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| Space Through Movement -
Linking perception to action |
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| Movement is closely linked to
depth perception. It is commonly believed that for
depth perception you need two eyes (binocular view).
However, people born with only one eye have no problems
moving through space without bumping into objects.
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With a series of experiments Smets, Overbeeke
& Strattmann (1986) showed that linking
the head movements to the perspectrive display
on the screen enables depth perception in
a monocular situation. As shown on the side,
when the motions of the camera is linked to
the head movements of the observer, the scene
shown on the monitor and the space of teh
observer become one.
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| The system, aka The Delft Virtual
Window System or simply DVWS, was patented and further
developed into practical applications over the next
years. |
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| The principle behind the system
is elegantly simple. When an observer rotates around
the monitor, a camera which image is project the
on the monitor rotates in relation to an object.
This is illustrated with the images below. For the
observer, it is possible to view the object from
various angles in a very intuitive and direct way.
For the observer the object has depth, is floating
in the monitor screen. |
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| Initial experiments in the early
80ies involved moving around at that time mini cameras
(about the size and weight of half a liter beer)
and crude head detection devices. Nevertheless,
the effect was very convincing. |
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| In a later experiment, using
modern computer and projection techniques
Djajadiningrat
(1998) used the same principle to build a
desktop virtual reality system, aka Cubby.
It beautifully showed that linking the head movements to
the perspective of the objects displayed on the screen enables
depth perception |
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| Again, the head movements are
linked to the perspective motions on the screen.
In the sequence below you see a subject in front
of Cubby. |
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| To the passive observer, for example
someone who is looking the active observer over the shoulder,
the screen projectsions will not make sense. They
appear strange blobs floating over the inside of
the cube. |
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| To the active observer, the one who controls
the camera - to whom's point of observation the perspective on the screen are linked - the strange
blobs form into a rigid spatial object. |
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| The next pages will describe how
the Delft Virtual Window System was implemented
for laparoscopic surgery. |
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