Knowledge

STAC Community Online Group

If you’re working with STAC or want to learn about it, consider following the STAC Google Group for regular news and invitations to join community meetings.

Querying OpenStreetMap Data with AWS Athena

The technical how-to describes how you can use AWS Athena to query OpenStreetMap data from Parquet files on S3. Athena is an analysis layer sitting on top of data source to simplify data access for application such as machine-learning tools or data dashboards. Using analysis-ready OSM data removes storage- and computation-heavy steps to obtain and convert the data into the desired format from the processing pipeline. The example use data from the Daylight Map, which is available from AWS’ Open Data Registry.

The Secret Life of GeoTIFFs

A GeoTIFF explainer in a Library-of-Congress blog; who would have thought?

Short History of Vector Tiles

It’s been ten years since Michal Migurski first blogged about a relatively new technology called vector tiles. Soon after, vector tiles became a standard technology to serve map data on the Web. Nathaniel V. Kelso recounts the history of vector tiles in a long thread.

(I linked to the unrolled version because it’s easier to read.)

Three Types of Circles for Geo-Data Applications

Circles are only supported in a few geo-data formats because most of today’s formats are based on the Simple Features specification, which doesn’t define circles.

Tom MacWright, writing on the Placemark blog, explores why circles are so hard to implement into geo-data applications and why Placemark ended up with three circle definitions: geodesic, degree and Mercator circles.

Creating PMTiles With Tippecanoe

A quick tutorial by Bert Temme about how to turn a shape file into PMTiles using Tippecanoe:

 In this blog we created in a few easy steps vector tiles from shapefile of worldwide railroads in PMTile format using Tippecanoe, and deployed to a standard webserver. No complicated backend WMS/WFS mapservers are needed anymore to get this working.

Content Negotiation for OGC APIs

Iván Sánchez Ortega reporting from his activities during the latest OGC code sprint:

when pygeoapi is requested a coverage from GIS client (preferring image/tiff or application/ld+json or the like), the raw data is returned. But when it’s a web browser (preferring text/html), then a webpage with a small viewer is returned.

It’s an interesting deep-dive into HTTP content negotiation, how it relates to geo-data problems and what OGC API implementations could do better.

“Extending PostGIS with TiMVT/TiFeatures and PgSTAC”

Development Seed¹ have published a summary of two talks from this year’s PostGIS Day. One talk introduces and compares two projects, TiMVT and TiFeatures, which simplify creating tile and OGC-Features services using data from a PostGIS database. The other talk covers PgSTAC, a set of SQL functions and triggers to stand up Postgres databases to host STAC catalogs.

“The Map”, a Documentary About the Redesign of New York's Subway Map

The Map is a short documentary about a revolutionary redesign of New York City’s iconic subway map. Filmmaker Gary Hustwit documents the process as digital agency Work & Co works with the MTA to create a new “live map” — one that updates in real-time — to help New Yorkers and tourists better plan their journeys. The film examines the evolution of wayfinding and user interfaces, and shows how good design and the latest digital technology can simplify one of the world’s most complex transit systems.

SVG Filters on Web Maps

Darren Wiens with a short and sweet example of how to enhance web maps using SVG filters. Check out the codepen to see an approach in action.

The beauty of the technique is that it’s independent of any mapping libraries. You can use SVG filters with Leaflet, OpenLayers, or MabLibre.