Starter Depth Cues Look around you, find three different objects: Something close to you Something a long way away One somewhere in between. How did you do that? Depth Cues 5

Learning Objectives Success Criteria 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 3D 2D 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. There are usually 2 kinds of depth cue: Monocular depth cues Binocular depth cues 10 Write down a short description of Size Constancy, in your own words. You have 2 minutes to complete this task.

Quick Note! – 2 min! Key word: Question: 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. 15

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. 16

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/perception-of-depth/ 26 www.heinemann.co.uk/hotlinks – enter express code 4837P – Webvision website which illustrates and defines different monocular depth cues

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. 31

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_Frankfurter/index.html 41

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. 55

Learning Objectives Success Criteria 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. 60