Questions for lesson 5

1
Questions for lesson 5

• Space Movement

2
Borders and 3D perception

• Why is the simple border enhancement carried out
  by the visual system important in three
  dimensional perception of an object?
• Gives contour from which can be deduced form and
  orientation. Form allows recognition. Contour
  also gives 2D position of object in space, and
  usually allows depth assessment.

3
Borders

• In a complex scene the visual system abstracts
  and enhances borders as the basis of contour,
  form and object recognition. What does this mean
  for web designers?
• Give another, different, example of abstraction
  by the visual system, and its implications for
  web design.
• Ensure object borders are clear and distinctive.
  Dont use effects that blur borders (e.g. shadow)
  without good reason.)
• Abstraction of axes, deduction of object
  structure, deduction of movement and orientation.
  Implication is we should ensure object structural
  axes are clear and distinctive.

4
Contours

• Why is it that a line or contour drawing gives
  almost as much information as full painting?
• Yet such pictures often look static, dry and
  a little unreal. What information is left out of
  a line drawing?
• see previous question. From borders we get
  contours, and shape
• Surface feel from color and texture, shadow and
  saturation depth cues. Areal contrasts. There is
  no blurring of boundaries.

5
Axes

• Is it possible to usefully represent an object
  without showing its form or shape contour?
• What would be the purpose of doing this?
• Yes - can show its structural axes, as in a stick
  figure
• To focus on objects structure or action, where
  we wish the user to recognize the action, rather
  than the object

6
Actions

• What might be a good reason to blur an objects
  contour?
• How can one indicate direction of movement in a
  static picture?
• to indicate movement
• use flow lines

7
Minimalization

• In South Park, the heads of the figures are
  bigger than their bodies. They have no knees or
  noses. Why is this unreality accepted?
• Because the figures are represented in a way that
  matches the way we process. We process end
  points, like the head/face, more than middle
  points, like the body. Likewise in a face or leg,
  noses and knees are middle points and so often
  ignored. We prefer more face information than
  body information to form perception, and the
  Southpark figures give this. Perception is about
  representing what is important not realism. Note
  this approach is very effective

8
Application

• Why is it important to know how the visual system
  abstracts relevant information?
• Because by presenting only the relevant
  information designers can save storage space,
  download time and development time. They can get
  more perceptual effect for less effort, i.e. more
  efficient. They can also get effects otherwise
  not effective in a small space such as a button,
  i.e. more effectual

9
2D vs 3D

• Why do people easily form 3D perceptions from 2D
  drawings?
• What are the monocular cues for depth?
• because retinal information is largely 2D - this
  is what the visual system does all the time

10
Depth

• What is meant by saying perspective lines are a
  cue for depth? Give an example.
• How does stereoscopic vision provide a cue for
  depth?
• We deduce depth from the objects position along
  the lines eg square on the lines
• each eye gives a different perspective. The
  amount of dot shift indicates the depth

11
Movement

• In a small image of a boat upon water, how can we
  indicate dynamically that the boat is moving in a
  given direction?
• How can we show a leopard jumping in animation?
• move the background the opposite way
• have one picture of the leopard starting to jump,
  one in the air, and one landing. Run them in
  sequence

12
Mental models

• Why is it good to use existing mental model?
• In the Windows Desktop interface, users are often
  confused when an active window demanding a
  response is hidden, and report their computer is
  hung. Why dont they check the hidden windows
  before calling the Help Line?
• Because the user already knows what they need to
  know. Reduces need for help and training.
• Because they do not expect an active request to
  be hidden - this does not correspond to their
  mental model of a desktop with documents

13
Question

• Given different people prioritize different
  aspects of a web site differently, some
  preferring text information content, and some
  colors and design for example, how is it possible
  to ever satisfy even a majority?
• Web site must provide something for everyone, and
  work on all levels - e.g. both information
  content and artistic design. Aim for all round
  balance rather than excellence in a single thing

14
Qestion

• Why is speling impurtant in profesionall webb
  paige desine?
• Many people are offended by bad spelling and
  process this aspect carefully. They may judge the
  entire site by this aspect. Therefore spelling is
  important for professional web page design