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Create Regions

May 20, 2011

You can convert a closed object into a two dimensional region. After you create a region, you can modify it using the various three dimensional tools. For example, you can create a region from a square, and then extrude the square to create a three dimensional cube.

You can create regions from closed objects, such as polylines, polygons, circles, ellipses, closed splines, and donuts.

Creating regions typically has no visible effect on a drawing. However, if the original object had a width or lineweight, that information is lost when you create the region.

Regions can be used for applying hatching and shading and extracting design information, such as the centroid, and using MASSPROP to analyze properties, such as area.


Besides using closed 2D objects, you also have various options to create a region, such as connecting multiple loops or endpoints of open curves. However the closed area inside the unclosed objects will not form regions. For example, crossed arcs or intersected curves.

BOUNDARY creates region by specifying inner points of closed area, to form a boundary with existing objects. If the objects are intersected with each other, ZWCAD takes the closed area nearest to the selected pointsas boundary.

Meanwhile, a combined region is created through union, subtract or intersect among several areas. When using union, subtract or intersect for complex regions, you can fill the area and analyse its area as well. The following region objects show combined areas of union, subtract or intersect orderly:

  •       Objects combined using UNION:


  •       Objects combined using SUBTRACT:


  •      Objects combined using INTERSECT:


To create a region

  1.   Choose Draw > Region.

  2.   Select the objects to create the region.

  3.   Press Enter.

The command bar displays a message that describes how many regions were created.

Draw toolbar

Command line REGION

Commands Reference

BOUNDARY: Creates a region or a polyline from an enclosed area

INTERSECT: Creates composite solids or regions from the intersection of two or more solids or regions and removes the areas outside of the intersection

MASSPROP: Calculates the mass properties of regions or 3D solids

REGION: Creates a region object from a selection set of existing objects

SUBTRACT: Combines selected regions by subtraction

UNION: Combines selected regions or solids by addition

System Variables Reference


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