Autostereoscopic 3D Displays.docx

1、Autostereoscopic 3D DisplaysAutostereoscopic 3D DisplaysEli Soman4/8/2008Table of Contents1. Introduction 12. Background 13. Types of Displays 13.1 Volumetric Displays 23.2 Light Field Displays 33.3 Parallax Displays 43.4 Holographic Displays 53.5 Varrier VR Displays 54. Creating Images and Media fo

2、r Autostereoscopic Displays 64.1 Creating Images for Holographic Displays 74.2 Creating Images for Volumetric Displays 75. Using Images and Media 86. Uses for Autostereoscopic Displays 97. Conclusion 10Works Cited 11Appendix A: Review Questions 121. Introduction What does autostereoscopic mean? It m

3、eans having the ability to see two separate images of the same object at the same time without any type of external assistance. The two separate images come from your left and right eye. Each eye sees a separate image in stereo, automatically, hence, autostereoscopic. This idea is being put into use

4、 along with three-dimensional displays. The most common way to view 3D images is through the use of special polarized glasses or specialized equipment that you wear on your head. This can be cumbersome, unnatural, and can take away from the viewers 3D experience (1). Autostereoscopic displays allow

5、viewers to see objects being projected in 3D without the need for special eyewear, headgear, or other wearable devices (2). This leads to a more free and normal viewing experience (3). Most autostereoscopic displays also allow for multiple viewers and can create more of a “television” experience. Th

6、ese displays are very attractive because they offer the best representation of real life objects by allowing the viewer to experience not only excellent definition and color, but depth as well (4) . There are some misnomers about these displays. Be suspicious of technologies claiming to produce 3D i

7、mages in midair, this is impossible due to something called physics. To see in three-dimensions light particles need something to bounce off of, be in front of, be behind, or be within some substance to create an image. There has to be some sort of material to get in the way of the photons to allow

8、them to reflect light (4). This tutorial will give you a better idea of what is involved in creating these 3D displays and the types of media needed for use with these displays.2. Background People have been excited about viewing images in three-dimensions since the invention of the stereoscope, whi

9、ch was the first handheld three-dimensional picture viewer (4). The first parallax stereogram was patented in 1903 by F.E. Ives (5). Another invention that created excitement in this area was the introduction of paper 3D glasses with red and blue lenses to view movies in 3D. This phenomenon swept th

10、e nation and was started in the 1950s (4). Most recently, these paper glasses have been replaced with plastic frames and polarized lenses, which are being used in theme parks and for some family movies. Since the 1970s researchers have been looking for ways to create 3D displays that have television

11、 like qualities. This is also referred to as 3DTV. These qualities include the ability for multiple viewers, no required head gear, and the ability to watch live broadcasts. 3DTV is expected to be the next revolution in television and may very well replace the current HDTV standard (2). For these di

12、splays to work they need to reproduce the visual cues that humans use to see in three-dimensions. We use several different types of visual cues for three-dimensional sight, which include: motion parallax, binocular parallax (2), and accommodation (6). Binocular parallax, also known as stereopsis, re

13、fers to each eye seeing a different image of the same object. This can be observed by closing one eye and seeing one image, then closing the other eye and seeing another image. Motion parallax, also known as occlusion, refers to the effect of seeing different images by moving the head (2). This can

14、be observed by looking at an object from a distance and then moving your head back and forth. By doing so, you will see different portions of the background behind the object being viewed in the foreground. Occlusion is one of the most powerful cues we use for seeing in three-dimensions. Another cue

15、, which is a weak cue, is the ability to quickly focus light rays to make a clear image. This is called accommodation. It is best when viewing objects from a small distance and weakens as we get older. The ability to recreate these visual cues with autostereoscopic 3D displays in an effective and re

16、asonable manner is paramount to the success of these displays (6). Computer science and technology are not advanced enough to make these displays, and the media required to use them, affordable to the public, but autostereoscopic displays do exist for consumer purchase. The use of these displays cou

17、ld create huge advancements in society, not only in the entertainment realm but in many other fields as well, including: information presentation, military, telecommunications, medicine, remote viewing, and art (2).3. Types of Displays There are several types of autostereoscopic displays, which incl

18、ude: volumetric, parallax, holographic, and a few others. There are several main attributes that make certain display types superior to others. One is the ability for multiple viewers at the same time, these are known as multi-viewer autostereoscopic displays. This is one of the ultimate attributes

19、desired in these types of displays. This allows for anyone to walk up to the display and view the three dimensional media being displayed without recalibrating the display, requiring head tracking, or wearing any special devices (3). Head tracking refers to the ability to monitor where a viewer is i

20、n reference to the display. The viewer is tracked by wearing some small device that is capable of being followed by a tracking system connected to a computer. The computer will decide what to display as the viewer moves around the display. Some of these displays will show a better image if head trac

21、king is involved and some require it for the displays to work properly. This is an obvious disadvantage because this usually only allows for one person to view the display in 3D at a time (3). Each type of display has their benefits and detriments. There is currently no display technology that has a

22、ll the required features that make up true 3DTV experience, but there are some that get very close.3.1 Volumetric Displays Volumetric displays are also known as volume displays, slice stacking displays, spatial displays, and space filling displays (4). Volumetric displays use some object or substanc

23、e to fill or scan a three-dimensional casing, and in some cases, voxels are used to display the image. Voxels are three-dimensional pixels that are used in some 3D displays. The extra dimension allows for the viewer to see depth cues. The voxel can be compared to the 2D pixel. Through the excitement

24、 of these 3D pixels a 3D images can be created (2). The image created by volumetric displays can have a ghost like see-through effect, which takes away from the definition of the object being displayed. These displays can only reproduce a limited amount of colors. Currently these displays are only a

25、ble to create monochrome images. This limits the displays ability to reproduce images taken outdoors or those with a large light field containing many colors. This limited range of colors also affects the ability to display occlusion cues (2).There are several technologies that have been developed t

26、o create these types of displays. One type is the varifocal mirror display. This display uses a mirror that is coated with a membrane. The coated mirror oscillates while a CRT displays an image. The mirror reflects the image from the CRT and the oscillation of the mirror creates a 3D effect. As the

27、mirror moves back and forth the image is reflected back to the viewer with depth and color. One of the major issues with these displays is creating a mirror with high optical quality that can be oscillated at high frequencies. Another major disadvantage is the low quality of resolutions of the image

28、s being displayed (4).Another way to create a volumetric display is through the use of an object to sweep out, or spin inside of, a three-dimensional volume. This is referred to as a spatial display. The object is some flat piece of material and is usually in a rectangular shape. The object is then

29、covered with light emitting diodes (LED). It can also be scanned by an external light source to create the image. The object is place vertical onto a rod that is connected to a motor, which is used to spin the rectangular object. As the object spins the LED lights are illuminated to create an image.

30、 The image has all three-dimensional cues. These types of displays will always have the disadvantage of mechanical moving parts that can break down, overheat, or affecting the ability to produce a high quality image (4).Volumetric displays can also be created by using a substance to fill a volume. T

31、he substance is agitated with an external light source, such as a laser, until it emits light. The ideal material has not yet been discovered. The material needs to have excellent optical quality, be cost efficient, and be light weight, for this type of volumetric display to see any type of wide spr

32、ead use (7).All of these displays share several attributes. They have the ability to be viewed from all angles by multiple people. A person could actually walk all the way around the display and view all sides of the image being displayed. The distance from which the image can be viewed from is wide and is only limited by the accommodation of the viewer. Because these displays cannot produce the colors of a true photo quality images the applications in which these displays can be used is limited and will be discussed later (4). These displays have obvious disadvantages. All of these