This is a continuous version of the chain code described in the previous section. is the tangent angle of a point on the boundary with reference to a fixed datum, for example the x-axis, and s is the distance along the
boundary. For a closed curve the function is periodic. Horizontal straight lines in the
description correspond to straight lines on the object boundary, whereas straight lines of uniform gradient in
space correspond to uniform circular arcs; i.e.
is changing at a constant rate. The first derivative of the
curve is often used to segment a boundary
into quasi-uniform segments, since boundary discontinuities result in a peak or delta function in
space.
Figure 9: The representation
[ Chain Codes |
Piecewise Polynomials ( Splines) ]
Comments to: Sarah Price at ICBL.
(Last update: 22th April, 1996)