An Exploratory Cartographic Visualisation of London through the Google Maps API
Maurizio Gibin; Alex Singleton; Richard Milton; Pablo Mateos; Paul Longley (2008). Applied Spatial Analysis and Policy, 1(2), 85-97. DOI: 10.1007/s12061-008-9005-5
Abstract
This paper begins by reviewing the ways in which the innovation of Google Maps has transformed our ability to reference and view geographically referenced data. We describe the ways in which the GMap Creator tool developed under the ESRC National Centre for e Social Science (NCeSS) programme enables users to ‘mashup’ thematic choropleth maps using the Google API. We illustrate the application of GMap Creator using the example of www.londonprofiler.org, which presents a repository of choropleth maps across a range of domains including health, education and other socioeconomic datasets against a backcloth of Google Maps data. Our conclusions address the ways in which Google Map mashups developed using GMap Creator facilitate online exploratory cartographic visualisation in a range of areas of policy concern.
Extended Summary
This research explores how Google Maps technology can be utilised to create innovative cartographic visualisation tools for spatial data analysis and policy decision-making. The paper describes the development and application of GMap Creator, a freeware tool that addresses a significant limitation in traditional Google Maps mashups - their inability to effectively display areally aggregated data through choropleth maps. Unlike conventional Google Maps applications that primarily show point data, this work demonstrates how complex geographical boundaries and thematic data can be visualised through pre-rendered image tiles integrated with Google’s mapping interface. The methodology employs a quadtree data structure where thematic information is rendered as 256×256 pixel tiles at different zoom levels, allowing users to overlay choropleth maps onto Google’s street and satellite imagery without compromising intellectual property rights or requiring complex vector data downloads. The research presents the London Profiler website as a practical demonstration, incorporating diverse datasets spanning health, education, and socioeconomic indicators. Key features include adjustable transparency controls, integration with external KML data feeds, and intuitive navigation tools that require minimal training compared to traditional GIS software. In the health domain, the system displays hospital admission ratios and general practice catchment areas through Percent Volume Contours, enabling healthcare planners to assess service provision against demographic characteristics. For higher education applications, the platform maps HEFCE participation data and related socioeconomic variables, potentially saving institutions substantial costs compared to individual GIS consulting services. The multicultural atlas component utilises surname and forename analysis to create detailed ethnicity classifications at output area level, providing more current and granular data than decennial census returns. The research identifies important limitations, particularly regarding interactive data analysis capabilities, as the tile-based architecture prioritises browsing over detailed interrogation of underlying data. While this approach enables scalable delivery to large numbers of users, it restricts advanced spatial analysis functions typical of desktop GIS applications. The study concludes that Google Maps mashups represent a valuable democratising technology for spatial data visualisation, making complex geographical information accessible to non-specialist users across policy domains. However, the research acknowledges ongoing challenges in balancing system scalability with analytical functionality, suggesting that future developments might explore hybrid approaches combining pre-rendered visualisation with server-side analysis capabilities. This work contributes to the broader understanding of Web 2.0 technologies in geographic information systems and demonstrates practical applications for evidence-based policy making in urban planning, public health, and educational administration.
Key Findings
- GMap Creator enables choropleth mapping through Google Maps API using pre-rendered tiles, overcoming traditional point-data limitations in mashup applications.
- The London Profiler demonstrates practical applications across health, education, and ethnicity domains with intuitive interfaces requiring minimal GIS training.
- Tile-based architecture allows scalable data delivery to numerous users but restricts interactive spatial analysis capabilities compared to desktop GIS.
- Healthcare applications include hospital admission mapping and GP catchment visualisation through Percent Volume Contours for service planning assessment.
- Higher education mapping of participation data could save institutions approximately £261,600 compared to individual GIS consultancy services across UK universities.
Citation
@article{gibin2008exploratory,
author = {Maurizio Gibin; Alex Singleton; Richard Milton; Pablo Mateos; Paul Longley},
title = {An Exploratory Cartographic Visualisation of London through the Google Maps API},
journal = {Applied Spatial Analysis and Policy},
year = {2008},
volume = {1(2)},
pages = {85-97},
doi = {10.1007/s12061-008-9005-5}
}