What Can Drones See at Night? Night vision explained
Only decades ago, these flying creatures were something straight out of a science fiction movie. Now, look at us not only talking about new designs and technologies, but also special features that keep on improving day by day.
I have always wondered about drones’ cameras night vision capabilities, so I decided to conduct a thorough search on this topic.
So, what can drones see at night? It depends on their camera technology. A regular drone camera cannot see much in a dark night with no artificial lights around, whereas a night vision camera drone would require a certain degree of ambient light to transfer a readable image. That said, drones equipped with thermal imagery do have particularly interesting dark vision capabilities.
Of course, there are many limitations involved with different night vision systems. This raises many questions like:
How do night vision cameras work?
What’s the difference between night vision and thermal vision?
In this article, I have handpicked the most valuable findings for you to have a clear understanding of this concept.
How do thermal imaging camera drones work?
Human bodies as well as other sources of temperature are constantly emitting thermal waves that are different from other cooler objects around them.
At a molecular level, the higher the temperature of any object, the more its atoms vibrate. This thermally induced movement is what generates infrared energy.
All these heat signatures allow thermal cameras mounted on drones to detect specific things they wouldn’t otherwise see. In fact, to each pixel in a produced thermal image corresponds an infrared heat sensor.
So technically, these little thingies can register the temperature degrees of thousands of points at once. For example: At a resolution of 640x480 pixels, the camera will detect a total of 307k heat points.
In a nutshell, videos and images displayed on thermal imaging cameras are essentially the results of capturing little dissimilarities in heat and rendering them into several color variations ranging from black (Cold) all the way to white (Hot).
With that in mind, imagine what can a flying infrared camera see in different environments? While this technology is the ultimate winner when the sun goes down, it remains way more expensive than its peers.
Night vision vs Thermal imagery:
While night vision has been around since world war II, it represents a rather different principle when compared to other technologies.
You might be quite familiar with those green aka super-spy screen displays we often see on movies and tv-series. Well, technically speaking, the human eye is in fact able to discern many more different shades of green as opposed to any other color.
How does night vision work?
Night vision cameras, also known as ‘image intensifiers’ are essentially electro-optical devices that transform all forms of ambient low light into green and black images visible to the human eye.
To do that, they rely on an ‘intensifier-tube’ that magnifies tiny amounts of light, even those invisible to the naked eye, making it possible to “see” in the dark.
The cool science behind intensifier-tubes stems from their ability to collect photons, convert them into electronic particles, pump those full of energy, then convert them back into the light. Kind of like a magical wand connected to a fancy-greenish-orb turned fortune-telling Chrystal-ball… Uhm, you get the idea.
Aside from that, when an object is brighter than its surroundings, it has a strong visual contrast. Which makes it easier to spot. However, when its radiance is not that dissimilar to other objects around it, the target becomes quite indistinct.
This creates a significant drawback in contrast accuracy for image intensifiers, especially when certain environmental and weather conditions come into play.
Another major holdup is the fact that such technology fundamentally relies upon some form of a light source to be around, starlight and moon glow being typical examples.
Notice the tricky part here?
Dark, as in total obscurity, is definitely not possible to ‘see’ through with an image intensifier. In actual fact, pictures dramatically drop in quality as soon as you approach duskier zones.
Which paves the way to another generation of night vision cameras, also referred to as infrared illuminators.
And, yes! Infrared being the same type of invisible energy detected by thermal sensors. But there’s a small catch…
Infrared Illuminator cameras
Infrared illuminators or Active illumination cameras project their own beam of infrared light. Quite unlike thermal imaging which is a passive system that mainly consists of reading differences in heat.
As it turns out, Infrared illumination cameras do contain a series of tiny LEDs, mostly placed around their lenses and continuously emitting infrared waves.
As these invisible waves of light bounce off of various objects, the camera’s imager detects them, making it possible to ‘see’ in total darkness.
Long story short, imagine a random night vision camera holding its own little flash of invisible light and pointing it at everything and everyone, once it reflects, it catches that wave like nobody’s business. And, there you have it!
Thermal imagery is currently widely used in medicine, search, and rescue, law enforcement surveillance, circuit boards defects detection, firefighting… As well as many other functions and sectors.
Although each camera system has its own ups and downs, thermal imaging remains the most effective and practical out there. One other thing I’ve mentioned regarding it though is that it’s extremely expensive.
I’ve also found that there’s a possibility to mount a thermal imaging camera onto your noisy hovering friend without the need to go out of your way and purchase an overpriced thermal imaging drone. Interesting, huh?