Shooting, Production of Stereo Images
When shooting stereo images, two individual fields are produced, one for each eye. While a single image only gives an idea of the spatial perspective, a real perception of the third dimension can be reached with the binocular viewing of stereo images!
Figure 1: The path from the motive through the stereo capture to stereoscopic viewing
The easiest way to produce stereo images is to use a real stereo camera (3D camera). This is a camera with two equal lenses simultaneouslyrecording both fields with only one shutter release.
Figure 2: Genuine twin-lense stereo camera
The distance between the two lenses is called the stereo base, for natural-looking stereo it should be about 65mm (eye distance). Since currently on the market only very few industrially produced true stereo cameras are offered for sale, some alternatives have been established in the stereo scene:
→ Widely used are two identical cameras, mounted side by side and simultaneously triggered by remote control. This can be done with an external trigger, by manipulation the camera hardware or with an optimized firmware hack for stereo purposes (Stereo DataMaker).
Figure 3: Stereo pair of two identical cameras
→ A Mirror-Rig is mounted by two individual cameras and a semi-transparent mirror so that both cameras can see the subject in the same manner, but do not interfere with each other. Using this technique, any small stereo bases are possible.
Figure 4: Mirror-Rig construction of two cameras and a semitransparent mirror surface
→ If the subject is completely static, the left and right shooting can also be carried out consecutively. For this, the camera is mounted on a sliding bar and moved between the two shots by the stereo base. Ideal for this technique are tabletop and macro photography, unsuitable on the other hand are landscapes as passing clouds or even in light wind moving leaves are bothersome when viewing.
|Real Stereo Camera||Team||Mirror-Rig||Shifting Technique|
|Quality ofSynchronization||very good||depending on technology: poor to very good||depending on technology: poor to very good||–|
|Coupling of Distance and Focal Length||very good||depending on technology: not available to very good||generally not available||unnecessary|
|Need for post-processing:|
|Stereo Window||generally necessary||urgently necessary||urgently necessary||urgently necessary|
|Geometric Errors||at modest claims sufficient||urgently necessary||urgently necessary||may possibly be sufficient|
|Chromatic Errors||generally not necessary||generally necessary||urgently necessary||generally not necessary|
Information: The SIG DGS Camera is currently developing a stereo camera on the basis of a Rasperry Pi.
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Photo credits: Figure 1,4: © Gerhard P. Herbig, Figure 2: Fujifilm FinePix Real 3D W3, © Fujifilm Corporation, Figure 3: SonyNEX 3D, ©Co van Ekeren