Whenever you look at a map, be it on the web, on your mobile or on your wall there's a compromise. The compromise is the map's projection. Or to put it another way, the way in which the roughly spherical lump of rock we live on can be unwrapped and displayed in a flat, two dimensional manner.

There's lots of way of doing this and the ways come with wonderful, almost eccentric sounding names. There's the pseudo-cylindrical projections; Sanson-Flamsteed, Luximuthal or Kavrayskiy's Fifth Projection (no idea what happened to the first four). There's the conic projections; Lambert's Conformal or War Office Polyconic. There's the pseudo-conic projections; Stabius-Werner and Bonne. Or there's the modified azimuthal projections; Wiechel's or Winkel's Tripel Projection.

There's just so many ways of projecting the Earth onto a map. But there's also the one we're all familiar with. It's Gerardus Mercator's Projection and we've been using it, probably without knowing it, since 1569 and it's showing no sign of going away.

Most things in life are a journey and the destination of this particular journey was to try and create a custom map style that represented the unique features and challenges of Tandale.

Which meant I needed to download and install TileMill, an interactive map design tool.

Which meant I needed to learn Carto, the CSS-like language for map styling.

Which meant I looked for a template project so I didn't have to start from scratch.

Which meant I found OSM Bright.

Which meant I needed to start small and find a map extract of Tanzania to work with.

Which meant I needed to install and configure PostgreSQL and PostGIS on my Mac.

Which brings me to the starting point of the journey and the reason for this post in the first place.

In a really perverse way, first impressions were not unlike the opening lines from Will Crowther's Colossal Cave Adventure game on the PDP-11. But rather than those impressions being this ...

You are standing at the end of a road before a small brick building. Around you is a forest. A small stream flows out of the building and down a gully.

.. my first impressions were this ...

You are standing in a gap between concrete buildings south of the equator. The sun beats down. Around you is a mass of similar buildings with corrugated iron roofs. A small stream flows in a gully between the buildings. The stream is made up of water and human waste. A river tries to flow nearby, but it's blocked by tons of rubbish and what water there is is black and bubbles noxiously. The smell is overpowering and overwhelming. People live here.

But this isn't a game and this place really exists. It's called Tandale and the polite way of referring to it is an unplanned development. Tandale is almost a city in its own right. It occupies a small area to the North West of Tanzania's largest city, Dar es Salaam. Tandale is an enclave, surrounded by the growing suburbs of Dar es Salaam. In 2002, a census showed there was a population of just over 45,000 people living here. Now, towards the end of 2012, the number must be much much higher.

There's a phrase in Latin that goes errare humanum est which roughly translates as everyone makes mistakes. This is true of so many things and maps are no exception. However much we try to make today's maps as authentic, up to date and accurate as we can, the occasional mistake slips in; it's more a case of when rather than if.

But if you find a mistake in a map, is it really a mistake or it is a deliberate error, placed there as a copyright trap to provide evidence of the origin of a copied map? This is a vague area at best. Some map makers are up front about this.

In November 2008 I was still working for Yahoo and a fledgling meetup event for people interested in maps, location, geo and mobile started up in London. It was, and still is, called GeoMob. I was at GeoMob's very first event, talking about Yahoo's Fire Eagle location brokering platform. Four years later and it was great to go back, see GeoMob still flourishing despite a brief hiatus in 2010, and meet up with a lot of old friends as well as meet some new ones.

And what an evening it was. Truly a veritable feast of maps. David Overton spoke about SplashMaps, his Kickstarter funded project to produce lightweight printable fabric maps for outdoors.

I didn't think it was possible to map happiness but apparently it is and George MacKerron showed how with the aptly entitled Mappiness project.

Nothing on the interwebs is forever. Services start up and either become successful, get acquired or shut down. If they shut down they usually end up in TechCrunch's deadpool. The same applies for APIs and when they finally go offline, they usually end up in the Programmable Web deadpool.

At around 1.30 PM London time yesterday, the Yahoo! Maps API got added to the Programmable Web deadpool for good. Despite the announcement I wrote about last year that it was being shutdown on September 13, 2011, up until yesterday the API was very much alive and well and still serving up map tiles, markers and polylines via JavaScript.

Ah ... art. Art is a contentious area for discussion. One person's work of art is another person's random spots of paint on a canvas. As Rudyard Kipling once put it, "it's clever, but is it art?".

Even artists can't seem to agree on this topic. Compare and contrast Picasso's comment that "everything you can imagine is real" with Warhol's contrarian stance that "an artist is somebody who produces things that people don't need to have".

Now add maps into the equation and you have a debate where people probably won't always agree. So it was with a conversation on Twitter between myself, Steve Chilton, chair of the Society of Cartographers and psychogeographer Graham Hooper. We were talking about a map like this one ...

I've said it before, many times, but I'm a 100% un-reconstructed map addict and make no apology for it. I've said this in posts I've written on this blog as well as using it as part of my introduction for talks at conferences. This post is a slightly more long winded version of why I am the map addict that I am.

I grew up in the suburbs of London. For as long as I can remember, every week day morning my father picked up his briefcase and walked to the local British Rail station (for this was way before the privatisation of the British rail network) and went to the fantastical place, to a child's mind at least, called Central London where he worked. He went there on a train. Which was amazing and wonderful to me at the time. I knew he worked in Central London because he had a book of maps of all the streets in Central London. It was old, dog-eared and probably out of date but it made the journey to and from work with him every day and I used to look at it in the evenings, after he'd come home for the day. This mystical and wondrous book was called the London A-Z. It looked something like this.

Dutch computer scientist Edsger Dijkstra, who was awarded the Turing Prize in 1972 is reported to have once said ...

If debugging is the process of removing bugs, then programming must be the process of putting them in.

With this in mind, if the process of taking geographical information and making this into a map is called mapping ... what do you call the opposite, the process where you take a map and deconstruct it back to what makes up the map in the first place.

Un-mapping? Anti-mapping? De-atlasing? Whatever you call it, you start out with a map and you end up with an oddly compelling form of art. Which is just what French artist Armelle Caron has been doing.

Start with the map. Let's take a map of Berlin. If you've spent any time in this city, the map will look pretty familiar. It's not the most granular or small scale of maps, but that doesn't matter. What happens next is most definitely art and is akin to magic.