AVS Modules						fractal field (6)

NAME
		fractal field - generate fractally distributed random fields 

AUTHOR INFO:	David E. Harris, Georgia Tech Research Institute

SOURCE FILE:	fracgen.c

TYPE:		data

INPUTS:		None

OUTPUTS:	fractal field:	field 2D uniform scalar byte
		gaussian field: field 2D uniform scalar byte (optional)

PARAMETERS:     Name		Type	  Default	Min	Max
	        Size		integer   6		2	10
	        Fractal Dim.	float     2.5		2.001   2.999
		Scale Value	integer	  255		1	255
		Reseed		one-shot  -		-	-

DESCRIPTION:
	This module generates a 2D scalar byte field whose elements are
statistically self-similar (fractal) in distribution without regard to scale.
(I.e. size.  Not to be confused with the intensity scale value parameter.)
A gaussian distributed random field is first created and then transformed to
the frequency domain by FFT.  The result is then filtered to agree with the
fractal power law and inverse transformed.  The second ouput port provides
access to the gaussian random field used to generate the fractal field.

   Size	        - This dial selects the size of the square field.  The number
		  is the exponent of 2 that will be used to generate the data.
		  Values from 2 to 10 will yield arrays from 4x4 to 1024x1024.
		  Changing this parameter will generate a new set of random
		  numbers.

   Fractal Dim. - For the purposes of this module, the fractal dimension can
		  be thought of as the degree of roughness of the field if the
		  field is treated as a surface or an image.  The higher the
		  fractal dimension, the rougher the image will look.  Changing
		  this parameter alone will not cause a new set of random
		  numbers to be generated.

   Scale Value	- The fractal field is a scaled to fit in the range 0--255.
		  This parameter allows the user to change the upper limit of
		  the range.

   Reseed	- This one-shot button gives a new seed to the random number
		  generator and causes a new field to be generated.
	
EXAMPLE 1: This network produces a fractal field and displays it as a grayscale
image.
	
                        FRACTAL FIELD
                              |
                           COLORIZE
                              |
                        DISPLAY IMAGE


EXAMPLE 2: This network produces a fractal field and renders it as an elevation
data set used to simulate landscapes.

      GENERATE COLORMAP         FRACTAL FIELD
              |__________       ______|
                        |       |
                      FIELD TO MESH
                            |
                     RENDER GEOMETRY
                            |
                     DISPLAY PIXMAP


See also: GAUSSIAN FIELD