Tag Archive: maps

Apr 08 2016

Book review: An Introduction to Geographical Information Systems by Ian Heywood et al

HeywoodI’ve been doing quite a lot of work around Geographical Information Systems recently. So I thought I should get some background understanding to avoid repeating the mistakes of others. I turned to An Introduction to Geographic Information Systems by Ian Heywood, Sarah Cornelius and Steve Carver, now in its fourth edition.

This is an undergraduate text, the number of editions suggests it to be a good one. The first edition of Introduction was published in 1998 and this shows in the content, much of the material is rooted in that time with excursions into more recent matters. There is mention of CRT displays and Personal Data Assistants (PDA). This edition was published in 2011, obviously quite a lot of new material has been added since the first edition but it clearly forms the core of the book.

I quite deliberately chose a book that didn’t mention the latest shiny technologies I am currently working with (QGIS, Open Layers 3, spatial extensions in MariaDB) since that sort of stuff ages fast and the best, i.e. most up to date, information is on the web.

GIS allows you to store spatially related data with the ability to build maps using layers of different content and combine this spatial data with attributes stored in databases.

Early users were governments both local and national and their agencies, who must manage large amounts of land. These were followed by utility companies who had geographically distributed infrastructure to manage. More recently retail companies have become interested in GIS as a way of optimising store location and marketing. The application of GIS is frequently in the area of “decision support”, along the lines of “where should I site my…?” Although, “how should I get around these locations?” is also a frequent question. And with GPS for route finding arguably all of us carry around a GIS, and they are certainly important to logistics companies.

From the later stages of the book we learn how Geographic Information Systems were born in the mid to late 1960s became of increasing academic interest through the 1970s, started to see wider uptake in the eighties and became a commodity in the nineties. With the advent of Google Maps and navigation apps on mobile phones GIS is now ubiquitous.

I find it striking that the Douglas-Peucker algorithm for line simplification, born in the early seventies, is recently implemented in my favoured spatially enabled database (MariaDB/MySQL). These spatial extensions in SQL appear to have grown out of a 1999 standard from the OGC (Open Geospatial Consortium). Looking at who has implemented the standards is a good way of getting an overview of the GIS market.

The book is UK-centric but not overwhelmingly so, we learn about the Ordnance Survey mapping products and the UK postcode system, and the example of finding a site for a nuclear waste repository in the UK is a recurring theme.

Issues in GIS have not really changed a great deal, projection and coordinate transforms are still important, and a source of angst (I have experienced this angst personally!). We still see digitisation and other data quality issues in digitized data, although perhaps the source is no longer the process of manual digitization from paper but of inconsistency in labelling and GPS errors.

One of the challenges not discussed in Introduction is the licensing of geographic data, this has recently been in the news with the British government spending £5 million to rebuild an open address database for the UK, having sold off the current one with the Royal Mail in 2013. (£5 million is likely just the start). UN-OCHA faces similar issues in coordinating aid in disaster areas, the UK is fairly open in making details of administrative boundaries within the UK available electronically but this is not the case globally.

I have made some use of conventional GIS software in the form of QGIS which although powerful, flexible and capable I find slow and ugly. I find it really hand for a quick look-see at data in common geospatial formats. For more in-depth analysis and visualisation I use a combination of spatial extensions in SQL, Python and browser technology.

I found the case studies the most useful part of this book, these are from a wide range of authors and describe real life examples of the ideas discussed in the main text. The main text uses the hypothetical ski resort of Happy Valley as a long running example. As befits a proper undergraduate introduction there are lots of references to further reading.

Despite its sometimes dated feel Introduction to Geographic Information Systems does exactly what it says on the tin.

Jan 06 2016

Book review: A History of the 20th Century in 100 Maps by Tim Bryars an Tom Harper

100mapsA History of the 20th Century in 100 Maps by Tim Bryars and Tom Harper is similar in spirit to The Information Capital by James Cheshire and Oliver Uberti: a coffee table book pairing largely geographic visualisations with relatively brief text. Looking back I see that The Information Capital was a birthday present from Mrs SomeBeans, 100 Maps was a Christmas present from the same!

The book is published by the British Library. The maps are wide ranging in scale, scope and origin. Ordnance Survey maps of the trenches around the Battle of the Somme nestle against tourist maps of the Yorkshire coast, and tourist maps of Second World War Paris for the Nazi occupiers. The military maps are based on the detailed work by organisations like the Ordnance Survey whilst other maps are cartoons of varying degrees of refinement, “crude” being particularly relevant in the case of he Viz map of Europe!

War and tourism are recurring themes of the book. In war maps are used to plan a battle, conduct a post mortem and as propaganda. It is not uncommon to see newspaper cartoon style maps with countries represented by animals, or breeds of dog. In tourism maps are used as marketing – the presentation and “incidental” details at least as important as the navigation. Sometimes the “tourism” relates to state events. Not quite fitting into either war or tourism is the crudest map in the book, a sketch of Antarctica on the back of a menu card, made by Shackleton as he tried to persuade his neighbour at a formal dinner to help fund his expedition.

A third category is the economic map showing, for example the distribution of new factories around the UK in the post-war period or the exploitation of oil in the Caribbean or the North Sea. This maps were published sometimes for education, and sometimes as part of a prospectus for investment or a tool of persuasion.   

The focus of the book is really on the history of Britain rather than maps, this is a useful bait-and-switch for people like me who are ardent followers of maps but not so much of history. It struck me the impact that the two world wars of the 20th century had on UK. Not simply the effect of war itself but the rise of women in the workforce, and independence movements in the now former colonies, homes for heroes, nationalisation – the list goes on. It seems the appetite for all these things was generated during the First World War but they were not satisfied until after the Second. The First World War also saw the introduction of prohibitions on opium and cocaine, prior to this they were seen as the safe recreation of the upper middle classes during the war they were seen as a risk to the war effort. America had lead the way with the prohibition of drugs, and later alcohol, seeing them as a vice of immigrants and working classes.

I didn’t realise there were no controls on immigration to the UK until the 1905 Alien Act, this nugget is found in a commentary on a map entitled “Jewish East London”. This map was based on Charles Booth’s social maps of London and published by the Toybnee Trust. The Jewish population had been increasing over the preceding 25 years following pogroms and anti-Semitic violence in the Russian Empire. The Trust published the map alongside articles for and against immigration controls but, as the authors point out, the map is designed with its use of colouring and legends to make the case against.

100 maps is not all about the real world, E.H. Shepard’s map of the Hundred Acre Wood makes it in, as well Tolkien’s map of Middle Earth. In both cases the map provides an overview of the story inside. I rather like the map of Hundred Acre Wood map with “Eeyores Gloomy Place – rather boggy and sad”, and a compass rose which spells out P-O-O-H.

The book is well-made and presented but in these times of zoomable online maps physical media struggle to keep up. The maps are difficult to study in detail at the A4 size in which they are presented. 100 maps makes some comment on the technical evolution of maps, not so much in the collection of data, but in the printing and presentation process. It is only in the final decades of the century that full colour printed maps become commonplace. It is around 1990 that the Ordnance Survey becomes fully digital in its data collection.

All in all a fine present – thank you Mrs SomeBeans!

May 02 2015

Book review: The Information Capital by James Cheshire and Oliver Uberti

Today I review TheInformationCapitalThe Information Capital by James Cheshire and Oliver Uberti – a birthday present. This is something of a coffee table book containing a range of visualisations pertaining to data about London. The book has a website where you can see what I’m talking about (here) and many of the visualisations can be found on James Cheshire’s mappinglondon.co.uk website.

This type of book is very much after my own heart, see for example my visualisation of the London Underground. The Information Capital isn’t just pretty, the text is sufficient to tell you what’s going on and find out more.

The book is divided into five broad themes “Where We Are”, “Who We Are”, “Where We Go”, “How We’re Doing” and “What We Like”. Inevitably the majority of the visualisations are variants on a coloured map but that’s no issue to my mind (I like maps!).

Aesthetically I liked the pointillist plots of the trees in Southwark, each tree gets a dot, coloured by species and the collection of points marks out the roads and green spaces of the borough. The twitter map of the city with the dots coloured by the country of origin of the tweeter is in similar style with a great horde evident around the heart of London in Soho.

The visualisations of commuting look like thistledown, white on a dark blue background, and as a bonus you can see all of southern England, not just London. You can see it on the website (here). A Voroni tessellation showing the capital divided up by the area of influence (or at least the distance to) different brands of supermarket is very striking. To the non-scientist this visualisation probably has a Cubist feel to it.

Some of the charts are a bit bewildering, for instance a tree diagram linking wards by the prevalent profession is confusing and the colouring doesn’t help. The mood of Londoners is shown using Chernoff faces, this is based on data from the ONS who have been asking questions on life satisfaction, purpose, happiness and anxiety since 2011. On first glance this chart is difficult to read but the legend clarifies for us to discover that people are stressed, anxious and unhappy in Islington but perky in Bromley. You can see this visualisation on the web site of the book (here).

The London Guilds as app icons is rather nice, there’s not a huge amount of data in the chart but I was intrigued to learn that guilds are still being created, the most recent being the Art Scholars created in February 2014. Similarly the protected views of London chart is simply a collection of water-colour vistas.

I have mixed feelings about London, it is packed with interesting things and has a long and rich history. There are even islands of tranquillity, I enjoyed glorious breakfasts on the terrace of Somerset House last summer and lunches in Lincoln’s Inn Fields.  But I’ve no desire to live there. London sucks everything in from the rest of the country, government sits there and siting civic projects outside London seems a great and special effort for them. There is an assumption that you will come to London to serve. The inhabitants seem to live miserable lives with overpriced property and hideous commutes, these things are reflected in some of the visualisations in this book. My second London Underground visualisation measured the walking time between Tube station stops, mainly to help me avoid that hellish place at rush hour. There is a version of such a map in The Information Capital.

For those living outside London, The Information Capital is something we can think about implementing in our own area. For some charts this is quite feasible based, as they are, on government data which covers the nation such as the census or GP prescribing data. Visualisations based on social media are likely also doable although will lack weight of numbers. The visualisations harking back to classics such as John Snow’s cholera map or Charles Booth’s poverty maps of are more difficult since there is no comparison to be made in other parts of the country. And other regions of the UK don’t have Boris Bikes (or Boris, for that matter) or the Millennium Wheel.

It’s completely unsurprising to see Tufte credited in the end papers of The Information Capital. There are also some good references there for the history of London, places to get data and data visualisation.

I loved this book, its full of interesting and creative visualisations, an inspiration!

Aug 23 2014

Book review: Greenwich Time and the Longitude by Derek Howse

greenwich_timeI am being used as a proxy reader! My colleague drj, impressed by my reviewing activities, asked me to read Greenwich Time and the Longitude by Derek Howse, so that he wouldn’t have to.

There was some risk here that Greenwich Time and the Longitude would overlap heavily with Finding Longitude which I have recently read. They clearly revolve around the same subjects and come from the same place: the National Maritime Museum at Greenwich. Happily the overlap is relatively minor. Following some brief preamble regarding the origins of latitude and longitude for specifying locations, Greenwich Time starts with the founding of the Royal Observatory at Greenwich.

The Observatory was set up under Charles II who personally ordered it’s creation in 1675, mindful of the importance of astronomy to navigation. The first Royal Astronomer was John Flamsteed. Accurate measurement of the locations of the moon and stars was a prerequisite for determining the longitude at sea both by lunar-distance and clock based means. Flamsteed’s first series of measurements was aimed at determining whether the earth rotated at a constant rate, something we take for granted but wasn’t necessarily the case.

Flamsteed is notorious for jealously guarding the measurements he made, and fell out with Isaac Newton over their early, unauthorised publication which Newton arranged. A detail I’d previously missed in this episode is that Flamsteed was not very well remunerated for his work, his £100 per annum salary had to cover the purchase of instruments as well as any skilled assistance he required which goes some way to explaining his possessiveness over the measurements he made. 

Greenwich Time covers the development of marine chronometers in the 18th century and the period of the Board of Longitude relatively quickly.

The next step is the distribution of time. Towards the middle of the 19th century three industries were feeling the need for precise timekeeping: telegraphy, the railways and the postal service. This is in addition to the requirements of marine navigators. The first time signal, in 1833, was distributed by the fall of a large painted zinc ball on the top of the Greenwich observatory. Thereafter, strikingly similar balls appeared on observatories around the world.

From 1852 the time signal was distributed by telegraphic means, and ultimately by radio. It was the radio time signal that ultimately brought an end to the publication of astronomical tables for navigation. Britain’s Nautical Almanac, started in 1767, stopped publishing them in 1907 – less than 10 years after the invention of radio.

With the fast distribution of time signals over large distances came the issue of the variation between local time (as defined by the sun and stars) and the standard time. The problem was particularly pressing in the United States which spanned multiple time zones. The culmination of this problem is the International Date Line, which passes through the Pacific. Here the day of the week changes on crossing the line, a problem discovered by the very first circumnavigators (Magellan’s expedition in 1522), identified when they reached travellers who had arrived from the opposite direction and disagreed on the day of the week. I must admit to being a bit impressed by this, I can imagine it’s easy to lose track of the days on such an expedition.

I found the descriptions of congresses to standardise the meridian and time systems across multiple nations in the 1880s rather dull.

One small thing of interest in these discussions: mariners used to measure the end of the day at noon, hence what we would call “Monday morning” a mariner would call “the end of Sunday”, unless he was at harbour – in which case he would use local time! It is from 18th century mariners that Jean Luc Picard appears to get his catchphrase “Make it so!”, this was the traditional response of a captain to the officer making the noon latitude measurement. The meridian congresses started the process of standardising the treatment of the day by “civilians”, mariners and astronomers.

The book finishes with a discussion of high precision timekeeping. This is where we discover that Flamsteed wasn’t entirely right when he measured the earth to rotate at a constant rate. The earth’s rotation is showing a long term decrease upon which are superimposed irregular variations and seasonal variations. And the length of the year is slowly changing too. Added to that, the poles drift by about 8 metres or so over time. It’s testament to our abilities that we can measure these imperfections but somehow sad that they exist.

The book has an appendix with some detail on various measurements.

Not as sumptuous a book as Finding Longitude it is an interesting read with a different focus. It has some overlap too with The History of Clocks and Watches by Eric Bruton.

Aug 03 2014

Book review: Finding Longitude by Richard Dunn, Rebekah Higgitt

finding-longitudeMuch of my reading comes via twitter in the form of recommendations from historians of science, in this case I am reading a book co-authored by one of those historians: Finding Longitude by Richard Dunn (@lordoflongitude) and Rebekah Higgitt (@beckyfh).

I must admit I held off buying Finding Longitude for a while since it appeared to be an exhibition brochure, maybe not so good if you haven’t attended the exhibition. It turns out to be freestanding and perfectly formed.This is definitely the most sumptuous book I’ve bought in quite some time, I’m glad I got the hardcover version rather than the Kindle edition.

The many photographs throughout the book are absolutely gorgeous, they are of the instruments and clocks, the log books, artwork from the time. You can get a flavour from the images online here.

To give some context to the book, knowing your location on earth is a matter of determining two parameters: latitude and longitude:

  • latitude is your location in the North-South direction between the equator and either of the earth’s poles, it is easily determined by the height of the sun or stars above the horizon, and we shall speak no more of it here.
  • longitude is the second piece of information required to specify ones position on the surface of the earth and is a measure your location East-West relative to the Greenwich meridian. The earth turns at a fixed rate and as it does the sun appears to move through the sky. You can use this behaviour to fix a local noon time: the time at which the sun reaches the highest point in the sky. If, when you measure your local noon, you can also determine what time it is at some reference point Greenwich, for example, then you can find your longitude from the difference between the two times.

Knowing where you are on earth by measurement of these parameters is particularly important for sailors engaged in long distance trade or fighting. It has therefore long been an interest of governments.

The British were a bit late to the party in prizes for determining the longitude, the first of them had been offered by Phillip II of Spain in 1567 and there had been activity in the area since then, primarily amongst the Spanish and Dutch. Towards the end of the 17th century the British and French get in on the act, starting with the formation of the Royal Society and Académie des sciences respectively.

One stimulus for the creation of a British prize for determining the longitude was the deaths of 1600 British sailors from Admiral Sir Cloudsley Shovell’s fleet off the Isles of Scilly in 1707. They died on the rocks off the Isles of Scilly in a storm, as a result of not knowing where they were until it was too late. As an aside, the surviving log books from Shovell’s fleet showed that for the latitude (i.e. the easier thing to measure), measurements of the sun gave a 25 mile spread, and those from dead reckoning a 75 mile spread in location.

The Longitude Act was signed into law in 1714, it offered a prize of £20,000 to whoever produced a practicable method for determining the longitude at sea. There was something of the air that it was a problem about to be solved. The Board of Longitude was to judge the prize. The known competitor techniques at the time were timekeeping by mechanical means, two astronomical methods (the lunar distance method, and the satellites of Jupiter) and dead-reckoning. In fact these techniques are used in combination, mechanical timekeepers are simpler to use than the astronomical methods but mechanical timekeepers needed checking against the astronomical gold standard which was the only way to reset a stopped clock. Dead-reckoning (finding your location by knowing how fast you’d gone in what direction) was quick and simple, and worked in all weathers. Even with a mechanical timekeeper astronomical observations were required to measure the “local” time, and that didn’t work in thick cloud.

There’s no point in sailors knowing exactly where they were if maps did not describe exactly where the places where they were going, or trying to avoid. Furthermore, the lunar distance method of finding longitude required detailed tables of astronomical data which needed updating regularly. So alongside the activities of the longitude projectors, the state mechanisms for compiling charts and making astronomical tables were built up.

John Harrison and his timepieces are the most famous part of the longitude story. Harrison produced a series of clocks and watches from 1730 and 1760, in return he received moderate funding over the period from the Board of Longitude, you can see the payment record in this blog post here. Harrison felt hard done by since his final watches met the required precision but the Board of Longitude were reluctant to pay the full prize. Although meeting the technical specification in terms of their precision were far from a solution. Despite his (begrudging) efforts, they could not be reliably reproduced even by the most talented clock makers.

After Harrison’s final award several others made clocks based on his designs, these were tested in a variety of expeditions in the latter half of the 18th century (such as Cook’s to Tahiti in 1769). The naval expedition including hydrographers, astronomers, naturalists and artists became something of a craze (see also Darwin’s trip on the Beagle). As well as clocks, men such as Jesse Ramsden were mass producing improved instruments for navigational measurements, such as octants and sextants.

The use of chronometers to determine the longitude was not fully embedded into the Royal Navy until into the 19th century with the East Indian Company running a little ahead of them by having chronometers throughout their fleet by 1810.

Finding Longitude is a a good illustration of providing the full context for the adoption of a technology. It’s the most beautiful book I’ve read in while, and it doesn’t stint on detail.

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