[bdon]

1) The Protomaps schema is mostly a re-implementation of the Tilezen project https://tilezen.readthedocs.io/en/latest/ which is a linux foundation project. OpenMapTiles, which OpenFreeMap uses, while open source, does not have a license that encourages derivative works or enables distributing styles under a standard FOSS software license (https://www.npmjs.com/package/protomaps-themes-base). That's also one motivation for developing Shortbread which is at this point less developed than Tilezen.

2) The file format (PMTiles) addresses a different audience than either MBTiles or Btrfs images. Both of those require administering a server for tiles, while PMTiles requires static blob storage and nothing else. You do have the option of using a server like MBTiles/btrfs which ought to be comparable in latency, and that's documented here: https://docs.protomaps.com/deploy/ as well as Lambda, Cloudflare Workers, Google Cloud Run and Azure Serverless functions.

3) There are no existing styles for MapLibre GL that work off the Tilezen layer, generalization and tagging scheme, so we need to develop one style, with multiple themes.

[maelito]

> OpenMapTiles, which OpenFreeMap uses, while open source, does not have a license that encourages derivative works

Can you elaborate on this ? I'm derivating OMT and am quite worried now ^^

[bdon]

OMT use a CC-BY license: https://creativecommons.org/faq/#can-i-apply-a-creative-comm... (edit: link)

This means that software that implements OMT, even if written from scratch, cannot be re-used by other FOSS projects (Apache, BSD, GPL, AGPL, other software in the OpenStreetMap ecosystem, etc) without affecting the license.

Ideally for Protomaps it should be possible to re-use just one portion - like only the label layer with your own layers from other sources, or even bundle it as a JS dependency in another open source project - without affecting the license of downstream projects.