Join Lines by Trace

(This functionality is available with the Computations module)

Joins contiguous lines or splines, with common end points, into one line or spline.

This dialog box is displayed after selecting the Edit/Join Line/By Trace command from the Computations task.

Join Lines by Trace dialog box

Item	Used to
Line No:	Select a line object, an end of which will be the start of the new traced line. On snapping, the rubber band will attach to the line end point closest to the cursor position, and that point number will be placed in the start point field. The line along which the trace will commence is highlighted. If this is not the required start point or line, snap again to the required line near its required end.
Start Point:	Select a point at the end of an existing line object, which will be the start of the new traced line. On snapping, the line along which the trace will commence is highlighted, and that line number will be placed in the Line No. field. If this is not the required start point or line, snap again to the required point near the required line.
Trace in both directions	Trace in both directions if the starting line selected has a contiguous line at the starting point.
Apply	Commence the trace operation. Alternatively, use the accept mouse button.
Accept	Accept the currently highlighted line as the required trace direction when more than one trace direction is available.
Reject	Reject the currently highlighted line as the required trace direction when more than one trace direction is available. An alternative trace line will then be highlighted.
Close	Close the dialog box.

The new line will be given the line number and attributes of the starting line.
The new line can only be contourable if all points in the traced lines are also contourable.
The traced line objects must be of the same type, either line strings or splines.