Physics behind 3D Movies

1. Physics behind 3D Movies

2. Case Study – 3D movies With 3D viewing technology offered in cinemas, many people are fast to snap up on the tickets to 3D movies. I watched Alice in Wonderland in 3D version at Shaw Theatre recently and wondered what was the science behind the 3D glasses.

3. How do our eyes work • Our eyes project a 3D image in the brain by seeing things from two different viewpoints as noted by the gap between our eyes and these 2 2D images are formed in the brain into 1 3D image. Thus, 3D images are formed and everything in the real world is 3D.

4. 2D Movies 2D movies work on a film being projected onto the screen. Everything is on the screen and in 2D. The light is unpolarized.

5. Polarized light and Unpolarized ight • Light is an electromagnetic wave • Electromagnetic waves consist of electric and magnetic component • Electric component (electric force field) moves up and down as the electromagnetic waves forward

6. Unpolarized light • From Sun, bulbs, candles • No fixed plant of oscillation • Yellow plane arrow changes angles but keeps direction of light • Random changes in direction of light 3D animation

7. Polarized Light • Filtered Light • Fixed plane of oscillation • Half of the intensity of unpolarized light

8. Unpolarized VS Polarized • For unpolarized light, no matter how the arrow turns, electric forces are always perpendicular to ray direction Polarized light Unpolarized light

9. Polarizers • Filters out the unpolarized light into single light planes • Have lines aligned in 1 direction and only allow 1 plane of light to pass • Circular polarization and linear polarization

10. Circular polarizer and linear polarizer • Circular polarizer used for 3D glasses

11. Circular polarizer and linear polarizer • Circular polarizer is just a quarter wave plate in addition to the linear polarizer • Linear polarized 3D glasses will work with all the old stereo projectors, StereoJet prints, and modern projector systems with linear polarizers attached • Circular polarized 3D glasses are specifically for the StereoGraphics Z-Screen and some 3-D digital projection systems.

12. Circular polarizer and linear polarizer • Not much difference as both saturates colors and eliminates reflections from water and windows for cameras • Circular polarizers are more expensive but can eliminate possible metering errors while linear polarizers are unable to

13. Filters to transform unpolarized light to polarized light • Polaroid filter • Enables only 1 polarization of light to pass through.

14. 3D Movies • Eyes are two inches apart, two different angles on viewing the same things creates a 3D image • 3D movies trick the brain by projecting two 2D images separately to the two eyes and recreate a 3D image in the brain

15. 3D Movies • 3D movies not viewed with the glasses are very fuzzy and eye-straining to look at • The same scene is projected simultaneously from two sources • Previous 3D movies used colour as filter but polarization is used

16. Colour and Polarization • Colour 3D uses contrast of colours • An anaglyph image is formed • Each lens is made up of a chromatically different colour – blue and red • Colour used to provide separation • Red part allows blue light to enter while blue part allows red light to enter

17. Colour as filter • A severe disadvantage is that film cannot have much colour as colour is used as filter in this case Stereo Monochrome image

18. Polarization • Two synchronised projectors project two respective views, each with a different polarization • Each side of the glasses allows 1 plane of light to enter

19. 3D Movies • Due to the 3D effect, viewers can feel the thrill of being in the movie themselves and get really close to the characters

20. Bites • 3D glasses if not cleaned properly can pass on eye infections to others • Can cause headaches and blurred vision • Forces viewers to focus on things in the foreground (which causes eyes to converge) and distance (which causes them to separate) simultaneously • Vergence accomodation conflict

21. Build your own 3D glasses activity • Cardboard • Scissors • Tape • Red and Blue acetate (Available from art store)

22. Build your own 3D glasses activity • Trace a pattern on the paper of the three parts of spec mainly the two sides and a middle portion • Place them on the cardboard and cut out the shapes • Cut eyeholes • Tape the blue and red acetate separately on the two eyeholes and you have a 3D glasses

23. Other Facts • 3D glasses used will not produce a 3D effect on home TV as light is unpolarized

24. 3D Imaging Effects

25. Existing 3D displays and technologies • Color Filter glasses (used in some modern 3D movies) • Polarizing glasses ( used in some modern 3D movies) • Shutter glasses • Separate display for each eye ( used in HMDs) • 3DTV

26. How does the 3-D effect work? • Our ability to see in three dimensions (also referred to as Stereo vision) comes from each our eyes seeing a slightly different view of the world. Our brain integrates these two images into one three dimensional picture. • A key element in producing 3D vision is parallax. Parallax is the horizontal distance between corresponding left and right image points.

27. Color Filter Glasses • Each eye has a different color filter in front of them • The brain integrates the two images together and combined image is 3 dimensional. • Common color filter combinations include red and green, and blue and green.

28. Advantages and Disadvantages • 3D material can be stored to any standard video media, and viewed with normal display devices • Glasses are inexpensive • Few possible color combinations causes images not of exceptional quality • Causes colors in the image to be compromised, causing objects coming out screen to appear gray.

29. Polarizing Glasses • This method is used with projection displays when 3D material needs to be displayed. • Glasses consist of 2 polarizing lens which have their polarization direction to be 90 degrees different. • The material which has to be shown is typically projected using 2 projectors,where each have polarizing lenses in front of them.

30. Advantage and Disadvantage • Pictures can be in full color • Glasses are still inexpensive • Projection surface must be specially made so as not to affect the polarization.

31. LCD Shutter Glass Method • Alternates images rapidly on the monitor screen for left and right images. • Viewer looks at screen through the shuttering eyewear. • Signal is a normal signal that has been specially recorded with the left and right images stored on the even and odd fields of the video signal.

32. Disadvantages • Image must be refreshed fast enough to avoid flicker • Synchronization errors, and occasional ghost images.

33. Head Mount Displays • Helmet like device where there are two separate displays installed. • Used in many high-end virtual reality systems, they deliver very realistic 3D graphics, and allow the viewer to turn their heads, giving the impression of a 3D world. • The only disadvantage to HMD devices is the extremely high price.

34. Hines Lab 3D TV • This device is built around a single liquid crystal panel, on which multiple images are arranged and projected to a rear-projection screen where they form the 3-D image. Stereo and motion parallax allow the viewer to confirm the position and roundness of objects as the observer changes positions.

35. 3D TV by Hines Lab

36. Advantages of 3D TV • The signal can be broadcast by a single television station over air ways or cable • Can be used as a computer display, or for video games • Can be projected to virtually any screen size • Projects all images simultaneously, in full color, and creates no flicker • Can be produced economically, because it uses a single LC panel and conventional optics.

37. Thank You