A Web based solution for spatio-temporal visualization - PowerPoint PPT Presentation

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A Web based solution for spatio-temporal visualization

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  1. A Web based solution for spatio-temporal visualization Bo Zhao University of Florida July 15th, 2009

  2. Issues • the dimension of spatio-temporal visualization • the cache of historical events • the limits of value types • the expression of different calendars

  3. the dimension of spatio-temporal visualization

  4. Big Bang and the spatio-temporal integrated model umbrella Big Bang Theory in Astronomy

  5. Spatio-Temporal Cube J. Ronald Eastman, Earth Trends Modeler, Clark University, 2008

  6. Temporal model

  7. Temporal model

  8. Understandability N = ? Spatio-temporal dimensions

  9. the cache of historical events

  10. the cache of historical events • What is cache?

  11. the cache of historical events • Synchrony: download all the events at once • Different data format support: KML, CVS, GeoRSS,Json • Sort the events at the client side • Asynchrony: download the events required • Limited data format support • Sort the events at the server side

  12. Markercluster • For vector data: Markercluster • cluster = new MarkerClusterer( map, markers, { gridSize: 1, maxZoom: 15}); http://cga-3.hmdc.harvard.edu/timeslider~/

  13. raster data cache? http://mesonet.agron.iastate.edu/cgi-bin/wms/nexrad/n0r-t.cgi?LAYERS=nexrad-n0r-wmst&TRANSPARENT=true&FORMAT=image%2Fpng&TIME=2005-08-29T23%3A00%3A00&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&EXCEPTIONS=application%2Fvnd.ogc.se_inimage&SRS=EPSG%3A4326&BBOX=0,22.5,22.5,45&WIDTH=256&HEIGHT=256 TIME=2005-08-29T23%3A00%3A00 http://www.openlayers.org/dev/examples/wmst.html

  14. WMS-T • wms_timeextent: return the valid time values for the layer. • wms_ timeitem: this is the name of the field in the DB that contains the time values. • wms_timedefault: this value is used if it is defined and the TIME value is missing in the request. http://mapserver.org/ogc/wms_time.html

  15. the limits of value types • the year range changes due to the programming language or libraries themselves. • Ruby: 3156527048337996BC to 3156527048337998AD • Python: 0 to 9999AD • For ECMAScript 3.0 (the standard for javascript), • 53-bit double floating point • (-2^53, 2^53 - 1) • (-9,007,199,254,740,992, 9,007,199,254,740,991) • the year range will be from 271821BC to 275760AD. [1] http://www.mail-archive.com/simile-widgets@googlegroups.com/msg01472.html [2] ECMAScript Language Specification, Page 117, Dec, 1999,

  16. Calendars (ISO8601) • From Julian Calendar to Gregorian Calendar • 1582, Oct. 5 to Oct. 14 doesn’t exit. • javascript still have this time period, in our program, we should remove this time period. • Different countries adopted the Gregorian Calendar at different time, so we have to pay attention to the exact calendar the events are using. • George Washington’s Birthday: • February 22, 1732 Gregorian Calendar • February 11, 1732 Julian Calendar • The October Revolution • October 25, 1917 Julian Calendar • November 7, 1917 Gregorian Calendar

  17. Future work • When user moving the map or specify the time, the calendars would be changed due to the current countries within the map extent. • Support Raster data

  18. Demo • http://code.google.com/p/cga-gmaps-tools/

  19. Thanks, any questions?