2004

228 | Chapter 15 Use Precision Tools
UCS dialog box show the available choices.
If you have already specified a UCS, you can control whether choosing a
preset option shifts the UCS relative to the current UCS orientation or rela-
tive to the default world coordinate system (WCS). This option has no effect
if you restore the WCS, restore the previous UCS, or set the UCS to the
current view.
Change the Default Elevation
The current elevation established by the
ELEV command defines the drawing
plane of the current UCS and is applied to individual viewports, depending
on the setting of the
UCSVP system variable. This variable determines
whether a UCS is saved and restored in each viewport. When
UCSVP = 1, that
is, when different UCS settings are saved in individual viewports, the
elevation settings are saved with each viewport both in model space and in
paper space layouts.
Generally, it is recommended that you leave the elevation set to zero and
control the XY plane of the current UCS with the
UCS command.
Change the UCS in Paper Space
You can define a new UCS in paper space just as you can in model space;
however, the UCSs in paper space are restricted to 2D manipulation.
Although you can enter 3D coordinates in paper space, you cannot use 3D
viewing commands such as
3DORBIT, DVIEW, PLAN, and VPOINT. AutoCAD
keeps track of the last 10 coordinate systems created in model space and the
last 10 in paper space.
Save and Restore UCS Locations by Name
If you plan to work extensively in 3D, you can save named UCS locations,
each having a different origin and orientation, for various construction
requirements. You can relocate, save, and recall as many UCS orientations as
you require.
To shift the XY plane
1 From the Tools menu, choose New UCS. Then choose 3 Point.
2 Specify an origin point for the new UCS (1).
For example, in a large drawing, you might specify an origin point near
the area in which you want to work.