Autodesk 00126-050008-1630A User Guide - Page 180

12 Tracing Tracing Parameters Description The Options tab Parameter Min Length Max Width Max Break Approximation Accuracy Orthogonalization Description This parameter defines the size of the minimum raster object that can be recognized. This parameter defines the maximum width of raster lines that can be approximated by lines, arcs, circles, and polylines. If the width of a raster line exceeds Max Width, then the only possible mode is Auto tracing and approximating with an outline object. Sets the length of the maximum ignored break in raster lines. If a raster line is broken into parts and you want to trace this line as an entire object, then set the value of Max break, than largest interval between the raster line parts. The program will ignore the breaks and create single vector object, approximating the whole raster line. By setting a comparatively large value of the parameter, you can, for example, trace dash-dotted raster lines, and arcs as single entities. You can enter the values of Min Length, Max width and Max break from the keyboard or measure them on the screen. This parameter determines the accuracy of approximating of the original raster object with a vector one. If the original image is distorted, for example, circles have the form of ellipses, then you should reduce the value of the Approximation Accuracy parameter. However, this leads to inaccuracies in recognition, for example, the program might take a short arc for a line. When the quality of a raster image is high, you can increase the value of the Approximation Accuracy parameter. Sometimes before tracing the quality of the raster image can be improved by application of a smoothing filter. If this option is on, then the tracing in Auto and Line modes aligns created segments either perpendicular to or parallel with the base direction. Providing the deviation of the original object from these directions is insignificant. The base direction is set in Base angle. The accepted deviation is determined automatically by the Approximation Accuracy parameter value. 185