| ARC/INFO |
ESRI's Geographic Information System software |
| AAT |
Arc attribute tables. Tables containing information for ARC/INFO line
coverages. |
| Arc |
A coverage feature class used to represent linear features (lines). |
| Attributes |
Characters or numbers describing some characteristic about a spatial
feature. |
| Bathymetry |
Sub-marine surface features. |
| Boolean Expression |
A type of expression which combines keywords to create complex logical
expressions. Keywords such as "and" "or" and "not".e.g.:
class = 'a' or 'b' |
| Cell |
The basic element in a raster based format (grids). Grid cells are
always square. |
| Clip |
Extraction of features present in one coverage as defined (spatially)
by bounding features of a clip coverage. |
| Coverage |
A term used by ARC/INFO defining a digital map layer which stores vector
information. |
| Feature Class |
A term used to define coverage elements such as arcs, nodes, or polygons. |
| Georeference |
To represent page coordinates on a planar map with real world coordinates. |
| GIF |
Compuserve Graphics Interchange Format. Gifs and Jpgs are the only
graphic formats recognized by World Wide Web browsers. |
| GIS |
Geographic Information System |
| Grid |
GIS data layer in raster format (cell-based representation) |
| Image |
A graphic representation of a real world object or area. Images can
include aerial imagery, satellite data and photographs. |
| INFO |
A tabular database manager used by ARC/INFO to store attribute and
relational datasets. |
| INFO Tables |
Individual files directly or indirectly related to geographic datasets
(map layers) which store attribute data. |
| Many-to-One Relate |
A relation between two tables in which many records in the attribute
table are related to one record in the relational table. |
| Metadata |
Documentation explaining the characteristics of a dataset |
| One-to-Many Relate |
A relation between two tables in which one record in the attribute
table is related to many records in the relational table. |
| PAT |
Polygon attribute table or Point attribute table which stores attribute
information linked to point or polygon features. A coverage can have either
a point or polygon attribute table but not both. |
| Pixel |
A contraction of the words picture element. The smallest unit of information
in a raster based format. A grid cell. |
| Point |
A feature class which represents a specific x,y coordinate. |
| Polygon |
A feature which represents areal elements. Polygons are defined by
bounding arcs and contain one label point which relate to the attribute
table. |
| Raster |
A method of storing image data which consists of cells (pixels) which
make up rows and columns. Each cell represents a feature. |
| Record |
A single row of thematic characteristics in an attribute table. |
| Relate Tables |
A process which establishes a temporary link between two tables (attribute
table and a relate table). The relation is linked through a common item
in each table and can be used to give access to additional information
not stored attribute tables. |
| Shaded Relief |
A method used to display topographic variation in a landscape using
the perspective shadowing resulting from a hypothetical position of a light
source. |
| Spatial Data |
Geo-referenced data (represents features on the ground) |
| Tabular Data |
Data that exists in a table or database format. |
| Theme |
A collection of geographic objects or features used to represent common
layers. |
| Topology |
The spatial relationship between coverage features. For example, the
topology of an arc contains its "from" and "to" nodes
and its left and right polygons. |
| Universal Polygon |
The first record in a pat representing the area outside the bounding
polygon. Its area as recorded in the pat (though it has no true spatial
area) equals the negative sum of all the polygons in the coverage. |
| Vector |
A coordinate based geographic data structure (in contrast to raster)often
used to represent linear features. |
| Vertex |
One of a set of x,y coordinates which combine to make a line feature. |
