Transcript Document

Dynamic Quick View,
interoperability and the future
Jon Blower, Keith Haines, Chunlei
Liu, Alastair Gemmell
Environmental Systems Science Centre
University 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 ice
high res (1/20°)
NSIDC Snow-water equiv.
(non-NetCDF)
ECMWF System 3
Reanalysis
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
WMS
OPeNDAP
– reading directly from NetCDF is
more efficient
NetCDF
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
NetCDF
NetCDF
TEP 2
TEP 1
OPeNDAP
Background imagery
(from NASA etc)
NetCDF
TEP 3
OPeNDAP
OPeNDAP
WMS
Requires minimal setup
Single point of failure
DQV website
Relies on fast, reliable
OPeNDAP servers
Possible future DQV architecture:
federated
TEP 1
NetCDF
OPeNDAP
WMS
TEP 2
NetCDF
OPeNDAP
WMS
TEP 3
NetCDF
OPeNDAP
WMS
Background imagery
(from NASA etc)
Requires each TEP to
install WMS
Third-party WMS
No single point of failure
More efficient
DQV website
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
[email protected]
To find website:
Google for "Godiva2"