Break 3D Polyline by Surface

This command breaks 3D polylines against a surface. The surface is defined by a 3D grid or triangulated surface model which can be selected from a .grd, .flt or .tin file. Alternately, the user can select 3D entities on the screen from which the program internally calculates a 3D grid. This routine is one step in 3D polyline design. In this example, a valley fill is designed using 3D polylines as follows:

1. Draw 3D Polyline - draw a 3D polyline at elevation 1450 across valley
2. Offset 3D Polyline - offset the 3D polyline at 2:1 slope and 10:1 for benches and top
3. Break 3D Polyline by Surface - trims the 3D polylines by the valley sides
4. Draw 3D Polyline - with OSNAP endpoint, draw 3D polyline perimeter around 3D polylines ends
5. Make 3D Grid File - create 3D grid file of fill surface
6. Plot 3D Grid - draw the 3D grid using 3D polyline perimeter as inclusion polyline
7. Viewpoint 3D - creates the last figure view

Prompts

Source of surface model (File/<Screen>)? press Enter The File option allows you to choose the .grd, .flt, or .tin file that models the site. Otherwise, a grid will be calculated by picking the grid location and selecting surface entities on screen (e.g., contour polylines). Using the File option can be quicker because the surface is already calculated. Also the .grd file can be drawn to preview the existing surface.
Pick Lower Left limit of surface area: pick a point
Pick Upper Right limit of surface area: pick a point
Make GRiD Setting Dialog OK
Select polylines to clip.
Select objects: pick the 3D polylines
Select surface entities.
Select objects: select objects that define the surface.
Erase polyline below surface (<Yes>/No)? press Enter If you answer yes, the segments of the polylines below the surface will be erased from the intersection, if any, of the polyline with the surface. Otherwise the polylines will only be broken into separate polylines at the intersection.
Specify layer names (Yes/<No>)? press Enter If you answer yes, you will have the option to place the broken polylines into different layers.

Before Break 3D Polyline by Surface	After Break 3D Polyline by Surface

3D view of fill with grid mesh