Can Thermal Imaging Cameras See Through These 19 Things?

​​
​A Guide by Infrascan Thermal Imaging Sydney

​Throughout the years, movies, comics and tv shows have portrayed thermal imaging as a way to see through various barriers like walls and multiple buildings.

With this in mind, most people, especially laypersons, have formed several misconceptions about the concept of thermal imaging. 

​What can thermal imaging cameras actually “see” through though?

In the following article, the things that can be and can’t be seen with the use of a thermal imaging camera will be listed. 

But before going to that, let us first define what thermal imaging is. 

Thermal imaging is the technique of improving the visibility of objects by detecting their infrared radiation and producing an image based on that information.
​

A thermal image of a baghouse chamber.
​

​It is used in various activities, mostly commercial and industrial, that require detection of the changes happening in an object or life form, including its anomalies. This is done by getting data from the temperature or the heat an object or life form radiates. 

The concept of thermal imaging is based on heat. All objects emit heat or infrared energy as a function of their temperature. The heat emitted by an object is known as its heat signature. With the increasing temperature of an object, the more radiation it emits. Thermal imaging makes use of infrared radiation with a special device called a thermal camera that acts as a heat sensor. 

Note: Unless an object is at absolute zero (-273.15°C), every object emits a small amount of infrared radiation and a thermal camera can detect it. Detecting the changes in an object will depend on the sensitivity of the thermal camera used.

The thermal camera is able to detect even minute differences in temperature. It collects the heat radiated by objects in the scene captured, then, creates an image based on that information.

Since most objects usually have a distinct heat signature, thermal cameras can be used to identify and distinguish it from another entity. These objects would then appear as distinct items in a thermal image.

Normally, thermal images are grayscale in nature, with black objects being cold and white objects being hot, with some variations of grey to depict the difference between the two. Some thermal cameras add colour to the images, in order to make them more distinct and heat signatures are easier to identify.

By knowing the definition and how thermal imaging is used, the objects that thermal imaging can and can’t see through will be tackled below.
​

1. Can thermal imaging see through walls?

​The answer is NO.
​
Thermal cameras cannot see through walls. This is a popular misconception that we’ve wrongfully believed because of movies. Walls are too thick and have enough insulation to block infrared radiation.
​
Instead, thermal cameras only see surface temperature changes that are caused by the objects behind the wall, but not actually seeing through it.

A thermal camera can only detect heat from the wall where it is pointed, but not what is behind it. However, if something inside the wall causes a notable change in temperature, a thermal camera will be able to detect it.

Vermin spotted in a drainage pipe hidden on a wall.
​

​For example, thermal imaging is usually used by building maintenance professionals to detect issues such as water leaks or missing insulation without taking apart walls to look at the problem.

This same principle also applies to other thick materials such as concrete.​
​​

2. Can thermal imaging see through concrete?

​The answer is NO.

The explanation to this answer to this is the same as the one applied for walls.

Thermal cameras cannot see through concrete. Concrete is too thick to block any possible penetration of infrared radiation.

Concrete blocks by ​uve sanchez on Unsplash
​

A thermal camera might be able to identify something inside the concrete like a pipe that causes a difference in the temperature on the surface of the concrete.
​

3. Can thermal imaging see through glass?

​The answer is NO.

Glass is a highly reflective material and acts as a mirror for infrared radiation.
​

Testing the thermal imaging camera with water inside the glass heater. 
​

If a thermal camera is pointed at a window, only a reflected temperature of the objects can be seen rather than seeing through it.

In the case of the photo above, the material behind the glass can’t be seen.

Glass will block low-frequency infrared radiation (red hot), but allow the passage of high frequency (white hot) IR.

Thermal imaging cameras not seeing through glass also applies to other reflective materials such as polished metal.

This same principle also applies to other reflective materials such as polished metal.
​

4. Can thermal imaging see through metal?

Thermal image of heat escaping from a furnace joint.
​

The answer is NO.

Metal is actually a peculiar material to do thermal imaging.

As mentioned for glass items, shiny metals or any metal objects that are smooth or polished will reflect infrared radiation.

This issue can cause setbacks to anyone trying to monitor pipes or machinery for overheating parts. However, oxidized metal or metal that has been painted with a matter material is easier to measure accurately with thermal imaging.

Thermal cameras can’t see through metal objects but highly conductive metals can reveal hot spots, cold spots, and the level of a substance inside a metal container.

See how InfraScan does high-temperature scanning with metal materials when you click this link.
​

5. Can thermal imaging see through aluminium foil?

​The answer is NO.

Any electrically conductive material will block infrared radiation. The greater the conductivity, the greater the blocking.
​

​Food wrapped in aluminum foil.
Photo by Oscar Söderlund on Unsplash
​

Since aluminium foil is a highly conductive material, it will kill all infrared radiation.
​​

6. Can thermal imaging see through plastic?

The answer DEPENDS on the thickness of the plastic.
​

Objects inside thin plastic.
Photo by Sophia Marston on Unsplash
​

Infrared radiation will pass through thin plastic, allowing a thermal camera to detect anything behind it, although visible light will be blocked. Most plastics allow IR to pass through - thicker plastics, on the other hand, will block infrared radiation.

7. Can thermal imaging see through smoke?

The answer is YES.

Thermal cameras are able to detect heat through the smoke and are usually used by firefighters for this purpose.
​

Smoke blocks out objects’ views in visible light.
Photo by David Lee on Unsplash
​

Soot particles in smoke effectively block visible light but allow infrared radiation to pass through, letting firefighters navigate through smoke-filled environments.
​

8. Can thermal imaging see through the dust?

​The answer is YES.

Thermal cameras are able to detect heat through the dust depending on the size of the dust particles, their density, and their temperature.
​

Dust created from extreme activity.
Photo by Kaeyla McGee on Unsplash
​

If the dust is hot enough, it will allow infrared radiation to pass through thus being able to see through it with a thermal imaging camera.
​

9. Can thermal imaging see through blowing sand?

The answer is YES.

The principle from seeing through dust applies to a thermal imaging camera’s ability to see through blowing sand.
​

Sand blown by the wind.
Photo by Wolfgang Hasselmann on Unsplash
​

Thermal cameras are able to detect heat even when there is blowing sand but it depends on the size of sand particles, their density, and their temperature to be able to see clearly through it.
​

10. Can thermal imaging see through the rain?

The answer is YES.

Rain often has the ability to severely limit the range of a thermal camera due to the radiation coming off of water droplets.
​

Rain affects the visibility of objects.
Photo by Charlie Deets on Unsplash
​

Although thermal imaging cameras can see in the above condition, the distance they can see is affected by the severity of the rain and are often limited by this.
​

11. Can thermal imaging see through the snow?

​The answer is YES.

The same principle for seeing through rain applies here with snow. Thermal imaging cameras can see through snow although it can be very limited depending on the severity of the snow.
​

Visibility depends on the severity of the snow.
Photo by Filip Bunkens on Unsplash
​

12. Can thermal imaging see through a fog?

The answer is YES.

Fog and rain often have the ability to severely limit the range of a thermal camera due to the radiation coming off of water droplets.

However, for most of the time, thermal cameras can penetrate fog much more successfully than visible light cameras or the human eye.
​

Road surrounded by fog.
Photo by Katie Moum on Unsplash
​

Hence, the reason why car manufacturers are incorporating thermal imagers into the sensor suites of vehicles.
​

13. Can thermal imaging see through water?

​The answer is NO. 

Thermal cameras generally don’t work well underwater. This is because of reasons related to the issues with glass.

Water blocks a lot of infrared wavelengths, similar to how an opaque barrier blocks visible light wavelengths. 

Another challenge why thermal imaging cameras can’t see through water is related to thermal conductivity and specific heat. Water has a higher heat capacity than air, requiring four times as much energy to raise or lower the temperature.

In simpler terms, it means that objects lose or gain their heat energy relative to water much faster, and over shorter distances. In thermal imaging purposes, objects are harder to differentiate submerged than they would in air.

However, marine life researchers are making use of thermal imaging cameras to detect life forms on the surface level from their research vessels.
​

Observing marine life up close.
Photo by Jakob Owens on Unsplash
​

To answer the question again, thermal cameras can detect life forms underwater but it depends on the wave activity to the depth of the water and the heat signature of the living organism. Hence, calm and clear water will work for a thermal camera better than muddied water.
​

14. Can thermal imaging cameras see through trees?

The answer is NO.

A thermal camera cannot detect objects through the trunk of a tree but it can help with spotting people or animals in forested areas.
​

A forest of trees.
Photo by Sebastian Engler ​on Unsplash
​

Search and rescue teams often make use of thermal imaging to spot heat signatures when searching through forests.
​

15. Can thermal imaging see through underground?

The answer is NO.​

Archaeologists make use of thermal imaging cameras to scan objects that are near-surface level or look for moisture seeping into the walls of dig sites.
​

Detecting objects underground requires several instruments such as this one.
Photo by Ignat Kushanrev on Unsplash
​

In some cases, images of underground features in archaeological sites are easily detected with the help of a thermal camera.
​

16. Can thermal imaging see through rocks?

The answer is NO, but it can help detect anomalies in some rock formations.

Infrared thermal imaging was used in a study on detecting intact rock bridges.
​

Rock bridge at sea.
Photo by Alfred Leung on Unsplash
​

Thermal imaging revealed cold thermal signatures for the surfaces of two rocks that had small areas of warm thermal anomalies. The study commended how thermography can remotely detect intact rock bridges, therefore, improving rockfall hazard assessment.
​

17. Can thermal imaging see through the human body?

The answer is NO.
​
It is widely known that thermal imaging can detect life forms but thermal imaging can’t see through bodies. 

However, recent technology has helped in seeing life forms through their heat points which can then be used to infer multiple disease patterns based on the body’s temperature distribution.
​

X-rays also help in seeing the human body.
Photo by LinkedIn Sales Navigator on Unsplash
​

The body temperature is an essential indicator of people’s health, and thus, much attention has been given to its determination. Thermography does not only provide accurate temperature measurement but also gives a detailed image of patients’ body temperature distribution.
​

18. Can thermal imaging see ghosts?

The answer is NO.

Usually seen in ghost hunting programs, thermal imaging cameras are used as a hunting tool to look for signs of ghosts.
​

Eerie grey road.
Photo by Bara Cross on Unsplash
​

As discussed in the previous points, a thermal imaging camera can be affected by so many different temperature sources, anomalies on the camera can usually be explained by normal phenomena, such as heating behind walls, or even reflected temperature from a human's body heat.
​

19. Can thermal imaging see in the dark?

The answer is YES.
​
Thermal imaging is not affected by the darkness since a thermal camera is able to detect the heat from objects whether there is light or not.​

Thermal imaging cameras are sensitive to heat radiation that comes from objects that are warmer than the surrounding environment. These can see the heat coming from life forms.
​

Dark room.
Photo by Anthony DELANOIX on Unsplash
​

These cameras are sensitive to heat radiation that comes from an object that’s warmer than the surrounding environment.  They can see the heat coming from a person or animal. Thermal imaging cameras can detect emitted energy through smoke, dust, fog, blowing sand, rain, and snow.  Visible light wavelengths bounce or are reflected off the obscurant particles due to the wavelength being short. The long wavelength of the infrared spectrum can pass through obscurants allowing a thermal imager to detect the emitted energy.
​

To summarize, thermal imaging cannot see through these things:

• Walls
• Concrete
• Glass
• Aluminium Foil
• Metal
• Rocks
• Trees
• Underground
• Human Body
• Ghosts
• Water

 

Thermal imaging can see through this but it depends on the condition:

• Plastic

 

Thermal imaging can see through these for sure:

• Smoke
• Dust
• Blowing Sand
• Rain
• Snow
• Fog
• Dark

You can also check out the cool infographic below that summarises the things mentioned in this article.
​

Now that we know the situations where thermal imaging could be used, isn’t it time to choose a thermal imaging service provider that gives you a bang for your buck?

Choosing a thermal imaging service provider that can provide good service

Wouldn’t it be nice if a thermal image service provider in Sydney that is able to give their customers value for their money?

With thermal imaging service providers, it is vital that they use thermal imaging cameras that are of high quality to ensure that accurate measurement is detected and recorded. The difference between the different types of thermal imagers is the resolution and clarity of the images they provide and this is where InfraScan Thermal Imaging Sydney comes into the picture.

Want to know the benefits of thermal scanning? Click here. 

Here at Infrascan, our team is proud to offer our services to various thermal imaging needs. Our team is equipped to handle high-temperature scanning of up to 1500°C safely and effectively, which makes it suitable for any kind of application most especially to building inspections and construction.

Infrascan Thermal Imaging Sydney uses an infrared camera to take infrared photographs of thermal anomalies. Our principal focus is thermal imaging of electrical switchgear, but we routinely scan bearings, gearboxes, transformers, motors, plant, and production equipment.

After conducting an inspection with thermal imaging, we provide our clients with reports detailing each fault, its location, and severity. We also comply with all of our client’s occupational safety and health procedures, all of our insurances are current, and we routinely supply Certificates of Currency.

Know more about us and our services by calling (02) 9449 8000.

Are there other alternatives to thermal scanning? Check out this link.
​