Scott M. answered • 12/26/19
Former Structural Steel business owner with 25 years' experience
While AutoCAD has essentially given way to Revit and 3D modeling, AutoCAD has many advantages over a drafting table. It is impossible to list them all here, but basically, in AutoCAD, you are working with real dimensions, in space. Same thing applies to modeling. If you draw a line that is intended to be 35' long, you can make it exactly that. If you have the ability to draw your project in real time dimensions, in space, just as you would if you were building the building, then it stands to reason that the drawings telling others how to construct the building would be more accurate. You can use this type of accuracy to figure out dimensional questions, etc. You are essentially drawing the building "life sized", as far as the program is concerned. It doesn't know any difference. Apply all of that to three dimensional members, just as you would actually construct the building with (as opposed to lines in the above description), and there you have the essence of 3D modeling. Add intelligent data to that, and you have BIM.
