OpenStreetMap in Athens – as accurate as London

Most of the work that we carried out at UCL in evaluating the quality of OpenStreetMap is focused on England, and particularly on London. This is mainly due to the accessibility of comparative datasets. The reason for this was the availability of data, as the Ordnance Survey research unit kindly provided me with the full Meridian 2 dataset for comparison. More detailed comparison, for which we used MasterMap, came from the wonderful Digimap service, though because of the time that it takes to process it we were limited in the size of the area that was used for comparison.

One of the open questions that remained was the accuracy of data collection in other parts of the world. Luckily, Ourania (Rania) Kounadi, who studied our MSc in GIS at UCL, had access to detailed maps of Athens. She used a 1:10,000 map from the Hellenic Military Geographic Service (HGMS) and focused on an area of 25 square kilometres at the centre of the city. The roads were digitised from the HGMS map, and then the Goodchild-Hunter procedure was used to evaluate the positional accuracy.

The results show that for most of the roads in the evaluation area there was an overlap of 69% to 100% between OSM and HGMS datasets. The average overlap was very close to 90%. Her analysis also included attribute and completeness evaluation, showing that the quality is high on these aspects too.

OSM positional accuracy for Athens

So a pattern is starting to emerge showing that the quality of OSM data is indeed good in terms of positional accuracy. This is surprising at first glance – how come people who are not necessarily trained in geographical data collection and do not use rigorous quality assurance processes produce data that is as good as the authoritative data?

My explanation for this, as I’ve written in my paper about OSM quality, is that it ‘demonstrates the importance of the infrastructure, which is funded by the private and public sector and which allows the volunteers to do their work without significant personal investment. The GPS system and the receivers allow untrained users to automatically acquire their position accurately, and thus simplify the process of gathering geographical information. This is, in a way, the culmination of the process in which highly trained surveyors were replaced by technicians, with the introduction of high-accuracy GPS receivers in the construction and mapping industries over the last decade. The imagery also provides such an infrastructure function – the images were processed, rectified and georeferenced by experts and thus, an OSM volunteer who uses this imagery for digitising benefits from the good positional accuracy which is inherent in the image. So the issue here is not to compare the work of professionals and amateurs, but to understand that the amateurs are actually supported by the codified professionalised infrastructure and develop their skills through engagement with the project.’
Rania’s dissertation is available to download from here.

ICA Commission on Use and User Issues workshop – April 2010 – Call for papers

This is call for papers for a workshop on methods and research techniques that are suitable for geospatial technologies. The workshop is planned for the day before GISRUK 2010, and we are aware of the clashes with the AAG 2010 annual meeting, CHI 2010 and the Ergonomics Society Annual Conference. However, if you would like to contribute to the book that the commission is developing but can’t attend the workshop, please send an abstract and inform us that you can’t attend.

In the near future I’ll publish information about another workshop in March 2010 about the usability and Human-Computer Interaction aspects of geographical information itself – see the report from the Ordnance Survey workshop earlier in 2009.

So here is the full call:

Workshop on Methods and Techniques of Use, User and Usability Research in Geo-information Processing and Dissemination

Tuesday 13 April 2010 at University College London

The Commission on Use and User Issues of the International Cartographic Association (ICA) is currently working on a new handbook specifically addressing the application of user research methods and techniques in the geodomain.

In order to share experiences and interesting case studies a workshop is organized by the Commission, in collaboration with UCL, on the day preceding GISRUK 2010.

CALL FOR PAPERS

While there is growing awareness within the research community on the need to develop usability engineering and use and user research methods that are suitable for geographical and spatial information and systems, to date there is a lack of organized and documented experience in this area.

We therefore invite researchers with recent experience with use, user and usability research in the broad geodomain (cartography, GIS, geovisualization, Location Based Services, geographical information, GeoWeb etc.) to present a paper specifically focusing on the research methods and techniques applied, with an aim to develop the body of knowledge for the domain.

To participate, please send an abstract of 1 page A4 at maximum containing:

• A description of the research method(s) and technique(s) applied
• A short description of the case in which they have been applied
• The overall research framework
• Contact details and affiliation of the author(s)

We are also encouraging PhD researchers to submit paper proposals and share experiences from their research. At the workshop there will be ample time for discussing the application of user research methods and techniques. Good papers may be the basis for contributions to the handbook that is planned for publication in 2011.

Abstracts should be submitted on or before 1 December 2009 to the Chairman of the Commission Corné van Elzakker ( elzakker@itc.nl )

Also see:
the website of the ICA Commission on Use and User Issues and  the GISRUK2010 website

GISRUK 2010 at UCL – Call for papers

Geographical Information Science Research UK (GISRUK) is a research conference that has been taking place in different university campuses around the UK (and once in Ireland) since 1993. Despite the name, it is open not just to researchers from the UK, but also to international participants, who are very welcome.

For me, GISRUK was the first international conference in which I presented a paper eleven years ago, so I have a soft spot for it. It was very friendly and welcoming for a starting research student (which I was at the time). It was especially useful to discover that all the famous academics who attended it were friendly and open to questions.

The conference will be held at UCL in April 2010, and the call for papers is now out, so consider submitting a paper.

The papers are rather short, about 1500 words, so there is plenty of time to write one in time for the deadline of the end of November.

Interacting with Geospatial Technologies

At the end of September, the manuscript of ‘Interacting with Geospatial Technologies’ was submitted to John Wiley & Sons. This is the reason for the silence on this blog since July while the final chapters were written.

The book, which is an introduction to usability and Human-Computer Interaction aspects of GIS and other geospatial technologies, was written because there is no other recent book that covers these aspects while taking into account the special characteristics of geographical information and the extensive use of maps.

There were several books in the early 1990s dedicated to human factors of GIS or to cognitive aspects of these systems. Since then, there have been many published articles, but no easy-to-access summary of the outcomes in a way that is useful for developers or people who want to understand how to design more usable systems. So, while working on a paper that called for developing ‘usability engineering for GIS’ in 2005, I figured out that, actually, it was time to write an introductory text in this area. In the end, this is an edited textbook written by me together with a group of excellent collaborators: Jochen Albrecht, Clare Davies, Catherine Emma Jones, Robert Laurini, Chao Li, Aaron M. Marcus, Stephanie L. Marsh, Annu-Maaria Nivala, Artemis Skarlatidou, Carolina Tobón, Jessica Wardlaw and Antigoni Zafiri.

So the book provides an introduction to user-centred design and usability engineering from a geospatial technologies perspective, theoretical aspects of human understanding of space and collaborative systems, practical aspects of cartography and map design that are useful for developers and application designers, guidance for evaluating geospatial systems and some tips for designing desktop, Web and mobile based systems. Each chapter includes case studies and examples that make the material more concrete.

The book is scheduled to be out by March 2010. A lot of work went into writing the various chapters and ensuring that the content is covering all the needed elements to create a usable GIS – I hope that it will be useful!

OpenStreetMap and Ordnance Survey Master Map – Beyond good enough

OSM overlap with Master Map ITN for A and B roads

In June, Aamer Ather, an M.Eng. student at the department, completed his research comparing OpenStreetMap (OSM) to Ordnance Survey Master Map Integrated Transport Layer (ITN). This was based on the previous piece of research in which another M.Eng. student, Naureen Zulfiqar, compared OSM to Meridian 2.

There are really surprising results. The analysis shows that when A-roads, B-roads and a motorway from ITN are compared to OSM data, the overlap can reach values that are over 95%. When the comparison with Master Map was completed, it became clear that OSM is of better quality than Meridian 2. It is also interesting to note that the results of higher overlap with ITN were achieved under stricter criteria for the buffering procedure that is used for comparison.

As noted, in the original analysis, Meridian 2 was used as the reference dataset, the ground truth. However, comparing Meridian 2 and OSM is not like with like, because OSM is not generalised and Meridian 2 is. The justification for treating Meridian 2 as the reference dataset was that the nodes are derived from high-accuracy datasets and it was expected that the 20 metres filter would not change positions significantly. It turns out that the generalisation impacts the quality of Meridian more than I anticipated. Yet, the advantage of Meridian 2 is that it allows comparisons for the whole of England, since the file size is still manageable, while the complexity of ITN would make an extensive comparison difficult, time-consuming and lengthy.

The results show that for the 4 Ordnance Survey London tiles that we’ve compared, the results put OSM only 10-30% from the ITN centre line. Rather impressive when you consider the knowledge, skills and backgrounds of the participants. My presentation from the State of the Map conference, below, provides more details of this analysis – and the excellent dissertation by Aamer Ather, which is the basis for this analysis, is available to download here.

The one caveat that will need to be explored in future projects is that the comparison in London means that OSM mappers had access to very high-resolution imagery from Yahoo! which have been georeferenced and rectified. Therefore, the high precision might be a result of tracing these images, and the question is what happens in places where high resolution images are not available. Thus, we need to test more tiles and in other places to validate the results in other areas of the UK.

Another student is currently comparing OSM to 1:10,000 map of Athens, so by the end of the summer I hope that it will be possible to estimate quality in other countries. The comparison to ITN in other areas of the UK will wait for a future student who will be interested in this topic!

Web Mapping 2.0 – an introduction to Neogeography in Geography Compass

In October 2007, Francis Harvey commissioned me to write a review article for Geography Compass on Neogeography. The paper was written in collaboration with Alex Singleton at UCL and Chris Parker from the Ordnance Survey.
The paper covers several issues. Firstly, it provides an overview of the developments in Web mapping from the early 1990s to today. Secondly, in a similar way to my Nestoria interview, it explains the reasons for the changes that enabled the explosion of geography on the Web in 2005: GPS availability, Web standards, increased spread of broadband, and a new paradigm in programming APIs. These changes affected the usability of geographic technologies and started a new era in Web mapping. Thirdly, we describe several applications that demonstrate the new wave – the London Profiler, OS OpenSpace and OpenStreetMap. The description of OSM is somewhat truncated, so my IEEE Pervasive Computing paper provides a better discussion.
The abstract of the paper is:

‘The landscape of Internet mapping technologies has changed dramatically since 2005. New techniques are being used and new terms have been invented and entered the lexicon such as: mash-ups, crowdsourcing, neogeography and geostack. A whole range of websites and communities from the commercial Google Maps to the grassroots OpenStreetMap, and applications such as Platial, also have emerged. In their totality, these new applications represent a step change in the evolution of the area of Internet geographic applications (which some have termed the GeoWeb). The nature of this change warrants an explanation and an overview, as it has implications both for geographers and the public notion of Geography. This article provides a critical review of this newly emerging landscape, starting with an introduction to the concepts, technologies and structures that have emerged over the short period of intense innovation. It introduces the non-technical reader to them, suggests reasons for the neologism, explains the terminology, and provides a perspective on the current trends. Case studies are used to demonstrate this Web Mapping 2.0 era, and differentiate it from the previous generation of Internet mapping. Finally, the implications of these new techniques and the challenges they pose to geographic information science, geography and society at large are considered.’

The paper is accessible on the Geography Compass website, and if you don’t have access to the journal, but would like a copy, email me.