1 Introduction to web mapping Dissemination of results, maps and figures ESTP course on Geographic Information Systems (GIS): Use of GIS for making statistics in a production environment Statistics Norway, Oslo, 26th to 30th of March 2012 Mr Ola Erik Nordbeck MSc Physical Geography/Adviser Statistics Norway Natural resources and environmental statistics PB 8131 Dep Kongens gate 6 N-0033 Oslo NORWAY Tel: Mob Attribution (by) Licensees may copy, distribute, display and perform the work and make derivative works based on it only if they give the author or licensor the credits in the manner specified by these.

2 Outline Web mapping Infrastructure Data and data modeling

3 Web mapping Is the process of designing, implementing, generating and delivering maps on the WWW and its product. Includes infrastructure and data designingimplementinggeneratingdelivering

4 Infrastructure, overview Clients Open Geospatial Consortium (OGC) Standards

5 Infrastructure, standards The most commonly accepted standards are created by the Open Geospatial Consortium (OGC) All OGC adopted standards are freely available through their web site, e.g. –WMS, Web Map Service –WFS, Web Feature Service –GEORSS, an emerging standard for encoding location (GEO) as part of a Web feed (Really Simple Syndication) –KML, Keyhole Markup language. Representation format for Google Earth software. Comparable to GML, but simpler –WCS, Web Coverage Service

6 Infrastructure, Web-pages ≠ Web-services Web-page = HTML data from the http server –HTML tags do formatting and embedded images –Conveys meaning using graphical and layout conventions –Directly user freindly –Data re-use only through “screen-scraping” Web-service ≈ Extensible Markup Language (XML) data from the http server –XML provides for custom tags and structure –Enables rich data description ⇒ direct data re-use –Processing required (e.g. styling) to make user freindly

7 Infrastructure, WMS vs WFS Web Map Service (WMS) –Data Request  getMap(area-of-interest, resolution, layers) –Response  A picture Web Feature Service (WFS) –Data Request  getFeature(featureType, filter-condition) –Response  An XML document describing features Filter ≈ SQL “where” clause –Scoped by data-model c8-d24c-11db c9a66 Sample 456dfg rock T15:15: :00

8 Infrastructure, Pictures vs data Pictures are immediately useable by users who understand the content and notation Data must be transformed to display for human consumption but can be used for other purposes as well c8-d24c-11db c9a66 Sample 456dfg rock T15:15: :00

9 Infrastructure, data storage Two dominant open source spatial databases: –PostGIS:  Adds support for geographic objects to the PostgreSQL object relational database  Preferred by the Norwegian Mapping Authority to commercial alternatives for WMS services due to better performance –MySQL:  Commonly used database, but with limited spatial functionality

10 Data modelling, overview Methodology: 1.Conceptual modelling 2.Feature types (digital object corresponding with identifiable, typed, object in the real world) 3.Unified Modelling Language Formalisation 4.UML->XML encoding rule, Conversion into XML (Geography Markup Language, GML)

11 Training: KML and Google Map Infrastructure: –Shape file to KML –KML on Google Servers –Google Maps for visualisation