Dynamic Quick View, interoperability and the future

Jon Blower, Keith Haines, Chunlei Liu, Alastair Gemmell

Environmental Systems Science CentreUniversity of Reading

United Kingdom

Introduction• We have developed an interactive website and map

server for data visualization– work originated in UK e-Science programme and National

Centre for Ocean Forecasting• Takes advantage of freely-available Web GIS tools• We have integrated our prototype with the MERSEA

system (via OPeNDAP)– not yet an approved MERSEA service

• We hope to demonstrate the exciting potential of this system and benefits of adherence to open standards– Will be very important in INSPIRE

• Potential use is much wider than marine science

Dynamic Quick View (DQV) Service• Gives very fast

previews of 4-D data on an interactive website

• Reads data from OPeNDAP servers at the MERSEA TEPs

• Draggable, zoomable map

• Allows the fast creation of animations

• Based on a standards-compliant Web Map Service

Selection of depth

Select from all the depth levels of the model

Selection of time (range)

Select from all the timesteps in the model

Selection of a time range leads to an animation

Finding the data value at a point

Click on the data layer, data value and precise position is shown

Lon: -64.08 Lat: 36.21 Value: 19.27

Timeseries plots

If a time range is selected, can create a timeseries plot at a point

Export to Google Earth• DQV website

contains link to load currently-visible data into Google Earth– Our WMS outputs in

KMZ format

• Can then view data alongside other KML datasets– e.g. DAMOCLES

• Can view animations of data

• No problem with map projections!

Visualize alongside third-party data• Hurricane Katrina,

August 2005

• Showing sea surface temperature (UK Met Office) and storm position/intensity (ECMWF)

• Winds cause upwelling of cooler subsurface water on right-hand side of the cyclonic storm track

Selection of non-MERSEA datasets also available

OSTIA (GHRSST-PP): SST and sea icehigh res (1/20°)

NSIDC Snow-water equiv.(non-NetCDF)

ECMWF System 3Reanalysis

Everything on the website can be exported to Google Earth

The Web Map Service• DQV website is built on a

custom-made WMS– backwards-compatible with

OGC spec, version 1.3.0

• Optimized for fast, dynamic generation of map images

• Enhancements to allow changing of colour scale, generation of timeseries plots, etc

• Reads data from CF-NetCDF files or OPeNDAP servers– reading directly from NetCDF is

more efficient

OPeNDAP

NetCDF

WMS

Important features of our WMS implementation

• Fast generation of images

• Handling of four-dimensional data

• Handling of data on unusual grids, e.g. NEMO

• Dynamic change of colour scale extent

• Generation of animations

• Export to Google Earth

Current DQV architecture: centralized

OPeNDAP

NetCDF

TEP 1

OPeNDAP

NetCDF

TEP 3

OPeNDAP

NetCDF

TEP 2

WMS

DQV website

Requires minimal setup

Single point of failure

Relies on fast, reliable OPeNDAP servers

Background imagery(from NASA etc)

Possible future DQV architecture: federated

OPeNDAP

NetCDFTEP 1

DQV website

Requires each TEP to install WMS

No single point of failure

More efficient

WMS OPeNDAP

NetCDFTEP 2

WMS OPeNDAP

NetCDFTEP 3

WMS

Third-party WMS

Background imagery(from NASA etc)

MERSEA data in third-party clients

NASA World Wind

Cadcorp SIS

Google Earth

In-situ data• Picture left shows

comparison of NEMO model and observations for Nov 2004

• Red dots show bad model-obs fits, green dots are good fits

• Google Earth allows very efficient browsing of these large datasets

• Could do the same for MERSEA systems, e.g. CORIOLIS

• Could read obs and model data from different sources and bring together in Google Earth or another client

DQV future enhancements

• Display of wind/current fields as vectors• Caching of image tiles for performance increase• Support for more map projections

– E.g. polar stereographic

• Display of observations on website• Integration with GeoServer, THREDDS

– Requires community assistance

• …Lots more!

Conclusions

• We have demonstrated a dynamic website for exploring MERSEA data quickly and interactively

• Based on an OGC Web Map Service– but with important enhancements– other WMS implementations will not support all the

features in DQV

• Gives interoperability with third-party services– view MERSEA data alongside third-party data– will be important in INSPIRE

• Exciting possibilities for the future!

Contact details

jdb@mail.nerc-essc.ac.uk

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