For a planar curve, an inflection point
occurs at a point where the curvature changes sign (see
Sect. 2.2). Note that a vanishing curvature does not
necessarily imply inflections, e.g. consider the curve
at
. Using curvature plots, which consist of segments normal
to the curve emanating from a number of points on the curve and whose
lengths are proportional to the magnitude of the curvature given in
(2.25) at the associated point, inflection
points and the variation of curvature can be easily identified as
illustrated in Fig. 8.3.