possibilities & pitfalls of web sites for spatial data dissemination

1. Barend Köbben International Institute for Geo-information Science and Earth Observation (ITC) possibilities & pitfalls of web sites for spatial data dissemination

2. Setting the stage Barend Köbben <kobben@itc.nl>

3. Overview • Why use maps? • Changing Cartography • Why use the Web? • WebCartography: • static ‘view-only’ web-maps • static ‘interactive’ web-maps • dynamic ‘view-only’ web-maps • dynamic ‘interactive’ web-maps • How the Web works

4. Why use graphics? • Graphics are international: • uitgang, exit, Ausgang, sortie, uscita, salida,etc... =

5. Why use graphics? • Graphics are holistic: • “a picture says more than a thousand words...” • “First road left, then cross the railroad and continue until you cross the river, then the first right and right again on the crossroads...”

6. Why use maps? • rainfall • 12, 13, 14 september • dirksland de bilt apeldoorn

7. Why use maps? • apeldoorn • de bilt • dirksland

8. Why use maps? • Maps give an instant and complete overview of spatial phenomena

9. Developments in cartography • 1950’sfirst computer maps • 1960’s / 1970’sautomation of existing tasks (line drawings) • 1980’scomputer-assisted map production • 1990’sfull integration of maps in GI (scientific) visualization from supply to ‘demand’ driven mapping Internet / Web environments • 2000’s location-based services in mobile environments

10. CHANGING CARTOGRAPHY  new kinds of maps • Interactive maps • Realism & false realism: Virtual worlds • Depiction of movement & change: Animated maps • Combining maps with other graphics, sound and moving images: Multimedia

11. Traditional vs. interactive maps • traditional map = view only map • bitmaps (scanned images) • interactive map (map as interface) • clickable map: leads to other (web) information; map as menu; • interactive map (user–defined contents) • maps on demand; user defines contents and/or symbolisation

12. Interactive maps

13. Virtual worlds • The world mapped “as it is” • Perspective view (instead of orthogonal) • Complete (not generalised) • Realistic (not symbolised) Photo–realism (or pseudo–realism)

14. Virtual Worlds

15. Animated maps • For showing dynamic phenomena • As animated maps (“movies”) • As dynamic real-time images (dynamic webpages) • For moving through Virtual Worlds • As animations (eg. animatedGIF, Quicktime movies) • With interactive contents (modelled worlds, eg. games, VRML)

16. Multimedia definition • “The combination of various media parts into a coherent whole” • Media parts: • maps, graphics, text, moving images, sound, text, etc... • Coherent whole: • The whole is more than the sum of the parts

17. CHANGING CARTOGRAPHY  new (digital) data dissemination a distributed, inter-linked collection of data + protocols to publish and retrieve this data(http, html, etc...) • On CD–ROM • On the World Wide Web:

18. Why use the Web? • WWW information is virtually platform-independent • unrivalled in its capacity to reach many users at minimal costs • easy to update frequently • the WWW allows for a dynamic and interactive dissemination of spatial data: New map types

19. Disadvantages • Potential user group is limited (though growing fast) and skewed (computer- literate and connected people) • Difficult to charge for use • Fast-moving: • Information is time-sensitive • Interactivity is a must

20. World Internet users Pie slices show regional shares of world population. Dark wedges show Internet users (numbers indicate Internet users as a percentage of the total population per region). Internet users of total world population: 5.7 % [UNDP 2000]

21. Technical constraints • Map and file size • Screen size & resolution • Download times • File formats • Standardised: GIF & JPEG (raster), SVG (vector) • Colour use • Only 216 “web-save” colours  Special map design needed

22. WebCartography • Some examples • Further examples: • http://kartoweb.itc.nl/webcartography/workshop Webcartography/index.html • Further reading: Kraak, Menno-Jan & Allan Brown (eds) (2001):Web Cartography, developmentsand prospects, London and New York: Taylor & Francis

23. WebCartography

24. Static maps – view only • Existing maps (scanned) • mainly interesting for Historical maps • Specially designed web-maps • eg. cartography students at ITC

25. Static maps – interactive interface • Map is entrance to other (map) information: ‘clickable maps’ • HTML clickable maps (Netherlands in provinces) • Flash maps of Overijssel (data, magnify) • User can change map content & visualisation: • from simple layers on/off… map of Overijssel (Flash) • …to fully interactive Tuerlersee topographic map (SVG)

26. WebCartography

27. Dynamic web maps • For showing dynamic phenomena • As animated maps (‘movies’) (eg. gondwana) • As dynamic real-time images (ANWB)

28. Dynamic web maps • For moving through Virtual Worlds • As a view-only animation (eg. animated GIF) • With an interactive interface (“movie”) (eg. quicktime) • With interactive contents (modelled) (eg. games, VRML)

29. Web graphics today • standardised raster formats: • fixed resolution (quality low or files large) • original content (“information”) is lost • difficult to get interactivity (other than ‘clickable maps’) • binary formats (no searching/indexing of information, no internationalisation) W3C standardised: GIF, JPEG • non-standard industry (proprietary) formats • raster or vector; offering diverse, possibilities Countless examples, eg: PDF, Flash

30. Web graphics of the future: • vector graphics, resolution-independent • "content" of information saved • client-side ‘rendering’ -> customisable for viewing environment • XML-based • W3C’s designated backbone for the future Web

31. XML (eXtensible Markup Language) • not a fixed format, but a ‘metalanguage’ —a language for describing other languages— • lets you design your own customized markup languages for limitless different types of documents • eg. Geographic Markup Language (GML) - OpenGIS standard for geographical information • written in SGML (the international standard metalanguage for text markup systems; ISO 8879) • much more than a webpage language • useable for storing and exchanging any kind of structured data

32. Scalable Vector Graphics (SVG) • graphic quality • 2D vector graphics + in-line raster (jpeg, gif, png) • all anti-aliased • scalability • vectors = resolution-independent (zoom, pan) • transformable, user defined ‘coordinate-spaces’ • interactivity • declarative (in SVG objects) • procedural (Javascript) • animated & dynamic maps • dynamic change of object attributes • declarative syntax (limited file size) • animation client-side

33. VRML model of Ramelerbrink: http://kartoweb.itc.nl/public_examples/Ramelerbrink_VRML.html Flyby Quicktime movie: http://kartoweb.itc.nl/public_examples/flyby.mov Interactive application of Gondwana continental drift: http://kartoweb.itc.nl/gondwana/gondwana.html Interactive contents (layers on/off) - Flash: http://kartoweb.itc.nl/public_examples/overijssel_interactive_contents.swf Interactive interface (magnifiy) - Flash: http://kartoweb.itc.nl/public_examples/overijssel_mapmagnifier.swf Interactive contents (map as menu) - Flash: http://kartoweb.itc.nl/public_examples/overijssel_interactive_interface.swf Interactive interface (map as menu) - HTML: http://kartoweb.itc.nl/public_examples/Clickable_map_NL_provinces/index.html Further examples of WebMaps: http://kartoweb.itc.nl/webcartography/workshop Webcartography/index.html Swiss map with LOD: http://kartoweb.itc.nl/public_examples/LOD_CH_SVG/LOD.html Swiss topographic map of Tuerlersee (hillshade & cross-sections): http://kartoweb.itc.nl/public_examples/Tuerlersee.html Morphing of London underground: http://kartoweb.itc.nl/public_examples/UndergroundMorph.html Links to examples: