How do thermal cameras work? Understanding heat vision

What is a thermal camera and how does thermal imaging work?

Thermal and infrared (IR) cameras are often treated as the same device because they use the same sensor technology to capture images. However, the two differ in purpose and operation.

Thermal cameras use sensors to detect heat emitted by a person or object, convert it into a heat signature, assign colors to it and display it as a temperature map. IR cameras detect radiation emitted by light, outlining objects based on the intensity of the radiation.

In short, thermal cameras are temperature-based observation devices that can detect infrared radiation. Their functional differences lead to distinct applications, with thermal imagery improving detection capabilities in perimeter security, predictive maintenance and intrusion under challenging environmental conditions.

The versatile use of thermal cameras is currently driving the market for devices, projected to grow from $1.8 billion in 2025 to over $5.8 billion in 2032. Below are examples of what thermal imaging can do that traditional video security cameras may struggle to detect.

• Vehicles: Thermal cameras detect heat signatures emitted by vehicles operating within the field of view. Identifying moving objects can be challenging in conditions such as heavy fog or rain, alerting security teams to any unknown or unexpected vehicle movements within the perimeter.
• Electrical hotspots: Devices can detect anomalies in machinery and equipment by analyzing heat signals. For example, if a factory production unit overheats, operators can take corrective action before it fails.
• Humans and animals: Thermal cameras can help detect hidden movements on the premises. Their heat signatures help security teams identify breaches in areas with low-light conditions.
• Structural defects: Many organizations use thermal cameras to help identify structural defects within their facilities. The devices can help detect anomalies such as air leaks in HVAC systems or water loss in buildings.
• Health screening: Thermal cameras can detect elevated body temperatures among people entering a facility, helping prevent illness and protect staff from its spread. They can also help observe medical facilities to contain potential leaks of hazardous materials.
• Gas detection: Many hazardous gases produced in industrial environments are difficult for humans to identify. Thermal cameras detect the heat signatures produced by gases such as methane or propane, helping protect staff on the premises.

Differences between thermal and IR detection

Although thermal and IR cameras operate similarly, they differ in how they display imagery to an observer. As mentioned above, thermal imaging relies on IR devices that detect the heat radiation emitted by objects or people. Understanding how both thermal and IR cameras work lies in defining their differences.

The primary operational difference between the two cameras lies in the sensors used in the thermal imaging device. Thermal imaging uses a microbolometer rather than a focal-plane array (FPA), typically used in IR cameras.

The core differences between thermal and IR detection are below:

How does thermal vision work?

• Sensors will detect IR radiation, where receptors will heat up according to their temperature
• The cameras will process the received data, mapping out an image of the areas based on temperature
• The processors will assign color values to each area of the image, typically red shades for hot and blue for cold
• The image sent to the camera displays as a heat map

How do infrared cameras work?

• Uses an FPA sensor that uses multiple detectors to measure IR radiation in a field of view
• The receptors measure and analyze the amount of radiation received
• The camera converts absorbed radiation into electric signals
• The processor combines all received information into a single image, highlighting areas by the amount of emitted IR radiation

Key components inside thermal cameras

The core components within a thermal camera enable the device to provide a temperature-based visualization of the current field of view. Components range from the optical system that captures radiation to the display unit that provides security teams with heat maps.

Here are the main parts that enable thermal imaging in a camera:

• Lenses: The optic systems inside the thermal camera that focus IR energy onto the sensors.
• Thermal sensors: These sensors, known as microbolometers, convert thermal radiation into electrical signals.
• Processors: The camera’s processors convert the signals into a heat map, assigning colors to pixels based on their temperature.
• Casing: The housing around the camera that helps protect internal components from damage.
• Display: The screen that shows the processed heat map, providing observers with a visualization of the camera’s field of view and identifying persons and objects by temperature.

What are the different types of thermal cameras?

While the components across the range of thermal cameras remain relatively similar, there are different types of devices to accommodate an organization’s security needs. Depending on the environment, there are a few main categories of cameras that can help improve an overall security system.

The three main types of thermal security cameras are below:

Fixed

Security planners will mount fixed cameras at designated locations requiring continuous oversight, providing constant heat signatures of people and objects within the device’s field of view. They typically feature high-resolution displays for team observation.

Applications of fixed thermal cameras often include areas requiring continuous observation, where standard commercial security cameras may have limited visibility. Security planners usually install them at access points or checkpoints on both internal and external premises.

Long-range

Long-range thermal cameras use sensors that detect heat signatures over greater distances, making them a preferred choice for security teams that require an extended field of view. Although the display is typically lower-resolution, it can serve as an excellent general-purpose camera within a layered security system.

Use cases for long-range thermal cameras include building sites, industrial facilities and other large premises that require improved visibility under challenging conditions.

Dual-vision

Dual-vision cameras combine thermal and standard-vision optics, enabling security teams to view both standard displays and heat maps concurrently. The devices are well-suited for facilities that require visual flexibility and extended detection capabilities, thereby providing personnel with greater visibility of the surrounding area.

The devices often include customizable options to accommodate specific security requirements, such as operation in harsh environmental conditions. Dual-vision cameras are an ideal choice for organizations with scaling security needs.

What can thermal imaging detect?

Thermal cameras can be a flexible, adaptable solution for environments that require extended observation capabilities under unpredictable conditions. The technology’s applications can extend beyond risk and threat mitigation, with many organizations using the devices as productivity tools and to bolster security.

Here are some of the common uses of thermal cameras:

• Perimeter detection: Thermal imaging can help identify intruders on premises where challenging exterior conditions compromise visibility. The perimeter cameras can alert personnel to breaches by detecting human heat signatures, thereby improving the security team’s response capabilities.
• Preventive maintenance: In industrial applications, thermal cameras can help scan equipment and heat maps can identify whether the machinery needs repairs or is approaching failure. The display can show scenarios such as overheating, where engineers can address the issue before it becomes costly or disruptive to the business.
• Building inspection: Thermal cameras can help detect structural defects. The temperature sensors can help identify insulation problems, gas and air leaks, moisture buildup and other potentially costly building deficiencies.
• Security operations: Thermal imaging can enhance efficiency by enabling objective identification in scenarios such as search-and-rescue and threat detection, particularly under challenging lighting conditions. Heat signatures allow security teams to identify objects and people more quickly, enabling faster responses to risks and threats.
• Health and safety hazards: Devices can help identify risks that are not readily visible to humans or standard video security cameras. The heat maps can identify hazardous gases or illnesses among personnel.

How to choose the right thermal camera

When evaluating thermal cameras for your organization, consider several factors to ensure they enhance your security system and productivity. There are different options available depending on your needs.

Here are some fundamental considerations when choosing thermal cameras for your premises.

• Resolution: Some thermal cameras offer higher resolution, but their detection range is shorter. Some applications of the technology may require better resolution to help identify operational or security anomalies.
• Thermal sensitivity: Thermal cameras can vary in sensitivity. Some can expand detection capabilities to identify subtle temperature fluctuations, thereby supporting applications such as predictive maintenance and healthcare.
• Detection range: Security teams should consider a thermal camera’s detection range alongside its intended use. Many devices have long-range observation capabilities, but the display resolution is lower with an extended sensor range.
• Customization: Consider whether your security team requires a more flexible device that can scale to meet requirements. Some thermal cameras offer extensive customization to adapt to the unique conditions of a premises.
• Budget: Technology costs are often a primary consideration for security planners. Various thermal cameras are available to suit different budgets.
• Use cases: Understanding how the technology will address safety and security gaps is necessary to ensure that the appropriate thermal camera is selected. Evaluate the features of different devices and choose the one that will most effectively enhance your security system.

Improving detection capabilities with thermal cameras

Security threats and risks are continuously evolving, with environmental conditions in certain areas becoming increasingly more severe. Detecting objects and unauthorized persons can be more challenging, requiring more proactive solutions to keep pace with evolving security needs.

Thermal cameras offer flexible solutions to a range of security and productivity needs, contributing towards operational efficiency by mitigating scenarios that could be costly or disruptive to an organization. Their detection capabilities in low- or no-light conditions can be an integral component of a scalable strategy, helping reduce the threats posed by the changing security landscape.