ArcEstimator

From Fmepedia

ArcEstimator is a Workbench Transformer.

Replaces the geometry of the feature with a two-dimensional circular arc whose shape is estimated from the first, middle, and last point of the linear feature passed in. The result is an approximation only and unless the linear feature is previously known to be circular; the result could be completely different than the original feature.

This is most useful when it the feature was known to have been a circular arc originally and was stroked into a line. This transformer can then be used to turn it back into an arc.

For example, a feature containing these points:

   2,1
   1,2
   0,2.236067977 (sqrt(5))

will be turned into an arc feature with this geometry:

   0,0

and these attributes:

   fme_primary_axis     2.236067977
   fme_secondary_axis   2.236067977
   fme_start_angle      26
   fme_sweep_angle      63
   fme_rotation         0

If the parameters for the arc are already available as attributes on the feature, then use the 2DArcReplacer or 3DArcReplacer transformer.