Growth Forms
George W. Hart
These are screen shots and video captures from a sculpture-generation
project I am working on.
Click on each image to see an
avi
animation of it growing and tumbling. (They are 15MB-70MB files.)
Start with an easy snakey thing. (Click the image for the
video.)
Simple radial growth
Coral-like structure (upwards
branching growth
only at tips)
Branching growth that also continues to grow everywhere
Four-limbed form
Octopus-like form
Pods with phylotaxis
Line growth, forming hyperbolic surface
Thing bearing fruit. (See below for a physical model.)
A 12-limbed thing that is not icosahedral
Spiky guy
A thing that grows holes which pop through its surface and increase its
genus.
It isn't like any natural growth process I know, but there is
something plausible about it.
Each form develops in real time from a
small ball of cells by following a simple algorithm that is written in
about a dozen lines of a "growth/form description language" which I am
in
the process of developing and implementing. At every stage in the
development, each form is a valid 3D object which can be built on a
rapid prototyping machine. Details are available in
this paper (which appeared in
Bridges 2009).
For the topologically curious, these cells are colored by
number of neighbors, corresponding to local curvature.
Here is a seven-inch plastic model (built by fused deposition modeling)
based on the stl file that is generated for an example above.
For fun, I painted it to match the above rendering, which helps bring
out its cellular structure.