Modelling Geometry for Linear Feature Generalisation

Abstract

This chapter addresses issues related to linear feature generalisation considered independently from their cartographic context. It highlights the importance of modelling the geometry of linear features in order to generalise them. The chapter proposes a constructive approach by segmenting lines and qualifying sections detected according to different criteria at several levels (‘hierarchical’ process). The aim of such an approach is twofold: to guide the choices of adequate sequences of generalisation operations and algorithms; and to provide basic tools for assessing the quality of the results of generalisation alternatives in terms of shape maintenance. The chapter addresses issues related to linear feature generalisation (especially simplification and enhancement of road features) considered independently from their cartographic context. Three kinds of issues need to be tackled in order to achieve good generalisation results for linear features: eliciting geometric knowledge on linear features; formalising rules for generalisation decisions of operations and algorithms; and assessing the quality of generalisation operations in terms of shape maintenance.