Reference Guide to Emerging Technologies to Implement NEPA

Aerial Photography -- Photographs of a part of the earth's surface taken by a camera mounted in an aircraft for mapping purposes. This usually consists of a series of overlapping vertical photos taken in strips that can form the basis for mapping.

Geographic Information Systems (GIS) -- A computer system for managing spatial data. A GIS, e.g., can provide a simultaneous consideration of geology, geophysics, geochemistry, and mineral deposits in a region for the purposes of mineral exploration.

Global Positioning System (GPS) -- A constellation of satellites originally developed by the U.S. Department of Defense as a navigation aid. It is now used by the civilian community for navigation and horizontal/vertical positioning of features.

Multispectral Satellite Remote Sensing -- When we use more than two wavelengths, the spectral signatures (or spectral curves) tend to show more separation among the materials. This improved ability to distinguish materials due to extra wavelengths. Hyperspectral sensors, which record in more than 50 wavelengths, are currently being launched experimentally.

Photogrammetry -- The science or art of obtaining reliable measurements by photography. For GIS applications, aerial photogrammetry often provides the foundation to develop base maps.

Pixel -- One picture element, the smallest discrete element that makes up an image.

Raster Data -- One method of storing, representing or displaying spatial data in digital form. It consists of using cell data (not necessarily square) arranged in a regular grid pattern in which each unit (pixel or cell) within the grid is assigned an identifying value based on its characteristics. Generally the format of satellite remote sensing data.

Remote Sensing -- The science and art of obtaining useful information about an object, area, or phenomena through the analysis of data acquired by a device that is not in contact with the object, area, or phenomena under investigation.

Thematic Map -- A chief use of remote sensing data is in classifying the myriad of features in a scene (usually presented as an image) into meaningful categories or classes. The image then becomes a thematic map (the theme is selectable, e.g., land use; geology; vegetation types; rainfall).

Vector Data -- One method of storing, representing or displaying spatial data in digital form. It consists of using coordinate pairs (x,y) to represent locations on the earth. Features can take the form of single points, lines, arcs or closed lines (polygons). Generally the format of GIS data.

The materials on this Web site were developed by Ken Markowitz as part of a presentation at the ALI-ABA Course of Study: Environmental Impact Assessment: NEPA (National Environmental Policy Act) and Related Requirements, December, 2001, Washington, DC.