E - L

E

Ellipsoid - A smooth mathematical surface which resembles a compressed sphere and is used to represent the earth's surface. (source -Survey Services 2003)

F

Format - The way in which data are systematically arranged for storage in a computer and for transmission between computers, or between a computer and a device. Standard format systems are used for many purposes.

G

Geocentric - Relating to, measured from, or with respect to the centre of mass of the earth (source -Survey Services 2003)

Geo-referencing - The process of delimiting a given object, either physical (e.g., a lake) or conceptual (e.g., an administrative region), in terms of its spatial relationship to the land; the geographic reference thus established consists of points, lines, areas or volumes defined in terms of some coordinate system (usually latitude and longitude, or UTM northings and eastings, and elevation). The background framework pertinent to geo-referencing includes: NTS and BCGS grids and related features.

Geocoding - The activity of defining the position of geographical objects relative to a standard reference grid.

Geographics or Geographic Projection - Representation of the earth's surface as a projection onto rectangular lines of latitude and longitude.

GIS - Geographic Information System. An organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, integrate, analyze, and display all forms of geographically referenced information.

Global Positioning system (GPS) - a satellite based device that records x,y,z coordinates and other data. GPS devices can be taken into the field to record data while driving, hiking, or flying. Ground locations are calculated by signals from satellites orbiting the Earth.

Graphics Interchange Format (GIF) - A common raster graphics data format used on the Internet to display images. Because of the method it uses to compress raster data, it works well (storing the same information in very few bytes) for simple graphics with up to 256 colors. However, for complex images such as photographs, JPEG is more useful. Unlike JPEG, the compression technology used in GIF (the Lempel-Ziv-Welch, or LZW, algorithm) is owned and copyrighted by Unisys, and data/software producers (but not users) must pay a licensing fee to use it.

H

I

J

Joint Photographic Experts Group (JPEG) - An industry committee that develops standards for digital photography. The acronym is commonly used for the raster data format this group created, which is more accurately called the JPEG File Interchange Format (JFIF). JFIF files are compressed in a fashion optimized for true-color images such as photographs and remote sensing imagery, and thus store them much more efficiently than GIF. The major drawback to JFIF, however, is that it is "lossy." That is, a small amount of information is lost in the compression process, making a JFIF image of slightly lower quality than the original image.

K

L

LIS - Land Information System - A system for capturing, storing, checking, integrating, manipulating, analysing and displaying data about land and its use, ownership and development.

Land Parcel - An area of land, usually with some implication for land ownership or land use.

Layer - A logical set of thematic data described and stored in a map library. Layers organize a map library by subject matter, e.g., soils, roads, wells, and extend over the entire geographic area defined by the spatial index of the map library.

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