Sourcing GIS data

Where does one get GIS data for teaching purposes? This is the sort of question one might ask on Twitter. However while, like many, I have learned to overcome, or at least creatively ignore, the constraints of 140 characters, it can’t really be done for a question this broad, or with as many attendant sub-issues. That said, this post was finally edged into existence by a Twitter follow, from “Canadian GIS & Geomatics Resources” (@CanadianGIS). So many thanks to them for the unintended prod. The linked website of this account states:

I am sure that almost any geomatics professional would agree that a major part of any GIS are the data sets involved. The data can be in the form of vectors, rasters, aerial photography or statistical tabular data and most often the data component can be very costly or labor intensive.

Too true. And as the university term ends, reviewing the issue from the point of view of teaching seems apposite.

First, of course, students need to know what a shapefile actually is. A shapefile is the building block of GIS, the datasets where individual map layers live. Points, lines, polygons: Cartesian geography are what makes the world go round – or at least the digital world, if we accept the oft-quoted statistic that 80% or all online material is in some way georeferenced. I have made various efforts to establish the veracity of this statistic or otherwise, and if anyone has any leads, I would be most grateful if you would share them with me by email or, better still, in the comments section here. Surely it can’t be any less than that now, with the emergence of mobile computing and the saturation of the 4G smartphone market. Anyway…

In my postgraduate course, part of a Digital Humanities MA programme, on digital mapping, I have used the Ordnance Survey Open Data resources, Geofabrik, an on-demand batch download service for OpenStreetMap data, Web Feature Service data from Westminster City Council, and  continental coastline data from the European Environment Agency. The first two in particular are useful, as they provide different perspectives from respectively the central mapping verses open source/crowdsourced geodata angles. But in the expediency required of teaching a module, they main virtues are the fact they’re free, (fairly) reliable, free, malleable, and can be delivered straight to the student’s machine, or classroom PC (infrastructure problems aside – but that’s a different matter) – and uploaded to a package such as QGIS.  But I also use some shapefiles, specifically point files, I created myself. Students should also be encouraged to consider how (and where) the data comes from. This seems to be the most important aspect of geospatial within the Digital Humanities. This data is out there, it can be downloaded, but to understand what it actually *is*, what it actually means, you have to create it. That can mean writing Python scripts to extract toponyms, considering how place is represented in a text, or poring over Google Earth to identify latitude/longitude references for archaeological features.

This goes to the heart of what it means to create geodata, certainly in the Digital Humanities. Like the Ordnance Survey and Geofabrik, much of the geodata around us on the internet arrives pre-packaged and with all its assumptions hidden from view.  Agnieszka Leszczynski, whose excellent work on the distinction between quantitative and qualitative geography I have been re-reading as part of preparation for various forthcoming writings, calls this a ‘datalogical’ view of the world. Everything is abstracted as computable points, lines and polygons (or rasters). Such data is abstracted from the ‘infological’ view of the world, as understood by the humanities.  As Leszczynski puts is: “The conceptual errors and semantic ambiguities of representation in the infologial world propagate and assume materiality in the form of bits and bytes”[1]. It is this process of assumption that a good DH module on digital mapping must address.

In the course of this module I have also become aware of important intellectual gaps in this sort of provision. Nowhere, for example, in either the OS or Geofabrik datasets, is there information in British public Rights of Way (PROWs). I’m going to be needing this data later in the summer for my own research on the historical geography of corpse roads (more here in the future, I hope). But a bit of Googling turned up the following blog reply from OS at the time of the OS data release in April 2010:

I’ve done some more digging on ROW information. It is the IP of the Local Authorities and currently we have an agreement that allows us to to include it in OS Explorer and OS Landranger Maps. Copies of the ‘Definitive Map’ are passed to our Data Collection and Management team where any changes are put into our GIS system in a vector format. These changes get fed through to Cartographic Production who update the ROW information within our raster mapping. Digitising the changes in this way is actually something we’ve not been doing for very long so we don’t have a full coverage in vector format, but it seems the answer to your question is a bit of both! I hope that makes sense![2]

So… teaching GIS in the arcane backstreets of the (digital) spatial humanities still means seeing what is not there due to IP as well as what is.

[1] Leszczynski, Agnieszka. “Quantitative Limits to Qualitative Engagements: GIS, Its Critics, and the Philosophical Divide∗.” The Professional Geographer 61.3 (2009): 350-365.


Question: (how) do we map disappeared places?

A while ago I asked Twitter if there was a name for a long period of inactivity on blogs or social media. Erik Champion came up with some nice suggestions

which raise questions about whether blogging represents either the presence or absence of ‘loafing’; and  replied with a certain elegant simplicity:

Anyway, having been either ‘living’ or ‘loafing’ a lot these last few months, this is my first post since February.

I want to ask another question, but 140 characters just won’t cut it for this one. How does one represent a place in a gazetteer, or any other kind of database or GIS for that matter, which no longer exists? To take an example of ‘Mikro Kaimeni’, a tiny volcanic island in the Santorini archipelago mapped and published by Thomas Graves in his 1850 military survey of the Aegean:


Some sixteen years after this map was made, Santorini erupted and Mikro Kaimeni combined with the large central island, Neo Kameni:


Can such places be hermenutic objects by virtue of the fact that they are representing in the human record (in this case Graves’s map), even though they no longer exist as spatial footprints on the earth’s surface? I suppose they have to be. The same could go for fictional places (Middle Earth, Gotham City etc). What kind of representational issues does this create for mapping in the humanities more generally?

Digital Destinations: What to do with a digital MA

King’s Careers & Employability gathers statistics on graduate employment destinations for the Higher Education Statistics Agency (HESA).  Such data is available for the Department of Digital Humanities’ cohorts for the three academic years between 2010/11 and 2012/13, that is to say graduates of the MA Digital Humanities, the MA Digital Asset and Media Management and the MA Digital Culture and Society of those years. This information, which includes the sectors and organizations that alumni enter, and their job titles, is gathered from telephone interviews and online surveys six months after their graduation. Of those who graduated in 2012/13, 93.8% were in full time work, with the remainder undertaking further study in some form. 38.4% of those approached did not reply, or refused to provide answers. A certain health warning must therefore be attached to the information currently available; and in the last couple of years the numbers on all three programmes have grown considerably, so the sample size is small compared to the numbers of students currently taking the degrees. But in surveying the data that we do have, it is possible to make some preliminary observations.

Firstly, the good news is that all of our graduates from 2012/13 who responded to the survey were in employment, or undertaking further studies, within those six months. In the whole three-year period, MA DAMM graduates entered the digital asset management profession via corporations including EMAP, and the university library sector (Goldsmiths College).  They also entered managerial roles at large corporations including Coca-Cola and the Wellcome Trust. Digital media organizations feature strongly in MA DCS students’ destinations, with employers including NBC, Saatchi and Saatchi and Lexisnexis UK, with roles including design, social media strategy and technical journalism. Librarianship is also represented, with one student becoming an Assistant Librarian at a very high-profile university library. Others appear to have gone straight in to quite senior roles. These include a Director of Marketing, PR and Investments at an international educational organization, a Senior Strategy Analyst at a major international media group, and a Senior Project Manager at a London e-consultancy firm. One nascent trend that can be detected is that graduates of MA DH seem more likely to stay in the research sector.  Several HE institutions feature in MA DH destinations, including Queen Mary, the University of Oslo, Valencia University, the Open University and the University of London, as well as King’s itself; although graduates entering these organizations are doing so in technical and practical, roles such as analysts and e-learning professionals, rather than as higher degree research students. A US Office of the State Archaeologist, Waterstones and Oxford University Press also feature, reflecting (perhaps) MA DH’s strengths in publishing and research communication. Many of the roles which MA DH graduates enter are specialized, for example Data Engineer, Conservator Search Engine Evaluator, although more junior managerial jobs also figure.

As noted, the figures on which these observations are based must be treated with some caution; and doubtless as data for 2013/4 and beyond become available, clearer trends will emerge from across the three MA programmes. Currently, there is a range of destinations to which our graduates go, spanning the private and research sectors, and there is much overlap in the types of organizations for which graduates from all three programmes work and the roles they obtain. However, two broad conclusions can be drawn. Firstly, that all three programmes offer a range of skills based on a critical understanding of digital theory and practice which can be transferred to multiple kinds of organization/role. Secondly our record on full employment shows that there is growing demand for these skills, and that those skills are becoming increasingly essential to both the commercial and research sectors.

Of Historic Units and Cypriot heritage

The team behind the Heritage Gazetteer of Cyprus were in Nicosia last week, presenting a near-final form of the project to an audience of experts in Cypriot history and archaeology. The resource the project has been tasked by the A. G. Leventis Foundation to produce is very nearly complete, and will be launched to the world in January 2015.

The HGC has always been about the names of places, and how these names change over time. As I have blogged about previously, and as we outlined in our presentation to the International Cartographic Association’s Digital Approaches workshop in Budapest in September, this name-driven approach, which is based on three layers of data – modern toponyms, ‘Historical Units’ and ‘Archaeological Entities’ represents the limits of the current project. However what it cannot do raises important intellectual questions about how digital representations of place are organized and presented online. The aim of this post is to capture some of these questions, particularly with regard to our ‘Historic Unit’ data layer.

To recap the definitions: a modern toponym is, quite simply, the official name currently in use, and the only data sources for this are official ones – currently in the form of the Complete Gazetteer of Cyprus (Konstantinides and Chrisotodolou 1987). In our presentation last Thursday, we reiterated our definition of an HU as:

“Entities of substantial geographical extent and significance, such as towns, archaeological sites and the extents of kingdoms”

And AEs as:

“A discrete feature, with a distinct spatial footprint, formed in a definable period”

This definition of an AE is relatively clear. Most importantly, the reference to a ‘distinct spatial footprint’ means that it is related to mappable feature, which is extrinsic to any definition in the HGC data structure. However, a colleague at the meeting expressed the general view when he described HUs as being “the most interesting aspect, but also the most problematic”. Currently, they are defined on the map as a polygon, drawn by the user when they create the HU record. In some cases, a polygon can be defined relatively straightforwardly. For example the Venetian walls of Nicosia form a discrete spatial footprint, that can be traced using the HGC’s geocoding tool. But in most cases, this requires a subjective judgement, and thus a subjective representation, that is arguably inimical to the positivist interpretation which any robust database requires; and imposes exactly the kind of Cartesian absolutism that I and others have railed against in several recent and forthcoming publications. Further, creating an HU in this way can lead to our grouping data points that are actually very different in nature. Sometimes an HU will equate to a modern toponym (such as Marchello, in Nea Paphos), and sometimes it does not. Hellenistic kingdom of Paphos is another example of a composite; whereas medieval/Venetian Nicosia is a defined location. As another colleague commented on the project recently:

“The concept of Historical Units is something that I think needs some additional definition. I understand that other standards have the same fuzzy things, but poorly defined things add increasing difficulty as the dataset grows. My reading … is that you mean geographical feature which is uncomfortably close to Archaeological Entity. Have you considered just calling them ‘historical features’ and having a containment / recursive relationship?”

As we take the HGC forward therefore, we propose to modify this artificial footprinting mechanism, so that an HU is rather represented by a set of thematically, but not necessarily geographically, conjoined AEs.

Nea Paphos - an example of an HU in the HGC
Nea Paphos – an example of an HU in the HGC

This speaks to a much more fundamental problem of how archaeological data – bearing in mind that the HGC is about names, and is thus more a creature of history than of archaeology – is recorded. Much rhetoric of the semantic web in the discipline, at least in its earlier phases, focused on the need to link archaeological datasets ‘organically’, where data produced by one site can be linked and contextualized with that from another, without the excavation teams of either having to adopt a priori methods or procedures for data production. This may hold true to an extent, but our experience with HUs especially shows that when combining such data, some kind ofa posteriori aggregation process must be undergone. Otherwise, quite simply, one adds little to the data by linking it. In our current model, this is imposed by the user doing the aggregating; but the subjectivity this introduces is fraught with difficulties. Therefore, our next steps will be to develop our categorising and attributing capabilities for AEs, and begin aggregating into HUs on that basis. They will therefore be grown from the ground up in a way that is guided by the HGC data structure, rather than imposed from the user downwards.

On to prehistory: the Ancient Places of Cyprus


I currently have the great good fortune to be a visiting scholar at Stanford University’s Center for Electronic Spatial and Textual Analysis (CESTA). I have two aims while here: working on the monograph (on spatial narratives – more blogging on this to follow) upon which my term’s research leave from King’s is contingent, and developing a new project, recently christened “The Archaeology of Place in Ancient Cyprus”. This is follows the A G Leventis Heritage Gazetteer of Cyprus, which I have blogged about previously; but rather than being concerned with historical names, which are written down and attested, this phase is focusing on the prehistoric period – where, of course, there are no written records, and thus no known place-names (and no documented attestations of their spellings, forms etc). In the Archaeology of Place, We are creating a seed dataset which seeks to represent Cypriot archaeology of the prehistoric period, before any contemporary place-names are documented.  This involves a multistage process of critical quantification: starting with published material on prehistoric sites and features, we are examining how these can be defined in objective (and computable) terms, and how different units of archaeology can be represented at different scales. This will lead to a broader examination the ‘toponymic spaces’ of prehistoric features: how do the areas they occupy on the Earth’s surface relate to more recent place-name structures? And what strategies can we use to grow this dataset in the future, beyond the corpus of material currently available in print?

Critical quantification is key to this project.  I have real problems with the way the words ‘quantitative’ and ‘qualitative’ are often used in the Digital Humanities. They – as far as I can see – are terms that have evolved over a long period of time in the social sciences, where they have a well-understood meaning and a solid methodological grounding. In the DH, they are frequently used as catchy labels for ‘things which either can or cannot be machine-read respectively’. This is undoubtedly not helpful, given the great complexity and diversity of ‘humanities data’ – a term which, itself, is surely too broad to be all that useful.

So we are beginning with what can definitely be quantified.  When I. A. Todd et al define a ‘tomb’ in the cemetery at Kalavassos for example, we can treat this is a piece of discrete information, much as we are treating an attested name as a discrete piece of information in the HGC (with its own URI, and the possibility of other URIs for “smaller” pieces of information, such as finds, with which it has a container relationship). But in the future we will consider what other attributes could be added to each of these, for example, relationships with modern features which might not have been documented at the time. Online images, and pieces of related data from the geoweb. Even social media elements. This will open up the possibility for more in-depth experimentation using GIS – for example investigating least-cost pathways between sites in the northern Vasilikos Valley with points of known importance on the south coast, and how the finds, features and pits of those sites might be used to enrich that analysis. We will also undertake a broader consideration of what this exercise tells us about the epistemology of archaeology, and its quantitative aspects, might mean. While it makes perfect sense for quantification to follow the ‘objectivity’ of the material involved – beginning with physical objects, with clearly defined sites, and obvious statements that can be made about their attributes – we are interested in where the affordances of the digital environment of a database might take us in terms of contextualising them with purely digital objects; and how this might help us mediate spatial narratives of Cyprus’s distant past.

(Not quite) moving mountains: recording volcanic landscapes in digital gazetteers

Digital gazetteers have been immensely successful as means of linking and describing places online. GeoNames for example, now contains 10,000,000 geographical names corresponding to over 7,500,000 unique features. However, as we will be outlining at the ICA Digital Technologies in Cartographic Heritage next month in relation to the Heritage Gazetteer of Cyprus project, one assumption which often underlies them is fixity: an assumption that a name and a place and, by extension, its location on the Earth’s surface are immutably linked. This allows gazetteers to be treated as authorities. For example, a gazetteer with descriptions fixed to locations can be used to associate postal codes with a layer of contemporary environmental data and describe relationships between them; or to create a look-up list for the provision of services. It can also be very valuable for research, where a digital edition of a text has mentions of places. If contained in a parallel gazetteer, these can be used to provide citations and external authorities to those places, and also to other references in other texts.

However, physical geography changes. In the Aegean, where  the African tectonic plate is subducting beneath the Eurasian plate to the north, the South Aegean Volcanic Arc has been created, a band of active and dormant volcanic islands including the islands of  Aegina, Methana, Milos, Santorini, Kolumbo, and Kos, Nisyros and Yali. Each of these locations has a fixed modern aspect, and can be related to a record in a digital gazetteer.  However, these islands have changed over the years as a result of historical volcanism, and this history requires  the flexibility of a digital gazetteer to adequately represent it.


The island of Thera. The volcanic dome of Mt. Profitis Elias is shown viewed from the north.

I recently helped refine the entry in the Pleiades gazetteer for the Santorini Archipelago. Pleiades assigns a URI to each location, and allows information to be associated with that location via the URIs.  Santorini provides a case study of how multiple Pleaides URIs, associated with different time periods, can trace the history of the archipelago’s volcanism.  The  five present-day islands frame two ancient calderas, the larger formed more recently in the great Late Bronze Age eruption, and the other formed very much earlier in the region’s history. Originally, it is most likely that a single island was present, which fragmented over the millennia in response to the eruptions. Working backwards therefore, we begin with a URI for the islands as a whole: This covers the entire entity of the ‘Santorini Archipelago’. We associate all the names that have pertained to the island group through history – Καλλιστη (Calliste; 550 BC – 330 BC); Hiera (550 BC – 330 BC) and Στρογγύλη (Strongyle; AD 1918 – AD 2000), as well as the modern designation ‘Santorini Archipelago’ itself.  These four names have been used, at different times as either a collective term for all the islands, or, in the case of Strongyle, for the (geologically) original single island. This URI-labelled entity has lower-level connections with the islands that were formed during the periods of historic volcanism:  Therasia, Thera,  Nea Kameni, Mikro Kameni, Palea Kameni, Caimeni  and Aspronisi. Each, in turn, has its own URI.


The Santorini Archipelago in Pleiades

Mikro Kameni  and Caimeni are interesting cases as they no longer exist on the modern map. They are attested respectively by the naval survey of Thomas Graves of HMS Volgae (1851), and Caimeni was attested by Thomaso Porcacchi in 1620. Both formed elements of what are now the Kameini islands, but due to the fact that they have these distinct historical attestations, they are assigned URIs, with the time periods when they were known to exist according to the sources, even though they do not exist today.

This speaks to a wider issue of digital gazetteers, and their role in the understanding of past landscapes. With the authority they imbue to place-names, gazetteers might, if developed without reference to the nuances of landscape changes over time, potentially risk implicitly enforcing the view, no longer widely accepted, that places are immutable holders of history and historic events; where, in the words of Tilley in A Phenomenology of Landscape: Places, Paths and Monuments (1994), ‘space is directly equivalent to, and separate from time, the second primary abstracted scale according to which societal change could be documented and ‘measured’.’ (p. 9). The evolution of islands due to volcanism show clearly the need for a critical framework that avoids such approaches to historical and archaeological spaces.