MultiSurface

MultiSurface is a geospatial geometry type used to represent a single geometric object composed of two or more distinct surface geometries. It is defined in Open Geospatial Consortium (OGC) standards as part of Geography Markup Language (GML) and related geometry models. Each member of a MultiSurface is a surface geometry—typically a Polygon or polygonal surface—that may be disjoint or share boundaries. A MultiSurface may include holes within its member surfaces, defined by interior rings in the polygonal geometry.

In data encoding, a MultiSurface is serialized as a collection of surfaceMember elements (or a surfaceMembers container), with each surfaceMember containing an individual surface geometry. All member surfaces generally share a common coordinate reference system, and coordinates are usually 2D (X, Y), though 3D coordinates (Z) can be used where supported.

MultiSurface is useful for modeling complex shapes that cannot be captured by a single polygon, such as cadastral parcels comprising several separate areas, architectural floor plans with multiple rooms, or land areas with internal gaps.

Spatial operations and predicates (such as intersection, union, and difference) apply to MultiSurface geometries through standard GIS geometry engines, treating the object as an aggregate of its surface members.

Relation to other types: It belongs to the family of multi-geometries. It is most akin to MultiPolygon when all members are polygons, but its semantics emphasize surfaces within a single aggregate within GML and related standards.