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

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

the dimension of spatio-temporal visualization

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

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

Temporal model

Understandability Spatio-temporal dimensions N = ?

the cache of historical events

What is cache?

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

Markercluster For vector data: Markercluster cluster = new MarkerClusterer( map, markers, { gridSize: 1, maxZoom: 15});

raster data cache? bin/wms/nexrad/n0r-t.cgi?LAYERS=nexrad-n0r- wmst&TRANSPARENT=true&FORMAT=image% 2Fpng&TIME= T23%3A00%3A00&SERVICE=WMS&VERSIO N=1.1.1&REQUEST=GetMap&STYLES=&EXCEPT IONS=application%2Fvnd.ogc.se_inimage&SRS =EPSG%3A4326&BBOX=0,22.5,22.5,45&WIDTH =256&HEIGHT=256 TIME= T23%3A00%3A00

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.

the limits of value types the year range changes due to the programming language or libraries themselves. Ruby: BC to AD 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 BC to AD. [1] [2] ECMAScript Language Specification, Page 117, Dec, 1999,

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

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

Demo

Thanks, any questions?