Any sufficiently advanced hack is indistinguishable from magic, a wise man once observed. That’s true with this cool build from [Jasmeet Singh] that magically opens a box when you wave a Harry Potter magic wand in the right way. Is it magic? No, it’s a neat hack that uses computer vision to track the wand and recognize when you make the magic gesture.
The trick is based on the same technique that Universal Studios use in their Harry Potter theme park, as detailed in a patent with the snappy title of “System and method for tracking a passive wand and actuating an effect based on a detected wand path“. The basic idea is that a retroreflective dot on the end of the wand reflects light from a set of infra-red LEDs around the camera. An infra-red sensitive camera detects this reflected light as a bright dot. This camera is tied into a computer vision system that tracks the path of the dot, then triggers the action if it follows a certain pattern.
The version that [Jasmeet] built uses a Raspberry Pi NoIR camera, and a Raspberry Pi 3 running OpenCV. This feeds into a machine learning graph that detects the letters of the alphabet. If the detected letter is an A (for Alomahora, the Harry Potter open spell), then the box opens. If it is a C, the box closes. This is all tied together using Python.
It’s a neat build that ties together a number of interesting techniques, and which could keep the kids amused for a while. You could also expand it further, such as adding a death ray that triggers if you trace an S for Sectumsempra. That’ll teach them not to mess with the dark arts.
if I had a lathe and a source for the retroreflective beads they use on the wands, I’d love to set up shop making custom handmade wands that work with the park’s system. I want to put one into my cane so I can use a “staff” to do the same thing and make all the kids boggle next time I go down there.
Looks like the wand with reflective tip is covered by the patent, so probably shouldn’t set up shop.
But for those who might want to enjoy the parks attractions without paying for the wands in the park, it’s great information.
Nope. You have to infringe on each and every element of what is claimed in the patent. The wand is but one of the elements. They claim the emitter, tracking system, etc. You can make wands all day long.
You don’t need a bead. Just some IR-reflective tape. Use a hole-punch to cut out a small circle to put on the end of your wand or cane. You can probably find some tape at a military-surplus store, or on Amazon.
Retroreflective tape is a thing, you know.
this guy doesnt know that there already is a wand movement for alohamora and close. smh. look up the games.
Nifty make. Will conductors have to worry about patent-infringement claims though?
I think only if they try to produce and sell the system. But if you make it yourself for yourself, or as a gift, I don’t think they can say anything.