Visions Of Chaos Reaction-Diffusion Tutorial

Reaction-Diffusion is a simulation of two or more chemicals that react with each other and spread out over a surface. Based on realtively simple processes these simulations can go from an initial random noise start that self-organise into natural looking patterns like stripes, spots and spirals.

Reaction-Diffusion Settings

Reaction-Diffusion

Model - The model dropdown selects various types of Reaction-Diffusion models supported by Visions Of Chaos. Each of them gives unique results. See the example section below to see the type of images and movies each type can create.

Specific Model Settings - As the model type is changed a series of parameters that control the equations are shown. When trying new values, change one at a time and make small changes. Some of the methods are very sensitive to large changes in the parameters.

Keep Chemical Values Above 0 - Ensures the concentrations of the chemicals never drops below 0. This is normally necessary for most of the methods.

Feedback - This is more of an experiment. Each step of the simulation the values for one of the chemical are fed into the substrate.

Reaction-Diffusion Display Settings

Reaction-Diffusion

Initial Frame Style - Allows the simulations to start from a random strt, specific shape or from an image.

Cycles Per Update - How many internal steps of the simulation are done before updating the display. Some of the methods can take a while for patterns to appear, so if you are creating a movie it will seem to run very slowly when played back. Increasing this value speeds up the movie.

Shade With Color Palette - Uses the currently loaded color palette to shade the display. If unchecked a palette is created between the color 1 and color 2 shades.

Lighting Effect - Gives a psuedo 3D look to the display.

Reaction-Diffusion AVI Creation Settings

Reaction-Diffusion

Create AVI Frames - Saves each display update as a frame BMP file that can then be combined into an AVI movie of the simulation. If you find the movie plays back too slowly, then increase the Cycles Per Update setting (see above).

Stop After - Automatically stops saving frames after a specified number of steps. The default value of 0 keeps running until you stop the simulation.

Reaction-Diffusion Batch Mode Settings

Reaction-Diffusion

Batch mode takes a series of BMP files and runs the current reaction diffusion method on each frame. This can create interesting effects. The BMP frames must be in the same format Visions Of Chaos creates FRA00000.BMP, FRA00001.BMP, etc.

Source Directory - Specify the directory the input FRAxxxxx.BMP files reside in.

Target Directory - A different directory that the processed BMP files will be created in.

Steps Per Image - How many reaction diffusion steps will be performed on each frame.

Reaction-Diffusion Examples

Turing - The Turing method comes from a 1952 paper Alan Turing wrote called "The Chemical Basis of Morphogenesis". It creates blobby and striped patterns.



Meinhardt - The Meinhardt method comes from Hans Meinhardt. See the paper "A Theory Of Biological Pattern Formation" for more details. This method tends to create maze-like stable patterns.



Gray-Sctott - For more info see the paper "Complex Patterns in a Simple System". The Gray-Scott method tends to create replicating cells, pulsating waves and growing maze patterns.



Complex Ginzburg-Landau - This method comes from Vitaly Ginzburg and Lev Landau back in the 1950s. It creates small spiral structures and cell like shapes.