Spline Direction, References, & Sweep Modifier in 3dsmax

One of the problems I run into for design visualization in 3dsmax on complex site models is managing extremely complex sweep objects, specifically to create the curbs for a site model.  The sweep modifier is a great tool for creating curbs (as well as trim profiles for architectural interiors).  The issue that option arises is that when the source of the linework is an Autocad drawing from a client, the lines don’t necessarily have a unified vertex direction.  The result of this is that sweep profiles can face the wrong way.  This is of course an easy fix:  you go into the spline sub-object level of your linework, and reverse the spline in question.

The trouble arises when you have very complicated scenes.  Like this one:

When you go back down the modifier stack to reverse the spline, you lose the visual reference to the sweep that you’re trying to fix the direction on. This isn’t a big deal when you have 3-4 sub objects, but when you cross over to dozens or hundreds, it becomes a more complex problem.  The software has to calculate the modifier stack every time you go in or out of sub-object mode, and you lose a little time each time you go back up the stack to check your results.

Here’s a video of a quick workflow that will help speed up this process.

TL;DR:  Make a reference copy of your spline object.  Apply the sweep modifier to the reference.  Edit sub-object spline direction on the original spline object.  The reference updates in realtime, giving you a visual cue as you make changes.