Use AprilTags to let guests open your front door

[Herb Peyerl] is part of a robotics team and in his robotics endeavors discovered AprilTags; small QR-code type printable patterns that are easily recognizable even by primitive artificial vision. Later, when thinking of good ways to get his guests through the front door of his property, AprilTags turned out to be a wonderful solution. Now all he has to do is send his guest a photo of the appropriate AprilTag, which he can present to the camera at his entrance gate using his smartphone.

He used an OpenMV board for this - thanks to its wide variety of available libraries, AprilTag recognition is already built in, and the entire script is only a hundred lines of MicroPython. An old surveillance camera has ditched its domed enclosure, and now the OpenMV board is doing guest access duty on a pole outside the front door of its property. He shared the code with us and says he personally runs a slightly modified version for security reasons - not that a random burglar is likely to stumble upon this post anyway. Also, it looks like the door would be easy for a burglar to get through without the need for a security bypass, and the practical benefits of this hack are undeniable.

In the unlikely event that a burglar reads this, though, don't be sad. We also happen to have a bunch of hacks for you. There are far less secure systems out there, from building RFID key fobs to gated community access control systems, sometimes all you need is a 12V battery. If you don't like burglary, this Doesn't matter either - we've already covered other guest access hacks, for example the one powered by the ESP8266.