Note: The @ConvertToLine function (in MEDIAL_AXIS or SKELETON mode) uses an 
   algorithm designed by Petr Felkel and Stepan Obdrzalek, which is provided as-
   is, with no warranties. The paper outlining this algorithm is referenced in 
   Straight Skeleton Implementation, 1998, "SCCG 98: Proceedings of the 14th 
   Spring Conference on Computer Graphics," pages 210-218, ISBN 80-223-0837-4 
   (Publisher: Comenius University, Bratislava).

Syntax

   @ConvertToLine([CLASSIC, ]<tolerance>) 
   @ConvertToLine(MEDIAL_AXIS, [<rejectionCode>]) 
   @ConvertToLine(SKELETON, [<rejectionCode>]) 

Arguments

   <tolerance> 
      
      The tolerance that defines the point density on the resulting line. The 
      resulting lines do not have points closer than the specified tolerance.

      Range: Any real number greater than 0. 

   <rejectionCode>

      Rejection code for features that get rejected. It cannot have a numeric
      value or be an empty string.

      Range: String
      
Description

   When called with an argument of MEDIAL_AXIS or SKELETON, the geometry of the 
   feature is replaced by its medial axis or straight skeleton ("angular 
   bisector network"), respectively. The medial axis is the subset of the 
   straight skeleton that does not include any edges sharing a vertex with the 
   original area. If rejectionCode is provided, then features, whose skeleton is
   impossible to calculate, INVALID_GEOMETRY code is shown.

      Note: In either of these modes, the algorithm may take a long time to run 
      on large input features. The efficiency is given as O(nm + nlogm), where n 
      is the total number of vertices, and m is the number of "reflex vertices" 
      - vertices causing the polygon to be non-convex.

   In CLASSIC mode, the function replaces the geometry of the passed-in feature 
   with a line. The line is generated by threading through the center of the 
   polygonal shape. This mode requires a single parameter: the tolerance. Lines 
   generated have points no closer than this distance apart. This function, when 
   combined with the TestFactory, enables FME to perform area generalization 
   operations.

   Unexpected output may result if input polygons self-intersect or have 
   duplicate vertices. Also, because Z coordinates are not considered in either 
   algorithm, all features processed by this function are forced to 2D.

   If non-area features are passed to this function, no changes will be made to 
   them and they are logged with a warning.