# Presentation: 053479

## Key Results from GALEON

- John Caron
- Ben Dominico
*UCAR/Unidata*

## Background

- Open GIS Consortium (OGC)
- Industry/government consortium for creating interoperable standards for GIS
- Commercial, not open source
- Web Coverage Service (WCS)
- Client-server protocol for “coverage” data (satellite data seems to be their main use case)
- XML over HTTP / SOAP
- Specification version 1.0 (1.1 almost ready)
- GALEON: OGC “interoperability experiment” for WCS clients and servers

**Notes:**
Not on Google

## GALEON Objectives

- Determine suitability of WCS interface for serving model data to GIS community (4D vs 2D)
- Examine possibility of extending WCS to add netCDF to current blessed encodings:
- GeoTIFF (TIFF with geospatial tags)
- HDF-EOS (HDF4 plus NASA metadata)
- DTED (NIMA/DOD digital elevation)
- NITF (NIMA/DOD images)
- GML (OGC XML data encoding)
- Experiment with GML (Geography Markup Language) dialects and netCDF files
- Make recommendations to WCS 1.1 spec

## Active Participants

**Unidata/UCAR** (Ben Domenico, John Caron)
**U of Florence and IMAA-CNR** (Stefano Nativi, Lorenzo Bigagli)
**International University Bremen** (Peter Baumann)
**George Mason University** (Liping DI, Wenli Yang)
**CadCorp** (Martin Daly, Frank Warmerdam (GDAL))
**Research Systems International UK Ltd** (David Burridge, Norman Barker) (IDL)
**NCDC**, National Climatic Data Center (Glenn Rutledge, Dan Swank)
**NERC **Natural Environment Research Council/British Atmospheric Data Center (Dominic Lowe, Andrew Woolf)
**Washington University St. Louis** (Stefan Falke, Rudolf B. Husar)
- Providing Specialized Expertise
**Interactive Instruments** (Clemens Portele)
**NASA** Geospatial Interoperability Office (John Evans)

## TDS GALEON Development

- Process WCS GET requests (not SOAP)
- Generate WCS XML documents
- Map bounding boxes to index ranges
- No regridding, no reprojection, want “raw” data
- Create GeoTIFF images
- Greyscale: min/max -> 1..255
- DataSample: Floating point (optional for readers)
- No standards for missing data, time/vertical
- Only implemented a few projections
- Create subsetted netCDF/CF files
- OPeNDAP WCS service
- http://motherlode.ucar.edu:8080/thredds/wcs?**dataset=*****dodsURL***

## NERC DataGrid Development

- Created prototype WCS server (with TPAC)
- Reads from various “backend providers”
- Currently OPeNDAP
- DataExtractor tool (NDG), GADS (Univ Reading), CSML (NDG)
- Serves subsetted NetCDF/CF
- Recommendations to clarify WCS
- Investigate CSML as potential format, referencing netCDF through xlink or gml:File.

## Other WCS/netCDF Servers

- Univ Florence (Nativi et al)
- Also experiment with NcML-GML
- Intl Univ Bremen (Baumann et al)
- Import netCDF data into PostgreSQL database
- Aggregate multiple files into a single database object
*Rasdaman* maps raster data to relational tuples, SQL variant queries.
- Wash Univ St Louis (Husar et al)
- Also tried to serve collection of irregularly located points
- George Mason University (Liping DI et al)

## WCS/NetCDF clients

- DataFed (Wash Univ St Louis)
- George Mason University
- SIS/GDAL, CadCorp (Martin Daly, Frank Warmerdam (GDAL))
- IDL, Research Systems International
- Non-WCS:
- ESRI (local NetCDF/CF files) ArcGIS 9.2

## Accomplishments

- Recommendation for NetCDF as a WCS encoding (1.0)
- Recommendations for changes to WCS 1.1 specification
- Peter Baumann
- Andrew Wolfe
- Stefano Nativi
- Develop netCDF “application profile” (1.1)
- Investigation of GML applications profiles for explicit netCDF semantics (ncML-GML, CSML)

## Plans for Phase 2

- For continued experimentation with WCS implementation, use GALEON OGCnetwork
- Additional client & implementations
- New datasets
- For WCS and GML specifications, continue as OGC GALEON Interoperability Experiment
- Collaborate closely with:
- OGC GEOSS Services Network (GSN)
- GMLJP2 (GML JPEG2000)

## CF-netCDF WCS 1.1 Profile

**Brief Description **
**Documentation**
**Standard names**
**Units**
**Coordinate types**
**Coordinate systems**
**Grid mappings**
**Time coordinate(s)**
**Code for Implementing netCDF Interface **
**Support**
**CF-netCDF and Coverage (ISO 19123) Data Model Mapping**
**Limitations**
**Compliance Testing**

## Changes Proposed in WCS 1.1

- WCS encoding “profiles” instead of fixed list of encoding formats
- Multiple “variables” or “parameters” or “fields” in a coverage (e.g., pressure, temperature, etc.)
- Coverages with 3 spatial dimensions
- Coverages with multiple time dimensions (e.g. forecast time in model output)
- Non-spatial “height” dimension, (e.g., atmospheric pressure, ocean density)
- Irregularly-spaced grids
- Are collections of point observations and trajectories coverages or features?

## Summary

- A handful of clients and servers have demonstrated feasibility
- Commercial vendors are actively participating (RSI, ESRI, CADCORP)
- GEOSS demonstrations involve WMS clients getting data from GALEON WCS servers
- Finished netCDF profile is key; other profiles are needed (e.g., OPeNDAP, HDF-EOS, GeoTIFF)
- Most WCS limitations are being addressed in 1.1
- With proposed changes, WCS should be viable for model datasets