Diffusion-limited aggregation

</COMMENT> <h4>Unfortunately, your browser does not support Java.<BR> A Java applet is the central focus of this page.<BR> You're encouraged to try again using a Java-aware browser.</h4>

Click here for a version using the native JVM.

This applet displays fractal drainage patterns.

Begin exploring by using the "Preset" choice at the bottom - and the "Restart" button below it - to see some of the possible configurations.

Configurable parameters include a number of manual colour-map controls (on the left) - and six main parameters of the fractal drainage system (on the right).

Take care if using the other controls on the right. They are usually very sensitive.

The model is a cellular automaton, based on the [Moore neighbourhood].

Toroidial boundary constraints are appled, so the images will tesselate seamlessly.

Optionally, a bumpmap technique is employed to give the images a sense of depth.

The controls on the right are described - using the metaphor of erosion of landscape caused by rain - as follows:

  • Add rate: rate of rain fall on high ground;
  • Seep rate: rate at which liquid seeps into the land;
  • Flow rate: speed of liquid flow;
  • Log resistance: quantifies the resistance the land puts up to the corrosive force of the liquid;
  • Ground rising: the ground constantly rises to replace material lost through erosion;
  • Upper threshold: height above which rain falls;
  • Lower threshold: height below which water is removed.

There's an introduction to fractal drainage patterns here, and an explanation of the modelling technique used in this applet here.

tim@tt1.org | http://fractaldrainage.com/