it over the civilian’s mission as well.

This is the first in a series of comparison videos between night vision and thermal that we will produce at TNVC. The next series will focus more on rural applications. We hope you found this data educational, relevant, and enjoyable. Stay tuned over the next few months for more.

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