Contour tracing is useful if you want to create a closed polyline that traces the boundary of an enclosed area, especially one bounded by several objects. You can copy the contour (polyline) and process it, for example, to calculate dimensions or to calculate the moment of inertia.
The AMCONTIN command traces the inner contour of an area. To begin the trace, select the boundary edges of the region or click within the enclosed area.
The AMCONTOUT command traces the outer contour of an area. To begin the trace, select the boundary edges of the region.
The AMCONTRACE command can trace the contour of an area, segment by segment. It also enables you to check whether a contour is open or closed.
This command gives you two choices: to show the open ends of the contour or to show the endpoints of the contour segments. If you choose to show the open ends of the contour, only the contour ends show. If you choose to show the endpoints, the system stops at every corner or vertex, shows the coordinates, and prompts you to determine whether it continues in single-step mode.
If the command finds an open end in the contour, it draws a small square around that point and reverses direction. If the command finds another open end in the same place in the contour when tracing in the reverse direction, that is where the contour is open.
The program places all contours created by these commands on AM_4 by default (the layer assigned to Auxiliary Lines in the Layer/Objects Settings dialog box, by default).