Drones with infrared cameras are used across many industries to capture different types of information beyond what we can see with our eyes. The term infrared is often used interchangeably with thermal but thermal imaging only uses a small range within the infrared spectrum.
In this article I’ll compare thermal and near infrared imaging (NIR) then look specifically at the near infrared type of drones. For more on drones with thermal cameras, check out this article.
Infrared Imaging for Drones Explained
Infrared refers to light waves between 0.7 to 1000 microns in length which is beyond what we can see with our human eyes. The shortest wavelengths in the infrared spectrum is NIR or near infrared. The mid wavelengths, between 3 to 15 microns, give off heat. These are thermal infrared waves. Thermal radiation is emitted from people, animals and objects. Drones with thermal cameras detect differences in the heat emitted from objects to create an image.
Above: the infrared spectrum can be split into 3 ranges with near (short) infrared wavelengths, thermal (mid) infrared wavelengths and far (long) infrared wavelengths. Image credit Nasa
Thermal vs Near Infrared
Although thermal and NIR are both forms of infrared, they produce different types of images. They each have their pros and cons so are suited to different uses.
Unlike thermal infrared imaging, which detects heat signatures, near-infrared imaging captures reflected or absorbed light. When used for night vision, this can be very low levels of light from stars or ambient lighting. In complete darkness, NIR requires an active source to work.
The main benefit of thermal infrared is that it’s passive meaning it can create images in complete darkness. Thermal infrared also works better than NIR to see objects through smoke, fog and dust.
NIR, on the other hand, creates a clearer image than thermal imaging and visualises all objects whether there is heat being emitted or not.
What are Drones with Near Infrared Cameras Used For?
Drones equipped with near-infrared imaging are most commonly used in agriculture, security, military and surveillance.
In agriculture, near-infrared imaging drones help monitor crop health, detect stress, optimize irrigation, and enable precision farming practices. In the field of environmental monitoring, these drones aid in assessing water quality, mapping land cover, and monitoring vegetation changes.
Additionally, near-infrared imaging drones are used for night vision as they can provide a clearer image than thermal in very low-light scenes.
Agricultural Drone with Infrared Camera
When near infrared sensors are used in agricultural drones, they are usually paired with normal RGB colour sensors for multispectral imaging.
Multispectral imaging is a technique used to capture and analyze information from multiple spectral bands or wavelengths of light. Unlike traditional color imaging, which captures information in just three primary colors (red, green, and blue), multispectral imaging uses sensors or cameras that can detect light across a broader range of wavelengths.
Multispectral imaging has several applications in agriculture and can provide valuable insights for farmers and agronomists. Here are a few ways in which multispectral imaging is helpful:
Crop health monitoring: Multispectral cameras or sensors capture images with multiple spectral bands to assess crop health and plant stress levels. By analyzing the spectral signatures of crops, multispectral imaging identifies areas of poor health, disease, nutrient deficiencies, or water stress before they become visually apparent. This means the farmer can apply targeted treatments before the damage to the plants is beyond repair.
Yield estimation: Multispectral imaging can aid in estimating crop yields by providing information about the vegetation’s density and vigor. By analyzing the spectral reflectance patterns, farmers can gather data on crop biomass, plant density, and canopy cover, helping them predict yield potential and optimize harvesting strategies.
Precision agriculture: Multispectral imaging is a valuable tool for precision agriculture practices. By mapping variations in vegetation health and vigor across a field, farmers can identify specific areas that require targeted interventions such as irrigation, fertilization, or pest control. This helps optimize resource allocation, reduce costs, and minimize environmental impact. Precision agriculture is becoming a key function of crop dusting drones.
Disease and pest detection: Multispectral imaging can assist in early detection of diseases, pests, and weed infestations. By analyzing spectral patterns, farmers can identify subtle changes in vegetation health associated with specific diseases or pest damage. This allows for timely intervention and targeted treatments, reducing the potential spread of diseases and minimizing crop losses.
Crop mapping and monitoring: Multispectral imagery can be used to create detailed maps of crop types, vegetation indices, and spatial variations within a field. This information helps farmers assess crop growth patterns, monitor changes over time, and make informed decisions about land management practices.
Above: Multispectral imaging with infrared for agriculture from the DJI Phantom 4. Image credit DJI
Phantom P4 with Multispectral Camera
The DJI Phantom has been evolving since 2013 and is a favourite of many drone pilots. The multispectral camera is an optional attachment built for the Phantom P4. The six lenses on the multispectral camera are tailored to detect different wavelengths to capture near infrared, red edge, red, green, blue and visible light (RGB).
This is a popular infrared drone for agriculture because the Phantom 4 can also be fitted with an RTK module making it highly accurate for mapping and creating orthomosaic images. Orthomosaics are created by stitching thousands of drone photos together to create a very detailed survey of an area.
Night Vision Drone with Near Infrared Camera
Zenmuse H20N with the DJI Matrice 300RTK
The Zenmuse H20N is an detachable camera that fits the Matrice 300 RTK. The H20N is specially designed for night vision and features both near infrared and thermal infrared with zoom. The near infrared is called the starlight sensor.
More on the DJI Matrice 300 RTK in this article.
Drones with Thermal Infrared Cameras
There are a lot of options when it comes to drones with thermal infrared capabilities. This is because they are designed for various uses, including search and rescue, construction, surveillance and security.
In Drones with Thermal Cameras I go through the best thermal drone camera with zoom, the cheapest option, the best non-DJI option, and the best long-range drone with a thermal camera. Overall, the Matrice 30T and the DeltaQuad View drone offer the highest resolution thermal imaging capability.
