If you’ve ever been to the Wizarding World of Harry Potter at one of the Universal Studios theme parks in Orlando, Hollywood, or Japan, you’ve likely seen people with magic wands conjuring spells at various stations marked with medallions in the walkway. With the flick of the wrist in the correct pattern at the right place, you can do thinks like activate a window display or make water fall from an umbrella onto passersby. These interactive wands are designed to look like the characters’ wands in the films, and cost $50 from the onsite Ollivanders and Gregorovitch’s shops or from Universal’s online store.
Getting behind the “magic” a bit, this all works as Universal devised a clever method of tracking wand gestures by using fixed infrared (IR) cameras as the sensors, IR emitters as the light source that may be co-located with the camera or near the conjurer, and retro-reflective material in the tips of the interactive wands, plus a bit of image processing to track the tip and determine the spell, and mechanism controls to trigger an event. From Universal’s patent, the interactive wands utilize a retro-reflective tip that readily reflects the IR light back to its source or desired sensor, and can be a small piece of material attached to the end of the wand like a dark colored bead or even just a special paint or coating of retro-reflective material that doesn’t stand out to the naked eye.
Normally these wands don’t have much use outside of the Universal park, but I’ve included some links below that show how people have managed to use them with homemade wand recognition equipment.
References:
System and method for tracking a passive wand and actuating an effect based on a detected wand path
How do the Harry Potter interactive wands at Universal Studios in Orlando work?
Everything you Need to Know about Interactive Wands at the Wizarding World of Harry Potter
I Bought A $US47 Interactive Harry Potter Wand And It Was Totally Worth It