multipol

Multipol, short for multipolygon, is a geometry type used in geographic information systems to represent a collection of polygonal areas as a single geometry. It is defined in the Open Geospatial Consortium (OGC) Simple Features specification and is widely supported by GIS libraries and databases, including GEOS, JTS, Shapely, PostGIS, and Spatialite.

A multipolygon consists of one or more polygons; each polygon may have holes, represented by interior rings. The collection is treated as a single entity for spatial operations such as intersection, union, containment tests, and area calculations, while preserving the separateness of its constituent parts.

In representations, a multipolygon is written in Well-Known Text (WKT) as MULTIPOLYGON (((x1 y1, x2 y2, ...)), ((...))). In GeoJSON, it appears as an object with type "MultiPolygon" and a coordinates array describing the list of polygons, each polygon made of linear rings.

Common use cases include modeling regions that consist of several disjoint parts—such as an archipelago, a country with exclaves, or administrative areas that are not contiguous. They are also used to simplify data structures by grouping multiple polygons into one feature for rendering or analysis.

Limitations may include higher computational cost for large numbers of polygons and more complex topologies. See also polygon, geometry collection, GIS, and OGС specifications.