"Additionally, our licenses are currently not compatible with the major software licenses, so it would be difficult to integrate CC-licensed work with other free software. Existing software licenses were designed specifically for use with software and offer a similar set of rights to the Creative Commons licenses." https://creativecommons.org/faq/
> Though I understand if you'd rather avoid using projects by people with weird legal opinions.
The scale of the Protomaps project is small (I'm the only full-time developer) and I don't have the resources to interpret novel copyright situations. I think it's best for the ecosystem to abide by the license terms stated by the open source developer, instead of challenging their validity.
If you would like to run this comparison for tileservers reading from disk, I wrote a small tool to simulate traffic based on access logs of OpenStreetMap tiles:
That is the definition of license incompatibility as described in the Creative Commons documentation above. The license is open source and a good fit for if you are running a paid map SaaS or free service as an end product, but is not compatible with the open source ecosystem as a building block.
I see, I think that's a good approach to enable serving with stock nginx as well as for companies that are built on Nginx or a plain HTTP serving stack already.
For PMTiles the module is loadable directly as a Caddy plugin (https://docs.protomaps.com/deploy/server#caddyfile) which I prefer to nginx for security and bugs (and automatic SSL), and also enables serving PMTiles from disk or a remote storage bucket without a separate service running.
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.
I agree, there are tradeoffs to using static storage - the intended audience for PMTiles is those that prefer using static sites instead of administering a Linux server.
I would be interested to see a comparison of Btrfs + nginx serving latency, vs `pmtiles serve` from https://github.com/protomaps/go-pmtiles on a PMTiles archive on disk. That would be a more direct comparison.
I think there's potentially some interesting use case for tiles in Btrfs volumes and incremental updates, which I haven't tackled in PMTiles yet!
The latency for small files and ranges of large files is pretty similar on most storage platforms, but there are some exceptions like Cloudflare R2.
The main reason PMTiles is one file and not two or more files is that it enables atomic updates in-place (which every mature storage platform supports) as well as ETag content change detection in downstream caches. All of the server and serverless implementations at http://github.com/protomaps support this now for AWS, S3-compatible storage, Google Cloud, and Azure.
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.
The latency you see on https://pmtiles.io/?url=https%3A%2F%2Fdata.source.coop%2Fpro... is representative of how PMTiles works on AWS S3, coming from the us-west-2 region. It will be reasonable to load for those in the western US and likely quite slow from Europe or Oceania.
If you want to make a direct comparison of Protomaps to OpenFreeMap, you need to compare serving OpenFreemap with NGINX from btrfs on disk, to running `pmtiles serve` on a `.pmtiles` file on disk, as described here: https://docs.protomaps.com/deploy/server
The OpenFreeMap page for me (in Taiwan) takes 1-2 seconds per tile, which is more than double the load tile for the PMTiles in us-west-2 example linked above.
The best solution to get latency competitive with commercial providers, for a global audience, is to cache tiles at CDN edge locations. I describe automated ways to do that with Cloudflare Workers and AWS Lambda + Cloudfront here:
This is zoom 0-15, or 1,431,655,765 addressed tiles. So it is designed for this scale - for a production internet site you can add a lambda, server or CDN as an additional layer for lower latency: https://docs.protomaps.com/deploy/
I maintain a small MVT rendering library for Leaflet - I'm overall satisfied with the performance on modern devices, but usually point greenfield projects at MapLibre instead, unless you need some very specific Leaflet plugin.
There is nothing stopping the OSM Foundation from say, offering a complete SQLite (or PMTiles) tileset download on planet.openstreetmap.org, technically, legally or otherwise. Creating and archiving the tiles shown on osm.org would be at least a couple terabytes once you get to around zoom level 16.
The key distinction is "official" - the only "official" data product of OpenStreetMap are its XML and PBF data dumps at planet.openstreetmap.org. The frequently-updated tiles you see on osm.org are "quasi-official", they're created by a separate project called OpenStreetMap Carto. These tiles have a special status within the OSM ecosystem for historical reasons; by virtue of OSM being map data, it should probably show something for human eyeballs on the website.
The design goals of OSM Carto are to show feedback to map editors; the linked vector tiles project is intended as a successor, or at least complement, to OSM Carto. The consumption of the tiles by third-party sites is a side-effect tolerated by OSMF; the general consensus within OSM seems to be that a consumable tile service for third parties is outside the scope of the project.
Leaflet is a separate project from OpenStreetMap - it's just one popular frontend for viewing tiles served from openstreetmap.org, like OpenLayers.
I don't believe the OSM Foundation has ever been involved in Leaflet development, as Leaflet development was supported in the past by commercial vendors of OSM data like CloudMade and Mapbox.
"Additionally, our licenses are currently not compatible with the major software licenses, so it would be difficult to integrate CC-licensed work with other free software. Existing software licenses were designed specifically for use with software and offer a similar set of rights to the Creative Commons licenses." https://creativecommons.org/faq/
> Though I understand if you'd rather avoid using projects by people with weird legal opinions.
The scale of the Protomaps project is small (I'm the only full-time developer) and I don't have the resources to interpret novel copyright situations. I think it's best for the ecosystem to abide by the license terms stated by the open source developer, instead of challenging their validity.