Geospatial Tools for Visibility Analysis

Provides tools for visibility analysis in geospatial data. It offers functionality to perform isovist calculations, using arbitrary geometries as both viewpoints and occluders.

visor

The goal of visor is to provide a set of tools for visibility analysis.

Installation

You can install the released version of visor from CRAN with:

install.packages("visor")

You can install the development version of visor from GitHub with:

# install.packages("pak")
pak::pak("CityRiverSpaces/visor")

Example

This is a basic example which shows you how to use visor to calculate the isovist for view points on an arbitrary geometry (a line) and a set of occluders:

library(visor)
library(sf)

# Define occluder geoemtries
occluders <- st_sfc(
  create_occluder(1, 1, 1, 0.5),
  create_occluder(4, 1, 1.5, 0.7),
  create_occluder(7, 1, 0.8, 0.8),
  create_occluder(2, 5, 2, 1),
  create_occluder(5, 5, 1, 1.5),
  create_occluder(1, 7, 1.2, 0.6),
  create_occluder(7, 7, 1.8, 0.9)
)

# Define the viewpoint source geometry
line <- st_sfc(
  st_linestring(matrix(c(0, 3, 9, 3), ncol = 2, byrow = TRUE))
)

# Generate viewpoints
vpoints <- get_viewpoints(line, density = 1)

# Calculate isovist
isovist <- get_isovist(vpoints, occluders, ray_num = 160, ray_length = 5,
                       remove_holes = FALSE)

plot(isovist, col = "blue")
plot(occluders, col = "grey", add = TRUE)
plot(line, col = "lightblue", add = TRUE)
plot(vpoints, col = "red", add = TRUE)