Leveraging Thermal Imaging Drones

Uncategorized Jul 16, 2020

Thermal Cameras

When looking at the type of work you can perform with your drone, the deciding factor is often what kind of payload the aircraft is carrying. For most commercial drones, the standard payload is a Red Green Blue (RGB) camera. 

RGB cameras see roughly the same spectrum of light that the human eye does. For this reason, RGB cameras are ideal for photography. Many staple gigs for commercial drone pilots are easily accomplished through the use of an RGB camera.

If you are interested in more technical work, like utility inspections, an RGB camera will often not be enough. For this type of work, you will need to have a payload capable of thermal imaging.

In this article, we will talk about what exactly thermal imaging is and how to use it (just a few considerations). We will also discuss some platforms available and the type of jobs you can potentially work with a thermal payload. 

What is Thermal Imaging?

When we talk about thermal imaging cameras on drones, we are looking at sensing the heat radiating off an object. So, let's get a little technical and dust off the cobwebs from our high school science class. 

All objects are made up of molecules that are continually moving. Theoretically, molecules can stop moving (absolute zero), but that is for an entirely different conversation. As molecules move, they generate heat. The heat radiated off objects moves in waves. 

You may remember seeing charts called light spectrum diagrams. These diagrams have a rainbow-colored bar with the type of electromagnetic radiation listed above the colors. The chart's left side starts with shorter wavelengths, higher frequency, and higher energy light and moves to longer wavelengths, lower frequency, and lower energy light on the right. 

Light Spectrum Diagram

Also listed are the corresponding types of radiation. They are left to right: gamma-ray, X-ray, ultraviolet, visible, infrared, microwave, and radio. The visible section is just a small portion that humans can see.  The majority of the spectrum is invisible to the human eye.

Thermal cameras can see the heat in the infrared section of the light spectrum. Instead of the lens focusing on visible light, as is the case with an RGB camera, the thermal camera has thousands of sensors (bolometers) in a sensor array that can detect temperature. 

Each of these sensors then converts the temperature into a pixel of a given color. The result is the thermal image we are familiar with and grants the ability to pinpoint a given temperature at a specific spot on the image.

One quick side note: Higher-end thermal cameras are radiometric, whereas entry-level cameras are not.  In order to have a temperature value on every pixel, the camera needs to be radiometric. Radiometric cameras record the relative temperature of the surrounding area. 

This additional reading effectively calibrates the camera to record an accurate representation of the temperature on each pixel. Non-radiometric thermal cameras can be used for things like roof inspects and first responder operations. If you are working on more technical missions, like solar panel inspections, you will need a radiometric camera.

Keep this point in mind when looking for your thermal payload. 

How to Use Thermal Cameras (Just a Few Settings)

Alright, let's close the textbooks and get back to drones. Now that we understand how thermal cameras work let's discuss a few settings to think about when employing the technology.

First, I highly recommend taking a course on understanding how to use and interpret the data from thermal imaging. Companies like FLIR offer these courses, and while they are not cheap, they will set you apart from the competition. I'll mention a few things to think about when using thermal cameras, but it is best to take a class if you really want to be proficient. 

Temperature selection (in range and type) are standard settings. Thermal cameras can be set to read in Celsius, Fahrenheit, and sometimes in Kelvin. Cameras have a temperature range to collect data in, but this can be narrowed to look at smaller temperature differences. Select the option that is specific to your client's needs.

Thermal cameras typically offer you the ability to capture data in different colors or gradients. You have probably seen thermal images that look like a rainbow of colors and also ones that are black and white. The pilot can select what gradient or color pallet best brings out the subject they are collecting information on.

Higher-end cameras will also allow you to adjust emissivity.  Emissivity is a measure of how effective a material is at reflecting infrared energy. If you know the emissivity of a material, you can use this to adjust the settings and make the surface temperature reading of a given material more accurate.

A Few Drone Thermal Options

When it comes to thermal cameras and drones, there are a lot of options. Although many manufactures make excellent products, my personal preference is to use FLIR cameras. The company has been around since 1978 and has built a reputation for high-quality products. Many of the larger OEMs (DJI & Parrot) use FLIR cameras on their drones.

There are two great entry-level drones with thermal cameras I would recommend. While these drones do not have the high resolution needed for some projects like in-depth utility inspections, they are a great way to get your foot in the thermal imaging door. The first is the Parrot Anafi Thermal, and the second is the DJI Mavic 2 Enterprise Dual.

The Anafi thermal and Mavic 2 Enterprise Dual both use the same FLIR camera, the FLIR Lepton. The camera's sensor resolution is 160X120.  

Parrot's drone has an MSRP of $1,900 and comes in a kit with everything you need to get started. The package includes a carrying case, the drone, skycontroller 3 (remote), three batteries, a charger, extra propellers, and a few additional accessories. 

The DJI Mavic 2 Enterprise Dual comes with the drone, remote, batteries, and other accessories. Additionally, if you are thinking of using the drone for first responder missions, it comes with a spotlight, beacon, and loudspeaker. The kit will cost you around $3,250.

The interchangeable payloads offered by DJI well represents the mid-range of thermal cameras. Platforms like the Inspire series of drones and the Matrice series can use several DJI payloads with good quality thermal products. 

The FLIR Dual Pro R (R for radiometric) and Zenmuse XT2 R are both excellent cameras. They are specifically designed to fly on the Matrice series of DJI aircrafts. The sensor resolution on both cameras if 640X512, so a good step up from the entry-level cameras. The FLIR Dual Pro R is around $6,600, and the Zenmuse XT2 R will set you back up to $12,700.

If money is no object and you need some high-end gear, I recommend researching Impossible Aerospace and Aeryon. Impossible Aerospace manufactures the US-1 drone, and Aeryon produces the SkyRanger R60.

The US-1 has an advertised flight time over 70 minutes and a battery charging time of 45 minutes. In theory, if you had two US-1 drones, you could always keep one in the air while the other is charging. The design is similar to Telsa in that the drone was built around the battery.

The payload can either be the FLIR Dual Pro R or for an upgraded sensor resolution of 800X600 the WIRIS Long Range camera. The US-1 starts at $25,000.

The SkyRanger 60R is used by security teams on military installations such as the US Marine Corps base in Twentynine Palms, CA. With a price tag of $150,000, it is well out of the range for most commercial drone pilots to afford. The drone uses FLIR's EO IR Mk II camera with a resolution of 640X512 but can track moving targets among other features requiring onboard image processing.

Potential Jobs

There are many different applications for the technology, and I will cover some of the more common drone applications.

Roof inspections place people at dangerous heights needlessly. Drones equipped with thermal cameras can easily handle this task without placing people in harm's way. Thermal cameras can identify sections of a roof where heat is escaping, a sign of either damage to the roof or the presence of moisture requiring repairs.

Utility companies have many assets that require constant monitoring and inspection. The overheating of equipment such as wind turbines and transformers indicates problems and potential fail points for the machinery. Thermal imaging can identify components as they begin to fail. Diagnosing these issues before a failure can save time and money. 

Along the same lines is the inspection of solar panels on residential and commercial properties. Many factors contribute to the degrading of solar cells. Temperature changes, humidity, UV damage, and thermal cycling can all breakdown a solar cell over time. As cells degrade, they will show up as hotspots on thermal imaging. Drones can cover the inspection of a solar field far faster and safer than people can.

Drones with thermal cameras are beneficial to firefighters. Thermal cameras can pinpoint hotspots in a fire and give crucial information on safe entry points and direct where water from firehoses should be employed on a burning structure.

Other first responder operations, like search and rescue, can also benefit from thermal cameras. The heat radiated by people lost in the wild is picked up by thermal cameras; however, it is not as easy as it sounds. Drones need to be close to the person, and the temperature around them needs to be lower or higher by a reasonable amount than the missing person's body temperature.

For example, if a person is lost in the woods at night, they would be easier to find with a drone's thermal camera than a person lost in the desert on a 100-degree afternoon.

Thermal cameras open the door to a wide range of additional work as a commercial drone pilot. Carefully consider whether or not the investment will expand your business.  If the answer is yes, research which platform is the best for the work you would like to undertake and make sure to get professional training.


Meet The Author

David Daly is a graduate of the United States Naval Academy and former United States Marine Corps officer. He is a consultant to the UAV industry and runs a commercial UAV company (Vigilante Drones) and a non-profit (Vigilante Cares) which uses drones to help military veterans with Post-Traumatic Stress Disorder (PTSD).  

As a commercial drone pilot I have found freedom like no other. Flying has become my passion both for business and as part of my personal journey with PTSD.  The peace I have found from flying inspired me to start Vigilante Cares, a nonprofit using drones to help veterans manage the symptoms of PTSD.  It is a true privilege to be a part of this industry and Altitude University.

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