by If you’ve ever wished you could see the world through the eyes of another animal, we have good news for you. We asked about that too and, being scientists specializing in color video, we’ve come up with a solution: a camera system and software package that allows you to record video in the colors of animal vision.
Many animals, including bees, birds and even mammals such as reindeer and mice can detect ultraviolet light. In fact, the lack of UV sensitivity in humans is more of an exception than the rule. At the other end of the visible light spectrum, human eyes have red-sensitive receptors and many animals – including bees, mice and dogs – are as blind to red as we are to ultraviolet light.
Even when it comes to blues and greens, colors seen throughout the animal kingdom, the exact wavelength of light that an animal would call “pure blue” or “pure green” is species specific. As a result, no two species see the world in the same colors.
We invite you to stare at the sky and realize that the blueness is the joint product of sunlight being scattered in the atmosphere and your own sensory system. The color you see is specific to you – in fact, for many animals, the sky is an ultraviolet color.
Now, slowly lower your eyes and try to imagine how the rest of the landscape might appear to other species. With our new camera system, we’ve taken one step closer to understanding this amazingly strange world inhabited by other animals.
Download the world in motion
Although we cannot imagine ultraviolet being visible to the animals that can detect it, we can imagine it with false color images. For example, for honeybees that are sensitive to three types of light (ultraviolet, blue and green), we can shift their visible colors into the human visible range so that ultraviolet appears as blue, blue becomes green, and that green becomes red.
Until now, we could only apply this process to immobile objects. False color photography relies on taking a series of photos through a series of fiber optic filters and then overlaying them, and this sequential method means that everything must be in the same position in all the photos.
This is a serious disadvantage. It creates a laborious process that limits the number of subjects that can be realistically imaged. For example, to photograph an eternal peacock feather from a hundred different angles would require screwing on and off each filter a hundred times.
Even worse, all information related to movement is discarded. But life is always in motion: trees sway in the wind, leaves flutter, birds jump on branches in search of insects scooting in the undergrowth. We needed a way to visualize all this movement.
The first challenge was to invent a camera that records in ultraviolet and visible light at the same time. The solution turned out to be a beam splitter. This specialized optical equipment reflects ultraviolet light as if it were a mirror, but allows visible light to pass through, just like clear glass.
We placed two cameras (nothing too fancy, the same kind you can buy in stores and online, but with one modified to record in ultraviolet) in a 3D-printed casing, so that the modified camera showed received ultraviolet light and a stock camera received visible light transmission. We overlaid and synchronized the recordings of these two cameras, and a series of conversion steps allowed us to calculate the amount of light that had reached the sensors of each camera.
From this, we could estimate the amount of light an animal’s eye would catch if it saw the scene from our camera’s point of view.
Try it yourself
All the codes needed to implement the video conversions and camera system plans are freely available online, as well as our best effort to explain how to build the camera from scratch.
Our goal is for other researchers to build their own cameras and use them to answer their own questions about how other species see the world. There are so many possibilities.
We can record the dances of peacocks and see how bright their feathers are with peahens. The sharpness of these feathers extends into the ultraviolet – our recordings show that the feathers look even more colorful to their target audience than to us.
We can accurately describe how frightening displays of caterpillars appear to bird predators, and understand why the flash of unexpected colorful patterns puts them off. We can ask questions about how animals move between spots on the forest floor to show or hide their colors.
We can also create image records of butterflies and other insects held in museum collections and offer animal view conversions as part of a digital library. And we can ensure that glass facades are sufficiently visible to birds that might otherwise collide with them.
But the most exciting questions are the ones we have yet to consider. It’s not until we start taking videos of the natural world in color as seen by animals that we begin to realize how much information is available. Discoveries await you in your own backyard.
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This article from The Conversation is republished under a Creative Commons license. Read the original article.
Daniel Hanley received funding from the National Geographic Society.
Vera Vasas does not work for, consult with, or own shares in, or receive funding from, any company or organization that would benefit from this article, and she has disclosed no relevant relationships beyond her academic appointment.
