the original source data, such as maps or other measurements or plans, on which a project (landscape, architectural or geographic) is based, and from which other data (e.g. slope, or intermediate layers) are derived

Those digital fields of reflectivity, mean radial velocity, and spectrum width data in spherical coordinates provided at the finest resolution available from the radar.

The basis on which natural resource data can be overlaid, such as a defined portion of the earth's surface represented by a topographic map.

set of information that provides a baseline orientation for another layer of primary focus, e.g., roads, streams, and other data typically found on USGS maps.

Basic level of data or features on a base map.

Fundamental cartographic information (e.g. coastlines, political boundaries) in relation to which additional data of a more specialized nature may be compiled or overprinted.

basic level of map data on which other information is placed for purposes of comparison or geographical correlation.