This image shows a simulated radiation measurement response exercise in EPA Region 10.

Aerial and satellite image data plays an important role in these efforts. Aerial views provide a valuable visual backdrop that helps EPA staff set up projects, plan data collection, look for nearby facilities that might be affected by chemical spills, and develop visuals that help others understand the problems being addressed. Sometimes image data is used to create GIS layers. Advances in software over the last decade have made the use of image data with vector-based GIS a fluid part of workflows. EPA's staff, constantly in need of the most current and high-resolution data available for analyzing the constantly changing environments they monitor, recently turned to commercial Web services to provide easy access to the most relevant imagery data available.

Eliminating the Imagery Bottlenecks

Until recently, finding and accessing image data have been bottlenecks. Like other imagery users, EPA has had to choose between two unsatisfactory solutions. Its staff could buy large datasets to use over a period of years, knowing that they would never use most of the data, or as needed, they could order smaller datasets that were still larger than they needed for a specific project, downloading them via FTP. Once the data file was opened in a software program, the required rectangle containing the needed data could be extracted. In either case, EPA customers were buying more data than they wanted and taking a long time to find the portion they needed. There was little assurance that they were getting the best or most recent images available.

In 2003, EPA staff at various regional offices around the country began using ImageConnect plug-ins for ArcGIS Desktop (ArcInfo, ArcEditor, ArcView) and ArcIMS obtained from Esri Business Partner GlobeXplorer's Web site to help solve this problem. They purchased individual and departmental subscriptions to the service to help solve this problem. Compared to previous methods, this solution provides more interactive Internet access to the petabyte (1,000 terabytes) of aerial and satellite imagery available on the company's servers, enabling EPA users to quickly find, view, compare, and download the data they need.

EPA-Wide Solution

In 2005, EPA's management in Washington, D.C., responded to employees' increasing demand for current high-resolution imagery by expanding GlobeXplorer data access to the entire agency. EPA employees could then integrate access within all of the ArcGIS Desktop products, as well as inside EPA's Enviromapper ArcIMS Web viewers. This was made even easier because ArcGIS is a desktop standard within EPA under an enterprise license agreement with Esri.

EPA's Internet Geoservices Team member Dave Catlin says, "The fact that we can share access to the service agency-wide and between multiple Esri applications makes things a lot easier and cheaper for us. Also, obtaining images can now be done in a few minutes for anywhere in the region."

EPA offices nationwide have been using GlobeXplorer plug-ins, which have helped expedite their activities and decision making.

For example, in these days of heightened sensitivity following the events of September 11, 2001, and Hurricane Katrina, emergency response has been a major EPA focus. Working in an office in a suburb of New Orleans, Louisiana, EPA staff and contractors have needed to get pre- and post-Hurricane Katrina imagery as quickly as possible.

From that office, EPA's Harvey Simon explains, "We needed high-resolution imagery, as well as good metadata both in the application and in separate files, to document what we were working with. It helps to be able to toggle back and forth to get a good picture. With Katrina, it was helpful that we didn't have to go through the process of getting a separate procurement."

Serving the mountain and plains states is EPA's Region 8, where Tony Selle is data team leader for a group of database managers who are working mainly in a Superfund program focused on ecosystem protection and remediation. "We frequently need current high-resolution imagery in places we can't anticipate, particularly remote and rural areas," he says. "Our emergency response program gets a lot of tanker truck rollovers, for example. EPA has to make a determination of seriousness and magnitude based on a phoned-in report. Then it is good to have pinpointed information."

More Information

For more information, contact Dave Catlin of EPA's Internet Geoservices Team (e-mail: catlin.dave@epa.gov) or Chris Becwar, GlobeXplorer (e-mail: cbecwar@globexplorer.com).