Thermal Imaging Camera

By Samuel Hittle & Keith Niemann

It's not a tough sell in today's fire service to convince companies the thermal imager has extensive value in functional mitigation. Over the years, we have gained appreciation for the value of the TIC far beyond just overhaul; it can be a useful tool in every facet of the fire ground. TICs are coming off our rigs for size up, fire attack, search, ventilation, RIT, HazMat, and more. Our increased reliance on this technology demands an increased appreciation for the inherent limitations and deceptive qualities that accompanies them. A more comprehensive training program extending beyond "Here is the on / off switch to power it up", "white is hot, black is cold", "look at the clarity" (in this perfect office environment), and "you will be able to see everything now" is necessary . This simplistic view is not adequate and can give companies a false sense of security or lead us to formulate poor strategic and tactical decisions.

"White is hot, black is cold, red is really hot"

Although this statement is true, it is also misleading. A more accurate statement would be "white objects are hotter than others surrounding it while black objects are colder than others surrounding it", with emphasis placed on the word hotter. A person, for example, in an ambient room will appear white even though they are not hot to the touch. They are usually the hottest surface detected by the camera, and therefore illustrated on the display with the brightest white coloring.

Thermal imagers assign shades of grey to the various surface temperatures of objects within its focal plane. Whether or not something is depicted as white or black is solely based on the dynamics of the atmosphere being viewed rather than predetermined temperatures. Take a cold object at the firehouse that appears dark in color when viewed by the camera at room temperature. Now place the same object in the freezer, the camera will display it as a whiter color. The point is that the temperature of the object did not change from cold to hot rather the atmosphere surrounding it was altered, causing the thermal imager to interpret it differently.

An example of this concept under fire conditions is seen in the Rhode Island Station Nightclub Fire reenactment conducted by NIST. As you watch the fire progress notice the surface area next to the visible flame is black (presenting cold). These areas are only interpreted as black because the significant temperature difference that separates them from that of the visible flame. We know, however, that these areas are quickly warming to their ignition temperature because they light off seconds later.

The addition of color pallets can make things even more confusing when trying to interpret what is truly happening based on color alone. In a well intentioned effort to help us identify elevated surface temperatures the industry is assigning red, orange, and yellow colors for certain temperatures. When a surface area reaches a predetermined temperature within a specific mode of operation (high sensitivity or normal vs low sensitivity or EI) everything at that temperature and above will show as red, orange or yellow.

When an operator fails to recognize which operating mode the camera is working in and relies solely on the premise that areas in red are really hot, the situation can become misleading. Surface temperatures that show red in the high sensitivity or normal mode may be depicted as white when the camera flips into in the low or EI mode. This can lead the interpreter to believe there is more fire than actually present when conducting business close to the fire area in high or normal mode while the same conditions present virtually harmless in the low or EI mode.

Shades of grey and color pallets are both necessary and useful for creating a useable image, however, a solid camera technician will rely on object recognition and temperature identification in order to make a sound assessment of what is occurring, to navigate the interior, and locate victims. After all, do we really need the upper walls to turn red in a house fire for us to realize it is hot? How the TIC interprets temperature is a complex and in depth process that will not be covered in this article but also must be understood.

"Take this so you can see what is going on"

Probably the most dangerous mind set we have with the TIC is that our vision is restored. The fact is, it is only partially returned and what vision is restored can work against us if we are not comfortable with how a camera functions. Our ability to see is ultimately restricted by the cameras limitations, the environment, and ourselves.

The camera allows us to penetrate smoke and view surfaces but is not an x-ray machine. We still have to manually check behind doors, shower curtains, under bedding, on the other side of glass, past insulation, beneath water, and on the other side of large objects like couches. Another constraint obstructing our view is the limited peripheral vision allowable with the focal lens. This is typically only 35%-60% of what is in front of the TIC.

The transition between operational modes also hinders our ability to distinguish among objects. In low or EI mode things are less diverse and clarity is almost completely lost once coloring occurs because the camera is more concerned with showing the area in a solid color then translating the contour and shape of the area or object affected. This is improving with advancements in camera technology but is a concern with the majority of the thermal imagers in operation today. Reflectors (i.e. metals, glass, water, glossy finishes) on the other hand can create confusion by allowing us to see too much by duplicating and sometimes tripling objects in the focal plane.

Another factor outside our control is the working environment. In saturated or cold smoke atmospheres the limited difference in temperatures amongst the room's contents makes it difficult for the camera to differentiate between them. Sometimes this is caused by suppression efforts, particularly when patterned nozzle attacks are employed. The disruption of the thermal layering equalizes temperatures within and because water is a reflector the steam conversion will obscure the view. Fires producing dense smoke can also challenge the infrared lens capacity to penetrate through and will limit our ability to see the display. A good rule of thumb is to wipe the display if you have to wipe your SCBA mask and stay beneath the smoke where viewing the screen is easier.

Radiant heat, thermal saturation, temperature indifference, and coverings can make it difficult to recognize victims. Remember they are not always going to be readily identified as a bright shade of white. In cooler atmospheres this may be the case but as elevated temperatures begin to occupy the over head space a victim on the floor will be cold in comparison and may appear grey or black. In extreme circumstances and depending on which camera you have the victim can even show as red if they have been subjected to enough thermal insult. Again, this is why we should be more concerned with object recognition than color.

Time and again, our worst enemy though is ourselves. Too often, we not only fail to recognize the TICs limitations but tend to have unrealistic expectations of what we will expect to see with the camera. We think that flashover will be obvious, holes and elevation changes are going to jump out (a hole viewed at the floor level is nearly impossible to see because of the vanishing point), or make the assumption that a building component must be structurally sound if the camera can see it (i.e. floors, walls, roof assemblies).

Failure to conduct live fire training makes it difficult for us to recognize the difference between vapors and actual flame impingement, size up how much push smoke has behind it, be acquainted with mode changes, and develop patience with vision obscurity that accompanies crews getting a knock on the main body of fire. Too often the operator thinks the camera is whiting out and abandons it instead of allowing the room to lift much like darkening down a fire in years past.

"Search will be easy and fast with this"

Companies are successful with thermal imaging when they have invested time in developing camera assisted search tactics conducive to their deployment strategy and trained to execute them, not because the department has provided them with a camera. It seems silly, but too many crews want to use the TIC like a magic search bullet placing more emphasis on the camera than search procedures. The camera is a tool that should be used to ASSIST a traditional style search creating more of a hybrid search than a "TIC search".

A simple hands on test illustrates how the search can be significantly slower if we try to perform a traditional style search with the camera without making tactical adjustments. Find an average size bedroom in your firehouse, training building, or acquired structure. Make sure to have the room furnished as best you can. Now place a hose dummy or CPR mannequin under the covers or behind the bed, black out a searcher and send them in. They will likely find the victim in 45 seconds or so. Next, smoke up the room or black it out so the same firefighter can search it again using the camera. It will probably take two or three times longer even though they have a general concept of how the room is laid out.

Why is this? Before they were feeling while moving which is familiar to them. With the camera they tend to focus only on sight looking at every object like they want to see the thread count in the sheets. Many times the firefighter gets close enough to the objective they could touch it like in a traditional search but then rely on the camera to identify the object in front of them. They fail to realize at close distances the camera will have trouble picking up enough thermal contrast to display a quality image. This is usually compounded with limited familiarity viewing a TIC which lends to them scanning the same area repeatedly.

This search style begs the question; if this person is the officer, who is watching the fire and maintaining crew accountability? It's like having the officer on the nozzle. The nozzleman's job is to open and shut the bail and put the stream where the officer directs it; the officer's job is to take in the whole picture. Camera work is no different. The officer/camera man should take a more detached position to scan and monitor the entire surroundings while efficiently directing the searchers to perform tasks the camera is incapable of (i.e. searching behind objects, under bedding, behind shower curtains).

With the officer between the searchers and the fire during this hybrid search style they can keep track of the other searchers, watch the fire conditions, and make good decisions on both. They are doing their job as the officer of the search team; only with better tools and more information. They can be in the hall of the house with a searcher in a bedroom doing a quick traditional search, scan down the hall planning the next room, observe if the fire conditions are improving/deteriorating including that which effects egress, locate alternate windows and doors for secondary exit, mentally map the contents and layout, and ensure firefighters searching are thorough not missing beds or closets blocked by debris. They can be in the doorway between a kitchen fire and the living room watching the fire attack crew make progress while telling the others searching that "the middle of the room is clear, make sure to get behind the couch that's to your left". The officer can stand on the ladder looking in the window during VES operations to help the searching firefighter locate the door, look for victims, and direct them areas of interest they may not be aware of.

Another pitfall that slows a search team down is when the officer "over watches" the screen during movements. When navigating through the structure the officer does not need to use the camera when moving from one location to another. Much like a firefighter who uses the camera to search is slowed by all the information given, the officer can also be overwhelmed and a 10 second travel time can increase to many times that. A more appropriate tactic is for the officer to come into the structure, scan appropriately, lower the camera, and then move to the next area of interest. This is much like turning the light off in your bedroom before going to bed, sight is not required to reach the destination, the room is scanned, a mental map of furniture and other hazards is noted, the lights go out, and a blind advancement is made. On the fire ground once relocated to the next area of interest another scan should be performed clearing as much as possible from this new perspective, the firefighters should be briefly shown the layout and then directed to perform specific tasks, and the next location ought to be determined. With some training you'll find this to be a natural way to pilot the structure. As long as your movements are not too far, 10-15 feet or room threshold to threshold, this system will help overcome the depth perception problems inherent with looking into the two dimensional screen.

Camera work is not beneficial because a camera is present. It requires a competent firefighter to interpret the image which is developed overtime with practice. Make sure to train like you fight, gear on, air on, in furnished search areas preferably with multiple entry/egress points. Being on air is especially important with directed searches. Clear transfer of information is imperative and can be difficult with SCBA if you have not practiced. Equally important is the ability of the officer /camera man to be comfortable holding and viewing the TIC with full PPE.

This article only touches the surface of successful camera operations. Remember the TIC is a tool to help us do more, not less. Camera work should facilitate sound fire ground practices not replace proven techniques. With training and practice we can prevent our thermal imaging experience from being something we get right after we needed it.

Tips to improve view

• Clean the IR lens and display window at the beginning of the tour
• Create or eliminate temperature contrast by rolling hand in front of lens, spraying water, placing a firefighter out in front, hiding the fire so the camera can operate in high sensitivity mode longer, changing depth to incorporate more or less objects viewed in the focal plane that effect temperature contrast, be aware of the cross hairs focus point)
• Stay low under the smoke to improve your view of the display
• Wipe the display window when you have to wipe your facemask
• Changing your perspective by relocating within the room will expose different angles or getting low will achieve views diminished by vanishing points
• Keep squared up to display. A slightly rotated screen is like a poorly positioned laptop screen.
• Be patient. Let conversion of water being applied to the fire lift and allow the TIC to catch up if the refresh rate is slow.
• Practice good scanning techniques. This will improve your peripheral view and ensure the refresh rate keeps up.

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