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| Implementing Movement Parallax for Laparoscopy - Making it work |
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A practical solution was found by elegantly combining a simple mechanism out side the abdoman and the fish-eye lens typically used
for laparoscopes. As a result, teh surgeon was provided with the possibilty to obtain perceptual information on the spatial structure through active exploration
using a normal laparoscope and standard equipment.
With a very simple set-up the idea to rotate around the point of entry was validated. The objective was to rotate
around the point of observation, allowing for percention, depth perception, of the spatial structure suing only a monoscopic image. Technical implementation
proved the difficult part. |
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| The set-up was your basic 'wood-and wire' construction but it proved the point that for obtaining spatial information
there is no need for a stationary fixation point, a fixed point that linked the remote scene with the local space, as originally assumed.
Ths shifting point of rotation is compensated for by the observer naturally. |
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| As the observer moves to the left, the tip of the laparoscope moves to the right. Because of the large fish eye lens, the
object of interest remains visible. Because of the actual travel of the laparoscopes tip the object is seen from a slightly different angle.
In combination the aimed for paralax shifts are created allowing the user to pick-up spatial information. |
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| An experiment showed that this movement allowed a subject to correctly solve the spatial puzzle; a knot made out of
three wires, one of the wires terminating in a white bol. Subjects were asked to indentify which root connects to the white bol. |
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| Clearly the advantage of this solution is the technical simplicity while still achiving the perceptual information needed. The entire mechanism
to move the (standard) laparoscope is entirely outside of the abdoman.
An initial prototype (see above) demonstrated both its simplicity as well as it effectiveness; the laparoscop is moves along the circularly shaped guide, ensuring a rotation
around the point where the laparoscope enters the abdoman. |
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