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Moving from Coverages to Geodatabases for Physical and Political Maps
National Geographic Atlas of the World, Eighth Edition, Updated with GIS
The eighth edition of the National Geographic Atlas of the World contains satellite views and maps of the earth's physical featuresinformation encompassing cities, nations, and the physical and natural worldsas well as political maps of all the countries on earth. It is also the only world atlas on the market with a fully integrated Internet component. The companion Web site to the atlas allows users to create custom views of maps, zoom into satellite globe imagery to detailed views of world landmarks, and download and print atlas updates.
Updating the Physical and Political Maps
The atlas is an update and expansion of the seventh edition. Updating a world atlas is a prodigious undertaking. Among other variables, countries change their boundaries, cities change their names, and highway construction changes the roads. To improve the update process, National Geographic has used digital techniques to produce the physical and political plates (i.e., two-page map spread) in the atlas since the seventh edition, when it first created the ArcInfo coverages that produced these plates.
In addition to making the more than 17,000 updates in the eighth edition, National Geographic decided to move from coverages to ArcGIS personal geodatabases for the physical and political plates. The decision to move to geodatabase format will keep National Geographic at the forefront of technology and enable it to make future updates using the most advanced techniques available.
To move from coverage to geodatabase format, National Geographic selected Esri's Professional Services Group and Esri's team member, Aerial Information Systems, Inc. (AIS). Kevin Allen, the director of Map Services at National Geographic, indicates that the selection of the Esri team was based on technical experience in creating both databases and geodatabases, past performance, and cost.
To keep the content and the appearance of the physical and political plates consistent, Esri, in cooperation with National Geographic, created a geodatabase model that accommodated the information in all the plates. David Watkins, the lead Esri cartographer, reports that the geodatabase design was necessarily created in an iterative fashion, since additional information was rolled into the geodatabase design as it was discovered. Ultimately, however, all the personal geodatabases conformed to the same database model.
To convey the updates that were necessary, National Geographic created a digital edit overlay for each plate by using Adobe Illustrator; each overlay highlighted the updates and the location of changes to features and text. In addition to converting the coverage data to personal geodatabases, Esri converted the Illustrator overlays to georeferenced TIFF files, then provided the geodatabases and the TIFF files to AIS, which edited the geodatabases with the latest version of the ArcMap application that is included in ArcGIS Desktop (ArcView, ArcEditor, ArcInfo). Primarily, ArcInfo was used for this project.
It was understood from the beginning that the ArcMap map documents would be converted into the Adobe Illustrator files with which National Geographic would publish the atlas. To streamline the ArcMap-to-Illustrator export procedure, layering in the map documents was predefined and symbology was customized to improve the work flow. For example, National Geographic provided its own Illustrator fill patterns, and the map document included these fill areas as solid fill symbols in a separate layer. This made it easy to replace the layer in the Illustrator file after the export. The same process was used for a custom color overlay and the dashed-line patterns.
After the conversion to Illustrator, National Geographic did some additional finishing, including some final text placement adjustments, adding titles, scale bars, and some of the other information associated with page layouts. Finally, Illustrator was used to create the color separations used by the printer.
Preparing the Index
Watkins says that the index, which constitutes about one-third of the atlas, represents another significant achievement. Each feature is identified in the index by name, type (e.g., river, mountain), location, page number, and reference coordinate. Although this might sound simple, implementing the entries successfully means complying with a multitude of indexing rules.
A feature that appears on several pages in the atlas, for example, is indexed only to the best page for that feature. Some features have multiple names; these features are indexed on both the preferred and secondary names. Some rivers run through several countries and have a different name in each country. These names are linked in the index by "see also" references. Watkins reports that generating the index was ultimately handled with the help of Esri's new PLTS software functionality that will be published in a future release of PLTS. The index, like the physical and political plates, was finished at National Geographic.
The Esri team completed its part of the work in less than a year (June 2003 to May 2004), and National Geographic spent several months doing the atlas finishing, given that it was solely responsible for the satellite imagery and the other plates Esri did not produce. "It's very important for people to realize that Esri did not produce this atlas," says Mary Rosenbaum, the Esri project manager. "Esri supported the work that went into part of it, but National Geographic deserves the credit for the atlas as a whole." The atlas was printed in Brazil and shipped back to the United States in time for Christmas. It has been such a big success in the marketplace that it is about to go into a second printing.
National Geographic wants to publish the next version of the atlas entirely with ArcGIS Desktop. "Publishing with ArcMap will simplify the process and speed it up," says Allen. "We're looking forward to the streamlined process that will be associated with the next edition."
For further information, contact Kevin Allen, director of Map Services, National Geographic (tel.: 1-800-638-6400), or David Watkins, lead cartographer, Esri (tel.: 909-793-2853, extension 1-1165; e-mail: email@example.com).