PolygonFeature

PolygonFeature is a vector geographic feature whose geometry is a polygon. It represents bounded areas such as land parcels, lakes, parks, or administrative units. Each PolygonFeature consists of a polygon geometry plus a set of attribute fields that describe its properties (for example name, type, area) and a unique identifier. The geometry typically includes one exterior boundary, called the outer ring, and zero or more interior boundaries called holes or inner rings. All coordinates are defined in a coordinate reference system, and operations assume a planar approximation for small areas or a projected CRS for more accurate area calculations; for geographic coordinates, area calculations may require spherical geometry.

Polygon features are stored in layers or feature classes within GIS databases or file formats. Common formats include Shapefile, GeoJSON, GML, and spatial databases such as PostGIS, SpatiaLite, or Esri geodatabases. Interoperability is governed by standards such as the Open Geospatial Consortium Simple Features specification, which defines polygon and multipolygon geometry types, coordinate order, and spatial predicates. PolygonFeature data can be accessed or edited by tools that support digitizing, snapping, topology checks, and attribute editing.

Typical operations on PolygonFeatures include spatial queries (e.g., contains, intersects), topological consistency checks to prevent overlaps or gaps, and geometric calculations like area, perimeter, centroid, and bounding box. Spatial indexing (such as R-trees) accelerates queries on large collections.

Applications of PolygonFeatures span land administration, environmental planning, urban zoning, cadastral mapping, and resource management. Accuracy depends on precise digitization, metadata about CRS and measurement units, and thorough quality control.