Starter
Look around you, find three
different objects:
1. Something close to you
2. Something a long way away
3. One somewhere in between.
How did you do that?
Depth Cues
Learning Objectives
• To recognise and understand monocular and
binocular depth cues.
• To identify different types of illusions.
• To understand size constancy.
Success Criteria
• To show understanding of monocular and
binocular depth cues.
• To create a display on either size constancy
or illusions
Depth Cues
• We can judge depth in the real world, in 3D.
• We can also understand depth in pictures in 2D.
• The clues we use to understand depth are called
depth cues.
• These are pieces of visual information that trigger or
cue our understanding of distance.
• Depth perception enables us to understand the size
of objects at different distances. This is called Size
constancy. Look at the worksheet to understand this
in more detail.
down
short 2description
of Size
•Write
There
are ausually
kinds of depth
cue:
Constancy,
in your
owncues
words.
– Monocular
depth
Binocular
depthto
cues
You– have
2 minutes
complete this task.
Quick Note! – 2 min!
• Key word:
– Size constancy: we perceive an object as the same
size even when its distance from us changes.
• Question:
– A girl is sitting on the beach eating and ice cream
with a chocolate flake in it. Far off in the sand, a
boy is crying because he has dropped his ice cream
and the flake has fallen out. Will the girl’s image of
each flake be scaled up or down, or neither?
Explain why.
Monocular depth cues
• ‘Mono’ means one, as in monocle.
• Monocular depth cues are clues to distance that only
need one eye.
• If you close one eye and look around, it is still obvious
which things are closer and which are further away.
• There are five monocular depth cues you need to
understand:
– Superimposition
– Relative size
– Texture gradient
– Linear perspective
– Height in the plane.
Monocular depth cues
• Around the room are five
different posters with
information about the five
different monocular depth cues.
• Your task is to complete the
worksheet, finding out as much
detail as possible about the
different five cues. You have 7
minutes (approx 1 min per depth cue).
• Taking it further:
– http://webvision.med.utah.edu/book/
part-viii-gabac-receptors/perceptionof-depth/
Binocular Depth Cues
• ‘Bi’ means two, as in binoculars.
• Binocular depth cues are clues to
distance that need both eyes.
Sometimes two eyes are important
for seeing depth.
• Close one eye and read both hands
out in front of you.
• Waggle them around then try to
touch the tips of your index fingers
together.
• This is difficult because you can only
use monocular cues.
• Try again with both eyes, and you
should find it easier due to the
binocular cues.
Binocular Depth Cues
• Take it in turns to watch the person next
to you, as they move a finger towards their
own nose.
• What happens to their eyes?
• When we are looking at things in the
distance our eyes point straight out, as we
look closer our eyes point inwards more.
This is a binocular view.
• Another view is called Stereopsis.
Complete the worksheet tasks to
understand Stereopsis. You have 7 minutes
• Taking it further:
– http://www.michaelbach.de/ot/sze_Frankfu
rter/index.html
Plenary
• Reflect on your work, by considering what
size constancy is about.
• On the work sheet, illustrate size constancy
by cutting out photocopied images of objects
from scenes and putting them in the ‘wrong’
place in the scene.
• OR
• Create a display identifying illusions, with
clear explanations for why they happen.
Learning Objectives
• To recognise and understand monocular
and binocular depth cues.
• To identify different types of illusions.
• To understand size constancy.
Success Criteria
• To show understanding of monocular and
binocular depth cues.
• To create a display on either size constancy
or illusions
Home work
• Again visit the website area, and look at the
three different links for the homework this
week:
•
•
•
•
•
•
Understanding size constancy:
http://psych.hanover.edu/krantz/SizeConstancy/page2.html
Monocular cues:
http://ahsmail.uwaterloo.ca/kin356/cues/mcues.htm
Stereovision:
http://www.vision3d.com/stereo.html
• These are designed to develop your thinking,
and raise your understanding of the concepts
discussed today.