area calculations in cad

[ali kashan]

guys i have a question about area calculations in autocad.
see what we usually do that if wer calculating slab area we calculate the whole slab and then subtract the areas coming as openings and ducts one by one. but i received a drawing from one of our project consultants, in that drawing they have the boundary of the slab area along with the openings and ducts as plines or boundaries. but that is all one entity and when we enter the list command for that boundary it give us the total area of the slab subtracting the openings and ducts automatically. any ideas how they are doing it or what we are missing here.
looking forward for this answer

[Anthony Miguel De Frias]

They are most certainly using what is called a REGION in Autocad and ADT.What they did was create boundarys, tansform them into regions and then used booleans to subtract the inner regions from the outer ones.
I hope that answers your question Ali

[Mariano Larregle]

ummm....to check if the slab with holes its a region the easy way its make a render or shade inside Autocad...if the area its a region render as flat solid.
Other theme you could use the option add and substract inside the command area in AutoCAD. If the areas are not polylines use the bpoly comand do do quickly enclosed poly's.
Any way if the slab/holes are region the command explode makes the areas as polyline.
Good luck

[Anthony Miguel De Frias]

If you want to to know if it's a Region or not, simply select it an go to properties (Ctrl + 1) and in the new window it will tell you exactly the number and kind of object you have selected!