1. How good are you are judging distance?

2. We are learning about...We are learning how to... Perceiving the world visually Depth perception Binocular depth cues Solve research problems Plan, evaluate and revise solutions to problems

3. Depth Cues Our sources of visual information about distance are collectively termed depth cues – Binocular depth cues – rely on both eyes – Monocular depth cues – do not require both eyes

4. Binocular depth cues Eye convergence Retinal disparity

5. Eye convergence When we focus on nearby objects, our eyes turn inward

6. Eye convergence Our brain uses information from the eye muscles to work out the distance of the object The nearer the object, the more the eyes must converge

7. Eye convergence When viewing more distant objects, the eyes do not converge, so convergence information is of no use

8. A problem to solve... What is the maximum range at which eye convergence is a useful depth cue? – Working in groups, use the equipment available (and/or whatever else you can find) to find out – You have 10 minutes to arrive at an answer

9. Put on your 3d glasses now...

10. Retinal Disparity

11. Retinal disparity Making an anaglyph image – Compose a scene using objects in the room – Place camera on a flat surface & take a picture – Move camera 6cm to the right (don’t turn it) – Take a second picture Give me the camera & I’ll make the anaglyph

12. Another problem to solve... How does a red/blue anaglyph image work? What do anaglyph images show us about how we perceive depth?

13. Anaglyphs The two images are slightly different, because they were taken from different positions Through the red lens, we can only see the blue image Through the blue lens, we can only see the red image

14. Retinal disparity Our brain combines the two retinal images to produce a 3d percept – The closer the object, the greater the disparity between the two retinal images – Our brain can use the degree of disparity to work out distance

15. Reflection Today you had two problems to solve. How effective were you at... – Collaborating on your solutions? – Planning ahead and revising your ideas where necessary? What helped and hindered you in solving these problems?

16. Explain how binocular depth cues allow us to perceive depth and distance – What sources of info? – How do they convey depth/distance? – What are their limits? About 1/3 of a side of A4