distance_analysis: Viewshed Distance Analysis

In STBrinkmann/GVI: R package for computing VGVI for Spatial Raster

Viewshed Distance Analysis

Description

Visibility changes with increasing distance, therefore a threshold for the study area can be evaluated beyond which an observer can't see any terrain. The distance_analysis function calculates the proportion of visible area for each distance value.

Usage

distance_analysis(
  observer,
  dsm_rast,
  dtm_rast,
  greenspace_rast = NULL,
  max_distance = 800,
  observer_height = 1.7,
  raster_res = NULL,
  summarise = FALSE,
  progress = FALSE,
  cores = 1
)

Arguments

observer	object of class sf with POINT geometries; Observer location(s) from where the distance analysis should be computed.
dsm_rast	object of class rast; rast of the DSM
dtm_rast	object of class rast; rast of the DTM
greenspace_rast	optional; rast of the binary Greenspace mask. Values of the Greenspace mask must be 1 for Green and 0 for No-Green
max_distance	numeric; Maximum buffer distance
observer_height	numeric > 0; Height of the observer (e.g. 1.7 meters)
raster_res	optional; NULL or numeric > 0; Resolution that the viewshed raster should be aggregated to. Must be a multible of the dsm_rast resolution
summarise	optional; Should the results be summarised over all observer locations?
progress	logical; Show progress bar and computation time?
cores	numeric; The number of cores to use

Details

If greenspace_rast is NULL only Visibility will be computet. Else, Greenspace and VGVI will be calculated, too. Visibility: Proportion of visible cells to all cells at each distance value (e.g. 1m, 2m, …). Example: 4 cells have a distance of 1m to the observer. Only 3 of them are visible, Visibility = 0.75

Greenspace: Proportion of green cells at each distance values, regardless of their visibility! Example: 4 cells have a distance of 1m to the observer. Only 2 of them are green, Greenspace = 0.50

VGVI: Proportion of visible green cells to all visible cells at each distance value. Example: 4 cells have a distance of 1m to the observer. 3 are visible but only 1 is visible green, VGVI = 0.33

Value

object of class tibble

STBrinkmann/GVI documentation built on March 11, 2024, 3:39 p.m.