If you’ve ever wondered or gotten frustrated at how cross-eyed 3D images work, don’t worry: you’re not alone. 3D images are those weird looking picture books that used to be everywhere when I was a kid. Of course, they’re still around, only this time they’re digital.
But the passage of time did nothing for my understanding of how cross eyed 3D images work; up until I was 30, I was just convinced it actually was magic. Logically, I knew it wasn’t, but I just couldn’t explain it so, hey, magic it is. Thankfully, the internet has made me less ignorant, and now, I want to share what I’ve learned about how cross eyed 3D images work and how you can see the hidden pictures within!
How to Make Cross-Eyed 3D Images Work
Much like if you were reading it on a physical book, your eyes are usually aimed directly at the surface of your computer or smart device monitor when viewing a 3D image. This usually works for most people, especially for kids who grew up with the old 3D Art Gallery books (remember those?), but for those who try their hardest but still can’t seem to see that butterfly or pirate ship, here are a few things you can try:
The “Dots” Method
Think of the two dots (usually it’s dots, but some publishers might use other shapes like stars or squares, basically anything that your eyes can easily focus on) method as sort of training wheels for free-viewing (that is, viewing things without necessarily focusing on anything) stereoscopic images (that is, 3D pictures).
The dots method places a couple of shapes on top of a stereo image that helps your eyes find the most optimum place for focusing, teaching you how to focus on an image without actually focusing on it (it sounds more complicated than it is, but it’s actually quite easy once you get into it.)
Parallel Viewing with the Dots
Think of parallel viewing as like the infamous Frankfurter Experiment. For a brief recap, the Frankfurter experiment lets you see a floating sausage using only two fingers placed a few centimeters away from your face. This is made possible by Parallel Viewing, and when used with the dots method, helps you see 3D images perfectly. Here’s how to do it:
- Train your eyes on the two dots on the stereoscopic image. Next, imagine looking through your screen, as if you’re trying to look at something in the distance. As you do this, you’ll notice that the dots slowly go from two to three. Congratulations, you’ve started seeing in 3D!
- Give your eyes a few seconds to adjust to seeing 3D. Remember how your eyes feel physically and try to maintain that feeling while you start moving your gaze down onto the stereoscopic photo. Do this slowly so you don’t lose focus (or, rather, un-focus).
Cross-Eyed Viewing with the Dots
Cross-eyed viewing is the easiest and probably one of the first things kids learn how to do when looking at 3D images. Growing up, however, I was discouraged by my mom from crossing my eyes (she said it would get stuck that way should I do it long enough), so this didn’t come as naturally to me as my other school friends.
Here’s how to cross eye view 3d images:
- Focus your eyes in front of the stereoscopic photo. To do this, use your finger by moving it from the image towards the center of your nose.
- As your eyes focus on your finger, you’ll start to cross them as your finger starts to move closer your face. Try to bring your finger at least 6 inches in front of your nose. Keep your eyes focused on your finger throughout this.
- Once your finger is in the right place, you’ll notice that the dots on the image have turned from two to four. Stay like this for a few seconds to give your eyes time to adjust to seeing in 3D.
- Once your eyes are used to seeing in 3D, move your finger slowly back onto the screen, while maintaining focus on it. You’ll start seeing the image pop up soon enough.
The Reflection Method
This is the ‘cheaters’ way of seeing 3D images because it relies less on training your eyes to see 3D images and uses more of the reflective surface of the screen. Here’s how to do it:
- Focus on the reflection of your device’s screen. Try to focus on the glare coming off the screen and not the image on the screen itself.
- While you remain focused on the reflection, use your peripheral vision to sort of ‘see around’ the glare and the reflection.
- As the image changes, give your eyes and your brain time to make sense of the 3D image it is now processing.
How Do 3D Images Work?
It’s actually basic biology and physics. Stereoscopic vision, or the ability see things in 3D, is actually an extremely important part of sight because it allows us to do essential things like depth perception, distance estimation, and other things related to visual and spatial reasoning.
Stereophonic vision is possible because each eye actually sees or perceives things differently from the other, albeit extremely similar. This difference is called binocular disparity and the brain processes both images in a slightly different way. This is what allows it to sort of see through or around an obstacle without actually moving. The brain takes the slightly different images your left and right eye see, then accounts for the difference by creating a sense of depth, distance, and space. Pretty neat!
This is why people who go blind in one eye have a harder time judging depth than people with sight in both eyes; their brain has a harder time judging distance with only one imaging input, making stereoscopic vision a very important aspect of being human.