https://www.theverge.com/2018/6/28/17514340/niantic-labs-pokemon-go-ar-demo-pikachu-occlusion

Pokémon Go creator Niantic announced today that it’s planning on letting third-party developers use its augmented reality platform to develop apps. To showcase how that technology, which Niantic calls its Real World Platform, is improving all the time, the company made a demo video to showcase a technique it calls occlusion.

Basically, Niantic used machine learning techniques it picked up from an acquisition of London-based startup Matrix Mill to create a neural network that could, in real time, obscure virtual images behind real-world objects. This will let creatures like Pikachu hide behind flower pots and park benches, and it will even obscure the virtual pocket monster behind dynamic parts of the scene, like moving people.