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Exploring Drafting
and functions common to most types of CAD
software. These include coordinate systems,
drawing aids, layers, linetypes, and blocks.
These features are discussed in the following
sections.
Coordinate Systems
As previously discussed, objects in a
CAD drawing are defi ned with coordinates.
Coordinates are points representing units of
real measurement from a fi xed point. Most CAD
programs provide a basic coordinate system
and the ability to create user-defi ned coordinate
systems. The most basic coordinate system in a
typical program is the world coordinate system.
This system is based on the Cartesian coordinate
system. In this system, objects are defi ned by
coordinates along the X axis (horizontal axis),
Y axis (vertical axis), and Z axis (the axis
projecting perpendicular from the XY plane).
Coordinates are located in relation to the 0,0,0
origin. See Figure 7-6.
The horizontal and vertical axes of the
Cartesian coordinate system divide the XY
be used to save a fi le as a different fi le type,
such as a drawing standards (DWS), drawing
template (DWT), or Drawing Interchange
Format (DXF) fi le.
The Export command allows the user to
“export” the fi le to additional fi le formats. This
command is often used when it is necessary to
“share” data in the drawing fi le with users of
other programs. The Export command can be
used to create a fi le in the Windows Metafi le
(WMF), bitmap (BMP), or stereolithography
(STL) fi le format. Additional commands similar
to the Export command are available for
generating other types of fi les, such as Portable
Document Format (PDF) fi les.
The Page setup, Plot, and Publish commands
are used for common plotting and drawing
distribution tasks. The Page setup command
is used to specify a plotting device and page
layout settings prior to plotting. The Plot
command is used to confi gure device settings,
specify the desired media, and plot the drawing.
The Publish command is used for advanced
plotting tasks, such as creating and “publishing”
multiple-sheet drawing sets. Publishing drawing
sets is common in architectural building projects,
where multiple sheets representing different
plan drawings can be organized into a single
document. Documents of this type can then be
plotted or “published” to hard copy. Another
option is to “publish” the document to a fi le,
such as a PDF fi le or a Design Web Format
(DWF) fi le, so that it can be viewed outside
the native program. DWF fi les are compressed
versions of drawing fi les that can be distributed
to other users or posted on the Internet. DWF
fi les can be opened and reviewed using special
viewer software that provides viewing and
markup tools.
Basic CAD System Functions
One of the main benefi ts of CAD drafting
is the added productivity and effi ciency made
possible by tools in the software. Many of these
tools are designed to automate the common
tasks associated with traditional (manual)
drafting. There are a number of basic features
Z
axis
Y axis
Y
X
Origin (0,0,0)
Z
X axis
Goodheart-Willcox Publisher
Figure 7-6. In the Cartesian coordinate system,
coordinates establish points of measurement along
the X, Y, and Z axes in relation to the 0,0,0 origin.
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