Chapter 2 Principles of Stereoscopic Depth Perception and ...
Chapter 2 Principles of Stereoscopic Depth Perception and ...
Chapter 2 Principles of Stereoscopic Depth Perception and ...
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2.4. <strong>Stereoscopic</strong> video production<br />
2.3.4 <strong>Stereoscopic</strong> displays used in this thesis<br />
For the experiments reported in <strong>Chapter</strong>s 3, 4, 6, <strong>and</strong> 7 <strong>of</strong> this thesis two<br />
different types <strong>of</strong> polarization-multiplexed displays were used. The first<br />
type <strong>of</strong> display that was used was an AEA Technology TV 3 20” stereoscopic<br />
display, which consists <strong>of</strong> two broadcast quality monitors 7 , arranged<br />
at right-angles, with crossed linear polarizing filters placed in front<br />
<strong>of</strong> each. The images are combined through a semi-reflective mirror, <strong>and</strong><br />
separated to the viewer’s two eyes by lightweight polarised spectacles that<br />
look <strong>and</strong> feel very much like sunglasses (see Figure 2.8 for a schematic representation<br />
<strong>of</strong> this type <strong>of</strong> display).<br />
The second type <strong>of</strong> polarization-multiplexed display used for experimentation<br />
was a large curved projection display with an aluminised surface<br />
to preserve polarization. The picture was projected using two projectors<br />
with crossed linear polarizing filters placed in front <strong>of</strong> each. Again, the<br />
observers had to wear polarised spectacles for proper view separation.<br />
2.4 <strong>Stereoscopic</strong> video production<br />
<strong>Stereoscopic</strong> video can be produced by using a stereoscopic camera, consisting<br />
<strong>of</strong> a co-planar configuration <strong>of</strong> two separate, monoscopic cameras,<br />
each corresponding to one eye’s view. The aim <strong>of</strong> stereoscopic video is to<br />
capture real world scenes in such a way that viewing them stereoscopically<br />
accurately simulates the information the viewer would receive in the<br />
real life situation. To achieve this, the stereoscopic filming process must<br />
be carefully planned <strong>and</strong> executed. <strong>Stereoscopic</strong> parameters need to be<br />
calculated <strong>and</strong> adjusted such that they accurately capture the disparities a<br />
viewer would receive from the actual scene 8 <strong>and</strong> do not cause any visual<br />
discomfort. The resulting three-dimensional scene must be free from visual<br />
errors <strong>and</strong> potentially conflicting information. Care needs to be taken<br />
to assure that the two stereoscopic images are calibrated in terms <strong>of</strong> contrast,<br />
brightness, colour, <strong>and</strong> sharpness <strong>of</strong> focus, <strong>and</strong> are also geometrically<br />
calibrated, that is, without rotation, vertical displacements, etc.<br />
Depending on the stereoscopic encoding format chosen, the left <strong>and</strong> right<br />
video signals can be kept separate through the entire signal path (i.e., im-<br />
7 Barco CPM 2053FS 50 Hz colour monitors<br />
8 Although, as we shall see in <strong>Chapter</strong> 3, slight exaggerations <strong>of</strong> what is deemed to be<br />
natural can sometimes be preferred<br />
69
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