Filled region perimeter

Recently I had a scenario where I need to extract the perimeter of an atrium in order to calculate the smoke extraction requirements. This proved to be a trickery problem than at first glance. In AutoCAD world, one would simply draw a polyline and extract the length property. However, since Revit doesn’t have polylines, we would need to draw multiple individual lines and then get the sum of all of the lengths. Manually trying to do this is not an option because when selecting multiple objects in Revit, no length parameter will be returned (unless all lines are exactly the same length but even in this case it wouldn’t be the sum).

Trying to automate the process with Dynamo also proved to be tricky as the atrium wasn’t continuously bounded by a single element, for example, a balustrade. Instead, it was bounded by a curtain wall, columns, walls (balustrades) and stairs. To further complicate things, certain elements were excluded from the calculation process. It was…