Tuesday, March 27, 2012

Interactive Terrain Shaping - Dynamic Feature Line Offsets

The next feature of ITS that I'd like to showcase is the ability to create dynamic feature line offsets.  In the context of the ITS user interface, these are called Offset Curves.  Whatever you call them, the idea is to create a parallel copy of a feature line and maintain a dynamic link back to the original.  ITS provides these in two flavors:  "regular" offset curves and draped offset curves.
To create an offset curve is pretty simple.  Launch the command...

...select a feature line, pick a side, and provide a distance...very much like the AutoCAD Offset command, except for the weird quirky thing that ITS does when it asks you to pick two points any time you specify a distance.

A cool bonus is that it automatically adds a dimensional constraint that gives you easy control of the separation between the two feature lines.  You can edit this like any other dimensional constraint to change the width of a berm, sidewalk, driveway, or whatever.

For a draped offset curve you use a different command...

Everything else is the same except this time you're prompted for a draping grid.  The resulting feature line is then projected to that grid but horizontally, continues to be parallel to the original feature line.

Now, what can this be used for?  Here are a couple of ideas, just off the top of my head:

  • Any parallel feature such as the sides of a road, driveway, sidewalk, pond berm, ditch, etc.
  • Tying in at a set distance from the origin.  You could do this by draping the offset curve on a grid created from an existing ground surface.
  • A gently sloped buffer area behind a curb or near a building.
  • Two breaklines for a temporary grading surface that maybe slopes downward at 2% away from a building, or something like that.
Keep in mind that these feature lines are not locked within the grading grids or anything.  You can use them to create a regular old surface just like any other day.

If you haven't downloaded and tried ITS, please do so right away.  We need to get some activity going on this thing or we're going to be stuck with buggy old grading tools forever!

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