The Gravel generator
function renders arbitrarily placed, round, little stones with different
sizes. This flexible function can also be used to render textures with
features like holes, e.g. sponge and cork.
The Synthesis values have the
biggest influence to the appearance of the texture. With the Density
parameter you can control the overall number of stones. Roughness regulates
the complexity of the pattern. Increase the value to add more
little stones. The overall size of the stones is manipulated by
the Size attribute. Use the Distortion feature to
get non-round stones like those illustrated in Image 2. The Noise
parameter causes the background being to change from black to a noise
value to change the brightness of the gravel texture.
Use the Noise/Erosion function with the
preset to make the gravel (with noise background) look eroded.