I made a last-minute dash down to the London OSM Hack Weekend and had a lovely time there.

I worked on a mobile app which I was pleased to get into a basically working state. It is called osmbi3, which stands for OpenStreetMap Building Information and/or Zombies. The aim was to geolocate the user and find nearby buildings using an Overpass query. This could then be linked to building management information or form the basis for some location-based game. Having managed the basic task, showing a map with annotated every building with an icon reading “yes!”, I set out to try and get OAuth working against the OpenStreetmap server from a mobile device, a task which I have yet to achieve.

So, what last weekend was a very simple but perfectly functional app, is now buggy as hell while it tries to do more. However the source code is on github and i will probably keep working on it, because I could use a very lightweight building editor which doesn’t require any typing.

I am doing a dangerous amount of app development now, helping finish up a project from the last codethecity event in Edinburgh, and working on a dinosaur card game app for - eventually with? - my boy. But it’s all apache cordova and webviews, so i’m not doing anything too evil.

Apart from a successful weekend’s hack, I was very glad to visit London put faces and voices to some names I only know from the internet; also to reconnect with some folks I hadn’t seen for the last ten years. If only more people in the wider community would make the journey up to State of the Map Scotland!

In reply to Steven Feldman on Twitter why do i object to vector tile services, it will definitely take more than 140 characters to explain, and then only partially explain.

The statement that i find vector tiles objectionable was triggered by a positive reaction nonetheless to Mapzen’s Vector Tile Service. I’m fascinated to see it serving up GeoJSON according to a tile-based URL scheme like that in use for raster, imagery tiles.

VectorMap District is an underrated Ordnance Survey Open Data project for mid-scale views of maps. You can get it from the OS open data download pages, selecting from a series of National Grid tiles from what may be a horribly familiar image:

The National Grid tiles that we download with clenched teeth today come from grids and scales designed to be read on paper maps.

Registers of Scotland are my employers and they are well known for being some distance from completing a full “cadastral map”, registering the ownership of all land and property in Scotland. Their Geographic Information Systems were probably once pioneering early-adoption when originally designed. But the database systems weren’t strong enough to handle data on more than a county basis, so that’s how the data got distributed amongst systems. Each county stores a set of overlapping tiles of OS data. It’s converted back from modern data format into an archival format the old systems can understand. There is quite a maintenance load involved in this process alone.

When the organisation systems really were paper maps, tiled and scaled to the National Grid, Registers stored its model of land in the form of “parcel books”. Chunks of OS maps, cut up and pasted onto cloth, painstakingly annotated with land ownership where it was registered, with extra copies at different scales describing “Research Areas” where work was ongoing and more than usual was known. The parcel books are beautiful, and in many ways more appropriate to the shared tasks of land registration and research than the GIS systems that are worked with today.

What does this have to do with vector tiles? My point here is that you get artefacts of the limits of the delivery system taking over the delivery system, being unnecessarily preserved. In addition, real problems are being masked by overdelivery of data, with a lot of detail unnecessarily handed over, or a lack of subtlety about what is appropriate scale in a given area. Standards evolved for raster data are a long way distant from what is now possible given the browser capability and bandwidth available in many places today.

Consider the OpenStreetMap API which limits data download to a maximum area or 50000 objects, whichever occurs the sooner. It doesn’t serve up neat square fragments, but sections of longer ways are spilling out the edges of the request. It’s hardly subtle as a regulating mechanism, but it’s effective enough. The query support in Overpass API is much more powerful, and an application of sufficient size is likely to want its own cached store of GeoJSON, not depend on a third-party service for fundamental mapping.

What I would prefer to see than vector tiles is a data generalisation service that would produce the equivalent of products like VectorMap District & Local from OpenStreetMap data, making it all easier to work with at different scales. Clear annotations about what data sources have been subjected to what algorithmic processes. I also want to see clearer integration with QGIS and other open-source desktop tools. And I think these things will make more difference to delivery and to re-use than vector tiles.

Edinburgh’s map is looking very full. I started doing building editing when I moved here, but now there’s not much to add, so I’ve started to add some building:levels tags in areas I walk through regularly.

An academic project, Mapping Edinburgh’s Social History has been doing a lot of work enhancing Edinburgh map, in particular adding addresses that will allow geocoding without postcodes, which only take you back as far as 1971. One of the MESH mappers, eric_, must be hawkishly watching the map, saw a recent batch of my edits and suggested that I start adding in roof:levels and building:material “but no pressure!”

While i’m into doing this if it has value to others and i’m surveying anyway, I have my doubts about building interpretation in a city full of architectural idiosyncracies such as Edinburgh. One is, what happens when the top storey of a building is embedded within a roof, like this?

You can see from the side of the building that the roof storey is not an add-on or an afterthought, that the side facade is genuinely five storeys high, so i’m really not sure whether to model this as building:levels=5 or building:levels=4 and roof:levels=1

The advantage of using the levels is that they’re easy to observe and record without any special surveying equipment (and yes i have thought about trying to use ultrasound with an arduino to take measurements of building heights in metres, but that wouldn’t give that much more accuracy value than building:levels alone.

Then of course in a mixed-style European city we often get scenarios like this, where an older high-ceilinged building is built next to a modern, low-budget low-ceilinged building: this shows adjacent buildings as part of the Summerhall complex:

Any thoughts from other local mappers would be appreciated. What i want to get out of this personally are some simple, impressionistic “haptic maps” using a 3D printer or maybe plaster cast into a mould. I’m not personally worried about precision, more curious to see what drops out of the existing tools, so building:levels are generally enough for me (and well supported by amazing tools like osm2world and osmbuildings.org.

The local Missing Maps organisers are keeping up the pace with the mapathons happening in Edinburgh every couple of weeks at the moment.

This time the word got out to the OSM community with plenty of notice, and the mapathon was duly mobbed by the Usual Suspects. I enjoy the pub meets as much as some, so it was a good chance to catch up with chrisfl, drnoble, fozy81 and eisa, while stevefaeembra was busily OCD mapping up a storm again, and we even flushed out Bob Kerr from his OSM semi-retirement, full of curiosity and helpfulness as ever.

This was my first attempt to ever use the HOT tasking manager in anger and I remain unconvinced about the validity of the task. The interpretation of aerial imagery remains delicate and uncertain, and the currency of date in the imagery is unknowable. How useful this is to displaced communities seeking shelter, who can tell? Are tracks to farm buildings really missing on the map? Is tagging for the renderer appropriate at the level of detail where a road may be a service road, residential, or a track, according to the iD pre-sets?

Meanwhile, many of the tasks marked as open seem almost complete; as a casual mapper, not familiar with the HOT standards of quality, i would have a hard time marking most squares as “Done” and it appears others have similar existential problems. One wants to create useful work, not busywork, for those validating the maps on the ground. As I’m mildly stricken with a cold and indulging in a “duvet day” today, I may keep going with some of the random tasks on the grid.

I’m partially converted to the iD editor, though the usual gripes came up in the general discussion - it remains far too easy for a new user to start deleting objects without an explicit check or warning or an obvious means of rowing back. We hear that RichardF has a relevant patch in, and deserves cake, let’s hope it gets accepted and released soon.

Thanks again to the redoubtable Margaux Meslé for so much organising and communications work, and for really making extra effort this time to reach out to the local OSM mapper community, it can only be of benefit to all, and i look forward to future mapathons.

While the inaugural Missing Maps mapathon in Edinburgh was a positive event, there are a few changes I’d make that I hope would improve the outcomes.

First, I’d make more effort to lead new mappers into the local community. I would emphasise that contributing to OpenStreetMap is not primarily about “armchair mapping”, but about local surveying, adding to and maintaining the map of one’s local area. There are regular meetups and mapping parties in many areas, and where there are not yet, a missing maps event presents a great chance to bootstrap a more active surveyor community.

I appreciate that in areas where the Humanitarian OpenStreetMap Team and The Missing Maps are focusing, there may not be local mappers with the leisure, infrastructure and bandwidth to contribute surveyed data to OSM, but it is almost always more work to correct poor armchair mapping than to build up from the ground.

Notes in progress:

NLS historical imagery, JOSM benefits of multi layers, iD and tag prescription, this was a technical audience and yes it was well balanced also

I had the fun experience last night of dropping in to an event organised by The Missing Maps. Unfortunately I couldn’t make the whole thing, nor could most of the local mapper community members in Edinburgh, as we only found out that the event was happening the evening before :/

This seemed to be an accident of occupying parallel, not quite overlapping, social media universes. The main channel for OpenStreetMap Scotland news and events tends to be the OSM Alba Twitter feed and we organise mapping parties via the wiki, with the Scotland mailing list a fairly new addition to the communications tools.

Whereas The Missing Maps are organising via Facebook and eventbrite mostly. I don’t know about you, but i tend to treat eventbrite as read-only, and I’ve historically refused to actively participate in Facebook. So we failed to overlap, and this wasn’t helped by the University of Edinburgh-hosted venue moving at the last minute. So garycmartin attempted to drop by but went to the wrong venue and couldn’t find a redirect. But the indefatigable stevefaeembra went along and represented well for the local mapper community.

I could only make the central 45 minutes, and got stuck on one question about recommended tags for roads, to which my answer was suffixed with “and this is my personal opinion, and there are many personal opinions in the OSM community”.

I have a few thoughts to share about the experience of seeing newbie mappers get a copious and well-thought-out introduction to the iD editor, but i’ll save those up for another diary entry. Despite the teething trouble with the venue and the community links, it was a worthwhile event, very well attended by a diverse looking group of people, many of whom turned out to be students on the University of Edinburgh’s MSc GIS course, and i saw an old colleague from the EDINA datacentre there; always glad to see OSM bringing people together in unexpected ways.