lamb_shade: Calculate Lambert Shading Map

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

Calculate Lambert Shading Map

Description

Calculates local shadow map for a elevation matrix by calculating the dot product between light direction and the surface normal vector at that point. Each point's intensity is proportional to the cosine of the normal vector.

Usage

lamb_shade(
  heightmap,
  sunaltitude = 45,
  sunangle = 315,
  zscale = 1,
  zero_negative = TRUE
)

Arguments

heightmap	A two-dimensional matrix, where each entry in the matrix is the elevation at that point. All points are assumed to be evenly spaced.
sunaltitude	Default '45'. The azimuth angle as measured from the horizon from which the light originates.
sunangle	Default '315' (NW). The angle around the matrix from which the light originates.
zscale	Default '1'. The ratio between the x and y spacing (which are assumed to be equal) and the z axis.
zero_negative	Default 'TRUE'. Zeros out all values below 0 (corresponding to surfaces facing away from the light source).

Value

Matrix of light intensities at each point.

Examples

if(run_documentation()) {
#Generate a basic hillshade
montereybay %>% 
 lamb_shade(zscale=200) %>% 
 plot_map()
}
if(run_documentation()) {
#Increase the intensity by decreasing the zscale
montereybay %>% 
 lamb_shade(zscale=50) %>% 
 plot_map()
}
if(run_documentation()) { 
#Change the sun direction
montereybay %>% 
 lamb_shade(zscale=200, sunangle=45) %>% 
 plot_map()
}
if(run_documentation()) {
#Change the sun altitude
montereybay %>% 
 lamb_shade(zscale=200, sunaltitude=60) %>% 
 plot_map()
}

tylermorganwall/rayshader documentation built on Nov. 21, 2024, 8:11 a.m.