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CS3451, Summer 2006, Project 1
Illusion of Motion
Douglas Miller, Email: gtg078@mail.gatech.edu
Catherine Herrington, Email: catherine@polter.net
Submitted May 23, 2006. Source code: Wheels.
Built with Processing



Artistic Intention

The intent of the circular configuration was to create an image that carried over the same circular idea. Symmetry was added to increase the appeal of the image. The outer circles were placed at a far distance away from the origin to increase the amount of exposed edges. It was found that having smaller sections exposed decreased the rotating effect. This configuration was used to overlap the beginning tube in the spiral configuration. The drift effect seemed to increase when contrasting colors were chosen for each side of the tube with one side being lighter than the other.



Drift Effect

The human eye tends to interpret motion in peripheral vision from very dark areas to slightly lighter areas and from very light areas to slightly darker areas. This effect is greatest when the areas of color or shading are small but discrete. With a repeated sequence of very dark, dark, very light, and light colors in areas just large enough for the major discrete differences to be noticeable even in peripheral vision, the repeated illusion of motion on a minor scale combines to fool the eye into seeing large scale motion in a still picture. This is especially effective when the edges between colors are short and curved. For maximum effect, several bands of apparent motion should be placed next to each other staggered so that no two adjacent areas in different bands have the same color.
Reference: Phenomenal Characteristics of the Peripheral Drift Illusion, by Akiyoshi Kitaoka and Hiroshi Ashida.

Implementation

Drawing the Configuration

The applet can be displayed in a circular configuration or in a grid configuration similar to Akiyoshi's "Rotating snakes". These configurations can be toggled between by clicking the right mouse button. Each configuration translates the origin to the center of the window. The actual translation of the rings is performed in the rings procedure, but the coordinates are specified in this section by the first two parameters of the rings procedure. The grid configuration is a very simple series of translations. The circular configuration draws the rings at a distance from the origin by translating in the x direction and uses rotation to go around the circle. Scaling is also used to change the size of the rings.

Drawing the Rings

The rings can be circular or spiral inwards, toggled by the left mouse button. The circular mode uses translation and rotation in the same way as the overall circular configuration to position the tubes in an individual ring and shrinks the scale by 20% between each ring to make the new ring fit inside the previous. Each ring is rotated some amount depending on the y coordinate of the mouse. The spiral mode does the same but scales by a smaller amount after each individual tube instead and varies the spacing between tubes with the y position of the mouse.

Drawing the Tubes

The tubes are rotated based on the x coordinate of the mouse. The black center is drawn as a rectangle centered on the location specified by previous transformations. Then the code translates to each side of the rectangle in turn, drawing an ellipse partially overlapping the rectangle. Which ellipse is dark and which is light is determined by a boolean used to make sets of rings alternate which direction the apparent drift is in.

How to Use the Applet