1. Graphics II “3D” Graphics Cameron Miller INFO410 & INFO350 S2 2015 INFORMATION SCIENCE Visual Computing

2. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 2 INFORMATION SCIENCE Outline  Depth Perception  Stereoscopic Techniques  Display Technologies

3. Depth Perception

4. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 4 INFORMATION SCIENCE Depth: Visual Cues  Overlapping objects (Occlusion)  Vertical position  Haze, desaturation  Change in size of textured pattern detail http://www.psypress.co.uk/mather/resources/jpg/Image10_3.jpg

5. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 5 INFORMATION SCIENCE Depth: Visual Cues  Linear perspective Typically illustrated as convergence of parallel lines http://media.komonews.com/images/130227_distant_road.jp g

6. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 6 INFORMATION SCIENCE Depth: Visual Cues  Subtended Visual Angle More specifically V (in radians) = 2 arctan(S/2D) http://sites.sinauer.com/wolfe4e/ch/03/act0301/intro1.gi f

7. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 7 INFORMATION SCIENCE Depth: Visual Cues  Accommodation of the eye l Kinesthetic sensations to the brain from tightening lense http://hyperphysics.phy- astr.gsu.edu/hbase/geoopt/imggo/eyeacc.gif

8. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 8 INFORMATION SCIENCE Depth: Visual Cues  Motion parallax l Objects further away appearing to move slower than close objects https://upload.wikimedia.org/wikipedia/commons/a/ab/Parallax.gif

9. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 9 INFORMATION SCIENCE Depth: Visual Cues  Stereopsis (Binocular Disparity) http://www.vision3d.com/images/bb.jpe g

10. Stereoscopy

11. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 11 INFORMATION SCIENCE Stereoscopy  Any technique which is capable of creating the illusion of a three dimensional image.  If two images have the same angle of difference (deviation) and each eye sees only the corresponding image, a spacial effect is created.

12. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 12 INFORMATION SCIENCE Stereoscopic Techniques: Anaglyph  Two differently colored images (one for each eye)  When viewed through glasses with corresponding color filters, a stereoscopic image can be seen http://img03.deviantart.net/3e99/i/2006/350/5/c/the_river2_3d_anaglyph_by_yellowishhaze.jp g

13. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 13 INFORMATION SCIENCE Anaglyph Problems  Ghosting l Where a color channel that should be filtered by the glasses is only partially filtered  Retinal rivalry l Where one image is seen for a few moments, then the other, then the first… etc. caused by brightness differences of colored objects  Color reproduction l Poor production of red through the cyan/red filters.

14. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 14 INFORMATION SCIENCE Anaglyphs: RGB Image & B/W Depth Map  Take original image and depth map and create a second image by displacing each pixel of the original by: 30.0 * (I-127.5) / 127.5  Where I is the intensity (0-255) of the corresponding pixel on the depth map and 30 is a user definable coefficient

15. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 15 INFORMATION SCIENCE Anaglyphs: RGB Image & B/W Depth Map  Many different ways to filter. Most simply, for each pixel:  It is suggested that the retinal rivalry can be reduced by applying gamma correction to brighten up the final red channel

16. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 16 INFORMATION SCIENCE Polarised Glasses  Instead of filtering the colors, the light waves are polarised at (usually) 45 and 130 degrees.  Corresponding filters on viewer glasses allow for stereoscopy https://upload.wikimedia.org/wikipedia/commons/thumb/9/94 /Wire-grid-polarizer.svg/680px-Wire-grid-polarizer.svg.png

17. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 17 INFORMATION SCIENCE Shutter Glasses  Present the image for the left eye while blocking the right eye’s view, then repeat for right eye (>120hz)  Full color 3D!

18. Autostereoscopy

19. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 19 INFORMATION SCIENCE Autostereoscopic Displays  Stereoscopy without the need for glasses  Support for multiscopy (“real” 3D)  Available Technologies: Lenticular lens Parallax barrier l Volumetric display

20. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 20 INFORMATION SCIENCE Autostereoscopy: Lenticular Lense  Array of magnifying lenses  When viewed with stereopsis, different images are magnified https://s-media-cache- ak0.pinimg.com/736x/ee/43/7a/ee437a75 526ed30919a70d61b4aebc85.jpg http://www.imagiam.com/wp- content/uploads/2013/11/plastic.jpg

21. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 21 INFORMATION SCIENCE Autostereoscopy: Parallax Barrier  Opaque barriers over portions of the image source to induce stereoscopy.  If fixed, relies on the viewer maintaining a constant position to work.  Pixel count for each eye is halved. http://www.3d- forums.com/threads/stereos copic-parallax.4/ https://upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Parallax_barrier_vs_lenticular_ screen.svg/512px-Parallax_barrier_vs_lenticular_screen.svg.png

22. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 22 INFORMATION SCIENCE Autostereoscopy*: Volumetric Display  “A display to create 3D imagery via the emission, scattering, or relaying of illumination from well defined regions in 3D space.” (Minoli, 2010)  Two general types: Swept Volume Static Volume

23. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 23 INFORMATION SCIENCE Volumetric Displays: Swept Volume  Projection of slices of a 3D scene onto a moving (typically rotating) display surface  Reliant on human persistence of vision https://www.youtube.com/watch?v=f8KBqajd2UQ

24. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 24 INFORMATION SCIENCE Volumetric Displays: Static Volume  Create imagery without any macroscopic moving parts in the image volume  Voxel activation produces a 3D image in space  Typically, electron beams interact with a gas filled volume to create light.

25. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 25 INFORMATION SCIENCE Volumetric Displays: Problems  Bandwidth! ~135GB/s to display 1024*768*1024 at 60fps  Difficult to create light out of nothing (Free space displays)  Difficult to create viewer position dependent effects (occlusion, opacity)

26. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 26 INFORMATION SCIENCE Autostereoscopy: The future.  Holographic displays Displays that provide all four eye mechanisms  Integral imaging Technology that allows the capture and reproduction of light fields (3D photography)

27. Head Mounted Displays

28. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 28 INFORMATION SCIENCE Head Mounted Displays  Displays right in front of the eye (CRT, LCD, OLED etc)  Most display only an image on the screen (VR)  Two different methods for AR Video See Through l Optical See Through

29. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 29 INFORMATION SCIENCE Head Mounted Displays: VST  Real world is captured with cameras and then replayed through the display  Stereoscopy support.

30. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 30 INFORMATION SCIENCE Head Mounted Displays: OST  A device capable of reflecting projected images, as well as allowing the user to see through the image into the real world.  Two main families of underlying technologies: Varifocal Mirror l Waveguide https://upload.wikimedia.org/wikip edia/commons/a/a8/A_Google_Gl ass_wearer.jpg

31. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 31 INFORMATION SCIENCE OST: Varifocal Mirror  A flexible curved mirror whose focal length can be changed rapidly, and can be positioned so that it reflects the image of a display monitor to the viewer.  Drawback: near objects do not obscure far objects http://users.auth.gr/~iantonio/HOME3DIm10.jp g

32. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 32 INFORMATION SCIENCE OST: Waveguides  A structure that stops the dissipation of waves into three dimensional space. (e.g fibre optic cable)  Many different types: Diffractive Holographic Polarised l And more.

33. Exam Questions

34. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 34 INFORMATION SCIENCE Potential Exam Questions  Anaglyph is a common stereoscopic technique. How does it work, and how are any limitations addressed by other (non auto) stereoscopic techniques?  Compare and contrast parallax barrier and leticular lense autostereoscopic technologies  In a situation where fully immersive virtual reality is required, which display technology(s) would best suit and why?

35. INFO410 S2 2015 3D Graphics (Cameron Miller) SLIDE 35 INFORMATION SCIENCE Bibliography Foley, J. (1995). Computer graphics: Principles and practice (2nd ed.). Reading, Mass.: Addison-Wesley Minoli, D. (2011). 3D television (3DTV) technology, systems, and deployment rolling out the infrastructure for next-generation entertainment. Boca Raton, FL: CRC Press Rolland, J., & Fuchs, H. (n.d.). Optical Versus Video See-Through Head-Mounted Displays in Medical Visualization. Presence: Teleoperators and Virtual Environments, 287-309 Sanftmann, H., & Weiskopf, D. (2011). Anaglyph Stereo Without Ghosting. Computer Graphics Forum, 1251-1259