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Use of GIS and Web-based Mapping for Census Data Dissemination

Use of GIS and Web-based Mapping for Census Data Dissemination. United Nations Statistics Division. Outline. UN Recommendations/Census Geography Programme Building a Geographic Database Digital Data Dissemination Strategies and Users SALB Project

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Use of GIS and Web-based Mapping for Census Data Dissemination

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  1. Use of GIS and Web-based Mapping for Census Data Dissemination United Nations Statistics Division United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  2. Outline • UN Recommendations/Census Geography Programme • Building a Geographic Database • Digital Data Dissemination Strategies and Users • SALB Project • Handbook on Geospatial Infrastructure in Support of Census Activities United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  3. Census Geography Programme: a continuous process • The recommendations derived from UN EGM and Workshops on GIS and census mapping emphasized the need for countries to consider the census geography programme as a continuous process, rather than the sequential mapping and dissemination operations. • It was also emphasized that the use of and application of contemporary geospatial technologies and geographical databases is beneficial at all stages of population and housing census process. Geospatial improve the efficiency in the preparatory, enumeration, processing and dissemination phases of the census United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  4. Census Cycle United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  5. GIS with Census mapping at all stages Pre-census Census Post-Census (Pre-enumeration) (Enumeration) (Post-enumeration) GPS/PDA GIS Digital Mapping GPS Photo/Video GIS Digital Mapping Satellite Imagery GIS Internet (Map-Server) Administrative and Reporting Units EAs Units United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  6. Administrative hierarchy • Every country has its own specific administrative hierarchy • Definition: A system by which the country and each lower level set of administrative units (except the lowest) are subdivided to form the next lower level. • Administrative areas for which census data will be reported United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  7. Illustration of a nested admin.Hierarchy • Relationships among all types of administrative and reporting unit boundaries are defined. • hierarchical levels may have actual administrative roles • Other units may have statistical roles alone United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  8. Coding Scheme • EA: a basic geographic feature • Need for an identifier: linking the geographic feature to the census data (attributes) recorded for them • EAs and administrative units: coding scheme • A unique code assigned to each EA, used in data processing • Coding scheme: scalability, flexibility, intuitiveness, compatibility • Example of a hierarchical coding scheme 1 2 0 3 2 4 4 0 1 2 0 0 5 Enumeration area district locality province United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  9. Geocoding Concept • “Geocoding can be broadly defined as the assignment of a code to a geographic location. Usually however, Geocoding refers to a more specific assignment of geographic coordinates (latitude, longitude) to an individual address (UN Report of the EGM on Contemporary Practices in Census Mapping and Use of GIS, 2007) • Geo-coding: not limited to address-matching • Geocoding covers a continuum of spatial scales: from individual housing units to enumeration area level up to higher administrative or national levels. United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  10. Complete EA map with all components overlaid on one map display Main components are: Street network, Buildings EA boundaries layer Annotation, Symbols, Labels Building numbers Neatlines Legend United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  11. Components of a Hypothetical urban EA map United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  12. Implementation of an EA database • All large operational GISs are built on geodatabases; • Arguably the most important part of the GIS • Geodatabases form the basis for all queries, analysis, and decision-making. • A DBMS, or database management system, is where databases are stored. United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  13. Entity-Relationship Example: EA entity can be linked to the entity crew leader area. The table for this entity could have attributes such as the name of the crew leader, the regional office responsible, contact information, and the crew leader code (CL code) as primary code, which is also present in the EA entity. R 1-1 1-N United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  14. Implementation of an EA database • : Example of an entity table – enumeration area United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  15. Components of a digital geographic census database United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  16. Different Geographies • A geography for data collection: • EA level or even dwelling level • Another geography for data dissemination: • Aggregated level (confidentiality) United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  17. Uses of Graphs: Enriching the Understanding of GIS Data Sets • Exploratory Spatial Data Analysis • Linked Maps, Graphs & Tables • Dynamic Feature Selection • Animation • Visualization over Time United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  18. GIS capabilities: Visualization United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  19. Digital Data Dissemination Users • The wide range of potential users of disaggregated census data means that the NSO needs to pursue a multi-leveled digital data dissemination strategy. • Broadly, we can distinguish between the following types of users: • Advanced GIS users • Computer literate users • Novice users United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  20. Internet Mapping: How it works • The server-side approach • The client-side approach • Hybrid approach United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  21. Server-side approach request for map map output Server Client • In server-side approach, the user sends a request for a map to the server holding the database. Mapping software on the server processes the request, produces a map—for example, in GIF format—and sends it back to the user. • Server-side approaches are good at providing access to relatively simple maps to a large, non-expert audience. They would thus be most suitable for a census office’s presentation of census maps to the general public. United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  22. Client-side approach request for map data and applets Server Client • In client-side approach, in contrast, most of the processing tasks are performed on the user’s (client’s) computer locally. • Client-side approaches are preferable for Intranets, where a smaller number of users, with relatively comprehensive knowledge of GIS and mapping, access to complex databases. They would thus be suitable for in-house GIS data access for census office staff. United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  23. Hybrid approach • Combination of server - and client-side approaches. • Combination of the advantages of client-and server-based strategies: • - They provide flexibility to the user in querying and manipulating maps locally, but transfer most of the processing load in demanding analysis tasks to the server. • - This requires some degree of communication between client and server concerning the available processing power. United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  24. Data Stores Clients Web Services KML/ SOAP KML/ SOAP Web Mapping Architecture (Ref. B. Dickinson) • Mapping applications are accessed through standard web technologies to meet the needs of a specific business process or user. United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  25. Web Map Services • A Web Map Service (WMS) is a standard protocol for serving georeferenced map images over the Internet that are generated by a map server using data from a GIS database. (developed by OGC) • WMS is a widely supported format for maps and GIS data accessed via the Internet and loaded into client side GIS software • Most GIS software support WMS • GIS APIs United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  26. Cont… • Client technology: from “dumb” mapping to “smart” mapping application - The overall trend for web-based mapping is with more highly interactive, user-driven client interfaces as well as the desire by the general internet user to see the underlying data as a 3D environment and not a 2D flat-earth map. • Server-technology: service-oriented architecture (SOA) and broad spatial capabilities United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  27. The Second Administrative Level Boundaries data set project (SALB) • The Second Administrative Level Boundaries data set project (SALB) has been launched in 2001 in the context of the activities of the UN Geographic Information Working Group (UNGIWG) and has for objective to provide access to a working platform for the collection, management, visualization and sharing of sub national data and information in a seamless way from the national to the global level. • unsalb.org United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  28. Handbook on Geospatial Infrastructure in Support of Census Activities (2009) http://unstats.un.org/unsd/demographic/standmeth/handbooks/default.htm United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  29. Conclusions • Consider the Census Geography Programme as a continuous process • Adapt best practices to suit specific census requirements • Partner with other stakeholders (the public and private sector) in order to • Build the NSDI • Work jointly on coding efforts • Produce value added products – higher demand for census data United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

  30. THANK YOU! United Nations Regional Seminar on Census Data Dissemination and Spatial Analysis Amman, Jordan, 16-19 May, 2011

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