R datasets: volcano

volcano is a matrix

The dataset volcano is a matrix with 61 columns and 87 rows that stores doubles:

class(volcano)
#
# [1] "matrix"

dim(volcano)
#
# [1] 87 61

typeof(volcano)
#
# [1] "double"

Github repository about-r, path: /packages/datasets/volcano/info.R

Plotting the volcano with rgl

The data of the volcano might be plotted with the rgl package.

2019-08-28: When I initially wrote the script, I used rgl.open(), rgl.bg(), rgl.surface() and rgl.bringtotop(). At that time, I didn't know that these are low level functions and should not be used, if possible. I now replaced them with the open3d() and surface3d() which produce the same result (yet I had to change the values in the matrix in the call of view3d).

The rgl.… functions are commented, for remembering purposes.

library(rgl)

#
# volcano is a matrix that stores z values. Make this
# fact more explicit:
#
z <- volcano

#
# Two vectors that contain the «meters» from the zero point.
# A cell in the grid is 10x10 meters, so we need to multiply
# the vectors by 10:
#
x <- 10 * (1:nrow(z)) # Should that not be ncol?
y <- 10 * (1:ncol(z)) # Should that not be nrow?

z_min = min(z)

z_diff = max(z) - z_min + 1

height_to_color <- terrain.colors(z_diff)

colors <- height_to_color[ z - z_min + 1 ];

open3d() # rgl.open()
# rgl.bg(color='white');
par3d(windowRect=c(34, 57, 727, 707))
surface3d(x, y, z, color=colors); # rgl.surface


view3d(
   userMatrix = matrix(
      c(
          0.972062767 , -0.1212740 , -0.2009648 , 0 ,
          0.234625295 ,  0.4775052 ,  0.8467230 , 0 ,
         -0.006723508 , -0.8702192 ,  0.4926187 , 0 ,
          0.000000000 ,  0.0000000 ,  0.0000000 , 1
      ),
      nrow  = 4,
      byrow = TRUE
  )
)

# rgl.bringtotop()

Github repository about-r, path: /packages/datasets/volcano/rgl.R

R datasets: volcano

volcano is a matrix

Plotting the volcano with rgl

See also