This section contains some basic information on the structure of both GIS data and Viewer-specific files. It also briefly touches on some file naming issues including environment variables. The advantages of the Librarian organization are ease of use, data integrity, and metadata standardization.
Librarian data is organized into tiles referenced by an index coverage.
The tiling scheme generally relates to the geographic partitioning of the particular source data. For example, open space data are tiled by town while hydrography data are tiled by USGS quad sheet. Each tile within a library contains individual coverages of all the various data layers available for that particular tile. AV directly supports Librarian data and makes use of Librarian's tiling scheme to manage the display of data as the extent of the view changes. Essentially, each image in the catalog represents its own tile that, unlike true tiles in libraries, does not necessarily bear an explicit geographic relationship to the other images in the catalog.