AutoCAD 3D Modeling: Creating Regions
August 12, 2003 Regions are special type of objects that look
like one-sided flat surfaces. On the other hand regions have
similar behavior to 3D solids. You can use regions to create
flat surfaces with round edges. The regions can also be used to
create 3D solids. There are two commands that are capable of
creating regions. The following tutorial shows you how to use
them both.
Notes:
- This tutorial is designed for AutoCAD 2004 though might be
applicable to other releases.
- In this tutorial user entries are in boldface.
- The
8
symbol represents pressing Enter.
1. Download
r16_create_regions.dwg.
Note:
If you are using AutoCAD 2002 or an earlier release download
r15_create_regions.dwg.
2. Open the drawing
in AutoCAD. The drawing consists of some 2D objects [Figure 1].
Figure 1
- Click on image to enlarge
3. Make sure that
DELOBJ system variable is equal to 1. If this system variable
equals 1 the REGION command will delete the object(s) that are
used to create the region(s).
4. Alter the shade
mode to Flat shaded.
5. Invoke REGION
(Draw menu > Region).
6. Select the
ellipse and then press Enter. A region replaces the ellipse
[Figure 2].
Figure 2
- Click on image to enlarge
7. Assign 0 to
DELOBJ to avoid deletion of original objects:
Command: delobj8
Enter new value for DELOBJ <1>: 08
8. Invoke REGION
and then select all objects:
Command: reg8
REGION
Select objects: all8
10 found
Select objects:8
1 closed, degenerate or unsupported object rejected.
1 loop extracted.
1 Region created.
Note:
The command has no effect on the existing region to the
right. The mid area cannot be converted to a region. It is
considered as a complex loop as its boundary objects are not
adjoining curves. REGION is incapable to analyze such loops. The
only valid loop is the one to the left. The border of the region
will remain on the screen due to assigning 1 to DELOBJ [Figure
3].
Figure 3
- Click on image to enlarge
9. To create a
region based on a complex loop you can use the BOUNDARY command.
Invoke BOUNDARY (Draw menu > Boundary). The Boundary Creation
dialog box appears [Figure 4].
Figure 4
- Click on image to enlarge
10. On Object type
section select Region from the drop down list.
11. Click Pick
Points button to the right. Then click in the middle loop.
12. Press Enter to
create the region [Figure 4].
Figure 5
- Click on image to enlarge
Note:
BOUNDARY is independent of DELOBJ value. It never removes the
boundary objects.
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.
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