FOSS4G UK 2018 Meeting and OpenLayers 4

I attended and presented at the FOSS4G UK conference in central London, in early March. I was scheduled to present in the cartography track, near the end of the conference, and it ended up being an excellent session, the other speakers being Charley Glynn, digital cartographer extraordinaire from the Ordnance Survey, who talked on “The Importance of Design in Geo” and outlined the release of the GeoDataViz Toolkit, Tom Armitage on “Lightsaber Maps” who demonstrated lots of colour compositing variants and techniques (and who also took the photo at the top which I’ve stolen for this post):

…and finally Ross McDonald took visualising school catchment areas and flows to an impressive extreme, ending with Blender-rendered spider maps:

My talk was originally going to be titled “Advanced Digital Cartography with OpenLayers 4” but in the end I realised that my talk, while presenting what would be “advanced” techniques to most audiences, would be at a relatively simple level for the attendees at FOSS4G UK, after all it is a technology conference. So, I tweaked the tittle to “Better…”. The main focus was on a list of techniques that I had used with (mainly) OpenLayers 4, while building CDRC Maps, Bike Share Map, TubeCreature and other map-based websites. I’m not a code contributor to the OpenLayers project, but I have been consistently impressed recently with the level of development going on in the project, and the rate at which new features are being added, and was keen to highlight and demonstrate some of these to the audience. I also squeezed on a bonus section at the end about improving bike share operating area maps in London. Niche, yes, but I think the audience appreciated it.

My slides (converted to Google Slides):

Some notes:

  • My OpenLayers 2/Leaflet/OpenLayers 3+4 graphic near the beginning was to illustrate the direction of development – OpenLayers 2 being full-featured but hard to work with, Leaflet coming in as a more modern and clean replacement, and then OpenLayers 3 (and 4 – just a minor difference between the two) again being an almost complete rewrite of OpenLayers 2. Right now, there’s a huge amount of OpenLayers 4 development, it has momentum behind it, perhaps even exceeding that of Leaflet now.
  • Examples 1, 3, 4 and 5 are from CDRC Maps.
  • Example 2 is from SIMD – and there are other ways to achieve this in OpenLayers 4.
  • Examples 5, 6 and 9 are from TubeCreature, my web map mashup of various London tube (and GB rail) open datasets.
  • Regarding exmaple 6, someone commented shortly after my presentation that there is a better, more efficient way to apply OpenLayers styles to multiple elements, negating my technique of creating dedicated mini-maps to act as key elements.
  • Example 7 is from Bike Share Map, it’s a bit of a cheat as the clever bit is in JSTS (a JS port of the Java Topology Suite) which handily comes with an OpenLayers parser/formatter.
  • Example 8, which is my London’s New Political Colour, a map of the London local elections, is definitely a cheat as the code is not using the OpenLayers API, and in any case the map concerned is still on OpenLayers 2. However it would work fine on OpenLayers 4 too, particularly as colour values can be specified in OpenLayers as simply as rgba(0, 128, 255, 0.5).
  • Finally, I mention cleaning the “geofences” of the various London bikeshare operators. I chose Urbo, who run dockless bikeshare in North-East London, and demonstrated using Shapely (in Python) to tidy the geofence polygons, before showing the result on the (OpenLayers-powered) Bike Share Map. The all-system London map is also available.

FOSS4G UK was a good meeting of the “geostack” community in London and the UK/Europe, it had a nice balance of career technologists, geospatial professionals, a few academics, geo startups and people who just like hacking with spatial data, and it was a shame that it was over so quickly. Thanks to the organising team for putting together a great two days.

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