The sharp corners of those stickers are the visual "features" that visual SLAM algorithms use to track movement. In order to maximize the Hololens' ability to track its location at "high speed" (10-15 miles per hour), we placed posterboards around the track with black rectangular stickers on them. The Hololens uses visible light cameras, an interial measurement unit, and also a structured grid of infrared light (along with an IR camera) and combines the data coming back from all of those sensors to produce an astoundingly accurate map of the environment despite the possibility of some error in one of those sensor streams. If you're not familiar, this is a concept from autonomous robots where there are a variety of sensors and as the device moves around it creates a map of its surroundings and keeps track of where it is in those surroundings. One thing I've learned the Microsoft Hololens does insanely well is inside-out SLAM (simultaneous localization and mapping). Since the hackaday crowd is an intellectually curious group, here are some behind-the-scenes details on the technology here. and thanks to some electronics I've added to the go-karts, those virtual power-ups can actually boost the speed of your real-life go-kart, or slow the speed of your competition (depending on which power-up you get). As you race around the track, you'll see holographic power-ups that you can collect by driving through them.
![real life mario kart real life mario kart](https://www.sickchirpse.com/wp-content/uploads/2013/09/Mario-Kart-Real-Life.jpg)
![real life mario kart real life mario kart](https://static01.nyt.com/images/2017/03/01/world/01mariokart-1/28mariokart-1-superJumbo.jpg)
First, please enjoy the Holokart demo video so you can see this in action! It's a real life version of Mario Kart, where you get into a physical (as opposed to virtual) go-kart, and put on a Microsoft Hololens augmented reality visor.