Autodesk 00126-050008-1640A User Guide - Page 170

12 Tracing This command performance is influenced by Export single contour checkbox in Trace tab of Conversion options dialog (see page 188). The black figure was traced with Export single contour checkbox off. The result was selected, exploded and then Fill attribute was set to FALSE. Note that the tiny black square was not affected. The black figure was traced with Export single contour checkbox on. The result was exploded and Fill attribute was set to FALSE. The result is outer contour. Tracing polylines (Linefollow) This method allows you to trace arbitrary raster lines with an approximating vector polyline. When tracing you must specify a point on the raster line, and the program automatically tracks this line (direction of the line follow can be specified) up to the nearest node or intersection point, and creates an approximating vector polyline that consists of line segments. The node of a raster line is either its end point, or a point where the raster line crosses the other raster object. During a single tracing session between two mouse clicks (it is called tracing step) you trace a set of polyline segments. One tracing step can take an arbitrary number of segments, depending on the line complexity and trace settings. After each tracing step you should choose the direction for further tracing, or complete the procedure. If the traced polyline crosses itself, then the tracing will be automatically completed. You can choose the direction by specifying a point on the next adjacent part of the raster line. You have options to redo the latest tracing step (except the first one), and the last polyline segment within a step. You can turn on the autodetection mode of tracing extension direction (see Trace tab in Conversion Options dialog). In this mode the program offers a possible direction, showing a special marker on the part that is selected as an extension. You can select another direction during the given period (by default the waiting mode is off - waiting pause is 0), or accept the automatic trace extension. If you do not choose any direction, then after the waiting period expires the program will automatically continue tracing in the selected direction. 175