ABSTRACT
The procedure presented in the last chapter holds for digital curves with uniformly spaced points only. In this chapter we present another sequential one-pass algorithm [121] which holds for uniformly as well as non-uniformly spaced points. The procedure is based on Pavlidis’ [106] concept of almost collinearity of a sequence of points. Initially the in-radius of triangles formed by the sequence of point’s triplets is introduced as a criterion function to measure collinearity. This is an indirect approach but justified by a proposition which establishes that the higher the in-radius is, the higher is the perpendicular distance. Unfortunately, evaluation of in-radius is computationally expensive. To reduce the computational load the in radius is replaced by the area and perimeter of triangles. The vertices of the polygon are located by comparing the area and perimeter with their critical value.
