Lecture 6B Scene Depth

Question 1

Emmert’s Law

Answer 1

-the perceived linear size of an object increases as its perceived distance from the observer increases
-apparent size of an afterimage is directly proportional to the perceived distance of the surface on which you see it.
Moon Illusion?

Question 2

Pictorial Cues

Answer 2

Visual: Monocular- Static cues- interposition, size, perspective

Question 3

How do pictorial cues work?

Answer 3

• each cue suggests a small number of possibilities from most likely to least.
• choose an interpretation compatible with greatest number of cues in local region.
• ex: picture frame that looks like we are looking at an angle, linear perspective.

Question 4

Conflicting picture cues

Answer 4

Special point of view effects. Something impossible.
Looks like something in one view point, but looks different in all different view points.
Ex: impossible triangle, impossible stairs.

Question 5

Ames Room

Answer 5

Forced perspective: perspective cues to depth override know size
used: KNOWN SIZE, linear perspective, parallel lines, height and field, texture gradient.
Used in Elf.

Question 6

Why does the two railroad lines, the further one looks longer, despite the same length?

Answer 6

Implied depth

Question 7

scene depth and size preattentive

Answer 7

Depth from shadows easy- can see the ones that pop up quickly
proximity horizon- further away, can see it as larger faster.

Question 8

Size Constancy- discounting the distance

Answer 8

perceived size = size on retina x perceived distance

image of object on retina gets smaller as the object gets farther away.
We judge the distance to estimate size

Question 9

Pictoral cues (flat, static images)

Answer 9

1. Occlusion- t junctions
2. linear perspective- works best on things on ground
3. known size
4. texture gradients- stuff on ground is uniform in size, change in size = change in distance
5. height in field-
6. atmospheric perspective- farther the distance, the more haze, the lower the contrast
7. shadows- shadow= ground objects, no shadow = float. distance btwn shadow and object = distance btwn object and ground.