View source: R/texture_shade.R
texture_shade | R Documentation |
Calculates a shadow for each point on the surface using the method described by Leland Brown in "Texture Shading: A New Technique for Depicting Terrain Relief."
texture_shade(
heightmap,
detail = 0.5,
contrast = 1,
brightness = 0,
transform = TRUE,
dx = 1,
dy = 1,
pad = 50
)
heightmap |
A two-dimensional matrix, where each entry in the matrix is the elevation at that point. |
detail |
Default '0.5'. Amount of detail in texture shading algorithm. '0' is the least detail, while '1' is the most. |
contrast |
Default '1',standard brightness. Amount of contrast in the texture shading. This transforms the resulting darkness using the formula 'tanh(input * contrast + brightness)'. |
brightness |
Default '0', standard brightness. Higher values will brighten the texture hillshade, while lower values will darken it. |
transform |
Default 'TRUE'. Whether to apply the 'tanh(input * contrast + brightness)' transformation. This transforms the resulting darkness using the formula 'tanh(input * contrast + brightness)'. |
dx |
Default '1'. The distance between each row of data (compared to the height axis). |
dy |
Default '1'. The distance between each column of data (compared to the height axis). |
pad |
Default ‘50'. The amount to pad the heightmap so edge effects don’t appear from the fourier transform. Only increase this if you encounter boundary effects. |
2D matrix of hillshade values.
#Create a direct mapping of elevation to color:
if(run_documentation()) {
#Plut using default values
montereybay %>%
texture_shade() %>%
plot_map()
}
if(run_documentation()) {
#Increase the level of detail
montereybay %>%
texture_shade(detail=1) %>%
plot_map()
}
if(run_documentation()) {
#Decrease the level of detail
montereybay %>%
texture_shade(detail=0) %>%
plot_map()
}
if(run_documentation()) {
#Increase the level of contrast
montereybay %>%
texture_shade(contrast=3) %>%
plot_map()
}
if(run_documentation()) {
#Increase the brightness for this level of contrast
montereybay %>%
texture_shade(contrast=5, brightness = 2) %>%
plot_map()
}
#Add a texture_shade() layer into a map
montbay = montereybay
montbay[montbay < 0] = 0
if(run_documentation()) {
montbay %>%
height_shade() %>%
add_water(detect_water(montbay), color="dodgerblue") %>%
add_shadow(texture_shade(montbay, detail=1/3, contrast = 5, brightness = 6),0) %>%
add_shadow(lamb_shade(montbay,zscale=50),0) %>%
plot_map()
}
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