Using PostGIS and MapServer in the Census Interaction Data Service
Presentation to
AGI Technical SIG'Open-Source in GIS'
British Antarctic Survey, Cambridge, 27th April 2006
Oliver [email protected]
www.geog.leeds.ac.uk/people/o.duke-williams/
ESRC Award number H507 255177
Contents
• What is CIDS
• What is PostGIS?
• What is MapServer?
• Why did we select these tools?
• How do we use them?
Census Interaction Data Service (CIDS)
• A Data Support Unit funded through the ESRC/JISC Census Programme 2001-2006
• Provide access to Census interaction data sets
• Data is provided via WICID, the Web-based Interface to Census Interaction Data
Census Interaction Data• What are the Census interaction data?
– Migration data– Journey to work data– Journey to school data
• Interaction data are flow data– Also referred to as ‘origin-destination’ data
• They have historically been under-used
CIDS challenges
• Data are large and sparse• Need to support many geographies• Need to provide simple interface to complex
data sets
0.0000000001%
0.0000000010%
0.0000000100%
0.0000001000%
0.0000010000%
0.0000100000%
0.0001000000%
0.0010000000%
0.0100000000%
0.1000000000%
1.0000000000%
10.0000000000%
100.0000000000%
0 10 20 30 40 50
Cell values
Pro
po
rtio
n o
f all
ecll
s
Proportion of interior cells in 2001 SMS Table MG301 of various values (detail)
Source: Dale, A. and Marsh, C. (eds) (1993) The 1991 Census User's Guide
Relationships between geographies used for 1991 Census outputs
WICID• Facilitate data extraction and downloading
• User-friendly
• Flexible query-building approaches
• Analysis functions
• Outputs in various formats
WICID components
• Apache web server• PostgreSQL DBMS
– PostGIS spatial extensions
• PHP• MapServer
– PHP/MapScript
What is PostGIS?
• An extension to the PostgreSQL database• Allows vector based geometric objects to
be stored and manipulated• Open GIS Consortium (OGC) standards
– Well Known Text (WKT)– Well Known Binary (WKB)– OGC Simple Features for SQL– OGC feature catalogues
What is MapServer?
• Open source package distributed by University of Minnesota
• One of a number of tools that can use PostGIS data
• Can also a variety of other formats
Why did we select PostGIS and Mapserver?
• Open source
• Already using PostgreSQL– Benefit of map and other data being stored in
the same database
• Mapserver includes PHP scripting abilities
• Can implement map based tools with very low client requirements
How do we use these tools?
• Maps created by MapServer
• Data queried directly by SQL
Selection tools
Selection tools
Selection tools
Distance usage
The future
• CIDS to CIDER
• Future uses of PostGIS and MapServer
CIDER
• Centre for Interaction Data Estimation and Research– August 2006 to July 2011– ESRC 2006 Census Programme
• Objectives– Continuity– Improvement– Expansion– Preparation
Use of PostGIS and MapServer
• Use of OS backdrops in maps
• Thematic maps for displaying results
• Downloads of spatial data
• Distance based generation of new geographies
Using PostGIS and MapServer in the Census Interaction Data Service
Oliver [email protected]
www.geog.leeds.ac.uk/people/o.duke-williams/
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