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WCS Data Exchange at the DataFed Server/Client  

WCS Data Exchange at the DataFed Server/Client  . Center for Air Pollution Impact and Trend Analysis (CAPITA) Washington University, St. Louis, MO. OGC TC Meeting Huntsville, AL March 2006 Team: R. B. Husar S. R. Falke K. Hoijarvi. GALEON IE – Examples DataFed as WCS Client.

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WCS Data Exchange at the DataFed Server/Client  

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  1. WCS Data Exchange at the DataFed Server/Client   Center for Air Pollution Impact and Trend Analysis (CAPITA) Washington University, St. Louis, MO OGC TC Meeting Huntsville, AL March 2006 Team: R. B. Husar S. R. Falke K. Hoijarvi

  2. GALEON IE – Examples DataFed as WCS Client U Florence/CNR-IMMA WCS Server THREDDS 4D (Time, X, Y, Z, H) data getCoverage for Map View getCoverage Height View getCoverage for Time View Surface Temp. dataset; Time, Lat, Lon Uniform spatial grid WCS getCoverage for Map View WCS getCoverage for Time View Returned NetCDF file grid file Client uses Unidata netCDF C library Each View is a slice through the 4D data cube

  3. Multidimensional AQ Monitoring Network Data Storage and Delivery through OGC Protocols WCS Data Access WMS Data View Services WCS SOS SOS SensorML WMS WFS Stations Observations Par-Meth Star Schema Param/Sensor/Method Station Info. Relational Data Model Observations

  4. DataFed WCS Server for Point Observation Data The current version of WCS (1.0) only supports grid and image data types. Coverages can include other representations of space-time varying phenomena, such as observations from an air quality monitoring network. An example WCS query for a point dataset in DataFed is:http://webapps.datafed.net/dvoy_services/ogc.wsfl?SERVICE=wcs&REQUEST=GetCoverage&VERSION=1.0.0&CRS=EPSG:4326&COVERAGE=AIRNOW.pmfine&FORMAT=CSV&BBOX=-125,22,-61,51,0,0&TIME=2005-06-27T15:00:00Z&WIDTH=999&HEIGHT=999&DEPTH=999 &BBOX=-100,22,-100,22,0,0&TIME=2005-06-20T00:00:00Z/2005-06-30T23:00:00Z

  5. Suggested Changes to WCS 1.1 Table 17 (SpatialDomain)

  6. Data Model for Air Quality Data Multidimensional Data Cube Most Views are slices through a cube of data organized by lat, lon, altitude, and time (X,Y,Z,T)

  7. Data Access through Adapters Sources Diverse formats Many data models Data WrapperData into geo-cubes Queries to views Virtual Data Cube Global geo-cube data model Makes queries data-neutral Query AdapterMaps query to protocol User selects protocols Output Protocol dependent User specified through Station-Point SQL Server, Files… DataFed SOAP,HTTP Get GeoTable CSV,XLS,GML SequenceImage, file OGC WCSHTTP Get, Post GeoGrid GML,NetCDF.. nDim GridOpenDAPNetCDF, … OGC WMSHTTP Get GeoImage GeoTIFF, PNG.. Other Traject., Event, Pic OGC WFSHTTP Get, Post Other MS Dataset.. DataFed An application framework for accessing, processing and browsing distributed datasets using loosely coupled web service components www.datafed.net

  8. Extra Discussion Slides

  9. ---The current WCS SpatialDomain requires BBOX. (Grid, Polygon, (or, in the future, Point) are optional). One could argue that if Polygon (or, in the future, Point) are specified, a BBOX is not required. So, SpatialDomain is mandatory and can be specified using one (or more) of BBOX, Grid, Polygon or Point. ---The current version of the WCS requires either a WIDTH,HEIGHT,DEPTH or RESX,RESY,RESZ to specify the size or resolution of the returned grid. When other non-grid data types are supported (polygon, point) these should be made optional since they are not relevant with non-grid data types. ---The current WCS specifies output formats. An table output format(s) will need to be added. This might include simple CSV tables or XML based tables. For example, DataFed supports CSV, .NET DataSet, and a netCDF table, which is a special table format, that will be adapted through future testing and to more standard formatting conventions.

  10. Coverage Definitions OGC Coverage Abstract Specification: "A coverage can be designed to represent a single feature, or a set of features. For example, a coverage may have a spatial domain containing a single parcel, or an entire platt. In the latter case, the coverage may be treated as modeling a single feature (the platt), or as a collection of features (the collection of parcels)."WCS 1.1 (draft): "Unlike WFS [OGC 02-058], which returns discrete geospatial features, the Web Coverage Service returns coverages representing space-varying phenomena that relate a spatio-temporal domain to a (possibly multidimensional) range of properties." Ron Lake, Galdos: "Loosely speaking a coverage is a sort of generalization of a geographic image - meaning it specifies the geometry of the coverage in some geographic space (e.g. some part of the earth's surface) and defines a function on that space. In image terms you can think in terms of the geometry as the image "grid" and the function as the radiometry or pixel values. The geometry can be a gridded structure (like most raster images) or can be a tesselated field, collections of polygons, a set of curves or curve segments or just a random collection of points. The function provides values at these points - such as soil samples (random point collection), road surface type (curve segments), crop type (polygons) and brightness (gridded image)."

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