deletions | additions       diff --git a/subsection_Background_of_the_Study__.tex b/subsection_Background_of_the_Study__.tex  index bb9e42b..5b2d1fe 100644  --- a/subsection_Background_of_the_Study__.tex  +++ b/subsection_Background_of_the_Study__.tex 
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  The gaming industry is pushing towards a game where it easily tracks people, object and space by an acceptable computational effort and convenient hardware investment \cite{larssen2004understanding}. Kinect is a motion sensing input device by Microsoft for the Xbox 360 video game console and Windows Personal Computers. Based around a web-cam style add-on peripheral for the Xbox 360 console, it enables users to control and interact with the Xbox 360 without the need to touch a game controller, through a natural user interface using gestures and spoken commands. This new technology allows the sensor to recognize your body and mirror your movements in the game, making you the controller. It was built to change the way people play games and experience enjoyment \cite{zhang2012microsoft}.    Here we enumerate four major challenges to vision based human action recognition. The first is low level challenges [93,13]. Occlusions, cluttered background, shadows, and varying illumination conditions can produce difficulties for motion segmentation and alter the way actions are perceived. This is a major difficulty of activity recognition from RGB videos. The introduction of 3D data largely alleviates the low-level difficulties by providing the structure information of the scene. The second challenge is view changes [63,93,37,92,68]. The same actions can generate a different "appearance" from different perspectives \cite{}. \cite{Aggarwal, Xia}.