I spent the weekend cooking up an L-system renderer in Processing that zooms into the fractal indefinitely. L-systems are defined by recursive re-write rules, so to zoom simply apply the re-write rule to visible edges, zoom in, and discard off-screen edges. The actual depth of re-write is limited and elements are selected for re-write pseudo-randomly, which creates additional fractal clustering effects.
The project, including the full-screen builds for osx/windows/linux, can be downloaded from Sourceforge. The applet version is available here.
Staring at this animation causes the motion perception fatigue(adaptation) effect. After looking at an expanding field for a long time, your motion detecting neurons give up and stop firing. When you look away at something that is not moving, you see opposite, inward motion. I find that effect can be exaggerated by sleep deprivation and stimulants like coffee.
Doubly interesting is that, after staring at this animation almost non-stop for 24 hours, the still screen-shot above to me appears to contract, even though my motion perception is normal for other objects. This would cancel out any perceived expansion from the actual animation. I wonder if this is a learned prior on the behavior of the "zoom" applet: my brain expects the patterns to expand, and adjusts motion detection to match.
Triply interesting is that, after staring at the still screenshot, which I perceive as contracting, I get an opposite motion fatigue effect : for a split second after looking away, I see expanding motion. This might indicate that the illusory expansion shares an adaptation mechanism with real motion.
update : It appears that the motion blur trails are related to the long-lasting illusory aftereffect. Additionally, the illusory motion is only perceived during saccade, which shares some similarities with other optical illusions. Does anyone else experience illusory motion with the above still ? Could this be related to some mechanisms of adjust motion perception during saccades, which are fast and themselves cause motion-blur on the retina ?
There might be something slightly off with my visual system, but complex and long lasting adaptation effects are well documented for other visual stimuli.