By Leila Lemos and Leigh Torres
A couple weeks ago the GEMM Lab trialed something new in our gray whale research: the addition of a thermal imaging camera to our drone.
For those who do not know what a thermal imaging camera is, it is a device that uses infrared radiation to form an object, and operates in wavelengths as long as 14,000 nm (14 µm). A thermal camera uses a similar procedure as a normal camera, but responds to infrared radiation rather than visible light. It is also known as an infrared or thermographic camera.
All objects with a temperature above absolute zero emit infrared radiation, and thermography makes it possible to see with or without visible light. The amount of radiation emitted by an object intensifies with temperature, thus thermography allows for perception of temperature variations. Humans and other warm-blooded animals are easily detectable via infrared radiation, during the day or the night.
Infrared radiation was first discovered in 1800, by the astronomer Frederick William Herschel. He discovered infrared light by using a prism and a thermometer (Fig.1). He called it the infrared spectrum “dark heat”, which falls between the visible and microwave bands on the electromagnetic spectrum (Hitch 2016).
Around 30 years later it was possible to detect a person using infrared radiation within ten meters distance, and around 50 years later it was possible to detect radiation from a cow at 400 meters distance, as technology became gradually more sensitive (Langley, 1880).
Thermography nowadays is applied in research and development in a variety of different fields in industry (Vollmer and Möllmann 2017). Thermal imaging is currently applied in many applications, such as night vision, predictive maintenance, reducing energy costs of processes and buildings, building and roof inspection, moisture detection in walls and roofs, energy auditing, refrigerant leaks and detection of gas, law enforcement and anti-terrorism, medicinal and veterinary thermal imaging, astronomy, chemical imaging, pollution effluent detection, archaeology, paranormal investigation, and meteorology.
Some of the most interesting examples of its application are:
- Detection of the presence of icebergs, increasing safety for navigators.
- Detection of bombs
- Non-invasive detection of breast cancer (Fig.2)
- Detection of fire, and detection of fire victims in smoke-filled rooms or hidden under plywood, by the fire departments (Fig.3)
In environmental research, the thermal imaging camera is an interesting tool used to detect wildlife presence (especially for nocturnal species), to monitor wildlife and detect disease (Fig.4), and to better understand thermal patterns in animals (Fig.5), among others.
Now that thermal cameras are small enough for attachment to drones, we are eager to monitor whales with this device to potentially identify injuries and infections. This non-invasive method could contribute another aspect to our on-going blue and gray whale health assessment work. However, dealing with new technology is never easy and we are working to optimize settings to collect the data needed. Our test flights with the thermal camera were successful – we captured images and retrieved the expensive camera (always a good thing!) – but the whale images were less clear than desired. The camera was able to detect thermal variation between our research vessel and the ocean (Fig. 6: boat and people are displayed as hot coloration (yellow, orange and red tones), while the ocean exhibited a cold coloration (purple). Yet, the camera’s ability to differentiate thermal content of the whale while surfacing from the ocean was less evident (Fig. 7). We believe this problem is due to automatic gain control settings by the camera that essentially continually shifts the baseline temperature in the image so that thermal contrast between the whale and ocean was not very strong, except for those hot blow holes shinning like devil eyes (Fig. 7). We are working to adjust these gain settings so that our next trial will be more successful, and next time we will see our whales in all their colorful thermal glory.
BBC. 2013. In pictures: Emperor penguins’ ‘cold coat’ discovered. Available at: http://www.bbc.co.uk/nature/21669963
Hitch J. 2016. A Brief History of Thermal Cameras. Available at: http://www.newequipment.com/technology-innovations/brief-history-thermal-cameras /gallery?slide=1
Langley SP. 1880. The bolometer. Vallegheny Observatory, The Society Gregory, New York, NY, USA.
MASC. 2017. Thermal Imaging Camera. Available at: https://duckduckgo.com/ ?q=detection+of+victim+fire+department+thermal+camera&atb=v76-7_u&iax=1&ia= images&iai=http%3A%2F%2Fwww.masc.sc%2FSiteCollectionImages%2Fuptown%2F Super_Red_Hot.jpg
NASA. 2012. Beyond the Visible Light. Available at: https://www.nasa.gov/topics/ technology/features/webb-beyond-vis.html
USGS. 2016. Study Shows Cold and Windy Nights Physically Drain Mangy Wolves. Available at: https://www.usgs.gov/news/study-shows-cold-and-windy-nights-physically-drain-mangy-wolves
Vollmer M. and Möllmann KP. 2018. Infrared Thermal Imaging: Fundamentals, research and Applications. Second Edition. Wiley-VCH: Weinheim, Germany.
Wildlife Research News, 2012. Tool: Infrared Monitoring. Available at: https://wildliferesearchnews.wordpress.com/2012/04/24/tool-infrared-monitoring/