Critical Point Detection Using the Length Ratio (LR) for Line Generalization

This article presents a review of existing methods for the detection of critical points cited in cartographic and computer science literature. Moreover, a theoretical assessment of algorithm validity with regard to cartographic representation demands is carried out. A method for the detection of critical points using the length ratio (LR) index is introduced, based on geometric principles. Four lines (three geomorphologic and one arbitrary) selected from relevant studies are used to check the method. Finally, the LR index is used to compare the results of two line simplification algorithms (pointremove and bendsimplify) applied on five successive line simplification tasks on the coastline of a small island.