Transcript PowerPoint version - Centre for Interaction Data Estimation and

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 Duke-Williams
[email protected]
www.geog.leeds.ac.uk/people/o.duke-williams/
ESRC Award number H507 255177
Contents
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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
complex
Proportion to
of interior
cells in
Relationships between
2001 SMS Table MG301 of
datageographies
sets
used for
various values (detail)
0
10
20
30
100.0000000000%
10.0000000000%
Proportion of all eclls
1.0000000000%
0.1000000000%
1991 Census outputs
0.0100000000%
0.0010000000%
0.0001000000%
0.0000100000%
0.0000010000%
0.0000001000%
0.0000000100%
0.0000000010%
0.0000000001%
Source:
Dale, A. and Marsh, C. (eds)
Cell values
(1993) The 1991 Census User's Guide
40
50
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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
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Continuity
Improvement
Expansion
Preparation
Use of PostGIS and MapServer
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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 Duke-Williams
[email protected]
www.geog.leeds.ac.uk/people/o.duke-williams/