Past Meetup

Anchor's a Way! Rendering OpenStreetMap's Maritime Data with Tegola

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The past five years have seen the dominant technology for delivering web maps shift from pre-rendered raster tiles to data-rich vector tiles. The most interesting open source vector tile server to emerge recently is Tegola. Supported by the National Geospatial-Intelligence Agency, Terranodo LLC is shepherding Tegola's rapid evolution. Written in Go, very straightforward to configure, and easily integrating with Mapbox GL, OpenLayers, and D3.js, Tegola may well find a place in your workflow, whether as an experimental development server running on your laptop or as a public-facing server under load in production. As proof-of-concept, a Terranodo team is currently working to replicate the OpenSeaMap project using Tegola. OpenSeaMap renders objects tagged using the *seamark* scheme according to the International Hydrographic Organization's publication, INT 1 - Symbols, Abbreviations and Terms used on Charts. This intricate symbology specification expresses detailed information about maritime infrastructure – beacons and buoys, rocks and wrecks, restricted areas and recommended routes, visual and audible signals – to ensure safe commercial, military, and recreational navigation through the planet's waters.

Eric Theise, who works with Colorado-based cartographer, Gretchen Peterson, on this project, will lead Maptimers through the following:

* a high level view of Tegola (check out Tegola at or at
* the existence and use of specialty tagging schemes to be found within OSM data, focusing on the seamark tag
* configuring Imposm3, another tool written in Go, used to import OSM data
* examples of simple, intermediate, and complex styling of nautical symbols via Mapbox GL
* finally, standing up a Tegola instance backed by a San Francisco data extract to examine some of the unique features of our Bay and its infrastructural and natural features

Comfort with Mapbox GL styling; the OpenStreetMap data ecosystem; and the command line will be assumed.
Maptimers will leave this meet-up with an appreciation of contemporary map serving technology, a better awareness of OpenSeaMap data that doesn't surface in common OSM-based applications, and an exposure to the use of sprites and creative use of the Mapbox GL API as a way to render complex symbology in accordance with international standards.

****About MapTime****

Maptime is, rather literally, time for mapmaking and talking about maps. Our mission is to open the doors of cartographic possibility to anyone interested by creating a time and space for collaborative learning, exploration, and map creation using open source mapping tools and technologies. This open learning environment for all levels and degrees of knowledge offers intentional support for the beginner. Maptime is simultaneously flexible and structured, creating space for workshops and for independent/collaborative work time.

Inspiration for Maptime comes from both hack nights and knitting circles, and discussing new mapping tools, and a space for people to create and learn together. Our goal is to provide a safe space for mapping with an open heart and without pretension. We hope you bring your own projects to work on, or just hang out and socialize or ask questions. Some people are experts, and some people are just getting started, but all of us are learning--which it's always best to do together!