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 ESRC Award number H

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 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 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

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-Williams