Understanding and Using the REGION Command in AutoCAD

The REGION command in AutoCAD is a powerful tool for creating solid regions from closed polylines and other closed objects. These solid regions can be used for a variety of purposes, such as calculating area, mass properties, and Boolean operations.

How to Use the REGION Command:

1. Select the Closed Object: Use the selection tools to select a closed polyline or a region that you want to convert into a solid region.
2. Start the REGION Command: Type REGION on the command line and press Enter.
3. Create the Region: AutoCAD will create a new solid region from the selected object.

Key Points to Remember:

• Closed Objects: The object you select must be a closed shape, such as a closed polyline or a circle. Open polylines cannot be converted into regions.
• Multiple Regions: You can select multiple closed objects and convert them into separate regions.
• Region Operations: Once you have created regions, you can perform various operations on them, such as:
  • Boolean Operations: Combine, subtract, or intersect regions.
  • Mass Properties: Calculate the area, perimeter, and centroid of a region.
  • Hatching: Apply hatch patterns to regions.
  • Solid Modeling: Use regions as the basis for 3D solid modeling.

Example: Creating a Region from a Closed Polyline

1. Draw a Closed Polyline: Use the PLINE command to draw a closed polyline.
2. Start the REGION Command: Type REGION on the command line and press Enter.
3. Select the Polyline: Select the closed polyline.
4. Create the Region: AutoCAD will create a solid region from the polyline.

Example: Using Regions for Boolean Operations

1. Create Two Overlapping Regions: Create two overlapping regions using the REGION command.
2. Perform a Boolean Operation: Use the UNION, SUBTRACT, or INTERSECT commands to combine or subtract the regions.

Tips for Effective Region Usage:

• Clean Up Geometry: Ensure that your polylines are clean and closed before creating regions.
• Check for Self-Intersections: Self-intersecting polylines may cause unexpected results when creating regions.
• Use the REGION Command Judiciously: Overusing regions can slow down your drawing performance, especially in large and complex models.
• Consider Using Solid Editing Tools: For more advanced solid modeling operations, consider using tools like SOLIDEDIT and 3D SOLID EDIT.

By understanding and effectively using the REGION command, you can create more precise and complex models in AutoCAD.