Mapping Lines of Sight

William Davies has created a really interesting demo map that uses turf.js to map viewsheds. He was inspired to create the map after seeing Esri's Campus Blue Lights map, which uses viewsheds to show where the beacons on emergency telephones can be seen on a university campus.

William's Viewshed map uses turf.js to show where lines of sight intersect with building polygons on a Mapbox map. The map animates a pair of sunglasses around the Egyptian pyramids. A circular polygon shows the viewshed from the point of view of the sunglasses. The holes in this circular polygon show where the sunglasses' point of view is interrupted by the pyramids and other buildings.

The map is very impressive. It is also a pretty neat demonstration of the power of turf.js for carrying out advanced geospatial analysis with interactive mapping libraries.

The Tallest Buildings in the Netherlands

The Tallest Buildings in the Netherlands is an impressive tour of the tallest skyscrapers in the Netherlands. All five of the tallest buildings are in Rotterdam. However the map also allows you to explore the building heights of every building in the Netherlands - in 3D.

Every building in the country has been modeled in 3D using the height data of buildings from the Dutch Land Registry. You can click on any of the buildings, anywhere in the country, to view its height in meters. All the buildings on the map are also color-coded by height.

If you want you can create a similar map using Mapbox. Display Buildings in 3D and Fly to a location based on scroll position might be two good example maps to get you started.

An alternative approach would be to use OSM Buildings. Webkid has published a very good tutorial on how to make Interactive 3D Maps With OSMBuildings. The tutorial explains how the Berliner Morgenpost's made their own Berlin's neue Skyline map. The Berliner Morgenpost's map was in turn inspired by the New York Times' Reshaping New York.

An Annotated Medieval Map of Britain

Mathew Paris' 13th Century Map of Britain is one of the very first geographical maps of Great Britain. However, despite being arguably the first modern map of Britain, it is still quite hard to navigate. A lot of the actual geography is wrong and the place-names can be difficult to translate into modern English.

I have therefore created an Annotated Matthew Paris Map of Britain. On my map you can simply click on a place-name on the map to discover the equivalent modern English place-name. For example if you click on 'Eboracum' on the map an information window will open informing you that this is the city we know as 'York'.

I have translated over 90% of the place-names on the map, however a few of the place-names have me bamboozled. If you have any ideas about the names I have failed to translate then please feel free to leave a comment on this post.

My map is only possible because of the Stanford Libraries. They have created an IIIF manifest of Corpus Christi College's original manuscript of Matthew Paris' map. I have therefore been able to use Leaflet-IIIF, a simple to use plug-in for using IIIF manifests in Leaflet, to create a Leaflet.js map from the IIIF manifest of Matthew Paris' map.

The Drone Alphabet

Latvian mobile phone company Tele2 has created a Latvian Alphabet using letters discovered in the shapes of the buildings, roads and rivers of Latvia. You can use this Latvian Alphabet to send a message to your friends entirely written in aerial images of Latvia.

Tele2 has searched aerial imagery captured by drones looking for shapes that resemble letters of the alphabet. They have been able to complete the whole alphabet using these aerial images of the Latvian landscape. Latvian Alphabet includes a fun application which you can use to type and view your own messages written in this new drone alphabet.

Of course there is nothing new in searching for the shapes of letters in aerial imagery. Rhett Dashwood's - Google Maps Typography, is a few years old now. Rhett's alphabet is made up of letter shapes discovered in geographical features in Google Maps aerial view. There is also Earth Clock, a digital clock assembled from numbers found in aerial views of the Earth (although like my old digital clocks it seems to be struggling to display properly now).

Italian Election Maps

Votes in the Italian election have not all been counted but enough votes are in to indicate that there will be a lot of negotiations in the coming weeks in order to form a a working coalition for government. The centre-right coalition appears to be slightly ahead in the Italian election, although the country appears to be heading towards a hung parliament, with none of the current coalitions having enough votes to take overall control.

The Five Star Movement appear to be the biggest winners in this election. This relatively new party refuses to position itself in the traditional left-right split in politics. In the European Parliament it has been in a group of quite extreme right-wing parties but it has many ideological differences with these other European right-wing parties. For example it has supported same-sex marriage and has ecological policies similar to European Green parties.


La Repubblica's interactive election map shows the results in each electoral region. Regional Elections 2018 is a traditional choropleth map in which each electoral district is colored to show the party of the leading candidate. If you hover over a district you can view the percentage of the vote won by the three leading candidates. You can also view the turnout in areas where the vote count is complete.

The Corriere della Sera has also opted for a traditional choropleth map for its election map. Its Risultati Elezioni Politiche 2018 colors each electoral district by the color of the coalition. The newspaper has used color intensity to show the margin of victory. Shades of individual colors indicate the strength of victory in each district. A lighter shade shows a smaller victory, while a stronger shade indicates a larger victory for the winning coalition.

Both maps show a big geographical split in the country. The Five Star Movement has dominated the south of Italy, while the centre-right coalition has proved popular in the north. The ruling centre-left coalition has lost a lot of support in this election, but it retains some areas of support in Northern Italy.

How to Reduce Gun Deaths

The Rand Corporation has released a Gun Policy Comparison Tool which allows you to see the likely effects of different gun laws on the number of gun related deaths in all US states.

The gun policy tool is very simple to use. You simply select any combination of fifteen different gun policies to view a choropleth map showing the impact those laws would be likely to have on each US state if they were introduced as nationwide laws. The laws that you select from range from permitless carry laws to the introduction of universal background checks. The results are based on a survey of 95 gun policy experts.

You can also view a range of different outcomes on the map for each combination of gun policies that you want to check. As well as the outcome on homicides in each state you can also view the likely positive or negative outcomes on different types of crime, on the sales of firearms and on the right to bear arms.

The SB 827 Interactive Los Angeles Map

Buying a home in California is very expensive. Particularly in the state's biggest cities. One solution would be to build more affordable housing. However California has a lot of building and zoning regulations which make building new homes difficult.

SB 827 is a new bill that is designed to encourage the building of high density housing near public transportation. The bill, if passed, would require that all areas within a half-mile of a high-frequency transit stop, or within a quarter-mile of a bus or transit corridor, allow buildings of 4 to 5 stories. It would also exempt these new buildings from minimum car parking requirements.

The Policy Club has released an interactive map which shows the potential impact of the bill on Los Angeles. The SB 827 Interactive Los Angeles Map shows the building parcels in LA which would become exempt from residential density restrictions, minimum parking requirements and building height limits if the California Senate passes SB 827.

The map clearly demonstrates that SB 827 has the potential to have a huge impact on the building of new homes in Los Angeles. Whether you think that is a good idea or not obviously depends on your point of view.

Street View Paintings

Ten years after Street View first appeared on Google Maps it is a little surprising that 360 degree panoramic art hasn't become a huge new artistic medium. Perhaps with the spread of more accessible VR headsets it is finally time to celebrate the great Street View artists of the 21st Century.

For example there is Julien Gauthier with his wonderful biopunk inspired BANGKOKXXIII - 360 Street. This 360 degree panoramic painting depicts a scene inspired by Paolo Bacigalupi's The Windup Girl. As you rotate around the panoramic image an Asian street scene looms over your point of view, with towering skyscrapers, an overgrown overpass and even a gigantic elephant.


The Grand Master of Street View art has to be Raúl Moyado Sandoval. Raúl has been creating panoramic paintings since 2013. Back in 2013 Raúl used the Google Maps API's Custom Street View feature to create immersive 360 degree landscape paintings.

Mobile Cyclorama has moved on from the Google Maps API. Raúl now creates 360 degree panoramic images which can be viewed using a VR headset, on a mobile device or on a desktop computer. There are six paintings to view in total. Mobile Cyclorama also includes a brief overview of the history of panoramic paintings, which actually date back to the 18th century.

Global Warming with a Flourish

One of my favorite mapped data visualizations of the last few years is The Guardian's In Flight – Interactive Map, an amazing presentation exploring the history of commercial air travel. The interactive story features an animated map visualizing 24 hours of plane flights around the world and a narrated documentary looking at the birth of commercial flights, the development of international air travel and a look at the potential future for the industry.

The In Flight map was developed for The Guardian by Kiln, a data visualization compnany based in London. Kiln has now released a platform which anyone can use to tell their own stories with data. Flourish is a JavaScript library which developers can use to create visualization templates that non-coders can then use to easily edit and publish data-driven and interactive content. Using Flourish it is possible to create your own interactive mapped visualizations.

Kiln has used Flourish to create their own mapped data visualization of 20 years of global warming. The Climate Weather Map uses 500 million weather records to show the highest and lowest temperatures around the world over the last 20 years. The map includes a timeline which animates through the 20 years of records, adding the record highest and lowest temperatures to the map by the date that they were recorded.

The story-telling element of the visualization is managed by forward and backward buttons. These buttons are used to zoom the map to specific locations on specific dates, when a country or continent experienced extreme weather. A brief explanation for each of these examples of extreme weather is provided above the map.

The Climate Weather Map is a nice demo map of what can be made with Kiln's Flourish library. You can view more examples of data visualizations created with Flourish on the Flourish Examples page.

Discovering Merlin's Castle

I have found the location of Merlin's castle on an ancient medieval map created by a a Benedictine monk in the 13th Century. Unfortunately, while I was busy packing up my bullwhip, fedora, satchel and leather jacket, I remembered that my discovery wasn't exactly new. My search for the Holy Grail has therefore been postponed once again.

The Parker Library at Corpus Christi College, Cambridge is currently holding an exhibition called Worlds Real and Imagined. The exhibition looks at early depictions of the world in the library's medieval manuscripts collection and oldest printed books. The exhibition includes Matrhew Paris' map of Scotland, Northern England and Wales. On which can be found Merlin's town.

If you can get to Cambridge then you can view the manuscripts and books yourself in the Wilkins Room of the Parker Library. If you can't get to Cambridge in person then don't worry as you can actually view the texts in far closer detail online. The Stanford library's curated feature on Worlds Real and Imagined includes digitized versions of all the manuscripts and books in the exhibition, which can be examined using the Mirador image viewer.

Among the maps in the exhibition is Matthew Paris' map showing the journey from London to the Holy Land (from the Chronica Maiora), Gerald of Wales' simple map of the British Isles (from Topographia Hiberniae) and a map of the Holy Land (The Travels of Sir John Mandeville). My favorite map in the collection is Matthew Paris' map of Northern England, Wales and Scotland (the Midlands and the South of England appear to have been lost).

This is one of four maps of Great Britain drawn by the 13th-century monk historian Matthew Paris. The map shows Hadrian's Wall, with Scotland lying to the north. The map also depicts Wales, where you can find Caermardin or Merlin's town (in some versions of the Arthurian legend Merlin was born in a cave outside Carmarthen).


You can find the reference to Merlin in the bottom left-hand corner of the map. The Welsh town now called Carmarthen is labelled on Maththew Paris' map as 'caermerdin id est civitas Merlini'. Translated from Latin this reads 'Caermerdin, i.e. the city of Merlin'.

The etymology of the Welsh town of Carmarthen at a stretch could derive from 'caer Myrddin' meaning Merlin's castle. However the etymology of Carmarthen is more generally believed to have derived from the Roman name for the town Moridunum, meaning 'sea fort'. It has been suggested that Myrddin (Merlin) got his name from the town (Caermyrddin) - in other words rather than the town having been named after Merlin, Merlin actually derived his name from the town.

You can read more about King Arthur's connections to Wales and Merlin's connections to Carmarthen in Visit Wales's Discover King Arthur’s Wales.