Clive R. Haynes FRPS
What is a 3D image?
In Victorian times 'bioscope scenes' viewed with a hand-held stereo viewer were very popular. Two pictures were taken of a scene and pasted together side-by-side for viewing through simple lenses. They were very good with excellent depth and clarity.
Recently there's been resurgence in interest in 3D with cinema films and television adopting the technique.
How to do it.
The viewpoint for pictures for most normal scenes, using say a 35mm to 100mm focal length lens (as per 35mm photography) needs to be about 3 inches apart - this is the average distance between the left eye and the right eye. Special devices can be bought to do this with extreme precision; however it can be done quite successfully by simply moving the camera. To do this take one picture (left) then lean to the right a little - go about 3 inches (75mm) keep everything level and without twisting the camera, take the second shot (right).
When taking the left
shot, look at the centre of the scene area for a 'reference object' and
remember where it is within the frame.
Note: For wide-angle lenses you'll find that it's often preferable to reduce the L to R separation and ignore 'toeing-in' this is due to the exaggeration and distortion of perspective by wide-angle views. For longer focal length lenses L to R separation will need to be greater than 3 inches. Indeed for distant scenes with long telephoto lenses the separation may be several feet. However, with greater separation it's more difficult to maintain correct registration. You'll need to experiment.
The two resulting
pictures can be viewed as a stereo pair. If they are slides, then a double
viewer can be used to recreate the 3D scene.
Work in RGB (colour)
I hope this covers most eventualities.
The accepted convention is to make the image for left eye image red and for the right eye, cyan.
Digital imaging has made the production of anaglyphs simple.
The word anaglyph incidentally, derives from the Greek - anaglyphos, anaglyptos - in low relief - ana, up/back, glyphein, to engrave or carve. 'Anaglypta' wallpaper has the same derivation!
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