How to Build a Fire Map

Last October Robin Kraft posted an online map of the northern California wildfires showing satellite imagery from before and after the fires (see previous entry); today he’s posted a blog entry explaining how he built it, in great technical detail. The timing is not accidental: “There is another fire raging in Los Angeles right now — if DigitalGlobe and Planet release their data, you can use this guide to make your own map.”

Dirty Reprojectors

Maps online invariably use the Web Mercator projection. The Dirty Reprojectors project aims to change that, at least in Mapbox. Anand Thakker explains.

Almost all web mapping libraries render maps using Web Mercator, making an assumption that you generally can’t change out-of-the-box. This has advantages, but it posed a real challenge for us when we set out to build the Washington Post’s live election results map, where using the Albers USA projection was an important requirement. To meet that requirement, we built a pipeline to pre-process geometries.

It’s a bit of a kludge, a way of fooling Mapbox into showing a different projection—latitude/longitude coordinates aren’t accurate any more—but it’s an impressive stab at a real problem. The Dirty Reprojectors web app demonstrates the possibilities, with all the projections available through the d3-geo and d3-geo-projection libraries. [James Fee]

Drawing Inspiration from Print Maps

Saman Bemel Benrud, a designer at Mapbox, looks to print maps for inspiration. “I like looking at print maps because they remind me how far web map design has to go. Even an average print map involves a designer making thousands of small decisions about where to place individual features and how to kern and size each label,” he writes. “You can’t work like that with web maps that are global and zoomable.” Still, he provides some favourite design elements from paper maps; it’d be interesting to see how they might be rendered online.