Free and Open Source Software for Geospatial (FOSS4G) Conference Proceedings Volume 13 Nottingham, UK Article 7 2013 OSM - GB: Using Open Source Geospatial Tools to Create OSM Web Services for Great Britain Amir Pourabdollah University of Nottingham, United Kingdom Follow this and additional works at: https://scholarworks.umass.edu/foss4g Part of the Geography Commons Recommended Citation Pourabdollah, Amir (2013) "OSM - GB: Using Open Source Geospatial Tools to Create OSM Web Services for Great Britain," Free and Open Source Software for Geospatial (FOSS4G) Conference Proceedings: Vol. 13 , Article 7. DOI: https://doi.org/10.7275/R5GX48RW Available at: https://scholarworks.umass.edu/foss4g/vol13/iss1/7 This Paper is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Free and Open Source Software for Geospatial (FOSS4G) Conference Proceedings by an authorized editor of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. OSM–GB OSM–GB Using Open Source Geospatial Tools to Create from data handling and data analysis to cartogra- OSM Web Services for Great Britain phy and presentation. There are a number of core open-source tools that are used by the OSM devel- by Amir Pourabdollah opers, e.g. Mapnik (Pavlenko 2011) for rendering, while some other open-source tools have been devel- University of Nottingham, United Kingdom. oped for users and contributors e. g. JOSM (JOSM [email protected] 2012) and the OSM plug-in for Quantum GIS (Quan- tumGIS n.d.). Abstract Although those open-source tools generally fit the purposes of core OSM users and contributors, A use case of integrating a variety of open-source they may not necessarily fit for the purposes of pro- geospatial tools is presented in this paper to process fessional map consumers, authoritative users and and openly redeliver open data in open standards. national agencies. If OSM is not effectively usable Through a software engineering approach, we have by this group, the gap between professional and focused on the potential usability of OpenStreetMap amateur map producers/consumers may never be in authoritative and professional contexts in Great filled and a sense of trust in OSM may never happen Britain. Our system comprises open source com- among those users. On the other hand, if OSM can ponents from OSGeo projects, the Open Street Map be used effectively by authorities, there will be a big (OSM) community and proprietary components. We chance that those users become active contributors, present how the open data flows among those com- leading to even more usability and reliability. ponents and is delivered to the Web with open stan- Having observed this research gap, this paper dards. Apart from the cost issues, utilizing the open- presents a system with a strong reliance on open source tools has offered some distinct advantages source geospatial components that can fit the British compared to the proprietary alternatives, if any was authoritative user’s requirements. The solution is available. At the same time, some technical limita- developed within the framework of a project called tions of utilizing current open-source tools are de- OSM–GB (OSMGB 2012). scribed. Finally a case study is shown for the usabil- In the rest of this paper, a software engineering ity of the developed solution. approach is taken to analyze the specific require- Keywords: OpenStreetMap, open source, open ments of authoritative users in Britain. Based on data, open standards. those requirements, the conceptual and detailed de- signs of our system are presented. The solution de- veloped also benefits from open standards and open Introduction data initiatives as will be explained later. Since its inception in 2004, OpenStreetMap (OSM) has become the main free source of digital maps Users’ Requirements made by the crowd. Although OSM is rapidly grow- ing in both contents and contributors, the belief that In the Great Britain context, the following require- it is made by amateurs is perceived to limit trust in ments were collected from authoritative users in the the value of this free data source within the tradi- first stages of the project, particularly through steer- tional GIS community. The quality aspects of OSM ing group meetings and direct contacts. The require- have been investigated by different researchers and ments are a combination of general and GB-specific with different tools (Girres and Touya 2010; Hak- functionalities, as will be explained in this section. lay 2010; Zielstra and Zipf 2010; Mooney and Cor- It is however noticeable that gathering the users’ coran 2011). We contend that to encourage uptake requirements is done within the open-source/open- of data, not only must the OSM community produce data contexts and implications, i. e. the users are better maps but the authoritative and professional generally willing to use the free software, data and use cases of OSM shall be facilitated. standards as opposed to the licensed products (for Because of the volunteer nature of the commu- many reasons including the known cost and updat- nity, many open-source geospatial tools have been edness issues) but they are looking for the best pos- developed around OSM in the recent years, ranging sible solution that fits their specific purposes. Oth- OSGEO Journal Volume 13 Page 41 of 114 OSM–GB erwise, the designed system may not address the re- OSM-XML is not a known format in our target au- quirements from the users that wish to benefit from thorities. At the time of this paper, there is no other the contractual or the quality-guaranteed services of- free public web service of vector OSM data for the fered by the available licensed products, e. g. the GB area, particularly in BNG. licensed map data from Ordnance Survey. Coordinate Reference System OGC Compliance In the context of Great Britain, one of the main con- The standards established by Open Geospatial Con- cerns in using a map in authorities is the availabil- sortium are the most widely accepted standards for ity of the map in the British National Grid (BNG or map delivery via the Web. The availability of OGC EPSG:27700) coordinate system. The OpenStreetMap compliant Web Services is a major advantage, if not website shows the map in Google Mercator (also a necessity, for a map service to be used by the au- called EPSG:900913), as is common in other public thorities. The main OGC standards for map deliv- maps (e. g. Google and Bing maps). The Open- ery are WMS (Web Map Service), WMTS (Web Map StreetMap tile service which can be used as the back- Tile Service), WMSC (Web Map Service, Cached) and ground in desktop GIS applications, is also only WFS (Web Features Service). The first three stan- in Google Mercator. The export facility of Open- dards are for raster map delivery and the last makes StreetMap website, as well as the OSM “planet files” the vector text based output in a number of estab- and replications use OSM-XML format, in which lished OGC standards including GML (Geographical the coordinates are encoded in Lat/Lon (EPSG:4326). Markup Language) and KML (Keyhole Markup Lan- There is other no free public service, at the time of guage). this paper, which can deliver OSM data in the BNG WMTS is currently run by the OpenStreetMap coordinate system. and some other mirrors in limited CRSs. Besides that, at the time of this paper, the only available Multiplicity of Layers world-wide WMS service is run by the University of Heidelberg called World OSM-WMS (GIScience Unlike public users, the authorities are specialized 2010), which is single-layer and is updated weekly. and need to have more flexibility in selecting the map No other WFS based on OpenStreetMap has been features they require. They need the map to be the- found for the GB area. matically separated in layers, so the users do their job by superimposing the required layers. For vector maps, thematic filtering of the features is commonly Consistent Access to National Open Maps feasible in GIS applications, but for raster maps such filtering is usually impossible. Although the features In Britain, Ordnance Survey provides a set of open of OpenStreetMap are tagged and the tags can be data (OS 2013) in different formats and resolutions. used to separate them into multiple layers, the OSM The authorities may have full access to the Ordnance website renders them all into a flat map. At the time Survey’s open and non-open maps, however if they of this paper, there is no free public service offer- are willing to work with OSM they prefer to have an ing multi-layered raster map for OSM. It is however integrated access to those national maps in the same possible to use the filtering functionality of the OSM platform, particularly for superimposing the maps API, subject to knowing the required tag combina- from different sources. The project’s focus has been tion for the specified thematic map, which produces on open data sets, thus integrating some parts of the raw text output. OS Open Data with OSM and delivering them in a single platform can enhance the usability of the fi- Raster and Vector Maps nal product. Among the OS Open Data products, VectorMap District (VMD) is the most comparable Raster maps are necessary but not enough if de- to OSM and so was selected to be delivered via the tailed map analysis is required in the authoritative OGC Web Services (WFS in this case) together with use cases. Querying and filtering by geometry or by OSM. At the time of this paper, no free WFS access attributes, applying routing algorithms, customized to the VMD is found (although the University of Ed- rendering and labeling are examples of the func- inburgh’s Digimap OpenStream service offers WMS tionalities that can only be achieved in vector maps.