Every drawing is equipped with a
coordinate system called WCS or rather World Coordinate System.
The WCS is fixed and you cannot change its location or
orientation. Instead the User Coordinate System or rather UCS is
used. You can move or rotate UCS in any direction. The placement
of objects is based on the current UCS so you can even use 2D
commands to create objects in 3D space with various
orientations.
There are two toolbars for controlling
UCS location and orientation: UCS [Figure 1] and UCS II [Figure
2].
Figure 1
Buttons from left to right:
-
UCS: Invokes the UCS command.
-
Display UCS Dialog: Shows UCS
dialog box.
-
UCS Previous: Enables the
previous UCS settings.
-
World UCS: Matches the UCS with
WCS.
-
Object UCS: Builds the UCS
based on the selected object.
-
Face UCS: Builds the UCS based
on the selected face.
-
View UCS: Matches UCS with
screen. The X axis horizontal, Y vertical, and Z perpendicular
to the screen.
-
Origin UCS: Moves the UCS
without changing its orientation.
-
Z Axis Vector UCS: Builds the
UCS based on the new direction of the Z axis.
-
3 Point UCS: Builds the UCS by
specifying the new origin, a point on positive X direction, and
a point on XY plane.
-
X Axis Rotate UCS: Rotates the
UCS about X axis.
-
Y Axis Rotate UCS: Rotates the
UCS about Y axis.
-
Z Axis Rotate UCS: Rotates the
UCS about Z axis.
-
Apply UCS: Applies the current
UCS to a selected viewport.
Figure 2
Buttons from left to right:
-
Display UCS Dialog: Shows UCS
dialog box.
-
Move UCS Origin: Moves the UCS
without changing its orientation.
-
Select UCS drop down list enables you
to select an orthographic and/or a saved UCS as the current UCS.
The following tutorial shows you how
to use the UCS and UCS II toolbars to manage User Coordinate
System.
Note:
This tutorial is designed for AutoCAD 2004 though might be
applicable for other releases.
1.
Download r16_ucs.dwg.
Note:
If you are using AutoCAD 2002 or an earlier version, download
r15_ucs.dwg.
2. Open the file in
AutoCAD. The drawing consists of a box and a circle [Figure 3].
Figure 3
3. Enable UCS
toolbar (View menu > Toolbars).
4. Make sure that
Endpoint OSnap is enabled.
5. Click View UCS.
The UCS is aligned with the screen [Figure 4].
Figure 4
6. Click 3 Point
UCS.
7. Click points 4,
3 and 1 as origin, positive x axis and xy plane directions
respectively [Figure 5].
Figure 5
8. Click Origin UCS
and then click point 7 as the new origin [Figure 6].
Figure 6
9. Click Z Axis
Vector UCS.
10. Click point 8
as the origin and point 1 as the direction of Z axis [Figure 7].
Figure 7
11. Click Object
UCS and then select the circle [Figure 8]. The orientation of X
and Y axes depends on the point that you click.
Figure 8
12. Select Face UCS.
13. Click on the
front face near point 8. Press Enter to accept the new settings
[Figure 9].
Figure 9
14. Click X Axis
Rotate UCS.
15. Rotate the UCS
45 degrees about X axis [Figure 10].
Figure 10
16. Rotate the UCS
-45 degrees about Y axis and then 25 degrees about Z axis
[Figure 11].
Figure 11
17. Click UCS (i.e.
click the first button to the left).
18. Select the Save
option and save the current UCS as "sample":
Command: _ucs
Current ucs name: *NO NAME*
Enter an option [New/Move/orthoGraphic/Prev/Restore/Save/Del/Apply/?/World]
<World>: s
8
Enter name to save current UCS or [?]:
sample
8
19. Click World UCS
[Figure 12].
Figure 12
20. Click UCS and
restore the "sample" UCS [Figure 13]:
Command: _ucs
Current ucs name: *WORLD*
Enter an option [New/Move/orthoGraphic/Prev/Restore/Save/Del/Apply/?/World]
<World>: r
8
Enter name of UCS to restore or [?]:
sample
8
Figure 13
21. Click UCS
Previous [Figure 14].
Figure 14
22. Invoke the
VPORTS command. Divide the drawing area into four equal
viewports [Figure 15].
Figure 15 - Click on image to enlarge
Note:
For more information on viewports read the following article:
► AutoCAD 3D Modeling: Tiled
Viewports
23. Enable UCS II
toolbar (View menu > Toolbars).
24. Click the upper
right corner viewport to make it current.
25. On UCS II click
Move UCS Origin.
26. Click point 3.
The UCS will be affected on the current viewport only [Figure
16].
Figure 16 - Click on image to
enlarge
27. On UCS toolbar
click Apply UCS. Apply the current UCS to all viewports [Figure
17].
Command: _ucs
Current ucs name: *NO NAME*
Enter an option [New/Move/orthoGraphic/Prev/Restore/Save/Del/Apply/?/World]
<World>: _apply
Pick viewport to apply current UCS or
[All]<current>: all
8
Figure 17 - Click on image to
enlarge
28. On View menu
select Viewports > 1 Viewport.
29. From the UCS
list select, World. Then select Bottom [Figure 18].
Figure 18
30. Click Display
UCS Dialog. The UCS dialog box appears [Figure 19].
Figure 19
31. From the list
select, sample.
32. Click Set
Current.
33. Click OK
[Figure 20].
Figure 20
Alireza Parsai is the founder of cadpanel.com. He is a
mechanical engineer with more than 12 years experience with
AutoCAD. Alireza is an Autodesk Authorized Author, the AutoCAD
consultant for Al Khawarizmi Institute, a contributing editor
for Augiworld magazine, a writer for CAD Digest, an instructor
for AUGI Training Program, and an elected speaker for Autodesk
University 2002. He has written 7 books in Farsi, 3 booklets in
English, and more than 30 articles for different magazines and
newsletters. You can reach him at
alireza.parsai@cadpanel.com or visit his website
www.cadpanel.com.
