Area Calculations in AutoCAD
Comments by: Odin Cary

I have been plagued by AutoCAD's Area command since the first release and I have yet to see any significant improvements in its native implementation.

Taking area totals in AutoCAD is far more work than it should be. I have been searching for easier ways to take quick totals of disjointed polygons so that my clients don’t have to constantly select each closed polygon one-by-one. With Lisp, other solutions are possible, but this trick is meant for those who don't have any Lisp solutions available.

My trick requires a little knowledge of basic 3D commands. First, the Boundary command is excellent for creating closed Polygons out of areas that have been constructed with numerous different object types (usually a multitude of lines); but, it also creates Regions. Regions are basically 2D solids and what makes solids attractive is this: solids can be "unioned". A series of disconnected Regions can be "unioned" and thus treated as one object. By having a set of "unioned" objects, one can take a total area in one selection. The drawbacks are that solid edges cannot be stretched in the way that polygons can (however, union, intersection and subtraction can be used) and solids create larger files.

What I do, is keep a set of polygons on one layer; when I want a new total, I copy the polygons, change them to a different layer, Region them, Union them and take the total area.

Here's how to do it:

Draw a couple of disjointed spaces with different object types; lines, polylines and splines, making sure that they form something that can be conceived of as closed spaces. Make a new layer current. Type: "boundary". Pull down the list box and set "object type" to "Region". "Pick points" inside spaces. Turn off all layers but the current one. Type: "union". select the regions and hit return. Type: "area". Type: "o" - for object. Select any edge of any of the regions and you will see the total of all spaces that were previously "unionized".