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Viewing computer 3D


Patience is a virtue

Do not expect to see the image in full 3D immediately. It can take several seconds to a minute looking at one stereo pair for a new observer to see stereoscopically, which is not surprising considering the complex brain processes involved. If the observer says "Oh yes, very nice," we know he has not seen in 3D. When he suddenly says "Oh my goodness, that is amazing!" his stereo vision is intact. If he tries to look around near objects to see far objects, stereo vision is definitely in action.

The 1/3 problem

The skill to see stereoscopically is learned in infancy, before the age of 3:

  1. One eyed people or those with serious visual defect in one eye never see in stereo. People whose eyes are out of alignment with each other fail stereo tests.
  2. Children with eye problems, who have not mastered stereo vision by the age of seven, have tremendous difficulty learning it later, when their disorder is surgically corrected. (Previously late learning of 3D vision was considered impossible, but there are rare people who have achieved stereoscopic vision later in life.)
  3. Children who can see in 3D, but develop an optical defect before the age of 3 which prevents stereo vision, can learn 3d vision again, when the defect is corrected at any later age.
  4. My grandchildren (5 & 7) want to know where the 3D goggles are when arriving at a movie theatre. They have seen very few 2D movies - 2D is for TV and even that will change shortly.

The 3D world is learned as infants reach into it and find objects in different places. Later they crawl into it and bump into all kinds of pleasures and disasters. By using all their senses, which agree with each other about the world, infants learn about the third dimension. The visual, stereoscopic impression of the 3D environment arose from combining all the senses together and coming to realise our two eyes are supreme at giving exquisite detail about where objects sit in relation to us and to each other.

The 1/6 children who fail to develop stereoscopic vision still know about a 3D world from all their other senses, and almost have the detailed knowledge provided by stereo vision, because the very powerful motion 3D is still available to them.

The 1/3 who cannot see 3D properly from two flat images separately presented to each eye can still function very well in the real world and only meet difficulty when they see 3D movies or the pictures on this web site and end up:

  1. Observing that 3D is contributing little or nothing to the image.
  2. Keep seeing double when objects are in front or behind the screen.
  3. Have pain or aching in the eyes.
  4. Have headaches or nausea, sometimes bad enough to make them flee from the cinema.

Soon 3D television will be available and only gentle 3D depth will be possible for a significant proportion of the population.

Are 3D pictures dangerous for children? I personally doubt there is any problem, but have no evidence either way.

Problems viewing 3D television


3DTV standards

3D TV (stereoscopic television) has hit the shops and there is no consensus on the best way to see it.

I can tell you how I see stereoscopically now, but there will be no attempt to review the mass of possible methods. For a start, consumers will not tolerate anaglyphs. 3D TV must be full colour, high definition. Many naive people refuse to wear glasses to see 3D (Or claim they will never put those "geek goggles" on.) Lenticular screens do show 3D with no glasses but you have to sit in exactly the right place or it fails. Ther can be more than one sweet spot, but lenticular is not ideal for family TV or for people who insist on wriggling about while watching TV.

Parallel view P, U

free view

prisms from surplus shed.



Cross view X

free view


Elliot viewer

Full colour stereoscopic pairs at 16:9 aspect ratio.

At this time, it is more important to make and store 3D images (and movies) in a form that can later be converted to whatever is needed to view them. The conversion is best done in the viewer's own computer, so that he can download stereo content and change it to whatever form is needed by his 3D viewing system. This means providing two images, one for each eye.

It is better if the image pair is in a form which can be seen in 3D without doing anything to them, and in my view that is cross-eye stereo format. Any size stereo pair can be seen cross-eyed but only small versions can be seen with parallel eyes, unless a mirror or prism viewer is used. Anaglyphs are much more popular on the internet (review the Flickr stereo groups) but anaglyph is a very bad choice for storing 3D content, because the colour is destroyed, while a stereo pair retains all colours. 3DTV will fail if  it is based on anaglyphs. Cross-eye pairs can be tranformed to any viewing system on the fly by using the free program: StereoPhotoMaker (SPM).

Consumers will demand full colour stereo with High Definition (1920x1080 pixels, aspect ratio 16:9 or 1.8. Even higher pixels counts are already essential for 3D movies. The wide screen aspect ratio is now standard for 2D TV and modern computer monitors in the shops are all at least 16:10 aspect ratio (8:5, 1.6). Most amateur stereoscopic photographers are already out-dated by not providing letter-box shaped 3D images.