What is 3D technology?

A 3D or 3-D (three-dimensional) film or S3D (stereoscopic 3D) film is a motion picture that enhances the illusion of depth perception. Derived from stereoscopic photography, a regular motion picture camera system is used to record the images as seen from two perspectives (or computer-generated imagery generates the two perspectives in post-production), and special projection hardware and/or eyewear are used to provide the illusion of depth when viewing the film. 3D films are not limited to feature filmtheatrical releases; television broadcasts and direct-to-video films have also incorporated similar methods, especially since 3D television and Blu-ray 3D.

Concept behind The 3D Technology

Human beings have two eyes which are about 3 inches apart from each other. This distance between the two eyes produce two slightly different images which are transmitted to the brain. The brain will then make a space in where distance and depth can be perceived .This process by which humans perceive three dimensions from two highly similar, overlaid images is known as “Stereopsis” and was first described by Sir Charles Wheatstone, In 1838. The working of 3d technology is such that in order to produce this same kind of space in your brain requires tricking your brain into seeing two different images from the same source. It places two minutely different images over each other or in alternating succession. The human being should then be wearing a set of 3D glasses that will help in dissecting this image and transmit it to the correct eye.

Types of 3D glasses

At present, there are around two main kinds of 3D glasses technologies which are called as active and passive. The active glasses are the ones which have got electronics that are meant to change the display. While on the other hand, the passive glasses are the ones that don’t have any electronics and they employ a different way to dissect the images. The active glasses required for the 3D technology techniques are also categorized into two main kinds which are called as liquid crystal shutter glasses and display glasses. Also, two of the presently used passive 3D glasses technologies are linearly polarized glasses and circularly polarized glasses.

The History Of 3D Technology

Stereoscopic cameras

The long history of 3D technology can be drawn the way back to the start of photography. A new invention by David Brewster in 1844, Stereoscope could take 3D photographic images. At the Great Exhibition in 1851, a picture of Queen Victoria taken by Louis Jules Duboscq, using the improved technology became very well known throughout the world. Soon, the craze for stereoscopic cameras caught on and these were quite commonly used by World War II.

Kinematascope

In the coming years, there were further improvements in the technology, as the history of 3D technology reveals. Kinematascope, a stereo animation camera was invented, followed the first anaglyph movie was produced in 1915. In 1922 the first public 3D movie, "The Power of Love", was produced and it was in 1935 that the first 3D Color movie was produced.

Space-Vision 3D

In the 1960s, in the history of 3D technology, a new technology known as Space-Vision 3D was released. This new technology removed the need to use two cameras to display 3D movies. The first movie to use this technology was "The Bubble" and the 3D experience still lured in huge audiences.

Stereovision

In 1970, Stereovision, a new 3D technology was developed, which used a special anamorphic lens that would widen the picture using a series of Polaroid filters. The first movie to be released in Stereovision was "The Stewardesses". Although costing only $100,000 USD, it went on to earn an amazing $27 million in North America.

Producing 3D films

Live action

The standard for shooting live-action films in 3D involves using two cameras mounted so that their lenses are about as far apart from each other as the average pair of human eyes, recording two separate images for both the left eye and the right eye. However, today shooting 3D movies is based on how the human eye looks at an image. It is an improvement to the existing 3D camera system. Many 3D camera rigs still in use simply pair two cameras side by side, while newer rigs are paired with a beam splitter or both camera lenses built into one unit.

Computer Graphics

There is a difference between creating three-dimensional graphics and images that appear to be 3D in the theater. Again, it's all just a matter of some high-tech geometry. To get a movie like Toy Story 3 into 3D, animators create two versions of each frame, one from the perspective of each eye. Because computer-generated movies don't need cameras, it's much easier to get perfectly synced images and to fine-tune any mistakes in post-production. The downside is that this technique requires a lot of time and elbow grease to get perfect. This creates a labor-intensive problem since animators need to create objects that can be seen in 3D from a variety of angles depending on where the user is looking and moving.

Types of 3D Technologies

Anaglyph 3D

Anaglyph images were the earliest method of presenting theatrical 3D and probably the easiest way to make 3D images. It separates the right and left image using colors. The image has two color "layers", and you separate the layers using glasses that have blue/red lenses (or cellophane paper, in the cheapest glasses). This is called Anaglyph 3D, it's cheap and easy to do as you don't need a new TV and the glasses are very cheap. The problem is that you lose colors in the image. It simply looks bad.

Polarized (passive) 3D

A Polarized 3D uses a polarizing filter on the image so the left and right images each has a different polarization. You use passive glasses that filter the right image for each eye. This technique is popular in the cinemas using two synchronized projectors. Two images are projected superimposed onto the same screen through different polarizing filters. The viewer wears low-cost passive eyeglasses which also contain a pair of polarizing filters oriented differently (clockwise/counterclockwise with circular polarization or at 90 degree angles, usually 45 and 135 degrees, with linear polarization). As each filter passes only that light which is similarly polarized and blocks the light polarized differently, each eye sees a different image. This is used to produce a three-dimensional effect by projecting the same scene into both eyes, but depicted from slightly different perspectives. Polarization can be done in two ways: Circular polarization and linear polarization. With linear polarization, turning the glasses sideways causes the filters to go out of alignment with the screen filters causing the image to fade and for each eye to see the opposite frame more easily. For circular polarization, the polarizing effect works regardless of how the viewer's head is aligned with the screen such as tilted sideways, or even upside down. The left eye will still only see the image intended for it, and vice versa, without fading or crosstalk. The polarization system has better color fidelity and less ghosting than the anaglyph system. However, all types of polarization will result in a darkening of the displayed image and poorer contrast compared to non-3D images or 2D images.

Active-shutter 3D

The new breed of 3D TVs and projectors make use of a simple idea - you display images for the left and right eye alternatively - once the image for the left eye, and once for the right. Now all you have to do is wear glasses that block each eye in sync with the display, and you get 3D. Active Shutter 3D glasses main advantage is that the image looks great - just as they look in 2D on the same display. Active-3D is costly, though. The display must refresh the screen fast enough - at least 60Hz for each eye, which means 120Hz for the display itself. The glasses are also expensive (over $100 usually) - they have to include 2 LCDs, and batteries. And you also has to synchronize the display to the glasses (usually using Infra-red).

No-glasses 3D (Auto-Stereoscopic)

Auto-Stereoscopic displays different pixels to each eye, using optics (lenses or barriers) to direct the correct pixels to each eye. The nice part is that you don't need to wear any glasses to experience the 3D image! But there are many problems with these new kinds of technologies. Basically there is just one location you can be in order to view the 3D correctly (just one viewpoint). You can add more viewpoints, but each viewpoint actually requires two 'dedicated display'. This means that if you want 10 places from which you can view the 3D, you need to be able to produce 20 sets of displays - that's a lot of pixels. Another issue is that the display is always in 3D. You can't view a 2D image. In this method Lenticular lens and parallax barrier technologies involve imposing two (or more) images on the same sheet, in narrow, alternating strips, and using a screen that either blocks one of the two images' strips (in the case of parallax barriers) or uses equally narrow lenses to bend the strips of image and make it appear to fill the entire image (in the case of lenticular prints). To produce the stereoscopic effect, the person must be positioned so that one eye sees one of the two images and the other sees the other that is nearly perpendicular to the screen, limiting the size of the audience.

Volumetric displays: Real 3D images

The most straightforward way to create a 3D display, is to actually creating it in 3D. These are called Volumetric displays, and scientists are working on all sorts of way to create them, which usually involves lasers and rotating or vibrating mirrors. A couple of years ago researchers create a volumetric display using a mirror that is rotating very very fast, and a projector that projects an image on it... this creates a 3D image that you can view all around (360 degrees).

Drawbacks of 3D

Some viewers have complained of headaches and eyestrain after watching 3D films. Motion sickness, in addition to other health concerns, are more easily induced by 3D presentations.

It is believed that approximately 12% of people are unable to properly see 3D images, due to a variety of medical conditions. According to another experiment up to 30% of people have very weak stereoscopic vision preventing them from depth perception based on stereo disparity. This nullifies or greatly decreases immersion effects of digital stereo to them.

Most of the cues required to provide humans with relative depth information are already present in traditional 2D films. For example, closer objects occlude further ones, distant objects are desaturated and hazy relative to near ones, and the brain subconsciously "knows" the distance of many objects when the height is known (e.g. a human figure subtending only a small amount of the screen is more likely to be 2 m tall and far away than 10 cm tall and close).

In fact, only two of these depth cues are not already present in 2D films: stereopsis (or parallax) and the focus of the eyeball (accommodation).

3D film-making addresses accurate presentation of stereopsis but not of accommodation, and therefore is insufficient in providing a complete 3D illusion.

Film critic Mark Kermode argued that 3D adds "not that much" value to a film, and said that, while he liked Avatar, the many impressive things he saw in the movie had nothing to do with 3D.

it is an expensive technology that adds nothing of value to the movie-going experience (since 2-D movies already provide a sufficient illusion of 3D).

Any 3D system cuts down the brightness of the picture considerably – the light loss can be as high as 88%.