# Module: RGeo::Feature::MultiPolygon

- Extended by:
- Type

- Includes:
- MultiSurface

- Included in:
- Cartesian::MultiPolygonImpl, Geographic::ProjectedMultiPolygonImpl, Geographic::SphericalMultiPolygonImpl

- Defined in:
- lib/rgeo/feature/multi_polygon.rb

## Overview

## SFS 1.1 Description

A MultiPolygon is a MultiSurface whose elements are Polygons.

The assertions for MultiPolygons are as follows.

a) The interiors of 2 Polygons that are elements of a MultiPolygon may not intersect.

b) The boundaries of any 2 Polygons that are elements of a MultiPolygon may not “cross” and may touch at only a finite number of Points. NOTE: Crossing is prevented by assertion (a) above.

c) A MultiPolygon is defined as topologically closed.

d) A MultiPolygon may not have cut lines, spikes or punctures, a MultiPolygon is a regular closed Point set:

e) The interior of a MultiPolygon with more than 1 Polygon is not connected, the number of connected components of the interior of a MultiPolygon is equal to the number of Polygons in the MultiPolygon.

The boundary of a MultiPolygon is a set of closed Curves (LineStrings) corresponding to the boundaries of its element Polygons. Each Curve in the boundary of the MultiPolygon is in the boundary of exactly 1 element Polygon, and every Curve in the boundary of an element Polygon is in the boundary of the MultiPolygon.

NOTE: The subclass of Surface named Polyhedral Surface is a faceted Surface whose facets are Polygons. A Polyhedral Surface is not a MultiPolygon because it violates the rule for MultiPolygons that the boundaries of the element Polygons intersect only at a finite number of Points.

## Notes

MultiPolygon is defined as a module and is provided primarily for the sake of documentation. Implementations need not necessarily include this module itself. Therefore, you should not depend on the kind_of? method to check type. Instead, use the provided check_type class method (or === operator) defined in the Type module.

## Method Summary

### Methods included from Type

add_subtype, check_type, each_immediate_subtype, extended, subtype_of?, supertype, type_name

### Methods included from MultiSurface

#area, #centroid, #point_on_surface

### Methods included from GeometryCollection

#[], #each, #geometry_n, #node, #num_geometries, #size

### Methods included from Geometry

#*, #+, #-, #==, #as_binary, #as_text, #boundary, #buffer, #contains?, #convex_hull, #crosses?, #difference, #dimension, #disjoint?, #distance, #empty?, #envelope, #eql?, #equals?, #factory, #geometry_type, #intersection, #intersects?, #is_empty?, #is_simple?, #overlaps?, #relate?, #rep_equals?, #simple?, #srid, #sym_difference, #touches?, #unary_union, #union, #within?