Polygons are great to have in digital maps, much like a canvas that we can render with beautiful colours. It is common that polygon boundaries are shared by linear features (e.g., municipalities divided by a river or a road). If polygons are used as part of the base to edit, update, and integrate digital maps, we have to reconcile the geometric differences among the shared boundaries and fix topological problems in edge matching. For many years we felt blessed that commercial software tools are available to reconcile shared boundaries, and to detect and fix topological problems. However, if wrestling with polygons leaves you feeling buried in slivers, discontinuities, gaps, and overlaps, youÍve got Post-Polygon Stress Disorder (PPSD).
PostgreSQL/PostGIS presented British Columbia Geological Survey an opportunity to identify the causes of PPSD. As a result, we have developed a geologic framework data model and implemented an anchoring mechanism in PostGIS to simplify the process of editing, updating, and integrating digital geological maps. We have dispensed with polygons and eliminated the problems from shared boundaries and edge matching.
Healing to PPSD is available in this poster: