If you've ever seen Web videos of a cardboard dragon that seems to move its head in whichever direction you go, you're familiar with a "Hollow Face" optical illusion, a term coined by former Professor Emeritus of Neuropsychology Richard Gregory at Britain's University of Bristol. This visual plays on the human brain's tendency to see a concave or "hollowed inward" image of any familiar object as convex or fully three-dimensional. There is a free, ready-to-assemble dragon produced by Binary Arts Corporation and available at the Mighty Optical Illusions website. But for originality, you can download that template and use it as a guide for your own dragon image.
- Skill level:
- Moderately Challenging
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Things you need
- Full-body dragon image (handmade or printed)
Plan how you'll do the illusion. First, download the free "Hollow-Head" dragon optical illusion template from the Mighty Optical Illusions website and study how the structure of the illusion is made. Pay close attention to the template's written instructions. See how parts of the head and eyes are actually drawn or printed at a particular angle, where certain inward ("valley") or outward ("mountain") folds are made, and how these parts and other tabs are glued together or inserted into one another.
Choose a dragon image that's suitable for the illusion's structure. Avoid using a dragon image that's too ornate. Choose an image with a clean or simple silhouette. If it's got too many whiskers or smoke billowing out of its mouth, for instance, these details might be too thin to fool the eye with the same range of angles as the rest of the dragon. Simply viewing such details sideways may already reveal the backside of the cardboard, thus destroying the illusion. If you have drawing skills or experience with manipulating existing images using software, you can draw or render your own dragon image.
Draw or print out the chosen dragon image onto paper, at the size and scale desired. Set it aside.
Sketch out the complete structure of the optical illusion onto cardboard, based on the downloaded template, at the size and scale that match the dragon image. Be sure to mark out where parts of the image should go, plus all of the same tabs, folds and instructions.
Cut out the dragon image then carefully glue its parts to conform to the cardboard structure of the optical illusion. Make sure the image parts do not overlap into structural tabs. Wait for the glue to dry.
Cut out the cardboard structure once the dragon image parts are glued into place. Be sure to cut out all of the tabs and slits as instructed.
Assemble the dragon. Make all of the folds ("valleys" and "mountains") as instructed. Then tuck all tabs into their correct corners and glue them into place. Once the glue dries, place the finished dragon optical illusion on your desk and enjoy your new toy.
Tips and warnings
- The bigger the dragon, the more persuasive the illusion will be.
- For extra effect, use a brilliantly-hued or vivid image of a dragon as the basis for the illusion. Display the finished toy with a source of light illuminating its entire body and face.
- If someone has trouble perceiving the optical illusion at first, advise him to cover one eye then view the dragon again.
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