The Magic Behind the Scenes
Before we start typing code, let's understand the three heavy lifters in PostGIS that make this all possible. You don't need to write complex algorithms; PostGIS handles the heavy spatial math for us.
Here are the three core functions you need to know:
Function | What it does |
|---|---|
| Generates the bounding box polygon for a specific Z (zoom), X, and Y tile coordinate in Web Mercator (EPSG:3857). |
| Transforms your geographic coordinates into the local coordinate space of the vector tile itself. It crops and scales your data to fit perfectly in that little square. |
| Aggregates all those local geometries and their properties into the final binary Protocol Buffer (Protobuf) format that the browser expects. |
Once you wrap your head around these three functions, building a tile server becomes a breeze!