2011

transverse cylindrical projection A map projection, in which the surface of
the Earth is drawn as it would appear if projected on a cylinder wrapped around
the earth in an east-west direction. Compare with cylindrical projection (page
2058).
UDL (Universal Data Link) File with.udl extension that includes the name
and location of the database table and the software used to create the file.
Windows uses a UDL file to identify a data source. Using the information in
this file, programs such as AutoCAD Map 3D can view and update data from
external databases.
undershoot Two or more lines within a specified tolerance of each other that
do not meet.
union Two or more conditions joined with the logical operator Or. An item
is selected only if the item meets at least one of the specified criteria. Compare
with
intersection (expression) (page 2065).
United States National Grid (USNG) A
Universal Transverse Mercator (UTM)
projection
(page 2078)-based grid reference system (page 2065)for the United States.
Universal Transverse Mercator (UTM) projection A specific implementation
of the Mercator projection, designed for use around the world. See also Mercator
projection
(page 2068).
vector A mathematical calculation of an object with precise direction and
length. Vector data is stored as X,Y coordinates that form points, lines, and
areas. Compare with
raster (page 2072).
versioning A database function that allows multiple copies of a spatial dataset
to be stored and tracked by date of creation, data of change, and so on.
vertical exaggeration An increase of vertical scale relative to horizontal scale,
used to make elevation changes easier to differentiate.
viewport (paper space) A view of modelspace from a layout.
wavelet A multiple resolution image file compressed using a lossy compression
that enables large graphics to load much faster due to the reduction in file
size. Wavelet compression is based on a mathematical algorithm in which
graphic images can be reduced to a small fraction of their original size.
weeding The removal of points along a selected 3D polyline, which may
represent a contour. The weeding factors determine the number of points
removed. You can use weeding to reduce the amount of point information
taken from the contours that may not be necessary to generate an accurate
surface.
2078 | Glossary