Data Graphics OpenStreetMap

Nike Grid – Visualising Runners on the Streets of London

My last eight posts have all been on bike share, time for a slight change of topic – running rather than cycling.

In the last few days, I’ve been taking part on the Nike Grid alternative reality game (a futuristic take on street-o). The concept is a great use of social media – with an active Facebook group, key updates pushed to participants phones and Facebook walls, and a Foursquare-esque concept of “checking in” to the phoneboxes which act as the run timers, starting and stopping clocks and noting locations. How do you “check in”? You make a (free) phone call.

There is a strong mapping element to the game – online maps show the locations of the key phoneboxes in each postcode, the maps appear in printed form and as artwork on the technical T-shirts included in player packs sent to key participants.

The maps are based on OpenStreetMap data, heavily stylised in black, grey and white with a “region”-specific pattern for the background and another pattern used for parks. The phoneboxes are “pin” style icons placed on top. The maps have been produced by Stamen Design in San Francisco. It’s not the first time they’ve done cool things with OSM data.

Stamen are also producing daily visualisations of the runs. The run lines have a hexagonal style to them, which goes along with the hexagonal tiling of the 48 postcodes being used in the game, although the start/end points are geographically accurate. A hexagonal cartogram is used on the main website to show the postcodes in pseudo-geographic space, in some of the visualisation the hexagons then “explode” and move to their correct place on the geographic map – a clever linking of cartograms and geographic maps.

Conferences OpenStreetMap

OpenStreetMap – The Quality Issue

This was the title of a presentation I gave today at the 46th Society of Cartographers Summer School (Lanyrd), which was in Manchester.

The abstract was:

OpenStreetMap is coming of age, but as it starts to be used more in the mainstream, the age-old questions of quality and completeness are coming to the fore. A range of data sources have been used to build up the map in the UK, from GPS traces to aerial imagery, historic mapping, NaPTAN and the OS Open Data release, each with their own benefits and limitations. This talk looks at a number of studies and tools developed to quantify, compare and address accuracy and coverage of the project in the UK, in an attempt to answer the key questions – is it complete yet and just how good is it?

OpenStreetMap – The Quality Issue

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The presentation makes references to two animations, which are the Milton Keynes Mapping Party traces and the US TIGER import sequence.

Conferences OpenStreetMap

OpenStreetMap 101

I presented this short set of slides to some visiting students from the State University of New York in Buffalo, this morning in UCL CASA, as part of a mini-conference the department organised for them. It’s a simple, visual introduction to the project.

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Additional notes: Slide 6 is a comparison of OSM, Google and Bing (or Yahoo). In Slide 10, the link is to here (20MB MPG). Slide 18 refers to OpenOrienteeringMap which can be found here. Slide 19 relates to two other visualisations I’ve made, see them here and here – OSM is being used for the background. Slide 20’s screenshots of BestOfOSM show Bern, Gaza City and Berlin Zoo.

Conferences OpenStreetMap

UCL – The Story so Far

At the beginning of the July, I transferred from UCL Geography “proper” to CASA (the Centre for Advanced Spatial Analysis), a research group at UCL allied to Geography department and a number of other areas. I am initially working on the MapTube product, specifically enhancing its coverage with respect to the spatial datasets available in the UK Data Store and London Data Store.

As part of my induction, I was asked to present a summary of my work at UCL so far. Here are the slides for that presentation.

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The presentation includes various screenshots of mapping data, including data from the OpenStreetMap, EDINA UKBORDERS and OS Open Data projects. Attributions can be found on the respective websites.

Data Graphics Mashups OpenLayers OpenStreetMap

Tube Stations in London – Visualisation

I was inspired by seeing this map and associated article on the New York Times website, linked from Going Underground, to create a similar mashup/visualisation of entry/exit volumes from the 300-odd tube stations in London. On their website, Transport for London provide the metrics for entries/exits from the stations, between 2003 and 2008, broken up into rush-hour, regular and weekend travel.

Each circle’s area is directly proportional to the flow numbers for that station (click on the circle to see the numbers.) The circles are rescaled between the first metric (total flows) and the rest, so direct comparison of metrics is possible except between the first and others, Blue circles represent an increase in flow and red a decrease.

If the mass of circles are obscuring each other, zoom in!

You can try it out here.

Some technical notes:

The background map is a custom render of OpenStreetMap data, with the tube lines highlighted in their traditional colour – it doesn’t always look quite “right” when you zoom in, due to the way the lines are tagged in my own copy of the OpenStreetMap database. The stations are even harder to disambiguate, so I’m using a free source from Wikimedia Commons, this means they don’t always line up.

Because your browser gets a copy of all the flow data when you load the page (yes I’ve heard of AJAX) it does run a little slowly in Internet Explorer, particularly the slider bars – these allow you to “drag” through the range of metrics or years.

Mashups OpenLayers OpenStreetMap

Manchester Map Mashup

I’ve created a mashup of lots of maps of Manchester as a proof-of-concept of how easy it is to mashup using OpenLayers. It’s not particularly pretty but does involve lots of maps.

See it here.

The layers are:

  • OpenStreetMap
  • Ordnance Survey Street View
  • Ordnance Survey 1:25000 First Series (1959)
  • Ordnance Survey New Popular Edition (1948)
  • Marr Map of Housing Conditions (1904)
  • Swire Map of Manchester (1824)

The first four maps are all hosted on OpenStreetMap servers.
The Swire map also contains an inset, dated 1650!

Conferences OpenStreetMap

GISRUK Navigation Challenge

This is the map GISRUK 2010 attendees are using to get from UCL, where the conference is, to the River Thames, where the boat await for the evening cruise. On the way, some of them are doing the challenge, which is to take the optimum route to visit any 6 of the 12 control points – a blue plaque at each one to prove their visit. The map was made using the OpenOrienteeringMap map builder.

[Download PDF]

(Note: The start point was actually from just east of “B” rather than the triangle.)

I haven’t yet computed the best route, I think it’s probably BAJFED or maybe BMCKED. There is no “trick” best route, as the points were fairly fixed by the locations of the blue plaques. But the solution is apparently not immediately obvious to the human eye.

Mashups OpenLayers OpenStreetMap

Accuracy vs Completeness: OSM vs Meridian 2

[Updated x2] Yesterday’s Ordnance Survey OpenData launch has provided the OpenStreetMap community with a potentially rich set of data to use to complete the map of Great Britain. OpenStreetMap’s accuracy and detail is generally excellent, however a problem which is (very arguably) more important than either accuracy or detail, in a map is that some parts of the country are substantially incomplete.

It’s not that the data quality is poor, it’s that someone with a GPS (or a satellite photo) has never been to that part of the country to gather the data in the first place. There are still significant parts of Scotland and Northern England which have many missing roads. The NPE (out-of-copyright) maps have been useful in starting to fill out these sections, but there’s always going to be a roads missing from a 60-year-old (or older) map.

So, the OS datasets could be very useful. Perhaps the most interesting of the datasets is Meridian 2, it is a vector dataset covering the whole country. One thing that needs to be watched out for though is that Meridian (which is a “complete” dataset of the country) is relatively inaccurate Pixellation or resolution isn’t a problem, it being vector based – but data is quite simplified.

I’ve built a mashup which allows direct comparision of the Meridian and OSM data for Great Britain. I’ve added in most of the available layer files that come with the Meridian package that has been released as part of the OS OpenData initative. The only two areal ones I’ve added are for woodland areas and lakes – everything is linear. I’ve added in labels for the roads and rivers, but no boundaries or point features, at this stage.

You can access the mashup here. (N.B. Not tested in IE so will probably break horribly in it.) Zooming in reveals the relative coarseness of the Meridian data – although crucially it is “substantially” complete for all but the smallest of roads, for the whole of the UK – not just for the major cities where the OSM contributors mostly live!

In the pictures below, the “solid”, thinner roads are Meridian and the fatter roads with “borders” are OSM.

Spot the missing roads in Meridian around Leytonstone in East London [Update 1 – Some sections of motorway are missing from my rendering but are present in the data – it is possible this problem extends to smaller roads too so take these screenshots with a pinch of salt]:

…but go further out of London, and it doesn’t look so good for OSM:

Interestingly, the Park Estate in central Nottingham is missing entirely from Meridian:

The Park Estate is a private estate and the roads are not maintained by the council – this might have something to do with it. I’ll be running around the Park Estate next weekend.

[Update 2 – Meridian is not intended to be used at scales larger than 1:50000, as per its documentation, so I shouldn’t really be comparing it with OSM which generally is based on data recorded at larger scales. So, bear in mind these screenshots are all larger than 1:50000 scale.] It’s difficult to authoritatively judge the relative accuracies of the two datasets without getting out on the streets or looking at aerial imagery – but you can infer a basic measure of accuracy by looking at how roads “wiggle” – or, in the case of the Mayfair squares below, how Meridian converges the square to a point:

A little unfair to compare the two here, as Meridian 2 was always meant to be a medium-scale dataset, whereas OSM can be all things to all people!

The tiles that make up the imagery are generated on demand (and cached for subsequent use) so may run slowly. You’ll need to zoom in quite a long way before all the features get added to the map. Use the slider on the top left to fade between the OSM and Meridian layers.

The images are derived from Ordnance Survey data © Crown copyright and database right 2010 and OpenStreetMap data which is CC-By-SA OSM and contributors.


Scottish Popular Edition Tracing for OSM

The provision of free-for-any-use spatial data for the UK may be changing dramatically on April 1 with the anticipated release of some Ordnance Survey mid/small-scale mapping and data for unrestricted use.

Until then, the only Ordnance Survey maps that have been able to be used to derive data from for the OpenStreetMap project in its bid to complete coverage in the UK, are those that are more than 50 years old and therefore not protected by Crown Copyright.

Scans of such maps, generally the New Popular Edition from the 1940s/50s, have been available for some time now – the scans were originally done for the NPEmap project (gathering copyright-free postcodes by asking people to geolocate them to the maps) and then were orthogonalised and reprojected from the British National Grid into the “Web Mercator” projection used by Google Maps, the “standard” OpenStreetMap website and numerous other online “slippy” maps.

Scotland wasn’t included at the time, partly because the maps were sourced differently. After consultation with the owners of the scans, I’ve taken the imagery, rectified, reprojected, stitched and tiled it using TimSC’s warp-gbos tools, so that it can now be used to trace Scottish data.

The source maps are at 1:63360 scale (one inch to a mile) and typically there remains an error of around 10m – up to 30m in some places, and of course more where the source map was drawn slightly incorrectly. So the imagery isn’t particularly useful for detailed mapping – particularly in cities which have seen significant growth in the last 50-80 years since the maps were made. However they are very useful for completing the rural road network, town and village names and natural features (hills, rivers) that are unlikely to have changed significantly recently – the low-res Landsat imagery can be used to show the presence of more recent forests or reservoirs.

In the above example, it would not be unreasonable to assume the path here still exists, and add it in – citing the source. You could also add the cliff, and reshape the lochs slightly from their current jagged Landsat-derived image. Adding in names for the hills and the lochs are also a definite benefit, although these old maps tend to have the Anglicised versions of names – newer editions of OS mapping for the Highlands of Scotland tend to use more authentic Scottish-Gaelic names. (Not an issue in this particular example, just north of Slioch in the Great Wilderness, as all the names on the map are in Gaelic.)

You can see the map tiles while editing OpenStreetMap data in Potlatch for Scotland, by selecting “UK Historic: Scotland” in the Potlatch preferences pane. They are available to zoom 15, although zooms 14/15 are simply smoothly interpolating pixels. The tiles are hosted on a computer under my desk here at UCL. There are better quality and higher resolution scans of more recent maps for some parts of Scotland, information about these is . The main advantage of the Scottish Popular Edition tiles over using just these they offer substantially complete coverage of Scotland.

(Strictly, some of the areas are using newer mapping which is still more than 50-years old, but is part of more recent editions than the Scottish Popular Edition).

So, the main benefit – having a map with full coverage of Scotland which can be traced from for OpenStreetMap – may be diminished, if a useable equivalent appears shortly which is only a few years out of date (i.e. Ordnance Survey Landranger/Explorer), but for now, they are still a useful source of base data.

If you just want to look at the mapping rather than editing them, you can see them here on my own site, or here on the NPEmap project.


UK Mapping Priority Areas – by Bus Stop?

The OSM wiki has a list of UK Mapping Priority areas, where there are a presumed substantial number of missing roads which need to be mapped. These can then get mapped at a mapping party. The probable introduction of a freely-derivable “complete” set of Ordnance Survey road data in ten days time may mitigate the need to do such first-step mapping, but for now there are many areas in the UK which could do with some on-the-ground data gathering.

As an alternative way of identifying such areas, I developed the “Lonely Buses” map. As an extension to this, I’ve now created a “top 50” list of areas that have the most number of bus-stops away from roads, i.e. areas with probable missing roads. You can see this list here. A basic form of reverse geo-coding is used to assign a name to each tile.

The list is automatically updated weekly. It is flawed in that it considers each “tile” exclusively, so if a town is split in half by tile edges, it will appear twice and lower down the list, compared to a similarly incomplete town being in the middle of its respective tile.

Looks like the Newcastle area is the No. 1 target area (within areas which have the government bus-stop dataset imported.)

Andover has a mapping party planned for mid-May and is currently No. 39 on the list. If you are in the area, sign up!