st_urban_sprawl: Calculate urban sprawl
In raff-k/VLSM: Vector-based Landscape Metrics

st_urban_sprawl

R Documentation

Calculate urban sprawl

Description

This function calculates the urban sprawl of urban area.

Usage

st_urban_sprawl(
  tool = "sf",
  geom.urban,
  geom.boundary = NULL,
  dist = c(100, 100),
  trans = function(x, trans.k) {     x - 1 + 1/(x + trans.k) },
  trans.k = 1,
  tol = 0.1,
  extent = NULL,
  force.extent = FALSE,
  override = FALSE,
  precision = 0,
  do.preProcessing = TRUE,
  return.geom = FALSE,
  env.rsaga = NULL,
  quiet = TRUE
)

Arguments

`tool`	tool to perform erase-vector-operation. Default is `"sf"`. However, for complex polygons `"grass"` is highly recommended. Fot the use of `"grass"` a valid GRASS GIS-session mus be initiated. `"saga"` is also supported, then `env.rsaga` must be properly set.
`geom.urban`	polygon of class `sf` representing the fragmentation geometry
`geom.boundary`	polygon of class `sf` representing subregions, e.g. administrative boundaries
`dist`	`vector` containing distance between lines in `x` and `y` direction. Default: `c(100, 100)` `m`
`trans`	transformation function `x-1+1/(x+trans.k)` with `x` as free line and `trans.k` as constant
`trans.k`	constant in `km` for transformation function `trans`. Default: `1`
`tol`	tolerance value for intersection with erased lines. Buffering procedure is used. Default: `0.1` `m`
`extent`	Numeric value representing extent for area. Format of vector: `c(xmin, xmax, ymax, ymin)`. Default: `NULL`
`force.extent`	If `TRUE` extent is used instead of `geom.boundary` (if both are present). Default: `FALSE`
`override`	If `TRUE` projection of geometry-operation is replaced by projection of `geom.urban`. This flag prevents errors when the original datum is not found by the `tool`. Dafault: `FALSE`
`precision`	precision for process `sf::st_set_precision`. See st_precision. Default: `0`
`do.preProcessing`	If `TRUE` (default), the input of `geom.frag` is, first, dissolved to single part feature, and second, splitted to multi-parts. By this step it is assured, that polygon connected to each other are summarized
`return.geom`	If set to `TRUE`, intermediate geometries are returned as well. Default: `FALSE`
`env.rsaga`	environment of `SAGA GIS`. If `st_erase` fails then `SAGA GIS erase` is used. Default: `NULL`, but in function call if not set: rsaga.env
`quiet`	If set to `FALSE`, actual state is printed to console. Default: `TRUE`.

Value

strong urban sprawl: 40-50%, less urban sprawl: 80-90%

Note

Code is based on the following references:

Ackermann, W., Schweiger, M., Sukopp, U., Fuchs, D., & Sachteleben, J. (2013). Indikatoren zur biologischen vielfalt: Landschaftszersiedlung (Biodiversity indicators. Development and accounting). Naturschutz und Biologische Vielfalt, 132.

Depending on the selected tool, the result of the vector-operation can differ significantly!

raff-k/VLSM documentation built on Oct. 13, 2023, 11:13 a.m.