Latest Posts

A Shared Perspective for PGIS and VGI – new paper

Part of the special issue on Public Participation GIS that was published in The Cartographic Journal, was a paper that was led by Jeroen Verplanke (ITC). This paper goes back to the workshop on participatory GIS in 2013, that was the leaving event for Dr Mike McCall in ITC, after which he continue to work in UNAM, Mexico. … Continue reading A Shared Perspective for PGIS and VGI – new paper

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Authoritative and VGI in a Developing Country: A Comparative Case Study of Road Datasets in Nairobi

The motivation behind the paper was that while there are numerous studies comparing VGI to authoritative data in the developed world, there are very few that do so in developing world. In order to address this issue in the paper we compare the quality of authoritative road data (i.e. from the Regional Center for Mapping of Resources for Development – RCMRD) and non-authoritative crowdsourced road data (i.e. from OpenStreetMap (OSM) and Google’s Map Maker) in conjunction with population data in and around Nairobi, Kenya.

Results from our analysis show variability in coverage between all these datasets. RCMRD provided the most complete, albeit less current, coverage when taking into account the entire study area, while OSM and Map Maker showed a degradation of coverage as one moves from central Nairobi towards more rural areas. Further information including the abstract to our paper, some figures and full reference is given below.

Abstract:

With volunteered geographic information (VGI) platforms such as OpenStreetMap (OSM) becoming increasingly popular, we are faced with the challenge of assessing the quality of their content, in order to better understand its place relative to the authoritative content of more traditional sources. Until now, studies have focused primarily on developed countries, showing that VGI content can match or even surpass the quality of authoritative sources, with very few studies in developing countries. In this paper we compare the quality of authoritative (data from the Regional Center for Mapping of Resources for Development – RCMRD) and non-authoritative (data from OSM and Google’s Map Maker) road data in conjunction with population data in and around Nairobi, Kenya. Results show variability in coverage between all these datasets. RCMRD provided the most complete, albeit less current, coverage when taking into account the entire study area, while OSM and Map Maker showed a degradation of coverage as one moves from central Nairobi towards rural areas. Furthermore, OSM had higher content density in large slums, surpassing the authoritative datasets at these locations, while Map Maker showed better coverage in rural housing areas. These results suggest a greater need for a more inclusive approach using VGI to supplement gaps in authoritative data in developing nations.

Keywords: Volunteered Geographic Information; Crowdsourcing; Road Networks; Population Data; Kenya  
Road Coverage per km2
Pairwise difference in road coverage. Clockwise from top left: i) RCMRD 2011 versus Map Maker 2014; ii) RCMRD 2011 versus OSM 2011; iii) RCMRD 2011 versus OSM 2014; iv) OSM 2014 versus Map Maker 2014 (Red cells: first layer has higher coverage; Green cells: second layer has higher coverage).

Full Reference:

Mahabir, R., Stefanidis, A., Croitoru, A., Crooks, A.T. and Agouris, P. (2017), “Authoritative and Volunteered Geographical Information in a Developing Country: A Comparative Case Study of Road Datasets in Nairobi, Kenya”, ISPRS International Journal of Geo-Information, 6(1): 24, doi:10.3390/ijgi6010024.

As always any thoughts or comments about this work are welcome.

Continue reading »

Authoritative and VGI in a Developing Country: A Comparative Case Study of Road Datasets in Nairobi

The motivation behind the paper was that while there are numerous studies comparing VGI to authoritative data in the developed world, there are very few that do so in developing world. In order to address this issue in the paper we compare the quality of authoritative road data (i.e. from the Regional Center for Mapping of Resources for Development – RCMRD) and non-authoritative crowdsourced road data (i.e. from OpenStreetMap (OSM) and Google’s Map Maker) in conjunction with population data in and around Nairobi, Kenya.

Results from our analysis show variability in coverage between all these datasets. RCMRD provided the most complete, albeit less current, coverage when taking into account the entire study area, while OSM and Map Maker showed a degradation of coverage as one moves from central Nairobi towards more rural areas. Further information including the abstract to our paper, some figures and full reference is given below.

Abstract:

With volunteered geographic information (VGI) platforms such as OpenStreetMap (OSM) becoming increasingly popular, we are faced with the challenge of assessing the quality of their content, in order to better understand its place relative to the authoritative content of more traditional sources. Until now, studies have focused primarily on developed countries, showing that VGI content can match or even surpass the quality of authoritative sources, with very few studies in developing countries. In this paper we compare the quality of authoritative (data from the Regional Center for Mapping of Resources for Development – RCMRD) and non-authoritative (data from OSM and Google’s Map Maker) road data in conjunction with population data in and around Nairobi, Kenya. Results show variability in coverage between all these datasets. RCMRD provided the most complete, albeit less current, coverage when taking into account the entire study area, while OSM and Map Maker showed a degradation of coverage as one moves from central Nairobi towards rural areas. Furthermore, OSM had higher content density in large slums, surpassing the authoritative datasets at these locations, while Map Maker showed better coverage in rural housing areas. These results suggest a greater need for a more inclusive approach using VGI to supplement gaps in authoritative data in developing nations.

Keywords: Volunteered Geographic Information; Crowdsourcing; Road Networks; Population Data; Kenya  
Road Coverage per km2
Pairwise difference in road coverage. Clockwise from top left: i) RCMRD 2011 versus Map Maker 2014; ii) RCMRD 2011 versus OSM 2011; iii) RCMRD 2011 versus OSM 2014; iv) OSM 2014 versus Map Maker 2014 (Red cells: first layer has higher coverage; Green cells: second layer has higher coverage).

Full Reference:

Mahabir, R., Stefanidis, A., Croitoru, A., Crooks, A.T. and Agouris, P. (2017), “Authoritative and Volunteered Geographical Information in a Developing Country: A Comparative Case Study of Road Datasets in Nairobi, Kenya”, ISPRS International Journal of Geo-Information, 6(1): 24, doi:10.3390/ijgi6010024.

As always any thoughts or comments about this work are welcome.

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The Rightful Place of Science: Citizen Science

‘The Rightful Place of Science: Citizen Science’ is a fairly slim and small format book. Darlene Cavalier and Eric B. Kennedy edited this short collection of papers that came out earlier in 2016. The book is part of a series, from the Consortium for Science, Policy, and Outcomes (CSPO) at Arizona State University. The series aims are … Continue reading The Rightful Place of Science: Citizen Science

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The Prevalence, Scaling and Variance of Urban Phenomena

This coming month (January 2017) sees the launch of another of Nature’s flagship journals Nature Human Behaviour. In it, Andres Gomez-Lievano, Oscar Patterson-Lomba, and Ricardo Hausmann explore an integrated model which explains the prevalence, scaling and variance of urban phenomena … Continue reading

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Tube Strike – Try Walking?

There’s a tube strike on today, with many tube stations expected to be closed. The inner city and central London are likely to be hardest hit, with stations closed in most in Zone 1 and all inside the Circle Line’s loop. Usefully, TfL recently published this map, which shows the central part of the Tube […]

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Crowdsourcing the Future?

About a month ago, on 7th December 2016, DR Kingsley Purdam (Manchester) organised a one day workshop on citizen science, and in particular on citizen science from a social science methodological perspective. The day organised with the support of the National Centre for Research Methods (NCRM). The purpose of the workshop/conference was to explore the … Continue reading Crowdsourcing the Future?

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My Year in Maps

Lots happened in 2016 to keep cartographers busy…here are some of my highlights (in no particular order).   Maps and the 20th Century: Drawing the Line at the British Library is an absolutely extraordinary exhibition at the British Library. The breadth and quality of maps on display is amazing. (Inspired by the exhibition, I am giving a […]

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Global Urban Constellations

Geographers have long grappled with the complex and ever changing configurations of global urbanism. Many terms have been coined to describe new 20th and 21st century urban forms: conurbations (Geddes, 1915), multi-nuclei cities (Harris & Ultman, 1945), megalopolis (Gottman, 1961), world cities (Hall, 1966), desakota (McGee, 1991),  fractal cities (Batty & Longley, 1994), network cities (Batten, 1995), … Continue reading Global Urban Constellations

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