How does a Pokémon game place Pokémon on the map in buildings?

Question

Android

Hi all. I'm new to this stuff, so don't be surprised by the question. How did the Pokémon game place Pokémon on the map in buildings or on the street. How the application learned the height or coordinates of buildings. Were there only Pokémon in the buildings or on the street as well? Generally, what algorithm prompt, please.