Autodesk 15606-011408-9320 - MAPGUIDE R6.3 CPU MODEL-UPG 4/5 MIN 2 CPUS INITL User Manual page 172

key An alphanumeric character string or an integer used to uniquely identify a map
feature or a record in an attribute table. You can form explicit or implicit links between
spatial features in an SDF file and records in an attribute table using a common key. See
also primary key.
latitude/longitude coordinate system A global coordinate system in which locations
are expressed by geographical coordinates (the geodetic latitude and longitude) that
depict angular measurements relative to the Earth's ellipsoid. These coordinates are
°
often expressed in decimal degrees or degrees minutes' seconds".
layer See map layer.
layer group A collection of related map layers. You create layer groups in Autodesk
MapGuide Author.
legend A key to or an explanation of the symbols in a map, and their meaning or val-
ues. In the Autodesk MapGuide Author View tab and in Autodesk MapGuide Viewer,
you can use the legend to turn layers on and off so that the map features they contain
are no longer visible or selectable.
line A drawing entity with start and end coordinates connected by a single straight
line. Lines typically represent the shape of map features too narrow to be displayed as
an area at the given scale (contours, street centerlines, or streams), or linear features with
no area (county boundary lines).
line spacing ratio The ratio of the distance between lines of text to text character
height. For example, if the distance between lines of text is 10 mm, and the line spacing
ratio is 0.5, the font height is 20 mm.
linetype A property of a line that defines its appearance. Examples of linetypes include
continuous, dashed, and dotted.
linked table or database A table or database linked to a layer using Autodesk
MapGuide Author. The records in the table are linked to the spatial features in the layer
via common keys.
map An abstract representation of the physical features of a portion of the Earth's sur-
face graphically displayed on a planar surface. Maps display signs, symbols, and spatial
relationships among the features. They typically emphasize, generalize, and omit certain
features from the display to meet design objectives. For example, railroad features might
be included in a transportation map but excluded from a highway map.
map feature Any spatial feature on a map. In the Autodesk MapGuide products, map
features can be points, polylines, polygons or text. Although raster images are techni-
cally not map features, you can display them in raster layers.
map layer A grouping of map features that are stored and displayed together. Individ-
ual map layers can be turned on and off to show or hide the features they contain. When
all map layers are displayed, they overlap like transparencies and show all features in the
map.
map projection The representation of the Earth, which is curved, on a flat map sur-
face. A map projection defines the units and characteristics of a coordinate system. The
three basic types of map projections are azimuthal, conical, and cylindrical.
|
172 Glossary