(^) Pictures: Top: Typical
MojoWorld landscapes of the
type to be found by flying over
the terrains offered by its
procedurally generated
planets. The examples here
are from MoodyBlue’s
MojoWorld stock, available
under Creative Commons at
http://www.deviantart.com/
moodyblue.
Picture: “Painterly quality
demo” by Mutinate.
“The construction of fractal terrains is
remarkably simple: it is an iterative loop
involving only four important factors, one of
which is generally a nonissue. First, we have
the basis function, or the shape that we build
the fractal out of, by repeating it at a variety of
scales. Next there’s the fractal dimension,
which controls the roughness of the fractal by
simply modulating the amplitude or vertical size
of the basis function in each iteration (i.e., each
time you go through the loop). Then there are
the octaves, or the number of times that we
iterate in building the fractal. Finally, we have
the lacunarity, or the factor by which we change
the frequency or horizontal size of the basis
function in each iteration. ... We’ve gone with a
default lacunarity just over 2.2 in MojoWorld
[v.1.0], to eek out a little more speed. If you
want images that are as good as they can be,
I’d recommend a value more like 1.9.”
— from Ken’s excellent chapter “Mojoworld:
Building procedural planets”, in the third edition
of the famous textbook Texturing and Modeling:
A Procedural Approach.
ann
(Ann)
#1