detect_water: Detect water

In tylermorganwall/rayshader: Create Maps and Visualize Data in 2D and 3D

Detect water

Description

Detects bodies of water (of a user-defined minimum size) within an elevation matrix.

Usage

detect_water(
  heightmap,
  zscale = 1,
  cutoff = 0.999,
  min_area = length(heightmap)/400,
  max_height = NULL,
  normalvectors = NULL,
  keep_groups = FALSE,
  progbar = FALSE
)

Arguments

heightmap	A two-dimensional matrix, where each entry in the matrix is the elevation at that point. All grid points are assumed to be evenly spaced. Alternatively, if heightmap is a logical matrix, each entry specifies whether that point is water or not.
zscale	Default '1'. The ratio between the x and y spacing (which are assumed to be equal) and the z axis. For example, if the elevation levels are in units of 1 meter and the grid values are separated by 10 meters, 'zscale' would be 10.
cutoff	Default '0.999'. The lower limit of the z-component of the unit normal vector to be classified as water.
min_area	Default length(heightmap)/400. Minimum area (in units of the height matrix x and y spacing) to be considered a body of water.
max_height	Default 'NULL'. If passed, this number will specify the maximum height a point can be considered to be water.
normalvectors	Default 'NULL'. Pre-computed array of normal vectors from the 'calculate_normal' function. Supplying this will speed up water detection.
keep_groups	Default 'FALSE'. If 'TRUE', the matrix returned will retain the numbered grouping information.
progbar	Default 'FALSE'. If 'TRUE', turns on progress bar.

Value

Matrix indicating whether water was detected at that point. 1 indicates water, 0 indicates no water.

Examples

library(magrittr)
#Here we even out a portion of the volcano dataset to simulate water:
island_volcano = volcano
island_volcano[island_volcano < mean(island_volcano)] = mean(island_volcano)

#Setting a minimum area avoids classifying small flat areas as water:
island_volcano %>%
 sphere_shade(texture="imhof3") %>%
 add_water(detect_water(island_volcano, min_area = 400),color="imhof3") %>%
 plot_map()

tylermorganwall/rayshader documentation built on Dec. 21, 2024, 4:29 p.m.