rayshader (version 0.37.3)

detect_water: 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
)

Value

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

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.

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()