polygons_clean: Clean up polygons after download
In ecological-cities/home2park: Spatial Provision of Urban Parks

polygons_clean

R Documentation

Clean up polygons after download

Description

Helper function to process and clean up polygons downloaded from OpenStreetMap.

Usage

polygons_clean(
  input,
  snap_tolerance = 5,
  min_area = units::set_units(0, "m^2"),
  aggregate_polygons = 15
)

Arguments

`input`	`sf` object (with projected coordinate reference system).
`snap_tolerance`	numeric. Argument for `tolerance` level passed to `sf::st_snap()`, used to rectify nearly coincident edges between polygons. Provided either as a units object (see `units::set_units()`), or a number in the units of the coordinate reference system. After `sf::st_snap()` is run, a polygon that is covered by another will be removed. Defaults to `5`. Set to `0` if you do not wish to rectify minor overlaps.
`min_area`	numeric. Specify minimum area of each polygon to be retained in the output, passed to argument `threshold` in `smoothr::drop_crumbs()`. Provided either as a units object (see `units::set_units()`), or a number in the units of the coordinate reference system. Defaults to `0` m^2.
`aggregate_polygons`	numeric. Argument for `dist` passed to `sf::st_buffer()`. Buffered polygons that overlap will be aggregated into multipolygons. Set to `NULL` if you do not wish to aggregate to multipolygons.

Details

Polygons contained in or overlapping others are removed. Polygons vertices are then snapped at a tolerance level based on snap_tolerance (if specified) to rectify nearly coincident edges, and polygons covered by others are subsequently removed. Polygons are then aggregated to multipolygons based on distance set in aggregate_polygons (if specified). All spatial relations (italicised) follow the DE-9IM standard.