Simon Willison’s Weblog

5 items tagged “geospatial”

Building a location to time zone API with SpatiaLite, OpenStreetMap and Datasette

Given a latitude and longitude, how can we tell what time zone that point lies within? Here’s how I built a simple JSON API to answer that question, using a combination of data from OpenStreetMap, the SpatiaLite extension for SQLite and my Datasette API tool.

[... 2152 words]

Geospatial Indexing in MongoDB (via) New in version 1.3.3. Handles “order by distance from” queries using a geohash approach under the hood, automatically searching nearby grid squares until the correct number of results have been gathered. Bounding box search is planned for a future release. # 2nd March 2010, 8:12 pm

JS-Placemaker—geolocate texts in JavaScript. Chris Heilmann exposed Placemaker to JavaScript (JSONP) using a YQL execute table. Try his examples—I’m impressed that “My name is Jack London, I live in Ontario” returns just Ontario, demonstrating that Placemaker’s NLP is pretty well tuned. # 23rd May 2009, 12:36 am

Flickr Shapefiles Public Dataset 1.0. Another awesome Geo dataset from the Yahoo! stable—this time it’s Flickr releasing shapefiles (geometrical shapes) for hundreds of thousands of places around the world, under the CC0 license which makes them essentially public domain. The shapes themselves have been crowdsourced from geocoded photos uploaded to Flickr, where users can “correct” the textual location assigned to each photo. Combine this with the GeoPlanet WOE data and you get a huge, free dataset describing the human geography of the world. # 22nd May 2009, 6:12 pm

Yahoo! Geo: Announcing GeoPlanet Data. The Yahoo! WhereOnEarth geographic data set is fantastic, but I’ve always felt slightly uncomfortable about building applications against it in case the API went away. That’s not an issue any more—the entire dataset is now available to download and use under a Creative Commons Attribution license. It’s not entirely clear what the attribution requirements are—do you have to put “data from GeoPlanet” on every page or can you get away with just tucking the attribution away in an “about this site” page? UPDATE: The data doesn’t include latitude/longitude or bounding boxes, which severely reduces its utility. # 20th May 2009, 9:12 pm