Rotatable, Scalable, and Editable Landscape Boulder/ Rock

Of all the Revit landscape families, a boulder/rock is one of the most difficult to create, control, and then modify. By nature, rocks vary quite a bit in size and shape. In Revit, one of the best ways to model irregular shapes is in CME (Conceptual Massing Environment) and not in the traditional Family Editor. But, as Tim Waldock notes on RevitCat, CME families (otherwise known as adaptive components) do not host to Topo.

Disappointing, to say the least, but unsurprising since Topo disregards most Revit rules.


So this rock is a traditional Site component that will host to Topo. It is both scalable and rotatable (though only about its y-axis). Width controls the size and Angle is the y-axis angle; both are instance parameters. Height is controlled via Width, and is constrained to half the width.


The family’s origin is in the center of the object. It is set up this way, so that when flipped on its back it will still be at the same height. As with most objects, the Offset will adjust how much it embeds in/ floats over its host.

Now, besides being moderately transformative, you can also change the shape of this rock (and if done carefully, it will still be scalable/ rotatable). It is a relatively simple object: a swept blend and a void sweep joined together.

rock_swept blendrock_void sweep

It is scalable because it is constructed primarily from splines. So to modify the shape, simply adjust the interior points of the spline(s). There are four splines that control the shape: the two profiles of the swept blend and the path and profile of the swept void.

If editing the sweeps, here are a few tips:

  • The void sweep path is difficult to edit, and causes the most problems in the object. It does not like sharp corners in the path. If you modify the path and create corners that are too sharp, the profile will not be able to sweep across the path and the object will unjoin. Here is an example of sharp corners:

rock_sharp corners     rock_unjoin error

  • If you want a more irregular shape, you need to find a happy medium between the swept blend and the void sweep. If your void sweep (path) is too small, the object will be rounded entirely to the void.  Or, conversely if the void sweep (path) is too large, the object will only be defined by the swept blend.


Other additional notes:

  • The Angle parameter is controlled so it won’t hit increments of 90. If you enter one, it will actually be 0.5 more.
  • There are a decent amount of constrained, formulaic parameters tied to the endpoints of the splines (all under Other). Feel free to adjust them, but you’ll be liable to break things.

3 thoughts on “Rotatable, Scalable, and Editable Landscape Boulder/ Rock

  1. Wow, that’s a lot of parameters…with some strange default values…especially when I convert the file to metric ;-)

    • I’ve always thought it strange that in the US you call feet/inches ‘English’.
      In England we call it ‘Imperial’ and thank heavens we don’t have to use it any more!

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