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-Williamso.w.duke-williams@leeds.ac.uk

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

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0 10 20 30 40 50

Cell values

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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 Duke-Williamso.w.duke-williams@leeds.ac.uk

www.geog.leeds.ac.uk/people/o.duke-williams/