Am started to get interested in Kothic-JS (see here) following a tip-off from Richard Fairhurst on the dev mailing list this week. Looks an exciting project, allowing you to render OSM data client-side using HTML5 canvas, thus cutting down on one of the most awkward tasks to deal with when running your own server: rendering tiles. Performance, on the demo showing Minsk and surrounds, looks pretty impressive, and given that these days, client-side resources are much, much less expensive than server, anything which moves the load from server to client must be worthy of further attention.
So I’ll almost certainly, given the time, be investigating kothic-js further as a more sustainable rendering solution for Freemap: currently I’m relying on the goodwill of Swansea University Computer Society and home-rendering selected Southern England counties.
However there still needs to be a lot of *data* stored server-side, in other words, everything you want to render. Up until today (for the purpose of the walking-route facility) Freemap stored rights-of-way and permissive paths for the whole of England and Wales in its postgis database. However this would obviously not be sufficient for providing data for rendering. Consequently, it now stores *all* highways, but *only* for a subset of English counties, and for all of Wales. The counties available are: Hampshire, W Sussex, Wiltshire, Surrey, Bucks, Cambridgeshire, Cumbria, Essex, Herefordshire, (now that’s interesting, why does the wordpress spellcheck recognise some of these counties and not others?), Norfolk, Suffolk, Somerset, Shropshire, Oxfordshire and Kent. Reason being that those are the ones for which geofabrik extracts are available, which allows county-by-county import and makes the osm2pgsql import less memory-intensive. I’ve asked Frederik for Cheshire, Derbyshire and N Yorks extracts too to try and complete the list of popular walkers’ destinations.
So what will the immediate impact on Freemap be? None unless you use the walking route facility or the data API. These will now only work in those counties, plus Wales, but it will recognise routes which don’t have a designation tag. It also means that due to the increased volume of data, the walking route generation is rather slow now – but we’ll have to live with that for the moment. Since rendering is not done on the server, rendering will be no slower and POI search doesn’t seem to be affected.
Back soon with some news of OpenTrail, the Freemap Android app.