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the right eye image by a transformation of the left eye image conforming to the
stereo disparity and then they reduce the processing cost for stereoscopic displays.
The main disadvantage of these methods lies in the lack of information in occluded
areas which is impossible to overcome in a generic way. Yet, to comply with our
demand of qualitative 3D content we focus on multi-shooting technologies.
Other works [10, 11] have been published in the general case of multi-cameras.
They define the projective relations between the images shot by multi-cameras in
order to calibrate the different cameras and then to reconstruct the 3D shot scene
from these multiple views. There is no link with any viewing device since the target
is a reconstruction module. In our case, flat multiscopic viewing requires a simpli-
fied shooting layout also called “rectified geometry”. Moreover the control of the
viewer's 3D experience implies to connect shooting and viewing geometries in or-
der to model and set the geometrical distortions between shot and perceived scenes.
Furthermore, some works have been done to improve the control of the viewer's
3D experience in stereoscopy and computer graphics fields [12, 13]. They usually
compare shooting and viewing geometries in order to choose a shooting layout fit-
ting a given depth range in virtual space to the “comfortable” depth range of the
display. We believe that choices that can be made in the shooting design may be
richer than a simple mapping of depth and could differ for each observation posi-
tion in the multi-view case. This requires a detailed model and a precise analysis
of possible distortions for the multiscopic shooting/viewing couple. Indeed, such a
model will provide the characteristics of shooting which will generate the chosen
distortions on the chosen viewing device. If some authors have described the trans-
formation between the shot and the real scene [12] in the stereoscopic case, none
of them has been interested in producing an analytic multi-observer and reversible
model allowing to pilot the shooting for all kinds of possible distortions. Thus, we
suggest a solution to produce 3D content according to the chosen rendering mode
and the desired depth effect.
Additionally, it is important to consider limits of the human visual system upon
the perceived quality of stereoscopic images. Some publications on human fac-
tors [14, 15, 16] have studied in detail the issue of viewer comfort for stereoscopic
displays. All these studies lead to a similar conclusion: the amount of disparity in
stereoscopic images should be limited so as to be within a defined comfortable
range. The main reason given for this is that the human visual system normally
operates so that the convergence of the eyes and the focus are linked. For all stereo-
scopic displays this relationship is thought to be stressed by requiring the viewers
eyes to converge to a perceived point much deeper than the display plane while still
being required to focus on the display plane itself. Limiting disparity ensures that
the viewers perceived depth is controlled and the convergence/accommodation link
is not stressed.
So we'll explain how to model and quantify the depth distortion from given ren-
dering and shooting geometries and also from a chosen rendering device and a de-
sired depth effect and how to design the appropriate shooting layout.
