## The All New FractalForums is now in Public Beta Testing! Visit FractalForums.org and check it out!

 Pages: [1] 2   Go Down
 Author Topic: IFS fractals from Mobius transforms  (Read 12924 times) Description: 0 Members and 1 Guest are viewing this topic.
fractalrebel
Fractal Lover

Posts: 211

 « on: December 16, 2009, 08:43:28 PM »

Iterated Function System (IFS) fractals are normally generated using affine transforms, which are linear transforms of the type:

xn+1 = a*xn + b*yn + e
yn+1 = c*xn + d*yn + f

Several affine transforms are used to generate an IFS fractal, with the choice at each iteration being made randomly.  Apophysis is an example of software for generating IFS fractals using affine transforms.

Another type of transform, the Mobius transform

$T(z) = (a*z + b)/(c*z + d)$     where z is complex

can also be used to generate IFS fractals. Mobius transforms are also known as fractional linear transforms. Several Mobius transforms are selected randomly at each iteration, analogous to affine transforms, to generate a fractal. The following image is a simple demonstration of this approach.
 F3M1I0_3LxGn_058.jpg (249.93 KB, 900x900 - viewed 691 times.) Logged

fractalrebel
Fractal Lover

Posts: 211

 « Reply #1 on: December 16, 2009, 08:53:26 PM »

Here is an IFS Mobius example which has been mapped to a Riemann sphere.
 Sieripinskish.jpg (104.31 KB, 900x900 - viewed 671 times.) Logged

kram1032
Fractal Senior

Posts: 1863

 « Reply #2 on: December 16, 2009, 09:02:50 PM »

very nice but the jpg compression kills them quite much...
 Logged
Safarist

Posts: 85

 « Reply #3 on: December 16, 2009, 09:03:11 PM »

Wow, nice! I can almost see spiders crawling all over that first one.

I'm curious how many transforms are involved and how you chose them.
 Logged
fractalrebel
Fractal Lover

Posts: 211

 « Reply #4 on: December 16, 2009, 10:09:19 PM »

Wow, nice! I can almost see spiders crawling all over that first one.

I'm curious how many transforms are involved and how you chose them.

The images were created with IFS Mobius which is in the Ultrafractal database. The number of Mobius transforms can vary from 2 to 6. The first image uses two transforms and the second one uses 4 transforms. Rather than acting on points, as is the case with affine transforms. the Mobius transforms act upon circles and lines. In the first image the transforms operate repeatedly on 4 starting circles which were chosen randomly as long as they met the Kissing Schottky criteria (see Indra's Pearls). In the second they operate on 3 starting circles chosen randomly which met the criteria of no overlap.
 Logged

fractalrebel
Fractal Lover

Posts: 211

 « Reply #5 on: December 16, 2009, 10:22:17 PM »

Here is one of my favorites, called Cosmic Chicken:
 CosmicChicken.jpg (158.11 KB, 900x720 - viewed 636 times.) Logged

fractalrebel
Fractal Lover

Posts: 211

 « Reply #6 on: December 16, 2009, 10:23:46 PM »

The Cosmic Chicken (or any other IFS fractal) can easily be used as an orbit trap. Here is an example:
 cosmicchickenorbittrap.jpg (208.78 KB, 900x720 - viewed 663 times.) Logged

kram1032
Fractal Senior

Posts: 1863

 « Reply #7 on: December 16, 2009, 10:36:07 PM »

cool
 Logged
Nahee_Enterprises
World Renowned
Fractal Senior

Posts: 2250

use email to contact

 « Reply #8 on: December 30, 2009, 01:11:54 AM »

Interesting !!
 Logged

stijnw
Guest
 « Reply #9 on: January 23, 2010, 11:40:44 PM »

This looks real nice! The first image reminds me of a popular flame-fractal I used as background image for quite some time...

Regards,
Stijn Wolters.
 Logged
paxinum
Guest
 « Reply #10 on: July 08, 2010, 05:23:58 PM »

All fractals here can be generated by Möbius mappings:

There is a book called Indras Pearls using only Möbius mappings.
 Logged
bib
Global Moderator
Fractal Senior

Posts: 2070

At the borders...

 « Reply #11 on: July 08, 2010, 06:13:25 PM »

Thanks paxinum for upping this thread.

The Cosmic Chicken (or any other IFS fractal) can easily be used as an orbit trap. Here is an example:

Very interesting fractalrebel. I did not find any IFS or Mobius trap shape or formula in reb.ulb or in the public classes. Would you mind sharing the UF parameter set or give some explanations ?
 Logged

Between order and disorder reigns a delicious moment. (Paul Valéry)
KRAFTWERK
Global Moderator
Fractal Senior

Posts: 1439

Virtual Surreality

 « Reply #12 on: July 09, 2010, 10:21:44 AM »

Whoah!

Can we lift this to the 3D KIFS?

Think I will skip my vacation and hang here...
 Logged

kram1032
Fractal Senior

Posts: 1863

 « Reply #13 on: July 09, 2010, 01:54:21 PM »

A 3D variant would be from just adding another variable...

I wonder about a mixed variation:

(a*x+b*y[+c*z]+d)/(e*x+f*y[+g*z])+h)

Or even further extended... You could do that from a polynomial of any degree, basically...

${a_1 x^2 + b_1 y^2 + c_1 z^2 + a_2 x + b_2 y + c_2 z + d1}\over{a_3 x^2 + b_3 y^2 + c_3 z^2 + a_4 x + b_4 y + c_4 z + d2}$

That would be a mix of a Möbius transform and a general 3-cone section.

You could extend that even further by allowing permutations....

x*x=x²     y*x=x*y     z*x=x*z
x*y         y*y=y²       z*y=y*z
x*z         y*z            z*z=z²

So... a*x²,b*y²,c*z²,d*2xy,e*2xz,f*2yz
 « Last Edit: July 09, 2010, 02:00:26 PM by kram1032 » Logged
KRAFTWERK
Global Moderator
Fractal Senior

Posts: 1439

Virtual Surreality

 « Reply #14 on: July 09, 2010, 02:26:33 PM »

Wahooooo here we go!!! 8-)

Sorry, holiday...
 Logged

 Pages: [1] 2   Go Down