Expand Brep/Surface outer edges

I did a bit of research and couldn’t come up with a simple way of doing it and I wonder if there is a pre-existing component to do this. I am trying to take a floor boundary region (Brep or Surface), find the outer edges, and expand them outwards by a certain dimension to create a new larger surface. Can anyone help or provide any insight on how I can achieve this?

Hi, I’m not sure what the problem is here, wouldn’t any “scale” command do what you’re talking about? Please, elaborate.

It gets more coplicated if I have a slab edge that is irregular…like this:

I tried to do something like what you said and end up with this:


I would have to somehow extend all lines and cut them at their intersections then create a surface/brep?

Geometry Expand.3dm (243.7 KB)
GeometryExpand.gh (33.0 KB)

R7 .3dm file cannot be opened in R6. Or you can internalize geometry in the GH file.

Sounds like you want an Offset Curve applied to the entire perimeter curve, not segments of it?

Please see GH file with the geometry internalized. Yes, it sounds like an offset curve would be what we need here (or maybe there is something out there that works better?). It gets more complicated with edges that have multiple changes nearby and would require trimming of the lines?

GeometryExpand.gh (51.8 KB)


GeometryExpand_2021May24a.gh (59.9 KB)

Version 'B’:

  • As before, Boundary ‘Sv.0’ is a single surface between offset edges.
  • Boundary ‘Sv.1’ is new, consisting of only the surfaces added by the offsets.


GeometryExpand_2021May24b.gh (31.4 KB)

Version ‘C’:


GeometryExpand_2021May24c.gh (35.7 KB)

1 Like

Thank you so much, Joseph! This is really helpful.