1. OSGIS 2012, Nottingham
Sandy Buchanan
Project Manager
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2. What is a Cartogram?
car·to·gram/ˈ kärtəˌ gram/
A map on which statistical information is
shown in diagrammatic form.
A small diagram on the face of a map,
showing quantitative information.
An abstracted and simplified map the base of
which is not true to scale.

3. Funded By Developed BY
ESRC EDINA

4. Example
Traditional Map with Cartogram – Area proportional
shading to cases

5. Example
Local Authority GCSE performance

6. Project Goals
• To enable social scientists and others to
create, share and reuse bespoke cartograms
• The project will offer a production strength
generic service and associated toolset.
• It will alleviate the problems associated with
production complexity and computational
expense.
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7. Technology Being Used
• Celery and RabbitMQ to manage the distributed
task queue including the ability for multiple
instances on multiple servers i.e. send it to the
cloud if required
• Using ScapeToad Cartogram generation.
ScapeToad is a cross-platform, open-source
application for producing cartograms. Its written
in Java and uses the ESRI Shapefile format for
input and output.
• The algorithm used to compute the cartogram is
based on the diffusion-based method for
producing density equalizing maps by Michael T.
Gastner and M. E. J. Newman

8. Technology Solution

9. Outputs
• The main output from the project is an API
• The API is then used to service a website
allowing non technical users to generate
cartograms.
• There is also a ‘widget’ allowing users to
embed the basic website functionality in their
own site.
• The API, can of course, be used directly

10. The API
• The API is accessed through the use of cURL
commands or a REST Console/Client. These are
available as add-ons for Chrome and Firefox web
browsers.
• Documentation and user guide available soon

11. The API
• The API
• Allow authenticated users to upload a validated, virus
checked shapefile.
• The shapefile can be ‘simplified’ to reduce computational
time.
• Select polygon layer to transform and the metric variable
linked to that layer that will become the metric layer for the
cartogram
• Utilise the Gastner/Newman diffusion-based algorithm
• Allow the computation to be farmed out to multiple servers if
required for complex cartograms
• Allow retrieval of new cartogram, shapefiles, distortion grid
and metadata

12. The Website
• Searchable gallery of user contributed
cartograms
• Cartogram generation interface
• Multiple cartograms from a single
shapefile
• Output generation
• Download
• Access to ‘Widget’ Code
• Access to API documentation
• Further Cartogram resources

13. Website

14. Job Management Screen

15. Shapefile and Metadata

16. Creation Parameters

17. Cartogram View and Download

18. Generate Widget Code

19. Embedded Widget

20. Progress
• API is complete
• Website is complete and about to be moved onto
production (a few workflow tweaks needed)
• Widget works
• Looking for volunteer testers