I recently found out that visualisation originated from maps – I always knew there was a reason I enjoyed Geography A-level 😉 I remember spending hours poring over maps when I was younger too. Visualisation does not just have its historical roots in maps however – given the various parallels below, the link from maps to visualisation makes a lot of sense.
I love looking at really old maps like these, trying to see how London has evolved over time – on this one you can make out the Tower of London, the original London Bridge, and “Spittle Fyldes” (actually a field):
Maps are considered to have not just recorded history but to have helped shape it too (more on that in a great book called Prisoners of Geography). Maps are also extremely useful to this day – for hiking, more engaging navigating and checking a satnav’s sanity, you still can’t beat an OS map (which have a certain beauty in their own right too!)…
…and to bring you bang up-to-date there are now indoor maps (becoming more prevalent with inter-connected retail parks, hospitals, universities and offices in some places), 3D maps (to give you a better idea of how a place looks in reality), and 3D printed maps:
How did visualisation begin through maps?
One of the earliest accepted forms of visualisation was Dr Snow’s map of London’s cholera deaths in 1854. Locations of public wells were represented on a streetmap, along with numbers of cholera deaths marked as black bars stacked perpendicular to the streets (complete map here). This particular part of the map allowed the Broad Street pump to be identified as a source of the disease:
More recently in the 1920s, maps started to include shapes scaled by area. Note the squares’ areas represent different empires’ population sizes in the first example below, and in the second example, scaled pictorial symbols represent the relative sizes of supplier countries for different raw materials:
Later there were maps to show the spread of disease – originally broadly in concentric circles as the main method of transport was over land, but is now more closely linked to air routes:
So you can perhaps now see why visualisation has its heritage in maps, it literally started out by being used on maps!
What else do maps have in common with visualisation, apart from history?
Intuitive to understand
People have been using symbols to represent particular things for centuries – cave paintings and Egyptian hieroglyphics being the earliest examples:
Maps nowadays include a variety of symbols in their “key” but some are more official & widely used. It can be a good game to try to find all the symbols from the legend on a map 🙂 The first example here is a legend for a treasure map, the others are for more realistic types of maps(!):
In the same way that a map has a key or legend to interpret it, so do visualisations – and the best don’t even need a legend. Symbols are chosen to be as intuitive or pictorial as possible, so often there isn’t really a need for a key. A lack of legend can improve understanding if the labels or symbols are directly on the visualisation / map, since then your eye doesn’t have to go back & forth from the legend to the map to decode each:
There are other types of ‘visual encoding’ used in visualisations too, and the best only include a maximum of 1 or 2 types at once, otherwise it takes too long for the brain to process. Encoding types that most clearly show comparative differences on a scale are at the top. At the bottom are those that just distinguish between different (but not necessarily better or worse) categories, e.g. colours aren’t on a commonly interpreted scale, and different shapes as symbols don’t have any inherent meaning:
Simplicity of message
Maps & visualisations are designed to make things simpler for humans to digest. As an example of both a map & visualisation in action, a chloropleth has beautiful simplicity – imagine how complex this data would be to understand, if displayed as a table of data!:
Another example of a visualisation in map form is the cartogram (Ben Hennig is the master of these: viewsoftheworld.net), which simply gets across a clear message, through re-scaling map areas by its associated datapoint:
Maps (as with data visualisations!) should be treated with care though – they can also be misleading, most famously for maps due to the Mercator effect of the globe. You might think from the standard world map that Africa is about the size of the US, but in fact due to the way world maps are “unfolded” from the sphere, in reality Africa could fit the US, China, India into its borders and still have space for most of Europe (more on why here and here, and on schools now starting to use a more realistic map here):
Beautiful to look at
With many things in life, the simpler the better – and it’s the same for visualisations as well as maps. Maps have been turned into art:
And some visualisations can similarly be beautiful too!
Interactivity is the area where I think data visualisations & maps can really go above & beyond traditional forms (and incidentally is where I specialise!).
There are some beautiful map videos (for example a video of Pangaea unfurling to become the continents as we know them today, and a video visualising the evolution of London ) but I think interactivity is even more impressive if it can be user-controlled: for example this map allows the user the explore migration of students across the world, depending on the country they happen to be interested in:
Visualisations, even when not in map form, can also be interactive – allowing not just for more familiarity through ‘play’ on the part of the user, but also to discover more insights through delving into trends (clicking to re-cut the data) to discover why. Try this out!
Inspired to see more maps?
A brilliant maps exhibition is on at the British Library currently here (closes 1st March though so you’ll have to be quick!). Also this great site has regular new map posts, including creating maps to show the different events going on in London, for example at Christmas time 🙂