Finding the boundary lines of an element is something that I have been trying to do in Dynamo for a little while now. There are several different tasks that you can automate in Revit once you have the boundaries of an element. First, you can automatically draw Area Boundary Lines for your planting plans. And particularly for Floors, you can use boundary lines to create duplicate Floors.

So I was quite pleased to discover Collector.ElementSketch in Spring Nodes.This node gets the curves of a sketch-based element, so for Floors it returns the boundary curves. For line-based elements, such as Walls and Stairs, it will only find the single line. But this node is still a good start into getting boundary lines.

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One of the issues that can arise when working with Slab Shape Floors is that the patterns will articulate along Interior Edges. And with certain patterns (particularly pavers) this can be a problem.

One solution I have used is to create a duplicate flat Floor that is only visible in plan. And with Collector.ElementSketch you can automate the process of creating duplicate Floors. Here is a simple definition:

Of course, you can add additional parameters if you want to give the Floors different parameters or even put them on different Worksets (check out Clockwork for setting element Worksets).

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And, as I mentioned, the other process that can be automated with Collector.ElementSketch is creating Area Boundary Lines around hardscape. For this to be most effective, you would need to be able to get the boundaries of all elements (not just Floors). But for now, it does work with Floors.

This definition has a few addition nodes in order to merge adjacent Floors before getting the boundary curves:

And here is the result. I left the Area Boundary Lines as the default purple so they would be a bit more visible.

Also just as a reminder, Collector.ElementSketch uses rollbacks so it might be slow for large datasets.