Extend sample lines until 3d surface border

[Anonymous]

Hi, I'm using Civil 3D 2018 and I have a 3D surface in which I drew an alignment. I want to create sample lines that extend to the surface border. The problem is the sample lines and the surface border aren't necessarily in the same plane, so they don't intercept. To bypass that, I want to create an object that would look like a "wall" that encloses the 3Dsurface and extends in the Z axis. Think of this like, for example, if the surface were a circle, then the resulting wall would be a vertical cilinder. 

Is there a way to do this? 

Thanks in advance.

[Neilw_05]

Sample lines do not have elevations. Think of them as vertical cutting planes that extend to infinity up and down.  They are used to plot the profile of a surface where it intersects the plane. It is not clear what you are wanting to do.

[autoMick · Accepted solution]

Sample lines can be made to extend between a left and right alignment.

So the process is:

- display surface as border only

- select the surface then 'extract objects' which will give you a polyline

- snip the polyline to give you the left and right borders

- convert the left and right polylines to alignments

- then when you define your samplelines based on a central alignment - you will see an option to use two other alignments as the left and right extents

Cheers

Mick

[Anonymous]

Thanks, worked like a charm

[Neilw_05]

Don't know how you figured out what the OP was trying to do. KUDOS for that.