Calculate Texture Shading Map
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: #Plut using default values montereybay %>% texture_shade() %>% plot_map() #Increase the level of detail montereybay %>% texture_shade(detail=1) %>% plot_map() #Decrease the level of detail montereybay %>% texture_shade(detail=0) %>% plot_map() #Increase the level of contrast montereybay %>% texture_shade(contrast=3) %>% plot_map() #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 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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