1. Exploring large marine datasets using an interactive website and Google Earth Jon Blower, Dan Bretherton, Keith Haines, Chunlei Liu, Adit Santokhee Reading e-Science Centre Environmental Systems Science Centre University of Reading United Kingdom

2. Background Marine science community uses terabyte-scale datasets –numerical model output –satellite data Online data visualization is very useful Existing tools (e.g. LAS; first Godiva site, right) have many useful features but lack interactivity New Web technologies and geobrowsers can speed up exploration of large datasets –Can view data in context and at range of spatial scales

3. The Web Map Service standard International standard for serving map images and metadata on the Web Supports different map projections Directly supported by most GIS software, including some geobrowsers (e.g. NASA WorldWind) We have developed a WMS for NetCDF data –Optimized for fast generation of map images on the fly from source files –Open Source + available on web (ask me for details!) This is the basis for our interactive website

4. Architecture of our system DATA WMS Web server HTML, Javascript Web server and WMS could be co-located WMS = OGC-compliant Web Map Service metadata (XML) images (PNG) DATA WMS Could use images from many other WMSs

5. The Godiva2 website Select a dataset and variable to display http://lovejoy.nerc-essc.ac.uk:8080/ncWMS/godiva2.html

6. OSTIA sea surface temperature data metadata loaded from WMS and menus populated map image overlays loaded from WMS click and drag map and use pan and zoom controls powered by OpenLayers

7. Zoomed in on Gulf Stream Adjust colour range for higher contrast

8. Gulf Stream 2: ocean eddies visible set the transparency of the overlay to view underlying bathymetry click the map to find the actual data value at a point (uses GetFeatureInfo in WMS spec) Value: 292.4

9. Semi-transparent overlay isotherms follow bathymetry

10. Viewing in Google Earth Godiva2 website contains link to load currently-visible data in Google Earth –Our WMS outputs in KML format Can then view data alongside other KML datasets No problem with map projections! –Although overlays still look funny near the poles… Can’t interact with the data as much as is possible on the website

11. Large datasets in Google Earth Some marine datasets are high- resolution with global coverage We want to be able to view these datasets efficiently in GE –Cannot load whole dataset at full resolution! Solution: use a NetworkLink –Reloads a new image from the WMS at an appropriate resolution every time the user moves the globe or zooms in/out –GE automatically appends the bounding box (BBOX) of the visible area to the WMS query Works well, but is a little annoying for the user –Every small movement causes a refresh sea_water_temperature Temperature of the Water Column 1 http://…/WMS.py?SERVICE=WMS&REQ UEST=GetMap&VERSION=1.3.0&FORMAT=a pplication/vnd.google- earth.kml+xml&LAYERS=amm/sst&ELEVATI ON=0&TIME=2006-12- 03T00:00Z&WIDTH=500&HEIGHT=500 1 onStop 0

12. What we would like to see in Google Earth Support for depth dimension –i.e. 3-D ocean bathymetry –Also for subsurface geological features Ability to add custom toolbars and behaviour –i.e. an API interface Direct support for Web Map Service standard –present (to some extent) in NASA WorldWind

13. Summary We have built an interactive data visualization website from open standards and open source software –"spreadsheet-style" interactivity –available for other groups to use –implemented as Java web app (WAR file) –we have extended WMS in some ways (but backward-compatible) Potential to overlay data from many different providers, for intercomparison Google Earth simple to use and good for display –but website gives much greater functionality and interactivity –New animation features in GE are a big plus for us We’d like to know more about other geobrowsers See poster presentation and demo on Thursday

14. Plug for event next year! 2-day workshop on Google Earth and other internet mapping tools Focus on scientific applications for geobrowsers and geo-websites 2-3 April 2007, Cambridge, UK Presentations and coding tutorials Please email resc@rdg.ac.uk or see me if you are interestedresc@rdg.ac.uk