dms_split_union_polygon

Geometric functions dms_split_union_polygon

syntax

• dms_split_union_polygon(polygon_data_item)
• dms_split_union_polygon(polygon_data_item, partition_attribute)

description

dms_split_union_polygon(polygon_data_item) dissolves every polygon of the argument into one geometry and then splits that into its single polygons: the combination of dms_union_polygon and dms_split_polygon in one operator, which is how neighbouring parcels become the separate blocks they form together.

With a partition_attribute the dissolve is per group first, and the split follows.

The result is a new uint32 Domain unit with one entry per part, carrying:

• geometry: the single polygon of that part, with its holes
• part_rel: with a partition_attribute, a relation towards its Values unit; without one the dissolve has a Void domain and there is no relation to carry

As everywhere in the dms polygon operators family, the elements do not have to be valid polygons.

applies to

• Attribute polygon_data_item with a polygon Value type: spoint, ipoint, wpoint, upoint, fpoint or dpoint
• Attribute partition_attribute (optional) with a Categorical value type, over the same Domain unit as polygon_data_item

conditions

1. The composition type of the polygon_data_item needs to be polygon.
2. A partition_attribute, when given, must have the same domain as polygon_data_item.

since version

20.20.0

example

unit<uint32> blocks := dms_split_union_polygon(parcel/geometry);

see also

• dms polygon operators - the family: the even-odd rule, the grid and what the result looks like
• dms_union_polygon, dms_split_polygon - the two halves separately
• geos_split_union_polygon, bp_split_union_polygon, bg_split_union_polygon, cgal_split_union_polygon - the same operator on the geometry libraries