If you’ve had the pleasure of visiting Universal Studios’ Harry Potter World, you probably noticed the various magic wand-activated interactive exhibits. These use a magic wand, which is sold for $55 at the park, to do things like turn on lights when you perform the correct movement pattern. But, $55 is a lot to spend when you consider the wand itself is completely passive and contains no electronics of its own.
The systems works with a simple IR (infrared) tracking system that is installed at each interactive display. A ring of IR LEDs is directed toward visitors, and when they point their magic wands towards the display, a camera tracks the reflected IR light to identify the movement of the wand. Because it’s just a reflection, the wand itself doesn’t need anything more than a reflective surface—no electronics required.
William Osman thought it was silly to pay $55 for nothing more than a hunk of plastic, so he tested a few methods for building his own wand. Each is just a handle of sorts (like a hot dog or cucumber), with different reflective materials attached to the end. The best results were achieved with facial tracking dots, which are used for mo-cap (motion capture) in films. But, other less expensive materials, like reflective tape, worked too. If you’re planning on visiting Harry Potter World, this is a cheap and easy way to avoid price-gouging on an official magic wand.