Class 34: Randomized (Unpredictable) Drawing

Held: Monday, 2 November 2009

Summary: We consider Scheme's random procedure, how one might use that procedure in writing simple simulations, and how the procedure can be used to generate unpredictable images.

Related Pages:

• EBoard.
• Lab: Randomized Drawing.
• Reading: Randomized Drawing.

Notes:

• Are there questions on exam 2?
• Reading for Tuesday: Characters and Strings

Overview:

• Random art.
• Why use randomness.
• The random procedure.
• Simulation.

Randomized Images - The Theory

• Non-mainstream art philosophy: The images that come from random processes (or from nature) can be as interesting as the images that come from artists who intentionally plan the canvas.
• One important movement: Dada. (Early 20th century; also a reaction to facism and industrialization and ...)
  • An example: Tristan Tzara's How to make a Dadaist Poem
• Disclaimer: After creation by random processes, some filtering of good from bad often happens.
• Modernized suggestion:
  • Randomized processes can provide inspiration
  • The ability to constrain some aspects of the process can provide a new mechanism for creation.

Randomized Images - Practice

• Many of the procedures we've written or used have numeric parameters.
• Those parameters can be generated randomly.
• Many of the procedures we've written take one of a restricted number of inputs (e.g., there are only so many brushes).
• Those inputs can also be selected randomly.

The random Procedure

• Scheme helps us by providing a (random n) procedure.
• n must be a positive integer.
• random returns an integer between 0 and n-1, inclusive.

Other Uses of Randomness

• We often use randomness in simulating unpredictable events, such as the rolling of an unbiased die.
• More requently, such randomness is used in larger-scale simulations.
• We'll stick with images, though.

Lab

• Do the lab.