Chapter 2 Principles of Stereoscopic Depth Perception and ...

2.4. Stereoscopic video production
age pickup, encoding/storage, and display) or can be stored on a single
recording device using field-sequential or side-by-side 3-D video formats
(Woods, Docherty & Koch 1996). For filming, storing and displaying
the stereoscopic material used for this thesis, separate channels were employed
throughout the signal path since this has the advantage of offering
full resolution pictures to each eye.
In the next section, the stereoscopic cameras that were employed for filming
the stimulus material used for this thesis are described. Subsequently,
the mathematical basis for calculating horizontal disparities will be presented,
both for parallel and converging camera set-ups. This chapter
concludes by describing the viewing factors that have an impact on stereoscopic
image perception.
2.4.1 Stereoscopic cameras
The stereoscopic footage that was used as stimulus material in the experiments
described in Chapters 3, 4, 6, and 7 of this thesis was shot using
two different stereoscopic cameras. The first 3-D camera, illustrated in
Figure 2.9, was an advanced studio camera developed in the European
Union RACE-II DISTIMA project by AEA Technology and Thomson Multimedia
(Dumbreck, Girdwood & Wells 1997). It is a versatile camera with
motorised and remotely controlled drives for normal lens functions (zoom
and focus) and for the two main stereoscopic camera parameters of camera
separation (the horizontal distance between the optical axes of the two
cameras), and camera convergence distance (the distance from the camera
at which the optical axes of the two cameras intersect). Importantly,
to make the camera suitable for shooting a wide range of scene types
and object distances, the camera design includes a semi-reflective mirror.
This mirror enables camera separation to be controlled down to zero, that
is, with completely overlapping left and right images, thus resulting in
a monoscopic or 2-D image. Because of the semi-reflective mirror extra
lighting is required during shooting since over half the light is lost in the
camera optical path. The DISTIMA stereoscopic studio camera was used
to shoot a 25 minute stereoscopic magazine programme called ’Eye to eye’
and was produced by the European Union ACTS MIRAGE project as high
quality material for demonstration purposes and human factors experiments
(Dumbreck et al. 1997). Some sections of the video illustrate the
potential of virtual reality studio technology by merging 3-D computer
generated backgrounds with ’real’ 3-D foregrounds (actors, presenter, fur-
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