For each cluster (xgc , ygc ),βgc , and Lgc demo the principal component rather than the individual feature point. Based on estimated βgc each cluster is named by lower or upper or horizon bounds. A cluster will be called a lower-bound if βgc ranges from 224.98

◦ to 314.98 ◦. A cluster will be called an upper-bound if βgc ranges from 134.98 ◦ to 44.98 ◦. A cluster will be called a horizon-bound if βgc limits either from 134.99

◦ to 224.99 ◦ or from 44.99 ◦ to 314.99 ◦. An ObjectDrop or ObjectPut event can be detected if any cluster on the video frame is proclaimed by lower-bound.AnObjectGet event can be detected if any cluster on the video frame is proclaimed by upper-bound. Horizon-bound cluster would play a vital role to detect video event e.g., somebody is running. We draw a circle with center (xgc , ygc ), direction βgc , and displacement vector Lgc for each lower-bound and/or upper-bound cluster on the camera view image to show the detector’s delectability.