Trace Alignment

(This functionality is available with the Computations module)

Creates a new alignment by tracing through existing contiguous line objects.

To run this option, select the Create/Alignment command and the Method/Trace command from the Computations task to display the relevant dialog box.

The alignment to be created will be given the attributes currently defined via the Attributes/Alignment command. You should use this command to set the required attributes before creating any alignments.

Trace Alignment dialog box

Item	Used to
Line No	Select a line object, an end of which will be the start of the new traced alignment. 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.
or
Start Point	Select a point at the end of an existing line object, which will be the start of the new traced alignment. 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	Select that the trace will extend in both directions. If the start point is also the end of another line, the trace will extend in two directions from the start point. Only a single alignment will result but its chainages will run in both trace directions from the start point. If this option is not selected or if there is not an additional line at the start point, then the trace will extend only in the direction of the selected line. Note 1: Trace an alignment from the centre of a line with a fork at one end. The process will stop and ask which way to go when it gets to the fork, if at this stage End is pressed, the alignment will still continue tracing in the other direction. Note 2: When you select the first line it creates an alignment in the direction of the first highlighted line, then traces backwards and then continues to trace forwards.
Apply	Commence the trace operation and create the alignment as it proceeds. 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.
End	Ends the creation of the current alignment and allows a new alignment to be started.