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Geo Data Portal Overview

The USGS Geo Data Portal (GDP) project provides scientists and environmental resource managers access to downscaled climate projections and other data resources that are otherwise difficult to access and manipulate. This user interface demonstrates an example implementation of the GDP project web-service software and standards-based data integration strategy.

A user of the GDP interface can supply their area of interest as a pre-existing GIS shapefile with one to many unique polygons or by drawing a single polygon using an interactive web-map. A user can select from available GDP project web-service processing algorithms, which include raw data subsetting. returning a NetCDF. or file and area-weighted statistics summarization, returning a text file of summary time series.

Processing algorithm options such as dataset component of interest, time period of interest and output file formatting must be specified. As the GDP project progresses, other processing algorithms and output formatting options will become available. Datasets available from the initial public release of the portal include historic weather and downscaled climate projections.

As the GDP project progresses, the catalog of data available from the portal will expand to include more climate, weather and geographic data resources. In order to allow processing of very large datasets, GDP project web services perform asynchronously. This allows a user to supply an email address and be notified upon process completion.

Go to the Geo Data Portal main landing page.

Please send any bug reports, feedback, or feature requests to gdp@usgs.gov

What's New with the Geo Data Portal?

Webinar and Training: (Note that these may be slightly out of date, most content still applies.)

A short screencast demonstrating how to use the Geo Data Portal can be seen here.

A one hour webinar summarizing the GDP project and examples of how it has been used was presented on August 29th, 2012.

A training seminar was recorded on Webex for a USGS audience. Note: To download the webex recording you will need a login for this wiki and the Webex recording player.

FAQs:

Click here for frequently asked question documentation.

Open File Report:

The GDP Open File Report is now available. This report describes the data integration strategy, provides an overview of the processing algorithms, and presents geospatial calculation testing results.

Geo Data Portal Algorithm Summaries

Area Grid Statistics (weighted):

id: gov.usgs.cida.gdp.wps.algorithm.FeatureWeightedGridStatisticsAlgorithm

Summary: This algorithm generates area weighted statistics of a gridded dataset for a set of vector polygon features. Using the bounding-box that encloses the feature data and the time range, if provided, a subset of the gridded dataset is requested from the remote gridded data server. Polygon representations are generated for cells in the retrieved grid. The polygon grid-cell representations are then projected to the feature data coordinate reference system. The grid-cells are used to calculate per grid-cell feature coverage fractions. Area-weighted statistics are then calculated for each feature using the grid values and fractions as weights. If the gridded dataset has a time range the last step is repeated for each time step within the time range or all time steps if a time range was not supplied.

Notes: This algorithm will work with gridded data from a Web Coverage Service or an OPeNDAP service. It will work with both time-series grids and non-time-varying grids. It expects a grid containing continuous numerical values. Given a categorical data type (integers), it will treat the data as if it were continuous. For large spatio-temporal request extents, it is recommended that users make test requests using a subset of the eventual need in order to verify that the response is as expected.

Area Grid Statistics (unweighted):

id: gov.usgs.cida.gdp.wps.algorithm.FeatureGridStatisticsAlgorithm

Summary: This algorithm generates unweighted statistics of a gridded dataset for a set of vector polygon features. Using the bounding-box that encloses the feature data and the time range, if provided, a subset of the gridded dataset is requested from the remote gridded data server. Polygon representations are generated for cells in the retrieved grid. The polygon grid-cell representations are then projected to the feature data coordinate reference system. The grid-cells are used to calculate per grid-cell feature coverage fractions. Area-weighted statistics are then calculated for each feature using the grid values and fractions as weights. If the gridded dataset has a time range the last step is repeated for each time step within the time range or all time steps if a time range was not supplied.

Notes: This algorithm will work with gridded data from a Web Coverage Service or an OPeNDAP service. It will work with both time-series grids and non-time-varying grids. It expects a grid containing continuous numerical values. Given a categorical data type (integers), it will treat the data as if it were continuous. For large spatio-temporal request extents, it is recommended that users make test requests using a subset of the eventual need in order to verify that the response is as expected.

OPeNDAP Subset

id: gov.usgs.cida.gdp.wps.algorithm.FeatureCoverageOPeNDAPIntersectionAlgorithm

Summary: This service returns the subset of data from an OPeNDAP service that intersects a set of vector polygon features and time range, if specified. A NetCDF file is returned.

Notes:This service will only work with gridded time series datasets via OPeNDAP. It writes a NetCDF-3 file which has limit of about 2GiB per variable. This service returns a rectangular spatial extent of data surrounding the polygons that are submitted. No clipping to the shapefile edges is performed.

WCS Subset

id: gov.usgs.cida.gdp.wps.algorithm.FeatureCoverageIntersectionAlgorithm

Summary: This service returns the subset of Web Coverage Service (WCS) data that intersects a set of vector polygon features. A GeoTIFF file is returned.

Notes: This service will only work with gridded data via the Web Coverage Service protocol. The response file size is limited by the web coverage service server being accessed. For very high resolution data sources, like the National Elevation Dataset, the spatial scale of requests may be limited.

Categorical Coverage Fraction

id: gov.usgs.cida.gdp.wps.algorithm.FeatureCategoricalGridCoverageAlgorithm

Summary: This processing service is used with categorical gridded data to assess the percent coverage of each category for a set of features. This service does not process gridded time series. Using the feature dataset bounding-box, a subset of the gridded dataset is requested from the remote gridded data server. The location of each grid-cell center is then projected to the feature dataset coordinate reference system. For each grid-cell in the subsetted grid, the grid-cell center is tested for inclusion in each feature in the feature dataset. If the grid-cell center is in a given feature, the count for that cell's category is incremented for that feature. After all the grid-cell centers are processed the coverage fraction for each category is calculated for each feature.

Notes: This service was originally designed for datasets like the National Land Cover Dataset. It will accept web coverage service sources with integer data types. For very high resolution data sources, the spatial scale of requests may be limited.

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