6 Reasons Why Aerial Surveyors Choose Thermal Camera Sensors

Introduction

One of the most interesting aspects of our industry is seeing how aerial survey work touches so many industries, from agriculture and forestry to environmental monitoring and search and rescue operations. 

Our clients often have many different types of sensor assets, and one of the most specialized are thermal camera sensors. 

In this article, we'll delve into the world of thermal camera sensors for surveying, exploring what they are, the different types available, how they are used, and the advantages and potential pitfalls of using them.

What Is Thermal Imaging?

Thermal imaging, also known as infrared imaging, is a technology that allows us to capture and visualize the heat radiating from an object or scene. 

Unlike traditional cameras, which capture visible light, thermal cameras work with infrared radiation, enabling them to "see" heat variations. This feature makes them invaluable tools in diverse survey applications.

6 Reasons Thermal Camera Sensors Are Used by Aerial Surveyors

Aerial surveyors employ thermal camera sensors in a variety of ways, depending on the goals and requirements of their projects. Here are some common applications and use cases for thermal camera sensors in aerial surveying:

1. Wildlife Monitoring: Thermal imaging is an invaluable tool for tracking and studying wildlife. Aerial surveyors can use thermal cameras to locate and monitor animals, particularly in low-light or nighttime conditions.
2. Agricultural Surveys: In agriculture, thermal cameras are used to assess crop health and identify areas affected by pests, disease, or irrigation issues. This information helps farmers make timely and informed decisions.
3. Environmental Monitoring: Thermal cameras assist in monitoring environmental conditions and identifying temperature anomalies. For example, they can detect water leaks, hotspots in power lines, and heat emissions from industrial facilities.
4. Fire Detection: Aerial thermal imaging is instrumental in early fire detection. It can identify hotspots and potential wildfire outbreaks, enabling rapid response and containment efforts.
5. Building Inspections: Surveyors can use thermal cameras to inspect the thermal performance of buildings, looking for insulation issues, heat leaks, or electrical problems.
6. Power Line and Utility Inspections: Thermal cameras are employed to inspect power lines and utility infrastructure. They can identify overheating components or poor electrical connections, helping to prevent potential failures or outages.

One of our clients, Aaron Schepers, President of Cornerstone Mapping, Inc shared his experience with using thermal camera sensors:

“Thermal imaging requires an excellent working knowledge of thermal remote sensing principles. The mapping application determines the time of year for the flight and whether data collection should occur during the day or nighttime.”

Aaron shared two images from his work that illustrate some real-world application of thermal imaging. 

The image below is from a state penitentiary shows how Cornerstone Mapping used a thermal camera sensor to map underground steam lines to identify leaks. Universities and large campuses also often use steam to heat their facilities.

The next image shows how thermal imaging was used to map the location of groundwater inflows into streams and rivers in a project for the USGS. 

Cornerstone Mapping flew hundreds of miles of streams in the Nebraska Sandhills to locate groundwater inflows that are not visually identifiable. 

Groundwater maintains a yearly average temperature of around 58 degrees F, while the soil is near freezing during the winter. As you can see from the image, thermal contrast readily identifies the locations of groundwater inflows.

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What is SWIR, MWIR, and LWIR?

Cameras made especially to detect infrared wavelengths include SWIR (short-wave infrared), MWIR (Mid-Wave Infrared), or LWIR (Long-Wave Infrared) cameras. 

These terms relate to the specific portions of the electromagnetic spectrum these cameras are designed to capture. 

The differences between SWIR, MWIR, and LWIR cameras revolve around what they’re made of and how they get used.

SWIR Cameras

SWIR cameras operate in the short-wave infrared spectrum, which typically covers wavelengths between 1,000 nanometers (1 micron) and 2,500 nanometers (2.5 microns). These wavelengths are beyond what the human eye can perceive (the visible spectrum), and they extend into the infrared region. SWIR capture light reflected or absorbed by an object.

SWIR cameras are useful for aerial survey because they can penetrate through fog, smoke, and smog pollution, making SWIR cameras ideal for IR imaging through adverse conditions.

SWIR cameras are also often used in night vision and security applications due to their ability to capture infrared radiation, even in low light conditions.

MWIR Cameras

MWIR cameras are engineered to capture infrared radiation in the mid-wave portion of the spectrum, typically ranging from approximately 3 to 5 microns in wavelength. MWIR cameras detect heat emitted by an object.

Unlike SWIR cameras, they don’t work well through dust, smoke, air pollution, or fog. However, they are very good at detecting gas leaks that the naked eye can’t see, making these cameras suitable for applications like industrial inspections.

MWIR sensors are also less susceptible to atmospheric conditions. This is critical for airborne survey operations. They can operate in various climates, including those with high humidity, making them particularly well-suited to marine and coastal environments. 

LWIR Cameras

LWIR cameras are designed to capture thermal radiation in the long-wave portion of the infrared spectrum, typically covering wavelengths from about 8 to 14 microns. Like MWIR, LWIR cameras detect heat emitted by an object.

LWIR cameras are highly effective at thermal imaging in outdoor environments and building inspections due to their capability to capture the heat emitted by objects and provide temperature-related information. 

What Are the Different Types of Thermal Sensors?

Aerial surveyors have several options when it comes to thermal sensors. Each type of sensor has its own set of advantages and limitations, making it essential for professionals to choose the one that best suits their specific needs. 

Here are some common types of thermal sensors:

1. Uncooled Microbolometer: Uncooled microbolometer sensors are cost-effective and are commonly found in thermal cameras designed for consumer and lower-end applications. Because they may lack the sensitivity and accuracy of other sensor types, they are most commonly used for aerial surveys with small unmanned drones.
2. Cooled InSb (Indium Antimonide) Sensor: InSb sensors are known for their superior sensitivity and image quality. These sensors require cooling to extremely low temperatures, which can limit their use in some applications due to added complexity and maintenance requirements. Because they are so sensitive to temperature differences, these tend to be most commonly used for military and scientific applications.
3. Cooled MCT (Mercury Cadmium Telluride) Sensor: MCT sensors offer the highest level of sensitivity and resolution. They are typically found in advanced, high-end thermal cameras used for specialized aerial surveying tasks. 
4. Microgrid Infrared Focal Plane Array (IRFPA): IRFPA technology allows for the production of compact, high-resolution thermal cameras that are ideal for aerial surveying applications where size and weight constraints are critical.
5. Multispectral Sensors: Some aerial surveyors use multispectral sensors that combine thermal imaging with other spectral bands, such as visible and near-infrared. This approach provides a more comprehensive view of the surveyed area, making it useful in various applications, including agriculture and environmental monitoring.

What Types of Lenses Are Used for Aerial Surveys?

In addition to the sensor type, the choice of lens is a crucial factor in aerial surveying with thermal cameras. 

Different lenses are suited to different surveying needs, and aerial surveyors must carefully select the right lens for their specific project. Here are some common types of lenses used in aerial surveys:

1. Fixed Focus Lens: Fixed focus lenses offer a fixed field of view and focus, making them simple to use. They are ideal for applications where the surveyed area is expected to be at a consistent distance from the camera.
2. Zoom Lens: Zoom lenses provide variable focal lengths and allow aerial surveyors to change the magnification level during flight. This versatility is especially useful when the surveyed area is vast or when different details need to be inspected at varying distances.
3. Wide-Angle Lens: Wide-angle lenses capture a larger field of view, making them suitable for applications where a broader perspective is required. They are often used in environmental monitoring and disaster assessment.
4. Telephoto Lens: Telephoto lenses offer high magnification, allowing for detailed inspection of objects or terrain over long distances. They are commonly used in applications like wildlife observation or search and rescue missions.

Advantages of Using Thermal Camera Sensors

Aerial surveyors have several compelling reasons for choosing thermal camera sensors in their work:

1. Visibility in Low-Light Conditions: Thermal cameras can "see" in complete darkness, making them indispensable for nighttime and low-light applications.
2. Temperature Detection: Thermal cameras can identify variations in temperature, highlighting anomalies that may be invisible to the naked eye. This is crucial for tasks like wildlife monitoring, search and rescue, and building inspections.
3. Non-Destructive Testing: Aerial thermal imaging allows for non-destructive testing of infrastructure and equipment. It can uncover hidden issues without the need for invasive procedures.
4. Speed and Efficiency: Aerial surveys with thermal cameras can cover vast areas in a short amount of time, enhancing efficiency and reducing surveying costs.
5. Enhanced Safety: Thermal imaging helps keep surveyors safe by identifying potential hazards like electrical faults or gas leaks.

Pitfalls of Using Thermal Camera Sensors

While thermal cameras offer numerous benefits, there are also some potential pitfalls to be aware of:

• Cost: High-quality thermal cameras and sensors can be expensive, which may limit access for smaller organizations or projects with limited budgets.
• Complexity: Cooling requirements for certain sensor types, calibration, and data analysis can be complex and may necessitate specialized training.
• Environmental Factors: Weather conditions, such as rain, snow, or fog, can affect the performance of thermal cameras. Extreme temperatures may also impact their sensitivity.
• Resolution Limitations: The resolution of thermal images is generally lower than that of visible light images, which can affect the level of detail in certain applications.
• Interpretation: Interpreting thermal images requires expertise, and misinterpretations can lead to incorrect conclusions.

How Do You Use Thermal Cameras

From wildlife monitoring and search and rescue missions to agriculture, environmental monitoring, and beyond, thermal camera sensors have become indispensable tools. How do you use thermal cameras in your business?

You can see all of our cameras… RGB, NIR, Achro, and more at AERIALSURVEY.com. Let us know what questions you have. We’d love to hear from you.

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