Autodesk 00126-050008-1640A User Guide - Page 167

WiseImage - User's Guide The procedure of first choosing Select Auto, and then a model is convenient if you trace the majority of objects in automatic mode and trace some objects by models, for example, distorted objects, that would not be recognized by auto recognition. Forced Tracing Forced tracing allows you to replace raster objects with vector ones of a specified type. You select one of the three object types to be used as reference objects for tracing (line, arc or circle), and then specify points on a raster object, drawing a vector entity above the raster entity. The tracing of hatch and symbol can also be interpreted as forced tracing. The program tries to trace the specified object with a vector figure of the selected type. If possible, then the raster object is traced. Unlike the Auto method, this method allows you to trace a selected part of a raster entity as well as entities with significant distortion. If during forced tracing the raster entities are deleted (tracing modes Convert to vector and Erase raster), then the raster objects intersected by them are not broken. The parameters Approximation, Max width and Max break affect these methods. If the object width is greater than the Max width parameter value or an object of the specified type cannot approximate its form, then the tracing is not performed. When tracing by the Line and Arc methods the ends (both or one of them) of reference lines and arcs can be extended beyond the limits of raster objects to be traced - on their imaginary extension. In this case a raster object is traced up to its end points. If the ends of the reference object lay within the raster object, then only a part of the raster object covered by the reference object is traced. If you want WiseImage to extend the recognized line to its natural limits, then turn on Auto Extend vectors checkbox in Trace tab of Conversion options menu (see more information on page 188). To trace a line 1. Run tracing using one of the following methods: On the Raster to Vector toolbar click Trace Line button. -orFrom rConvert menu select a tracing mode, then Line. If some available raster images are inserted into the picture, then the selection dialog box appears. Select the image that you want to trace with this box. By specifying two points, draw a line covering the raster object to be traced. 172