Generalization of Drainage Network with Density Differences

Abstract

It is one of the main tasks to simplify drainages in map generalization.The difficulties lie in selectively omitting some rivers while maintaining the overall characteristics of the drainages.A new rule of ordering river entities based on counting the amount of their tributaries is proposed,which indicated the density differences of river entities among different areas.A complex index that combined length,grade and level is designed for structured river selection.An approach is developed to compute the new grades and complex indexes of river entities,based on structuring river segments into river-entity trees.A case study of drainage network generalization shows that the complex index is effective to combine the length,grade and level of river entities,and maintain the density differences of drainage network to some extent.