Archive for the ‘ Exercises ’ Category

Breathing Wall Visualization

The previous discussions about form constants involved certain noise types traveling across the visual cortex which were then twisted by the wiring between retina and brain to produce archetypical psychedelic visuals. One interesting thing to consider is in order to produce these form constants, the magnitude of this noise was mapped to a certain hue. If it is instead mapped to a depth value, other simple psychedelic visual effects occur.

In this example low frequency noise at a random direction across the complex plane is mapped to depth values, and produces the classic “breathing walls” effect using a model identical to that used to generate Type I form constants. This effect is typically most visible when most of the visual field is filled with an object at a consistent distance from the observer. If one were to observe a scene with many actors at various depth values this noise effect will be less prominent, but observation of an object filling the visual field with a constant depth value (such as a wall) will result in this noise field becoming more apparent.

Form Constant Visualization – Type I

Form constants are archetypical visual patterns generated by noise in the visual cortex which is then twisted by the wiring between retina and brain. Type I form constants were described as “tunnels” by Kluver, and postulated to be generated by the non-contoured roll noise pattern described by Cowan and Ermentrout. I decided to visualize this model in higher resolution to further explore the generated forms. All of the following use sinusoidal noise to approximate visual cortex noise for the first half of the video, and then show the transformed result of the mind’s eye for the latter half of the video. The direction of travel of noise across the complex plane can be shown to produce three form constant subtypes.

Sinusoidal noise traveling along the imaginary axis produces a tunnel effect.

Sinusoidal noise traveling along the real axis produces a ripple effect.

Sinusoidal noise traveling in any direction other than an axis produces a spiral.

Note that all of the previous effects are simply a single sinusoidal noise function in a selected direction. If multiple sinusoidal functions are layered in linear superposition, more complex and visually appealing patterns form.

This examples uses four linearly superimposed sinusoidal noise functions with random wavelength and orientation parameters.