poly2grid_untiled

syntax

poly2grid_untiled(polygon_data_item, gridunit)

definition

The poly2grid_untiled function results in grid data-item with a relation to the domain-unit of the polygon_data_item

The resulting data item has:

as domain-unit the gridunit argument
as values-unit the domain-unit of the polygon_data_item argument

description

This function is the same as poly2grid but writes singly threaded on a single mutable shadow tile that is then split into separate tiles after rendering all polygons. Compared to poly2grid, this poly2grid_untiled function will:

take longer to calculate (as it doesn’t process tiles in parallel),
use more memory (to store the intermediate mutable shadow tile),
but uses less CPU time (as polygons preparation is not repeated for each tile with which their bounding box intersects),
the results are independent of the actual tiling (which could not be always true for poly2grid as the conversion to a tile-local coordinate system might cause tiling-dependent flip-cases).

applies to

data item polygon_data_item with a wpoint, spoint, upoint, ipoint, fpoint or dpoint value-type
unit gridunit with a wpoint, spoint upoint, ipoint, fpoint, dpoint value type

conditions

The composition type type of the polygon_data_item needs to be polygon.
The domain-unit of the polygon_data_item must be of value type uint32.

since version

8.7.0

example

attribute<source/district> DistrictGrid (gridunit/gridcel_10m) := 
   poly2grid_untiled(Source/District/border, gridunit/gridcel_10m);