Terms starting with I

IMAGE CLASSIFICATION

A quantitative method that classifies or identifies objects or patterns on the basis of their multispectral values; the normal output is analogous to an image map requiring no visual interpretation. 

IMAGE MAP OR GEOREFERENCED IMAGE MAP

An image that has been processed to be like a map in appearance, scale, geometry, boundary, and projection with a degree of precision that satisfies the user. Measurements made from an image map yield results equal to those made from the corresponding planimetric, topographic, or other map. Similarly, either the image map or the conventional map can be overlaid and matched with the other.

IMAGERY

Visible representation of objects and (or) phenomena as sensed or detected by cameras, infrared and multispectral scanners, radar, and photometers. Recording may be on photographic emulsion (directly as in a camera or indirectly after being first recorded on magnetic tape as an electrical signal) or on magnetic tape for subsequent conversion and display on a cathode ray tube.

INDEX

Special data structure used in a database to speed search records in tables or spatial features in geographic data sets.

INFRARED SCANNER (THERMAL MAPPER)

Instrument that detects infrared radiation and converts the detected energy to an electrical signal for recording on photographic film or magnetic tape.

ISOGONIC CHART

Chart showing isogonic lines properly labeled with their magnetic declination.

ISOGONIC LINE

Line joining points on the Earth's surface having equal magnetic declination as of a given date.