geos_overlay_polygon

Geometric functions > geos_overlay_polygon

syntax

geos_overlay_polygon(polygon_data_item)
geos_overlay_polygon(polygon_data_item1, polygon_data_item2)

description

geos_overlay_polygon computes the spatial overlay between polygon sets, resulting in a new domain containing all intersecting polygon pairs with their combined geometry.

With one argument, geos_overlay_polygon(polygon_data_item) computes a self-overlay: all pairs of polygons within the dataset that spatially overlap are found and their intersection geometries are computed.

With two arguments, geos_overlay_polygon(polygon_data_item1, polygon_data_item2) computes an overlay between two polygon datasets. All pairs of polygons from the two datasets that spatially overlap are found and their intersection geometries are computed.

The geos_ prefix of the function name indicates that the implementation of the operator uses geos.

applies to

attribute polygon_data_item1 with a polygon value type
attribute polygon_data_item2 (optional) with a polygon value type, compatible with polygon_data_item1

conditions

The composition type of the arguments needs to be polygon.
The value types of both arguments must be compatible (same point type).

result

The result is a container (new domain unit of type uint32) with:

geometry: the intersection polygon geometry for each overlapping pair
first_rel: relation to the domain of polygon_data_item1 (absent if domain is void)
second_rel: relation to the domain of polygon_data_item2 (absent if domain is void, or in 1-argument form)

since version

14.0

example

unit<uint32> overlay := geos_overlay_polygon(land_use/geometry, district/geometry)
{
    attribute<fpoint>    geometry;
    attribute<land_use>  first_rel;
    attribute<district>  second_rel;
}