You can relocate and rotate
the user coordinate system for convenient coordinate entry, grid
display, grid snap, Ortho mode, and other drawing tools.
Understand the World and
User Coordinate Systems
There
are two coordinate systems: a fixed system called the world coordinate
system (WCS) and a movable system called the user coordinate system
(UCS). By default, these two systems are coincident in a new drawing.
Normally in 2D views,
the WCS X axis is horizontal and the Y axis
is vertical. The WCS origin is where the X and Y axes
intersect (0,0). All objects in a drawing file are defined by their
WCS coordinates. However, it is usually more convenient to create
and edit objects based on the movable UCS.
Work with the User Coordinate System
Virtually
all coordinate entry as well as many other tools and operations
reference the current UCS. 2D tools and operations that depend on
the location and orientation of the UCS include the following:
- Absolute and relative coordinate entry
- Absolute reference angles
- Definition of horizontal and vertical
for Ortho mode, polar tracking, object snap tracking, grid display,
and grid snap
- Orientation of horizontal and vertical
dimensions
- Orientation of text objects
- View rotation using the PLAN command
Moving or rotating the UCS can make it easier
to work on particular areas of a drawing.
You can relocate the user coordinate system
with methods such as the following:
- Move the UCS by defining a new origin
point.
- Align the UCS with an existing object.
- Rotate the UCS by specifying a new origin
point and a point on the new X axis.
- Rotate the current UCS a specified angle
around the Z axis.
- Revert to the previous UCS.
- Restore the UCS to be coincident with
the WCS.
Each
of these methods have a corresponding option in the UCS command.
Once you have defined a UCS, you can name it and then restore it
when you need to use it again.
To define a new UCS origin
in 2D
- Specify a point for the new origin.
The UCS origin (0,0) is redefined at the point
you specify.
To change the rotation
angle of the UCS
- Specify a rotation angle.
To restore the UCS to be
coincident with the WCS
-
- In the UCS dialog box, Named UCSs tab,
select World.
- Click Set Current.
- Click OK.
To restore the previous
UCS
-
- In the UCS dialog box, Named UCSs tab,
select Previous.
- Click Set Current.
- Click OK.
To save a UCS
-
The new UCS is displayed in the UCS list as
UNNAMED.
- In the UCS dialog box, Named UCSs tab,
select UNNAMED and enter a new name. (You can also select UNNAMED,
and right-click. Click Rename.)
- Click OK.
You can use up to 255 characters, including
letters, digits, and the special characters dollar sign ($), hyphen
(-), and underscore (_). All UCS names are converted to uppercase.
To restore a named UCS
-
- In the UCS dialog box, Named UCSs tab,
you can view the origin and axis direction of a listed UCS. Select
the UCS name. Click Details.
When you have finished viewing the list, click
OK to return to the UCS dialog box.
- Select the coordinate system you want
to restore. Click Set Current.
- Click OK.
To rename a UCS
-
- In the UCS dialog box, Named UCSs tab,
select the coordinate system you want to rename. (You can also select
UNNAMED, and right-click. Click Rename.)
- Enter a new name.
- Click OK.
To delete a named UCS
-
- In the UCS dialog box, Named UCSs tab,
select the UCS you want to delete.
- Press Delete.
You cannot delete the current UCS or a UCS with
the default name UNNAMED.
CommandsUCS
Manages user coordinate
systems.
UCSICON
Controls the visibility
and placement of the UCS icon.
UCSMAN
Manages defined user
coordinate systems.
System VariablesPUCSBASE
Stores the name of the
UCS that defines the origin and orientation of orthographic UCS
settings in paper space only.
UCSFOLLOW
Generates a plan view
whenever you change from one UCS to another.
UCSNAME
Stores the name of the
current coordinate system for the current viewport in the current
space.
UCSORG
Stores the origin point
of the current coordinate system for the current viewport in the
current space.
UCSORTHO
Determines whether the
related orthographic UCS setting is restored automatically when
an orthographic view is restored.
UCSXDIR
Stores the X direction
of the current UCS for the current viewport in the current space.
UCSYDIR
Stores the Y direction
of the current UCS for the current viewport in the current space.
