Graphics Reference
In-Depth Information
The overall enjoyment or annoyance of 3D video streaming applications or services is in-
fluenced by several factors such as human factors (e.g., demographic and socio economic
background), system factors (e.g., content and network related influences) and contextual
factors (e.g., duration, time of the day and frequency of use). The overall experience can
be analysed and measured by QoE related parameters which quantify the user's overall
satisfaction about a service [110][111]. Quality of Service (QoS) related measurements
only measure performance aspects of a physical system, with main focus on telecommu-
nications services. Measuring QoS parameters is straightforward since objective, explicit
technological methods can be used, whereas measuring and understanding QoE requires
a multi- disciplinary and multi-technological approach. The added dimension of depth in
3Dviewinginfluencesseveralperceptualattributessuchasoverallimagequality,depthper-
ception, naturalness, presence, visual comfort, etc. For instance, an increased binocular
disparityenhancesthedepthperceptionofviewers,althoughinextremecasesthiscanlead
to eye fatigue as well. Therefore, the overall enjoyment of the 3D application could be
hindered by the eye strain experienced by the end user. The influence of these attributes on
the overall experience of 3D video streaming users is yet to be investigated.
Theeffectoftransmissionoverband-limitedandunreliablecommunication channels(such
as wireless channels) can be much worse for 3D video than for 2D video, due to the
presence in the first case of two channels (i.e., stereoscopic 3D video) that can be impaired
in a different way; as a consequence the 3D reconstruction in the human visual system
may be affected. Some networks introduce factors directly related to temporal domain de-
synchronizationissues.Forinstancedelayinoneviewcouldleadtotemporalde-synchron-
ization and this can lead to reduced comfort in 3D viewing. The methods employed to
mitigate these artifacts (e.g., error concealment) need to be carefully designed to suit 3D
video applications. The simple application of 2D image/video methods would not work ef-
fectively in this case, as discussed in [112] for different error concealment algorithms for
3D video transmission errors. In [112] it is observed that is some cases switching back
to the 2D video mode is preferred to applying 2D error concealment methods separately
for left and right views to recover missing image information during transmission. There
could be added implications introduced by these artifacts into ourHVS.Thereforeartifacts
caused as a result of 3D video streaming can be clearly appreciated only by understanding
howourHVSperceivesdifferent3Dvideoartifacts.Framefreezingmechanismsemployed
to tackle missing frames caused by transmission errors or delay could lead to temporal de-
synchronization where one eye sees delayed content compared to the other eye. There are
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