The Challenge Of Open

One of the great things about the combination of maps, geo, location and London is that roughly once a month there's some kind of meetup happening in the city on these themes. One of the longer running players in this space is the Geospatial Specialist Group of the British Computer Society which is being relaunched and reinvigorated as the Location Information SG. Earlier this week I gave a talk, but what to talk about? Read On…

Welcome To The Republic Of Null Island

In English, null means nothing, nil, empty or void. In computing, null is a special value for nothing, an empty value. In geography, null tends to be what you get when you’ve been unable to geocode a place or an address and haven’t checked the geocoder’s response. What you end up with is a pair of coordinates of 0 degrees longitude and 0 degrees latitude, a point somewhere in the middle of the Atlantic Ocean, south of Ghana and west of Gabon. It’s here that you’ll also find Null Island, if you look hard enough.

The website for the Republic of Null Island (like no place on earth) says this about the island’s location …

The Republic of Null Island is one of the smallest and least-visited nations on Earth. Situated where the Prime Meridian crosses the Equator, Null Island sits 1600 kilometres off the western coast of Africa.

… but Null Island is an in joke created by Nate Kelso and Tom Patterson as part of the Natural Earth data set in January 2011.


It’s totally fictitious and is designed as a gentle poke in the ribs for people who don’t check the return value from their geocoder and end up putting a pin on a web map in the middle of the ocean. As Natural Earth’s release notes mention …

WARNING: A troubleshooting country has been added with an Indeterminate sovereignty class called Null Island. It is a fictional, 1 meter square island located off Africa where the equator and prime meridian cross. Being centered at 0,0 (zero latitude, zero longitude) it is useful for flagging geocode failures which are routed to 0,0 by most mapping services. Aside: “Null Islands” exist for all local coordinate reference systems besides WGS84 like State Plane (and global if not using modern Greenwich prime meridian). Null Island in Natural Earth is scaleRank 100, indicating it should never be shown in mapping.

Look carefully enough, especially on web sites that handle large amounts of data from third parties and which helpfully supply a map for some additional context, such as property sites, who should really know better and Null Island may just appear before your eyes.


Take for example, who have a 3 bedroom property near Enfield in North East London for sale, yours for just £995,000. Whathouse helpfully provide a map tab on their property listings to that if you’re not familiar with where the N9 postal district of London is, you can find out.


This is in London, the capital of the United Kingdom, which as far as I know hasn’t suffered massive continental drift to end up in the middle of the ocean.


Zoom the map out and you can see why this unique property seems to be alone in the middle of the ocean; it’s really on Null Island. Either that or someone hasn’t been checking their geocoding results properly. A bad geocoding result is almost probably definitely the reason for this little geographic faux pas, but a part of me likes to think that Null Island really does exist and you really can spend close to a million pounds securing a 3 bedroom apartment on one of geography’s most tongue in cheek places.

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Cartography, The Musical

I like maps. Even if you’ve never read posts on this site, the name “Mostly Maps” should probably be a giveaway. What you may not know is that I don’t really like musicals. Now granted I’ve seen Rent and Spamalot, but that’s because Alison and I were in New York and the former was recommended by one of my best friends and for the latter I’m a massive Python fan. Maps and musicals aren’t something that go together. But that may be about to change.

Cast your mind back to the dawn of history, before mobile phones were smart and when GPS was just an Australian rugby club, which is sometime in the very early 2000′s. If you lived in London, your essential navigation guide wasn’t a maps app, but a copy of the A-Z as the Geographer’s A-Z Street Atlas was better known. This was the map you carried around London rather than a mapping app on your phone. I still have several editions on the bookshelf at home, each one being bought when its predecessor got so dog eared as to be unusable or just started falling apart.


The probably apocryphal backstory is that the A-Z’s founder, Phyllis Pearsall got lost in 1935 following a 1919 Ordnance Survey map on the way to a party and decided to make her own map. To do this she got up at 5.00 AM and spent 18 hours a day walking the 3,000 odd miles of London’s 23,00 or so streets. This tale is disputed, with Peter Barber, the British Library’s Head Of Maps, being quoted as saying “The Phyllis Pearsall story is complete rubbish, there is no evidence she did it and if she did do it, she didn’t need to“. Given that Pearsall’s father was a map maker who produced and sold maps of London, he’s got a point.

But regardless of the accuracy of the legend around Phyllis Pearsal, it’s a great story, especially for those of us who used the A-Z each and every day around London. But is it a musical story? Neil Marcus, Diane Samuels and Gwyneth Herbert seem to think so and they’re the team behind The A-Z Of Mrs. P, a musical about London’s iconic street atlas and its founder that’s currently playing at the Southwark Playhouse. Reviews have been mixed, but anything that throws some attention on the A-Z is welcome in my book, even if it is a musical.


You may have noticed that at the foot of each post I always try to provide source and attribution for photos or images that I use. I think I’m going to have to expand this to include the inspiration for each post. In this particular case, credit is due to Alison. If it’s not a sign of true love when your wife texts you to tell you about something map related she’s seen, then I don’t know what is. I guess you don’t spend nearly 15 years being married to a self professed map nerd without knowing a good map related story when you see one.

The A-Z Of Mrs. P poster by Su Blackwell.
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In India Just Because You Can Map Something, Doesn’t Always Mean You Should

It’s easy to get stuck in a mental rut, to think that everyone thinks and feels the same way you do about a subject. But sometimes you need to get away and visit another country and another culture to find out that maybe there’s more than one way of looking at a subject. For me that subject is, unsurprisingly, maps and the other country was India.

Some countries are easier to map than others. Up to the end of the Cold War, it was commonplace for the UK’s Ordnance Survey to not show prohibited places, although this practice has been effectively stopped due to the widespread availability of satellite imagery. Further afield, there’s contested borders and territorial disputes which makes mapping some administrative boundaries something of a challenge; a proof of the old adage about pleasing some people some of the time but not all people all of the time.

It’s easy to think that not mapping an area is a thing of the past. That we can and should map everywhere. That mapping is simply the combination of human effort, a bit of technology and a lot of data. Indeed OpenStreetMap’s beginner’s guide states upfront that the data you add improves the free world map for everyone. But as I found out, in India, there’s a lot more subtlety and nuance behind this admirable creed.

Firstly there’s the act of mapping itself. As with pre-Cold War Britain (and to be fair, some parts of Britain today), India has placed restrictions on what can and cannot appear on a map. When working for Nokia’s HERE Maps, I ran a program to use crowd mapping to improve the company’s maps in India and came across these restrictions first hand. My point here is not to agree or disagree with a government’s stance on mapping restrictions but merely to point out that they exist.


But it’s not just the government who would prefer you not to map places, it’s the people as well in some cases. According to recent figures, India has a population of around 1.27 billion people; of these, over 65 million live in slums. Sadly this wasn’t a shock; I’d been well prepared for slums from my visit to Dar es Salaam in Tanzania at the end of 2012.


In Dar es Salaam, you map slums to help the occupants find vital facilities; fresh water, sanitation, health care and so on. You use the map to bring the slum to the authorities attention so they do something about it. Making a map is vital. But not necessarily so in India. Indian slums are hidden in plain sight. Everyone knows they’re there, but they don’t always bring attention to themselves. Putting a slum on the map runs the risk of bringing some potential prime real estate land to the attention of an unscrupulous property developer; some of whom have been known to raze a slum to the ground overnight and displacing the residents through the judicious use of bulldozers.

Another subtlety that doesn’t apply in the United Kingdom are the locations of the Cheel Ghar in Indian cities, which translates to Tower of Silence in English. These are the circular raised structures where Parsi followers of the Zoroastrian faith leave their dead and let exposure to the sun and birds of prey reduce the body to bare bones. Originally these towers were outside the boundaries of the city, but the rapid growth of India’s metropolitan areas have engulfed the Cheel Ghar, leaving them as small forested oases inside the urban sprawl. Even if you know where they are, and I walked past one without knowing it until it was pointed out to me, putting these sacred places on a map would not be deemed acceptable by adherents of that faith. Just because you can map something, doesn’t always mean you should.


But even if you make an accurate and detailed map, how do you cope with the vagaries and eccentricities of the Indian addressing system? I asked someone at the GeoMob meets GeoBLR meetup we ran in Bangalore how they’d geocode (turn addresses into longitude and latitude) a batch of a thousand or so addresses. The answer was blunt and succinct … “Geocode that many addresses? We wouldn’t”. There’s a long running joke in India to effect that the country does has GPS, but it doesn’t stand for Global Positioning System, instead it stands for General Populace System. You look at an address, get to the nearest spot and then ask someone, repeating the process until you reach your destination.

Given how visual and landmark based Indian addresses are, this approach makes a lot of sense. In India I stayed at 3 different hotels in New Delhi, Mumbai and Bangalore. In Delhi, the address was Ring Road, New Delhi; in Mumbai it was Western Express Highway, Santacruz East and in Bangalore Swami Vivekananda Road, Off M.G. Road, Ulsoor. Standing outside each hotel and looking around, the addresses made a lot of sense, in Bangalore I was just off the M.G Road, named after Mahatma Gandhi; there’s a lot of M.G. Roads in India, the equivalent of High Street in Britain. Other addresses include location clues such as near, opposite and by. If you really, really need to geocode an address you look it up on a digital map and make a note of the coordinates; a very manual and not at all scalable way of dealing with the problem.


Reading all of the above back to myself before I click on Publish makes me realise that in hindsight it’s blindingly obvious that each country will have its own set of edge cases. India is no exception. A massive amount of credit for what I learned in India should go to Sajjad, Sumandro and Kaustubh, the team behind Bangalore’s GeoBLR geo themed meetup. Thank you all, you taught me a massive amount and expanded my horizons considerably.

Tower of Silence (for Parsi Sky Burial): Mumbai by James Oleson on Flickr.
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The London Underground Strike Map

If you’re trying to get out and about in London today you’ve probably noticed that the Tube is on strike. Again. You could read the list of closed stations that are on Transport for London’s website and try and work out quite how, if at all, you’re going to get to where you want to be. Or you could look at a map.

This map. Now why didn’t TfL think of doing this?


Strike map by Ian Visits on Flickr.
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