Trying to extend odd shaped surfaces

Rhino Rhino for Windows
1

Can I offset/extend a surface like this? Say I want the external border to be the size of the dashed line?

image
image1077×982 7.69 KB

2

No, you need to use _DupBorder to make curves from the edges, offset the outer edge curve and use _PlanarSrf with the offset curve and hole curve to create a new surface.

Regards
Jeremy

3

Thanks. That what I’ve been doing, but there are so many commands in Rhino that I don’t know about, I thought I’d ask. I’ve got a lot of this to do and was hoping for some unknown command that would make it quicker.

4

@jeremy5 Why are you certain ExtendSrf won’t work? Just curious.

5

  1. ExtendSrf only works on a single edge at a time, so for a surface like this

    image
    image556×476 7.31 KB

    you would need to run it four times.

  2. If you do try to run ExtendSrf four times on that surface, you can do the top and bottom, but it won’t actually then work on the sides

    image
    image806×744 28.4 KB

This hasn’t changed in the R9 beta. A “chain edges” option, if feasible, could be a helpful development for R10. Although while the above surface, being planar, may be feasible, a non-planar surface could be more of a challenge.

Regards
Jeremy

6

Something like this? ExtendSrfWithOffset.py (3.5 KB)

7

This variant works with flat surfaces and polysurfaces. ExtendPolySrfWithOffset.py (4.0 KB)