The document discusses using geobrowsers for thematic mapping. It examines the current capabilities of geobrowsers like Google Earth and Google Maps for thematic mapping. It also explores how thematic mapping could be better supported in geobrowsers through techniques like choropleth maps, proportional symbol maps, and using the third dimension. The author developed a Thematic Mapping Engine to generate thematic maps in geobrowsers using open data and standards.

1. Using geobrowsers for thematic mapping Bjørn Sandvik MSc in Geographical Information Science University of Edinburgh Postgraduate Research Conference 17-19 March 2008 Supervisors: Bruce Gittings and James Reid

6. Thematic Mapping Engine Thematic Mapping Parameters OpenLayers PHP Library Web Interface Web Processing Service Thematic Mapping Engine

7. Choropleth map in Google Earth $map = new ThematicMap(); $map->setType("choropleth"); $map->addData($values); $map->addBorders($borders); $map->setColourRange($colors); $kml = $map->getKML(); Data source: UNdata

8. Using the 3rd dimension $kml = $map->getKML(‘3D’); Data source: UNdata

9. Proportional symbol maps $map->setType(“symbol"); $map->setBasenam($basemap); $map->setSymbolSize(”pop”); Data source: UNdata and Tom Patterson

10. Challenge 1: polygon holes Data source: UNdata

11. Challenge 2: Mercator Can OpenLayers do better?

12. Challenge 3: Performance

13. Challenge 4: Complexity function kmlSymbolCalculator( $longitude, $latitude, $distance, $points, $altitude ) { $EARTH_RADIUS_EQUATOR = 6378140.0; $RADIAN = 180 / pi(); $long = $longitude; $lat = $latitude; $long = $long / $RADIAN; $lat = $lat / $RADIAN; $f = 1/298.257; $e = 0.08181922; $kml = '<Polygon>' . PHP_EOL . ' <outerBoundaryIs>' . PHP_EOL . ' <LinearRing>' . PHP_EOL . ' <coordinates>'; for ( $bearing = 0; $bearing <= 360; $bearing += 360/$points) { $b = $bearing / $RADIAN; $R = $EARTH_RADIUS_EQUATOR * (1 - $e * $e) / pow( (1 - $e*$e * pow(sin($lat),2)), 1.5); $psi = $distance/$R; $phi = pi()/2 - $lat; $arccos = cos($psi) * cos($phi) + sin($psi) * sin($phi) * cos($b); $latA = (pi()/2 - acos($arccos)) * $RADIAN; $arcsin = sin($b) * sin($psi) / sin($phi); $longA = ($long - asin($arcsin)) * $RADIAN; $kml .= &quot; &quot;.$longA.&quot;,&quot;.$latA; } $kml .= ' </coordinates>' . PHP_EOL . ' </LinearRing>' . PHP_EOL . ' </outerBoundaryIs>' . PHP_EOL; return $kml; }

14. Challenge 5: Temporality

15. Best to follow standards? Thematic Mapping Engine DDI/DCMI SDMX Metadata ISO 19115:2003 OGC SLD/SE extension? Best practices Thematic mapping techniques GML / WFS WKT / WKB GeoJSON XML CSV Array JSON TMS Parameters Storage Data in Data out Geobrowser WMS Map Tiles KML WFS / GML GeoJSON GeoRSS

19. Website and blog thematicmapping.org