 |
|||
|
|
|||
| ||||||||||
|
|  MIL-D-89009
Text feature table. The implementation of a text feature
class in a VPF attribute table.
Text primitive. Characters placed in specific locations in a
coordinate system. Text is a cartographic object, rather than a
geographic entity, since it does not participate in topology. A
text array indicates a fixed-length string of characters. A text
string indicates a variable-length collection of characters.
Thematic attribute. A column in a table that provides a
thematic description of a feature. For example, a feature class
that contains rivers may have attributes such as width, depth, and
name.
Thematic index. A file that allows software to access the
row ids of its associated table. In a VPF table, the index is
created on a column. Four special indexes are used for feature
tables: point, line, area, and text thematic indexes.
Theme. An organizational concept used in the design of
spatial databases. Common themes in spatial geographic databases
are transportation, hydrology, and soil/land suitability.
Tile A spatial partition of a coverage that shares the same
set of feature classes with the same definitions as the coverage.
The topology of each tile is independent of that of each other
tile in the coverage.
Tiled coverage. A coverage that has been physically
partitioned into tiles.
Tiling scheme. The scheme used to define tile shape and size
and to identify tiles (assign identification numbers).
Topology. The branch of mathematics concerned with geometric
relationships unaltered by elastic deformation. In geographic
applications, topology refers to any relationship between
connected geometric primitives that is not altered by continuous
transformation. VPF recognizes four levels of topology. Level 0
topology manipulates the purely geometric aspects of the spatial
data. No topological information is stored in level 0 topology.
Level 1 topology maintains a nonplanar graph. Level 2 topology
maintains a planar graph. Level 4 topology explicitly represents
the faces defined by the planar graph.
Traverse A software operation that uses winged-edge topology
to retrieve a series of neighboring edges to satisfy a query of a
network.
76
|
|
Privacy Statement - Press Release - Copyright Information. - Contact Us |
Click
here for thousands of PDF manuals