Held: Wednesday, 16 April 2014

Back to Outline 42 - Higher-Order Procedures, Revisited. On to Outline 44 - Pause for Breath.

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

• Reading: Random Drawing
• Lab: Random Drawing
• EBoard 43 (Source 43) (HTML 43) (PDF 43)

Overview

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

Administrivia

Upcoming Work

• No reading for Friday. Friday will be a chance to work on projects and ask questions and such.
• Homework for next Tuesday: Projects.
• Lab writeup: 3 and 4.

Admin

• Thanks for patience yeserday.
• Mentor sessions tomorrow night at 7pm and 9pm.
• There was a mixup on the due date of the third exam. It is due Tuesday of week 13. The compensation is that you don't have work due in week 14. (You still have to show up and learn stuff, and we might have a quiz, but you won't have an assignment due.)
• Friday's quiz will be on the obvious stuff (vectors, analysis, hop, and randomness)
  • We'll try not to put everything on the same problem.

Extra Credit

• CS extra Thursday: Charlie Eddy on his project.
• CS pub night Thurday at 8pm in Lyle's pub.
• Get and wear one of the "1 in 4" shirts next week. Pick up shirt Tuesday through Thursday, wear on Friday.
• Any other Sexual Assualt Awareness Week activity.
• Iowater project April 19 - Tag drains. Mail [iowater] for details.
• http://www.strikingly.com/pioneerweekend

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.
• Disclaimer: Many of the random processes still include some artistic intention.
  • Jackson Pollock's painting style provides an interesting combination of intent and randomness.
• Modernized/computational suggestion:
  • Randomized processes can provide inspiration
  • The ability to constrain some aspects of the process can provide a new mechanism for creation.

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.

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".
• Demo: Randomizing the brush

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