Casner,S.

BOZ

This text is partially taken from [CAS91]

"BOZ is an automated graphic design and presentation tool that designs graphics based on an analysis of the task for which a graphic is intended to support"[CAS91].

( The name BOZ is taken from the Charles Dickens book: "Sketches By BOZ".)

BOZ designs a graphic with two aims:

  1. making logical facts more clear to the user
  2. help searching for needed information.

BOZ´s task-analytic approach uses the following five components:

  1. a logical task description language
  2. a perceptual operator substitution
  3. perceptual data structuring
  4. a perceptual operator selection
  5. a rendering component
  1.  
  2. Logical task description language The first component of BOZ provides a means of describing the information processing activities that a graphic is intended to support. This language, the input of BOZ, contains two basic components:
    1. A notation for describing logical procedures, similar such Pascal with type definitions, logical operators and a main body and
    2. a notation for expressing logical facts manipulated by a logical procedure.
  3. Perceptual operator substitution In this component every logical operator (LOP) is classified into a equivalent class of perceptual operators. This Substitution relies on two important components:
      • a catalog of perceptual operators
      • a primitive graphical languages
      • a set of perceptual operators (POP) by the primitive graphical languages
      • a equivalent classes for POP´s (every POP is exactly in one class)
    2. Substitution algorithm
      (consider every LOP in a POP-class)
  4. Perceptual data structuring This part analyzes relationships between operators by representing each operator as a vector defined over the domain sets that the operator manipulates. "A complete sketch of all relationships between vectors reveals how information is to be collected together into graphical objects and partitioned among presentations." There are four types of relationships that can hold between vectors: conjoin, parallel, orthogonal and disjoint.
  5.  
  6. Perceptual operator selection The 4th component chooses a single perceptual operator to substitute each logical operator from the list of possibilities generated by the perceptual operator substitution component. There are three important issues:
    1. BOZ seeks to choose that perceptual operator that is performed most efficiently and accurately by human user. BOZ uses a two-tier ranking system based on Mackinlay´s APT program to find the best perceptual operator.
    2. The POP´s must be expressiveness. A selected perceptual operator must be associated with a primitive graphical language that is powerful enough to encode the logical facts manipulated by that operator. BOZ adopts Mackinlay´s technique for deciding expressiveness.
    3. The third criterion for operator selection concerns the combinability of perceptual operators. If two operators should be encode in the same graphical object and they are not combinable we must disqualify them.
  7. Rendering component The last component translates logical facts into graphical facts.
    "The graphics generated by the rendering component support two-way interactions between sets of logical facts and their graphical images. In addition of being able to effect changes in a graphical presentation through manipulation of the internally facts the user can change the stored logical facts by manipulating the graphical objects in the presentation."

Visualization Concepts

Last modified on March 29, 1999, G. Scott Owen, owen@siggraph.org