compute_viewshed {viewscape}

compute_viewshed

Description

The compute_viewshed function is designed for computing viewsheds, which are areas visible from specific viewpoints, based on a Digital Surface Model (DSM). It provides flexibility for single or multi-viewpoint analyses and allows options for parallel processing, raster output, and plotting.

Usage

compute_viewshed(
  dsm,
  viewpoints,
  offset_viewpoint = 1.7,
  offset_height = 0,
  r = NULL,
  parallel = FALSE,
  workers = 0,
  raster = FALSE,
  plot = FALSE
)

Arguments

dsm

Raster, the digital surface model/digital elevation model

viewpoints

sf point(s) or vector including x,y coordinates of a viewpoint or a matrix including several viewpoints with x,y coordinates

offset_viewpoint

numeric, setting the height of the viewpoint. (default is 1.7 meters).

offset_height

numeric, setting the height of positions that a given viewpoint will look at. (defaut is 0)

r

Numeric (optional), setting the radius for viewshed analysis. (it is defaulted as NULL)

parallel

Logical, (default is FALSE) indicating if parallel computing should be used to compute viewsheds of multiview points. When it is TRUE, arguements 'raster' and 'plot' are ignored

workers

Numeric, indicating the number of CPU cores that will be used for parallel computing. It is required if 'parallel' is 'TRUE'.

raster

Logical, (default is FALSE) if it is TRUE, the raster of viewshed will be returned. The default is FALSE

plot

Logical, (default is FALSE) if it is TRUE, the raster of viewshed will be displayed

Value

Raster or list. For single-viewpoint analysis, the function returns either a raster (raster is TRUE) or a viewshed object. Value 1 means visible while value 0 means invisible. For multi-viewpoint analysis, a list of viewsheds is returned.

Examples

# Load a viewpoint
test_viewpoint <- sf::read_sf(system.file("test_viewpoint.shp", package = "viewscape"))
# load dsm raster
dsm <- terra::rast(system.file("test_dsm.tif", package ="viewscape"))
#Compute viewshed
output <- compute_viewshed(dsm = dsm,
                           viewpoints = test_viewpoint,
                           offset_viewpoint = 6)