ppmforge generates three kinds of "random fractal forgeries," the term coined by Richard F. Voss of the IBM Thomas J. Watson Research Center for seemingly realistic pictures of natural objects generated by simple algorithms embodying randomness and fractal self-similarity. The techniques used by ppmforge are essentially those given by Voss[1], particularly the technique of spectral synthesis explained in more detail by Dietmar Saupe[2].
ppmforge: planet: -seed 666 -dimension 2.40 -power 0.80 -mesh 1024 ppmforge: -inclination 4 -hour 15 -ice 0.87 -glaciers 0.75 ppmforge: -stars 100 -saturation 125.
#!/bin/bash WIDTH=460 HEIGHT=460 SEED=666 MESH=2048 DIMENSION=2.80 POWER=0.65 NOMBRE=96 DELAY=15 # for GIF animation source functions_gif.bash for i in $(seq 1 $NOMBRE) do dest=/tmp/planete$(printf "%03d" $i).ppm hour=$i ice=$( echo "($i / $NOMBRE) + 0.001" | bc -l ) ppmforge -hour $hour -seed $SEED -mesh $MESH \ -dimension $DIMENSION \ -power $POWER -ice $ice \ -width $WIDTH -height $HEIGHT > $dest annotate $i $dest done convert -delay $DELAY /tmp/planete*.ppm planete.gif