.MBTILES

Introduction

MBTiles is a format for a set of map tiles in a single file, created by Mapbox. Web maps are drawn from small square tiles, one set for each zoom level, and a whole region can need millions of them. Keeping them in one file makes a tile set easy to copy, to serve and to use offline in mobile apps.

The tiles can be images, PNG, JPEG or WebP, or vector tiles, which hold the map’s shapes and are styled when they are drawn.

Structure

An MBTiles file is an SQLite 3 database, so it starts with SQLite format 3. It has two parts:

• a metadata table of name and value pairs, giving the tile set’s name, format (such as png or pbf), bounds, centre and zoom levels; for vector tiles a json entry lists the layers
• a tiles table with the columns zoom_level, tile_column, tile_row and tile_data, the tile itself as a blob

Rows are numbered from the bottom of the map, in the TMS scheme, so the row is flipped compared with the usual web map numbering. Vector tiles are stored gzip-compressed. Many files make tiles a view over other tables so that identical tiles, such as open sea, are stored only once.

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