Make a 3D bar plot with colors in function of bar's height
Create a 'peaks' grid
G = GMT.peaks(); # The grid
cmap = grd2cpt(G); # Colormap with the grid's data range
Plot that grid as 3D prisms. Here we use the default fig width of 12 cm
bar3(G, # 'G' is the grid created above
lw=:thinnest, # Line thickness (0.25 pt)
color=cmap, # Paint the prisms with colormap computed from grid
show=true) # Show the result
As one-liners (to facilitate copy-paste):
G = GMT.peaks(); cmap = grd2cpt(G);
bar3(G, lw=:thinnest, color=cmap, show=true)