Index

3D viewing methods:
Use of a pair of
passive glasses

Main menu
3D viewing methods menu

Anaglyphs and company: The principle and the making are simple. It consists in making the separation of both images of the stereo-pair using two coloured filters. This process was discovered by Wilhelm Rollman in 1853 using red and blue line on a black background. In 1858, Joseph D'Almeida realised the first 3d projection with a magic-lantern and viewing with red-green glasses. Finally, Louis Ducas du Hauron in 1891, invented and patented the successive printing of the two images of a stereo-pair on the same paper. the first one in red and the second one in green (or bleu).
Defect: The use of blue or green opposed to the red forbids the correct viewing of colours, whereas choosing the cyan instead, leads to a quite correct reproduction of colours if neither of the two filters colours are present. There is a kind of "norm" consisting in putting the red filter in front of the left eye and the cyan filter in front of the right eye. Some smart people, are still patenting optimised process by changing the colours of the filters used. There is no special advantage and the defects are also the same. It can be noticed that the amber-blue combination sold in quantity as "Color Code" works quite well for tomatoes with blue sky as a background. Nevertheless, it causes great visual discomfort due for the great contrast between the two filters.
Anaglyphs are now developing its number of fans because it is easy to set and view on a computer screen or with video-projector. To shows that you may have a look at the very active Yahoo group "Anaglyphs" (11676 messages in 2005 with a great proportion of anaglyphs in the posts). If you want you can have a look at the group's archives and see the artworks of the world greatest anaglyphs creators. Of course, you can sign-in for this Yahoo group and post your anaglyphs on it in order to take profit of advices of members to progress with the help of the very best specialists.

Polarised: The separation of two projected images by means of a pure optic process should seams magical. There is another solution using polarised filters. Each of the two projectors is equipped with polarised filters with the polarisation plans set at 90° difference between both. Glasses are composed by a pair of filters with the polarisation set the same way as the corresponding projector. That's it! Well, nearly, because you need a projection surface conserving the polarisation of the light. This is the first problem, a silver screen, so expensive, if compulsory. There are two more disadvantages. Due to a certain lose of light by the polarisers, it is necessary to use potent projectors. The setting is more complex than the setting of conventional slides.
Advantages: The reproduction of colours is very realistic. The polarised glasses are, as anaglyph glasses, quite easy to buy and cheap. Thus, that method results, the favourite of stereoscopists for group presentation.

phpMyVisites | Open source web analytics

2006-7 Docteur Christophe