This command allows you to identify closed polylines to be used as inclusion or exclusion boundaries. These boundaries are applied in Surface and Grading Menu commands such as Two Surface Volumes and Triangulate & Contour. Inclusion polylines limit processing to inside the polyline. For example an inclusion polyline for volumes would be the limit of disturbed area. Exclusion polylines prevent processing inside the polyline. For example a building perimeter could be an exclusion polyline for contouring. Tag Predefined Boundaries assigns a site name to polylines and whether the polyline is for inclusion or exclusion.
Many Surface commands will prompt for inclusion and exclusion polylines. The advantage to Predefined Boundaries is that you don't have to select the boundary polylines each time that you run the Surface command. Instead the program will recognize that the boundary is already specified and will prompt Use predefined boundary Area 1 (<Yes>/No)? This lets you just press enter to use your predefined boundary. If you want to pick the boundaries, you can type N for No. When you have more than one set of boundaries, the program lets you choose from a list of the boundary names as shown in dialog.
Boundary name <Site 1>: Area 1
Select Inclusion perimeter polylines.
Select objects: pick the closed polylines
or press Enter for none
Select Exclusion perimeter polylines.
Select objects: pick the closed polylines
or press Enter for none
Pulldown Menu Location: Surface > Predefined Boundaries
Keyboard Command: plzone
Prerequisite: Closed polyline
File Name: \lsp\plzone.lsp