Verifying and improving map specifications of river network selection for automatic generalization of small-scale maps

Automated generalization is highly desired for effective map production. This research focuses on the initial stage of generalization, namely object selection. The study aims to conduct river network automatic selection based on map specifications contained in the Minister of Internal Affairs and Administration regulation. The research covers river network selection from the General Geographic Objects Database from 1:250,000 to 1:500,000 detail level. Within the research scope, three selection variants were designed. The first was a basic variant that only included the implementation of the specifications contained in the regulation. The other two were experimental variants: an extended variant and an extended-modified variant with the parameters and data enrichment proposed by the authors. The extended variant has been supplemented with the Id_MPHP index usage, derived from the Map of Hydrographic Division of Poland (MPHP), which defines the hierarchy of watercourses in the river network. The extended-modified variant was implemented according to the guidelines of the regulation, with the use of the Id_MPHP index and additionally with the help of the parameter denoting “priority” watercourses, which was assigned by the authors. The results of the work constitute the generalization models designed in ArcMap 10.8. with the use of Model Builder functionality as well as the maps presenting the selection variants output visualizations. The results were compared visually as well as verified with the reference atlas map generalized by an experienced cartographer. As a result, the map specifications concerning the selection process presented in the regulation proved to be insufficient to generalize river networks properly. The variants proposed in this research made it possible to improve the selection results and enabled the automation of the river selection process. Additional specifications and parameters proposed in this work may constitute an essential supplement to the guidelines contained in the regulation.