WK5

• What are retinal images limited to in terms of dimensions?

  Two spatial dimensions
• How do we perceive depth despite retinal images being two-dimensional?

  We use depth cues to interpret the third dimension
• What are the types of depth cues mentioned?

  Binocular cues, monocular cues, pictorial cues, non-pictorial cues
• What does occlusion refer to in depth perception?

  When one object obscures another from an observer's view
• What type of cue provides information about depth order but not distance?

  Ordinal cue
• What is a metric cue?

  A cue that provides information about absolute or relative distance
• What does image size alone provide in terms of depth perception?

  No information about distance
• How does the size of an object's image relate to its distance from the eye?

  Larger when the object is closer

  
• What is the relative size cue?

  A depth cue based on comparing sizes of similar objects
• What does height in the visual field indicate?

  It is a depth cue indicating relative distance
• What is a texture gradient?

  A combination of relative size and height in the visual field
• What does foreshortening signify in depth perception?

  That more foreshortened elements are further away
• What is aerial perspective based on?

  The assumption that light is scattered by the atmosphere
• What type of information do shadows provide in depth perception?

  Some metric depth information
• What is linear perspective?

  A pictorial depth cue where parallel lines appear to converge
• What is the vanishing point in linear perspective?

  The point where parallel lines appear to converge

  
• What is the significance of perspective cues in art?

  They help create a depth impression in images
• What is the role of occlusion in ancient Egyptian art?

  Only occlusion is used, lacking other depth cues
• What are the main monocular pictorial cues and their characteristics?

  1. Occlusion: Ordinal cue, useful near to > 30 m
  2. Relative size: Metric (relative), useful near to > 30 m*
  3. Relative height: Metric (relative), useful near to > 30 m*
  4. Texture gradient: As 2 & 3
  5. Aerial perspective: Ordinal, useful >> 30 m
  6. Shadows & shading: Metric?, useful < 10 m?
  7. Linear perspective: Metric (relative), useful ~2 to >> 30 m
• How are size and distance related in visual perception?

  Size perception is influenced by the perceived distance of objects
• What does Emmert's Law state about perceived size?

  Perceived size depends on how far away objects appear
• What is the Size-Distance Invariance Hypothesis (SDIH)?

  It accounts for Emmert's Law and predicts size constancy
• What is size constancy?

  The perception of objects as constant size despite changes in image size
• How does size constancy perform for objects further than 20 meters?

  It is imperfect and may show differences in perceived size
• What do humorous photos often rely on in terms of visual perception?

  They exploit the relationship between perceived size and perceived distance
• What do size illusions reveal about our visual systems?

  They show how depth cues are interpreted as 3D scenes
• How do visual systems interpret images?

  They interpret images as cues about real-world objects and surfaces
• What is the purpose of illusions in understanding visual processes?

  They help uncover the stimulus messages that the visual brain reads